blop

* Fix prefix option for FuzzyTermQuery

* Update changelog

CHANGELOG.md

@@ -1,9 +1,15 @@
+Tantivy 0.13.0
+======================
+- Bugfix in `FuzzyTermQuery` not matching terms by prefix when it should (@Peachball)
+
 Tantivy 0.12.0
 ======================
 - Removing static dispatch in tokenizers for simplicity. (#762)
 - Added backward iteration for `TermDictionary` stream. (@halvorboe)
 - Fixed a performance issue when searching for the posting lists of a missing term (@audunhalland)
 - Added a configurable maximum number of docs (10M by default) for a segment to be considered for merge (@hntd187, landed by @halvorboe #713) 
+- Important Bugfix #777, causing tantivy to retain memory mapping. (diagnosed by @poljar)
+- Added support for field boosting. (#547, @fulmicoton)
 
 ## How to update?
 

Cargo.toml

@@ -5,7 +5,7 @@ authors = ["Paul Masurel <paul.masurel@gmail.com>"]
 license = "MIT"
 categories = ["database-implementations", "data-structures"]
 description = """Search engine library"""
-documentation = "https://tantivy-search.github.io/tantivy/tantivy/index.html"
+documentation = "https://docs.rs/tantivy/"
 homepage = "https://github.com/tantivy-search/tantivy"
 repository = "https://github.com/tantivy-search/tantivy"
 readme = "README.md"
@@ -13,25 +13,23 @@ keywords = ["search", "information", "retrieval"]
 edition = "2018"
 
 [dependencies]
-base64 = "0.11.0"
+base64 = "0.12.0"
 byteorder = "1.0"
 crc32fast = "1.2.0"
 once_cell = "1.0"
 regex ={version = "1.3.0", default-features = false, features = ["std"]}
-tantivy-fst = "0.2.1"
+tantivy-fst = {path="../tantivy-fst", version="0.3"}
 memmap = {version = "0.7", optional=true}
 lz4 = {version="1.20", optional=true}
-snap = {version="0.2"}
+snap = "1"
 atomicwrites = {version="0.2.2", optional=true}
 tempfile = "3.0"
 log = "0.4"
-serde = "1.0"
-serde_derive = "1.0"
+serde = {version="1.0", features=["derive"]}
 serde_json = "1.0"
 num_cpus = "1.2"
 fs2={version="0.4", optional=true}
-itertools = "0.8"
-levenshtein_automata = {version="0.1", features=["fst_automaton"]}
+levenshtein_automata = "0.2"
 notify = {version="4", optional=true}
 uuid = { version = "0.8", features = ["v4", "serde"] }
 crossbeam = "0.7"
@@ -40,7 +38,7 @@ owning_ref = "0.4"
 stable_deref_trait = "1.0.0"
 rust-stemmers = "1.2"
 downcast-rs = { version="1.0" }
-tantivy-query-grammar = { version="0.11", path="./query-grammar" }
+tantivy-query-grammar = { version="0.13", path="./query-grammar" }
 bitpacking = {version="0.8", default-features = false, features=["bitpacker4x"]}
 census = "0.4"
 fnv = "1.0.6"

README.md

@@ -40,7 +40,7 @@ performance for different type of queries / collection.
 # Features
 
 - Full-text search
-- Configurable tokenizer (stemming available for 17 Latin languages with third party support for Chinese ([tantivy-jieba](https://crates.io/crates/tantivy-jieba) and [cang-jie](https://crates.io/crates/cang-jie)) and [Japanese](https://crates.io/crates/tantivy-tokenizer-tiny-segmenter))
+- Configurable tokenizer (stemming available for 17 Latin languages with third party support for Chinese ([tantivy-jieba](https://crates.io/crates/tantivy-jieba) and [cang-jie](https://crates.io/crates/cang-jie)), Japanese ([lindera](https://github.com/lindera-morphology/lindera-tantivy) and [tantivy-tokenizer-tiny-segmente](https://crates.io/crates/tantivy-tokenizer-tiny-segmenter)) and Korean ([lindera](https://github.com/lindera-morphology/lindera-tantivy) + [lindera-ko-dic-builder](https://github.com/lindera-morphology/lindera-ko-dic-builder))
 - Fast (check out the :racehorse: :sparkles: [benchmark](https://tantivy-search.github.io/bench/) :sparkles: :racehorse:)
 - Tiny startup time (<10ms), perfect for command line tools
 - BM25 scoring (the same as Lucene)
@@ -59,18 +59,17 @@ performance for different type of queries / collection.
 - Configurable indexing (optional term frequency and position indexing)
 - Cheesy logo with a horse
 
-# Non-features
+## Non-features
 
 - Distributed search is out of the scope of Tantivy. That being said, Tantivy is a
 library upon which one could build a distributed search. Serializable/mergeable collector state for instance, 
 are within the scope of Tantivy.
 
-# Supported OS and compiler
-
-Tantivy works on stable Rust (>= 1.27) and supports Linux, MacOS, and Windows.
 
 # Getting started
 
+Tantivy works on stable Rust (>= 1.27) and supports Linux, MacOS, and Windows.
+
 - [Tantivy's simple search example](https://tantivy-search.github.io/examples/basic_search.html)
 - [tantivy-cli and its tutorial](https://github.com/tantivy-search/tantivy-cli) - `tantivy-cli` is an actual command line interface that makes it easy for you to create a search engine,
 index documents, and search via the CLI or a small server with a REST API.

appveyor.yml

@@ -18,5 +18,5 @@ install:
 build: false
 
 test_script:
-  - REM SET RUST_LOG=tantivy,test & cargo test --verbose --no-default-features --features mmap
+  - REM SET RUST_LOG=tantivy,test & cargo test --all --verbose --no-default-features --features mmap
   - REM SET RUST_BACKTRACE=1 & cargo build --examples

examples/pre_tokenized_text.rs

@@ -9,11 +9,10 @@
 // - import tokenized text straight from json,
 // - perform a search on documents with pre-tokenized text
 
-use tantivy::tokenizer::{PreTokenizedString, SimpleTokenizer, Token, Tokenizer};
-
 use tantivy::collector::{Count, TopDocs};
 use tantivy::query::TermQuery;
 use tantivy::schema::*;
+use tantivy::tokenizer::{PreTokenizedString, SimpleTokenizer, Token, Tokenizer};
 use tantivy::{doc, Index, ReloadPolicy};
 use tempfile::TempDir;
 

query-grammar/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "tantivy-query-grammar"
-version = "0.11.0"
+version = "0.13.0"
 authors = ["Paul Masurel <paul.masurel@gmail.com>"]
 license = "MIT"
 categories = ["database-implementations", "data-structures"]
@@ -13,4 +13,4 @@ keywords = ["search", "information", "retrieval"]
 edition = "2018"
 
 [dependencies]
-combine = ">=3.6.0,<4.0.0"
+combine = {version="4", default-features=false, features=[] }

query-grammar/src/lib.rs

@@ -1,5 +1,3 @@
-#![recursion_limit = "100"]
-
 mod occur;
 mod query_grammar;
 mod user_input_ast;

query-grammar/src/query_grammar.rs

@@ -1,171 +1,209 @@
-use super::user_input_ast::*;
+use super::user_input_ast::{UserInputAST, UserInputBound, UserInputLeaf, UserInputLiteral};
 use crate::Occur;
-use combine::char::*;
-use combine::error::StreamError;
-use combine::stream::StreamErrorFor;
-use combine::*;
+use combine::error::StringStreamError;
+use combine::parser::char::{char, digit, letter, space, spaces, string};
+use combine::parser::Parser;
+use combine::{
+    attempt, choice, eof, many, many1, one_of, optional, parser, satisfy, skip_many1, value,
+};
 
-parser! {
-    fn field[I]()(I) -> String
-    where [I: Stream<Item = char>] {
-        (
-            letter(),
-            many(satisfy(|c: char| c.is_alphanumeric() || c == '_')),
-        ).skip(char(':')).map(|(s1, s2): (char, String)| format!("{}{}", s1, s2))
-    }
-}
-
-parser! {
-    fn word[I]()(I) -> String
-    where [I: Stream<Item = char>] {
-        (
-            satisfy(|c: char| !c.is_whitespace() && !['-', '`', ':', '{', '}', '"', '[', ']', '(',')'].contains(&c) ),
-            many(satisfy(|c: char| !c.is_whitespace() && ![':', '{', '}', '"', '[', ']', '(',')'].contains(&c)))
-        )
+fn field<'a>() -> impl Parser<&'a str, Output = String> {
+    (
+        letter(),
+        many(satisfy(|c: char| c.is_alphanumeric() || c == '_')),
+    )
+        .skip(char(':'))
         .map(|(s1, s2): (char, String)| format!("{}{}", s1, s2))
-        .and_then(|s: String|
-           match s.as_str() {
-             "OR" => Err(StreamErrorFor::<I>::unexpected_static_message("OR")),
-             "AND" => Err(StreamErrorFor::<I>::unexpected_static_message("AND")),
-             "NOT" => Err(StreamErrorFor::<I>::unexpected_static_message("NOT")),
-             _ => Ok(s)
-           })
-    }
 }
 
-parser! {
-    fn literal[I]()(I) -> UserInputLeaf
-    where [I: Stream<Item = char>]
-    {
-        let term_val = || {
-            let phrase = char('"').with(many1(satisfy(|c| c != '"'))).skip(char('"'));
-            phrase.or(word())
-        };
-        let term_val_with_field = negative_number().or(term_val());
-        let term_query =
-            (field(), term_val_with_field)
-            .map(|(field_name, phrase)| UserInputLiteral {
-                field_name: Some(field_name),
-                phrase,
-            });
-        let term_default_field = term_val().map(|phrase| UserInputLiteral {
-            field_name: None,
-            phrase,
-        });
-        attempt(term_query)
-            .or(term_default_field)
-            .map(UserInputLeaf::from)
-    }
-}
-
-parser! {
-    fn negative_number[I]()(I) -> String
-    where [I: Stream<Item = char>]
-    {
-        (char('-'), many1(satisfy(char::is_numeric)),
-         optional((char('.'), many1(satisfy(char::is_numeric)))))
-            .map(|(s1, s2, s3): (char, String, Option<(char, String)>)| {
-                if let Some(('.', s3)) = s3 {
-                    format!("{}{}.{}", s1, s2, s3)
-                } else {
-                    format!("{}{}", s1, s2)
-                }
-            })
-    }
-}
-
-parser! {
-    fn spaces1[I]()(I) -> ()
-    where [I: Stream<Item = char>] {
-        skip_many1(space())
-    }
-}
-
-parser! {
-    /// Function that parses a range out of a Stream
-    /// Supports ranges like:
-    /// [5 TO 10], {5 TO 10}, [* TO 10], [10 TO *], {10 TO *], >5, <=10
-    /// [a TO *], [a TO c], [abc TO bcd}
-    fn range[I]()(I) -> UserInputLeaf
-    where [I: Stream<Item = char>] {
-        let range_term_val = || {
-            word().or(negative_number()).or(char('*').with(value("*".to_string())))
-        };
-
-        // check for unbounded range in the form of <5, <=10, >5, >=5
-        let elastic_unbounded_range = (choice([attempt(string(">=")),
-                                               attempt(string("<=")),
-                                               attempt(string("<")),
-                                               attempt(string(">"))])
-                                       .skip(spaces()),
-                                       range_term_val()).
-            map(|(comparison_sign, bound): (&str, String)|
-                match comparison_sign {
-                    ">=" => (UserInputBound::Inclusive(bound), UserInputBound::Unbounded),
-                    "<=" => (UserInputBound::Unbounded, UserInputBound::Inclusive(bound)),
-                    "<" => (UserInputBound::Unbounded, UserInputBound::Exclusive(bound)),
-                    ">" => (UserInputBound::Exclusive(bound), UserInputBound::Unbounded),
-                    // default case
-                    _ => (UserInputBound::Unbounded, UserInputBound::Unbounded)
-                });
-        let lower_bound = (one_of("{[".chars()), range_term_val())
-            .map(|(boundary_char, lower_bound): (char, String)|
-                 if lower_bound == "*" {
-                     UserInputBound::Unbounded
-                 } else if boundary_char == '{' {
-                         UserInputBound::Exclusive(lower_bound)
-                 } else {
-                     UserInputBound::Inclusive(lower_bound)
-                 });
-        let upper_bound = (range_term_val(), one_of("}]".chars()))
-            .map(|(higher_bound, boundary_char): (String, char)|
-                 if higher_bound == "*" {
-                     UserInputBound::Unbounded
-                 } else if boundary_char == '}' {
-                     UserInputBound::Exclusive(higher_bound)
-                 } else {
-                     UserInputBound::Inclusive(higher_bound)
-                 });
-         // return only lower and upper
-        let lower_to_upper = (lower_bound.
-                                    skip((spaces(),
-                                          string("TO"),
-                                          spaces())),
-                                    upper_bound);
-
-        (optional(field()).skip(spaces()),
-         // try elastic first, if it matches, the range is unbounded
-         attempt(elastic_unbounded_range).or(lower_to_upper))
-            .map(|(field, (lower, upper))|
-                 // Construct the leaf from extracted field (optional)
-                 // and bounds
-                 UserInputLeaf::Range {
-                     field,
-                     lower,
-                     upper
+fn word<'a>() -> impl Parser<&'a str, Output = String> {
+    (
+        satisfy(|c: char| {
+            !c.is_whitespace()
+                && !['-', '^', '`', ':', '{', '}', '"', '[', ']', '(', ')'].contains(&c)
+        }),
+        many(satisfy(|c: char| {
+            !c.is_whitespace() && ![':', '^', '{', '}', '"', '[', ']', '(', ')'].contains(&c)
+        })),
+    )
+        .map(|(s1, s2): (char, String)| format!("{}{}", s1, s2))
+        .and_then(|s: String| match s.as_str() {
+            "OR" | "AND " | "NOT" => Err(StringStreamError::UnexpectedParse),
+            _ => Ok(s),
         })
-    }
+}
+
+fn term_val<'a>() -> impl Parser<&'a str, Output = String> {
+    let phrase = char('"').with(many1(satisfy(|c| c != '"'))).skip(char('"'));
+    phrase.or(word())
+}
+
+fn term_query<'a>() -> impl Parser<&'a str, Output = UserInputLiteral> {
+    let term_val_with_field = negative_number().or(term_val());
+    (field(), term_val_with_field).map(|(field_name, phrase)| UserInputLiteral {
+        field_name: Some(field_name),
+        phrase,
+    })
+}
+
+fn literal<'a>() -> impl Parser<&'a str, Output = UserInputLeaf> {
+    let term_default_field = term_val().map(|phrase| UserInputLiteral {
+        field_name: None,
+        phrase,
+    });
+    attempt(term_query())
+        .or(term_default_field)
+        .map(UserInputLeaf::from)
+}
+
+fn negative_number<'a>() -> impl Parser<&'a str, Output = String> {
+    (
+        char('-'),
+        many1(digit()),
+        optional((char('.'), many1(digit()))),
+    )
+        .map(|(s1, s2, s3): (char, String, Option<(char, String)>)| {
+            if let Some(('.', s3)) = s3 {
+                format!("{}{}.{}", s1, s2, s3)
+            } else {
+                format!("{}{}", s1, s2)
+            }
+        })
+}
+
+fn spaces1<'a>() -> impl Parser<&'a str, Output = ()> {
+    skip_many1(space())
+}
+
+/// Function that parses a range out of a Stream
+/// Supports ranges like:
+/// [5 TO 10], {5 TO 10}, [* TO 10], [10 TO *], {10 TO *], >5, <=10
+/// [a TO *], [a TO c], [abc TO bcd}
+fn range<'a>() -> impl Parser<&'a str, Output = UserInputLeaf> {
+    let range_term_val = || {
+        word()
+            .or(negative_number())
+            .or(char('*').with(value("*".to_string())))
+    };
+
+    // check for unbounded range in the form of <5, <=10, >5, >=5
+    let elastic_unbounded_range = (
+        choice([
+            attempt(string(">=")),
+            attempt(string("<=")),
+            attempt(string("<")),
+            attempt(string(">")),
+        ])
+        .skip(spaces()),
+        range_term_val(),
+    )
+        .map(
+            |(comparison_sign, bound): (&str, String)| match comparison_sign {
+                ">=" => (UserInputBound::Inclusive(bound), UserInputBound::Unbounded),
+                "<=" => (UserInputBound::Unbounded, UserInputBound::Inclusive(bound)),
+                "<" => (UserInputBound::Unbounded, UserInputBound::Exclusive(bound)),
+                ">" => (UserInputBound::Exclusive(bound), UserInputBound::Unbounded),
+                // default case
+                _ => (UserInputBound::Unbounded, UserInputBound::Unbounded),
+            },
+        );
+    let lower_bound = (one_of("{[".chars()), range_term_val()).map(
+        |(boundary_char, lower_bound): (char, String)| {
+            if lower_bound == "*" {
+                UserInputBound::Unbounded
+            } else if boundary_char == '{' {
+                UserInputBound::Exclusive(lower_bound)
+            } else {
+                UserInputBound::Inclusive(lower_bound)
+            }
+        },
+    );
+    let upper_bound = (range_term_val(), one_of("}]".chars())).map(
+        |(higher_bound, boundary_char): (String, char)| {
+            if higher_bound == "*" {
+                UserInputBound::Unbounded
+            } else if boundary_char == '}' {
+                UserInputBound::Exclusive(higher_bound)
+            } else {
+                UserInputBound::Inclusive(higher_bound)
+            }
+        },
+    );
+    // return only lower and upper
+    let lower_to_upper = (
+        lower_bound.skip((spaces(), string("TO"), spaces())),
+        upper_bound,
+    );
+
+    (
+        optional(field()).skip(spaces()),
+        // try elastic first, if it matches, the range is unbounded
+        attempt(elastic_unbounded_range).or(lower_to_upper),
+    )
+        .map(|(field, (lower, upper))|
+             // Construct the leaf from extracted field (optional)
+             // and bounds
+             UserInputLeaf::Range {
+                 field,
+                 lower,
+                 upper
+    })
 }
 
 fn negate(expr: UserInputAST) -> UserInputAST {
     expr.unary(Occur::MustNot)
 }
 
-fn must(expr: UserInputAST) -> UserInputAST {
-    expr.unary(Occur::Must)
+fn leaf<'a>() -> impl Parser<&'a str, Output = UserInputAST> {
+    parser(|input| {
+        char('(')
+            .with(ast())
+            .skip(char(')'))
+            .or(char('*').map(|_| UserInputAST::from(UserInputLeaf::All)))
+            .or(attempt(
+                string("NOT").skip(spaces1()).with(leaf()).map(negate),
+            ))
+            .or(attempt(range().map(UserInputAST::from)))
+            .or(literal().map(UserInputAST::from))
+            .parse_stream(input)
+            .into_result()
+    })
 }
 
-parser! {
-    fn leaf[I]()(I) -> UserInputAST
-    where [I: Stream<Item = char>] {
-            char('-').with(leaf()).map(negate)
-        .or(char('+').with(leaf()).map(must))
-        .or(char('(').with(ast()).skip(char(')')))
-        .or(char('*').map(|_| UserInputAST::from(UserInputLeaf::All)))
-        .or(attempt(string("NOT").skip(spaces1()).with(leaf()).map(negate)))
-        .or(attempt(range().map(UserInputAST::from)))
-        .or(literal().map(UserInputAST::from))
-    }
+fn occur_symbol<'a>() -> impl Parser<&'a str, Output = Occur> {
+    char('-')
+        .map(|_| Occur::MustNot)
+        .or(char('+').map(|_| Occur::Must))
+}
+
+fn occur_leaf<'a>() -> impl Parser<&'a str, Output = (Option<Occur>, UserInputAST)> {
+    (optional(occur_symbol()), boosted_leaf())
+}
+
+fn positive_float_number<'a>() -> impl Parser<&'a str, Output = f32> {
+    (many1(digit()), optional((char('.'), many1(digit())))).map(
+        |(int_part, decimal_part_opt): (String, Option<(char, String)>)| {
+            let mut float_str = int_part;
+            if let Some((chr, decimal_str)) = decimal_part_opt {
+                float_str.push(chr);
+                float_str.push_str(&decimal_str);
+            }
+            float_str.parse::<f32>().unwrap()
+        },
+    )
+}
+
+fn boost<'a>() -> impl Parser<&'a str, Output = f32> {
+    (char('^'), positive_float_number()).map(|(_, boost)| boost)
+}
+
+fn boosted_leaf<'a>() -> impl Parser<&'a str, Output = UserInputAST> {
+    (leaf(), optional(boost())).map(|(leaf, boost_opt)| match boost_opt {
+        Some(boost) if (boost - 1.0).abs() > std::f32::EPSILON => {
+            UserInputAST::Boost(Box::new(leaf), boost)
+        }
+        _ => leaf,
+    })
 }
 
 #[derive(Clone, Copy)]
@@ -174,13 +212,10 @@ enum BinaryOperand {
     And,
 }
 
-parser! {
-    fn binary_operand[I]()(I) -> BinaryOperand
-    where [I: Stream<Item = char>]
-    {
-       string("AND").with(value(BinaryOperand::And))
-       .or(string("OR").with(value(BinaryOperand::Or)))
-    }
+fn binary_operand<'a>() -> impl Parser<&'a str, Output = BinaryOperand> {
+    string("AND")
+        .with(value(BinaryOperand::And))
+        .or(string("OR").with(value(BinaryOperand::Or)))
 }
 
 fn aggregate_binary_expressions(
@@ -208,37 +243,81 @@ fn aggregate_binary_expressions(
     }
 }
 
-parser! {
-    pub fn ast[I]()(I) -> UserInputAST
-    where [I: Stream<Item = char>]
-    {
-        let operand_leaf = (binary_operand().skip(spaces()), leaf().skip(spaces()));
-        let boolean_expr = (leaf().skip(spaces().silent()), many1(operand_leaf)).map(
-            |(left, right)| aggregate_binary_expressions(left,right));
-        let whitespace_separated_leaves = many1(leaf().skip(spaces().silent()))
-        .map(|subqueries: Vec<UserInputAST>|
-            if subqueries.len() == 1 {
-                subqueries.into_iter().next().unwrap()
-            } else {
-                UserInputAST::Clause(subqueries.into_iter().collect())
-            });
-        let expr = attempt(boolean_expr).or(whitespace_separated_leaves);
-        spaces().with(expr).skip(spaces())
-    }
+fn operand_leaf<'a>() -> impl Parser<&'a str, Output = (BinaryOperand, UserInputAST)> {
+    (
+        binary_operand().skip(spaces()),
+        boosted_leaf().skip(spaces()),
+    )
 }
 
-parser! {
-    pub fn parse_to_ast[I]()(I) -> UserInputAST
-    where [I: Stream<Item = char>]
-    {
-        spaces().with(optional(ast()).skip(eof())).map(|opt_ast| opt_ast.unwrap_or_else(UserInputAST::empty_query))
-    }
+pub fn ast<'a>() -> impl Parser<&'a str, Output = UserInputAST> {
+    let boolean_expr = (boosted_leaf().skip(spaces()), many1(operand_leaf()))
+        .map(|(left, right)| aggregate_binary_expressions(left, right));
+    let whitespace_separated_leaves = many1(occur_leaf().skip(spaces().silent())).map(
+        |subqueries: Vec<(Option<Occur>, UserInputAST)>| {
+            if subqueries.len() == 1 {
+                let (occur_opt, ast) = subqueries.into_iter().next().unwrap();
+                match occur_opt.unwrap_or(Occur::Should) {
+                    Occur::Must | Occur::Should => ast,
+                    Occur::MustNot => UserInputAST::Clause(vec![(Some(Occur::MustNot), ast)]),
+                }
+            } else {
+                UserInputAST::Clause(subqueries.into_iter().collect())
+            }
+        },
+    );
+    let expr = attempt(boolean_expr).or(whitespace_separated_leaves);
+    spaces().with(expr).skip(spaces())
+}
+
+pub fn parse_to_ast<'a>() -> impl Parser<&'a str, Output = UserInputAST> {
+    spaces()
+        .with(optional(ast()).skip(eof()))
+        .map(|opt_ast| opt_ast.unwrap_or_else(UserInputAST::empty_query))
 }
 
 #[cfg(test)]
 mod test {
 
     use super::*;
+    use combine::parser::Parser;
+
+    pub fn nearly_equals(a: f32, b: f32) -> bool {
+        (a - b).abs() < 0.0005 * (a + b).abs()
+    }
+
+    fn assert_nearly_equals(expected: f32, val: f32) {
+        assert!(
+            nearly_equals(val, expected),
+            "Got {}, expected {}.",
+            val,
+            expected
+        );
+    }
+
+    #[test]
+    fn test_occur_symbol() {
+        assert_eq!(super::occur_symbol().parse("-"), Ok((Occur::MustNot, "")));
+        assert_eq!(super::occur_symbol().parse("+"), Ok((Occur::Must, "")));
+    }
+
+    #[test]
+    fn test_positive_float_number() {
+        fn valid_parse(float_str: &str, expected_val: f32, expected_remaining: &str) {
+            let (val, remaining) = positive_float_number().parse(float_str).unwrap();
+            assert_eq!(remaining, expected_remaining);
+            assert_nearly_equals(val, expected_val);
+        }
+        fn error_parse(float_str: &str) {
+            assert!(positive_float_number().parse(float_str).is_err());
+        }
+        valid_parse("1.0", 1.0f32, "");
+        valid_parse("1", 1.0f32, "");
+        valid_parse("0.234234 aaa", 0.234234f32, " aaa");
+        error_parse(".3332");
+        error_parse("1.");
+        error_parse("-1.");
+    }
 
     fn test_parse_query_to_ast_helper(query: &str, expected: &str) {
         let query = parse_to_ast().parse(query).unwrap().0;
@@ -269,15 +348,24 @@ mod test {
             "Err(UnexpectedParse)"
         );
         test_parse_query_to_ast_helper("NOTa", "\"NOTa\"");
-        test_parse_query_to_ast_helper("NOT a", "-(\"a\")");
+        test_parse_query_to_ast_helper("NOT a", "(-\"a\")");
+    }
+
+    #[test]
+    fn test_boosting() {
+        assert!(parse_to_ast().parse("a^2^3").is_err());
+        assert!(parse_to_ast().parse("a^2^").is_err());
+        test_parse_query_to_ast_helper("a^3", "(\"a\")^3");
+        test_parse_query_to_ast_helper("a^3 b^2", "(*(\"a\")^3 *(\"b\")^2)");
+        test_parse_query_to_ast_helper("a^1", "\"a\"");
     }
 
     #[test]
     fn test_parse_query_to_ast_binary_op() {
-        test_parse_query_to_ast_helper("a AND b", "(+(\"a\") +(\"b\"))");
-        test_parse_query_to_ast_helper("a OR b", "(?(\"a\") ?(\"b\"))");
-        test_parse_query_to_ast_helper("a OR b AND c", "(?(\"a\") ?((+(\"b\") +(\"c\"))))");
-        test_parse_query_to_ast_helper("a AND b         AND c", "(+(\"a\") +(\"b\") +(\"c\"))");
+        test_parse_query_to_ast_helper("a AND b", "(+\"a\" +\"b\")");
+        test_parse_query_to_ast_helper("a OR b", "(?\"a\" ?\"b\")");
+        test_parse_query_to_ast_helper("a OR b AND c", "(?\"a\" ?(+\"b\" +\"c\"))");
+        test_parse_query_to_ast_helper("a AND b         AND c", "(+\"a\" +\"b\" +\"c\")");
         assert_eq!(
             format!("{:?}", parse_to_ast().parse("a OR b aaa")),
             "Err(UnexpectedParse)"
@@ -315,6 +403,13 @@ mod test {
         test_parse_query_to_ast_helper("weight: <= 70.5", "weight:{\"*\" TO \"70.5\"]");
     }
 
+    #[test]
+    fn test_occur_leaf() {
+        let ((occur, ast), _) = super::occur_leaf().parse("+abc").unwrap();
+        assert_eq!(occur, Some(Occur::Must));
+        assert_eq!(format!("{:?}", ast), "\"abc\"");
+    }
+
     #[test]
     fn test_range_parser() {
         // testing the range() parser separately
@@ -343,32 +438,67 @@ mod test {
     fn test_parse_query_to_triming_spaces() {
         test_parse_query_to_ast_helper("   abc", "\"abc\"");
         test_parse_query_to_ast_helper("abc ", "\"abc\"");
-        test_parse_query_to_ast_helper("(  a OR abc)", "(?(\"a\") ?(\"abc\"))");
-        test_parse_query_to_ast_helper("(a  OR abc)", "(?(\"a\") ?(\"abc\"))");
-        test_parse_query_to_ast_helper("(a OR  abc)", "(?(\"a\") ?(\"abc\"))");
-        test_parse_query_to_ast_helper("a OR abc ", "(?(\"a\") ?(\"abc\"))");
-        test_parse_query_to_ast_helper("(a OR abc )", "(?(\"a\") ?(\"abc\"))");
-        test_parse_query_to_ast_helper("(a OR  abc) ", "(?(\"a\") ?(\"abc\"))");
+        test_parse_query_to_ast_helper("(  a OR abc)", "(?\"a\" ?\"abc\")");
+        test_parse_query_to_ast_helper("(a  OR abc)", "(?\"a\" ?\"abc\")");
+        test_parse_query_to_ast_helper("(a OR  abc)", "(?\"a\" ?\"abc\")");
+        test_parse_query_to_ast_helper("a OR abc ", "(?\"a\" ?\"abc\")");
+        test_parse_query_to_ast_helper("(a OR abc )", "(?\"a\" ?\"abc\")");
+        test_parse_query_to_ast_helper("(a OR  abc) ", "(?\"a\" ?\"abc\")");
     }
 
     #[test]
-    fn test_parse_query_to_ast() {
+    fn test_parse_query_single_term() {
         test_parse_query_to_ast_helper("abc", "\"abc\"");
-        test_parse_query_to_ast_helper("a b", "(\"a\" \"b\")");
-        test_parse_query_to_ast_helper("+(a b)", "+((\"a\" \"b\"))");
-        test_parse_query_to_ast_helper("+d", "+(\"d\")");
-        test_parse_query_to_ast_helper("+(a b) +d", "(+((\"a\" \"b\")) +(\"d\"))");
-        test_parse_query_to_ast_helper("(+a +b) d", "((+(\"a\") +(\"b\")) \"d\")");
-        test_parse_query_to_ast_helper("(+a)", "+(\"a\")");
-        test_parse_query_to_ast_helper("(+a +b)", "(+(\"a\") +(\"b\"))");
+    }
+
+    #[test]
+    fn test_parse_query_default_clause() {
+        test_parse_query_to_ast_helper("a b", "(*\"a\" *\"b\")");
+    }
+
+    #[test]
+    fn test_parse_query_must_default_clause() {
+        test_parse_query_to_ast_helper("+(a b)", "(*\"a\" *\"b\")");
+    }
+
+    #[test]
+    fn test_parse_query_must_single_term() {
+        test_parse_query_to_ast_helper("+d", "\"d\"");
+    }
+
+    #[test]
+    fn test_single_term_with_field() {
         test_parse_query_to_ast_helper("abc:toto", "abc:\"toto\"");
+    }
+
+    #[test]
+    fn test_single_term_with_float() {
         test_parse_query_to_ast_helper("abc:1.1", "abc:\"1.1\"");
-        test_parse_query_to_ast_helper("+abc:toto", "+(abc:\"toto\")");
-        test_parse_query_to_ast_helper("(+abc:toto -titi)", "(+(abc:\"toto\") -(\"titi\"))");
-        test_parse_query_to_ast_helper("-abc:toto", "-(abc:\"toto\")");
-        test_parse_query_to_ast_helper("abc:a b", "(abc:\"a\" \"b\")");
+    }
+
+    #[test]
+    fn test_must_clause() {
+        test_parse_query_to_ast_helper("(+a +b)", "(+\"a\" +\"b\")");
+    }
+
+    #[test]
+    fn test_parse_test_query_plus_a_b_plus_d() {
+        test_parse_query_to_ast_helper("+(a b) +d", "(+(*\"a\" *\"b\") +\"d\")");
+    }
+
+    #[test]
+    fn test_parse_test_query_other() {
+        test_parse_query_to_ast_helper("(+a +b) d", "(*(+\"a\" +\"b\") *\"d\")");
+        test_parse_query_to_ast_helper("+abc:toto", "abc:\"toto\"");
+        test_parse_query_to_ast_helper("(+abc:toto -titi)", "(+abc:\"toto\" -\"titi\")");
+        test_parse_query_to_ast_helper("-abc:toto", "(-abc:\"toto\")");
+        test_parse_query_to_ast_helper("abc:a b", "(*abc:\"a\" *\"b\")");
         test_parse_query_to_ast_helper("abc:\"a b\"", "abc:\"a b\"");
         test_parse_query_to_ast_helper("foo:[1 TO 5]", "foo:[\"1\" TO \"5\"]");
+    }
+
+    #[test]
+    fn test_parse_query_with_range() {
         test_parse_query_to_ast_helper("[1 TO 5]", "[\"1\" TO \"5\"]");
         test_parse_query_to_ast_helper("foo:{a TO z}", "foo:{\"a\" TO \"z\"}");
         test_parse_query_to_ast_helper("foo:[1 TO toto}", "foo:[\"1\" TO \"toto\"}");

query-grammar/src/user_input_ast.rs

@@ -85,14 +85,14 @@ impl UserInputBound {
 }
 
 pub enum UserInputAST {
-    Clause(Vec<UserInputAST>),
-    Unary(Occur, Box<UserInputAST>),
+    Clause(Vec<(Option<Occur>, UserInputAST)>),
     Leaf(Box<UserInputLeaf>),
+    Boost(Box<UserInputAST>, f32),
 }
 
 impl UserInputAST {
     pub fn unary(self, occur: Occur) -> UserInputAST {
-        UserInputAST::Unary(occur, Box::new(self))
+        UserInputAST::Clause(vec![(Some(occur), self)])
     }
 
     fn compose(occur: Occur, asts: Vec<UserInputAST>) -> UserInputAST {
@@ -103,7 +103,7 @@ impl UserInputAST {
         } else {
             UserInputAST::Clause(
                 asts.into_iter()
-                    .map(|ast: UserInputAST| ast.unary(occur))
+                    .map(|ast: UserInputAST| (Some(occur), ast))
                     .collect::<Vec<_>>(),
             )
         }
@@ -134,26 +134,38 @@ impl From<UserInputLeaf> for UserInputAST {
     }
 }
 
+fn print_occur_ast(
+    occur_opt: Option<Occur>,
+    ast: &UserInputAST,
+    formatter: &mut fmt::Formatter,
+) -> fmt::Result {
+    if let Some(occur) = occur_opt {
+        write!(formatter, "{}{:?}", occur, ast)?;
+    } else {
+        write!(formatter, "*{:?}", ast)?;
+    }
+    Ok(())
+}
+
 impl fmt::Debug for UserInputAST {
-    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             UserInputAST::Clause(ref subqueries) => {
                 if subqueries.is_empty() {
                     write!(formatter, "<emptyclause>")?;
                 } else {
                     write!(formatter, "(")?;
-                    write!(formatter, "{:?}", &subqueries[0])?;
+                    print_occur_ast(subqueries[0].0, &subqueries[0].1, formatter)?;
                     for subquery in &subqueries[1..] {
-                        write!(formatter, " {:?}", subquery)?;
+                        write!(formatter, " ")?;
+                        print_occur_ast(subquery.0, &subquery.1, formatter)?;
                     }
                     write!(formatter, ")")?;
                 }
                 Ok(())
             }
-            UserInputAST::Unary(ref occur, ref subquery) => {
-                write!(formatter, "{}({:?})", occur, subquery)
-            }
             UserInputAST::Leaf(ref subquery) => write!(formatter, "{:?}", subquery),
+            UserInputAST::Boost(ref leaf, boost) => write!(formatter, "({:?})^{}", leaf, boost),
         }
     }
 }

src/collector/count_collector.rs

@@ -1,7 +1,6 @@
 use super::Collector;
 use crate::collector::SegmentCollector;
 use crate::DocId;
-use crate::Result;
 use crate::Score;
 use crate::SegmentLocalId;
 use crate::SegmentReader;
@@ -44,7 +43,11 @@ impl Collector for Count {
 
     type Child = SegmentCountCollector;
 
-    fn for_segment(&self, _: SegmentLocalId, _: &SegmentReader) -> Result<SegmentCountCollector> {
+    fn for_segment(
+        &self,
+        _: SegmentLocalId,
+        _: &SegmentReader,
+    ) -> crate::Result<SegmentCountCollector> {
         Ok(SegmentCountCollector::default())
     }
 
@@ -52,7 +55,7 @@ impl Collector for Count {
         false
     }
 
-    fn merge_fruits(&self, segment_counts: Vec<usize>) -> Result<usize> {
+    fn merge_fruits(&self, segment_counts: Vec<usize>) -> crate::Result<usize> {
         Ok(segment_counts.into_iter().sum())
     }
 }

src/collector/custom_score_top_collector.rs

@@ -1,6 +1,5 @@
 use crate::collector::top_collector::{TopCollector, TopSegmentCollector};
 use crate::collector::{Collector, SegmentCollector};
-use crate::Result;
 use crate::{DocAddress, DocId, Score, SegmentReader};
 
 pub(crate) struct CustomScoreTopCollector<TCustomScorer, TScore = Score> {
@@ -42,7 +41,7 @@ pub trait CustomScorer<TScore>: Sync {
     type Child: CustomSegmentScorer<TScore>;
     /// Builds a child scorer for a specific segment. The child scorer is associated to
     /// a specific segment.
-    fn segment_scorer(&self, segment_reader: &SegmentReader) -> Result<Self::Child>;
+    fn segment_scorer(&self, segment_reader: &SegmentReader) -> crate::Result<Self::Child>;
 }
 
 impl<TCustomScorer, TScore> Collector for CustomScoreTopCollector<TCustomScorer, TScore>
@@ -58,7 +57,7 @@ where
         &self,
         segment_local_id: u32,
         segment_reader: &SegmentReader,
-    ) -> Result<Self::Child> {
+    ) -> crate::Result<Self::Child> {
         let segment_scorer = self.custom_scorer.segment_scorer(segment_reader)?;
         let segment_collector = self
             .collector
@@ -73,7 +72,7 @@ where
         false
     }
 
-    fn merge_fruits(&self, segment_fruits: Vec<Self::Fruit>) -> Result<Self::Fruit> {
+    fn merge_fruits(&self, segment_fruits: Vec<Self::Fruit>) -> crate::Result<Self::Fruit> {
         self.collector.merge_fruits(segment_fruits)
     }
 }
@@ -111,7 +110,7 @@ where
 {
     type Child = T;
 
-    fn segment_scorer(&self, segment_reader: &SegmentReader) -> Result<Self::Child> {
+    fn segment_scorer(&self, segment_reader: &SegmentReader) -> crate::Result<Self::Child> {
         Ok((self)(segment_reader))
     }
 }

src/collector/facet_collector.rs

@@ -5,7 +5,6 @@ use crate::fastfield::FacetReader;
 use crate::schema::Facet;
 use crate::schema::Field;
 use crate::DocId;
-use crate::Result;
 use crate::Score;
 use crate::SegmentLocalId;
 use crate::SegmentReader;
@@ -84,9 +83,9 @@ fn facet_depth(facet_bytes: &[u8]) -> usize {
 /// use tantivy::collector::FacetCollector;
 /// use tantivy::query::AllQuery;
 /// use tantivy::schema::{Facet, Schema, TEXT};
-/// use tantivy::{doc, Index, Result};
+/// use tantivy::{doc, Index};
 ///
-/// fn example() -> Result<()> {
+/// fn example() -> tantivy::Result<()> {
 ///     let mut schema_builder = Schema::builder();
 ///
 ///     // Facet have their own specific type.
@@ -262,7 +261,7 @@ impl Collector for FacetCollector {
         &self,
         _: SegmentLocalId,
         reader: &SegmentReader,
-    ) -> Result<FacetSegmentCollector> {
+    ) -> crate::Result<FacetSegmentCollector> {
         let field_name = reader.schema().get_field_name(self.field);
         let facet_reader = reader.facet_reader(self.field).ok_or_else(|| {
             TantivyError::SchemaError(format!("Field {:?} is not a facet field.", field_name))
@@ -328,7 +327,7 @@ impl Collector for FacetCollector {
         false
     }
 
-    fn merge_fruits(&self, segments_facet_counts: Vec<FacetCounts>) -> Result<FacetCounts> {
+    fn merge_fruits(&self, segments_facet_counts: Vec<FacetCounts>) -> crate::Result<FacetCounts> {
         let mut facet_counts: BTreeMap<Facet, u64> = BTreeMap::new();
         for segment_facet_counts in segments_facet_counts {
             for (facet, count) in segment_facet_counts.facet_counts {

src/collector/mod.rs

@@ -85,7 +85,6 @@ See the `custom_collector` example.
 */
 
 use crate::DocId;
-use crate::Result;
 use crate::Score;
 use crate::SegmentLocalId;
 use crate::SegmentReader;
@@ -147,14 +146,14 @@ pub trait Collector: Sync {
         &self,
         segment_local_id: SegmentLocalId,
         segment: &SegmentReader,
-    ) -> Result<Self::Child>;
+    ) -> crate::Result<Self::Child>;
 
     /// Returns true iff the collector requires to compute scores for documents.
     fn requires_scoring(&self) -> bool;
 
     /// Combines the fruit associated to the collection of each segments
     /// into one fruit.
-    fn merge_fruits(&self, segment_fruits: Vec<Self::Fruit>) -> Result<Self::Fruit>;
+    fn merge_fruits(&self, segment_fruits: Vec<Self::Fruit>) -> crate::Result<Self::Fruit>;
 }
 
 /// The `SegmentCollector` is the trait in charge of defining the
@@ -185,7 +184,11 @@ where
     type Fruit = (Left::Fruit, Right::Fruit);
     type Child = (Left::Child, Right::Child);
 
-    fn for_segment(&self, segment_local_id: u32, segment: &SegmentReader) -> Result<Self::Child> {
+    fn for_segment(
+        &self,
+        segment_local_id: u32,
+        segment: &SegmentReader,
+    ) -> crate::Result<Self::Child> {
         let left = self.0.for_segment(segment_local_id, segment)?;
         let right = self.1.for_segment(segment_local_id, segment)?;
         Ok((left, right))
@@ -198,7 +201,7 @@ where
     fn merge_fruits(
         &self,
         children: Vec<(Left::Fruit, Right::Fruit)>,
-    ) -> Result<(Left::Fruit, Right::Fruit)> {
+    ) -> crate::Result<(Left::Fruit, Right::Fruit)> {
         let mut left_fruits = vec![];
         let mut right_fruits = vec![];
         for (left_fruit, right_fruit) in children {
@@ -240,7 +243,11 @@ where
     type Fruit = (One::Fruit, Two::Fruit, Three::Fruit);
     type Child = (One::Child, Two::Child, Three::Child);
 
-    fn for_segment(&self, segment_local_id: u32, segment: &SegmentReader) -> Result<Self::Child> {
+    fn for_segment(
+        &self,
+        segment_local_id: u32,
+        segment: &SegmentReader,
+    ) -> crate::Result<Self::Child> {
         let one = self.0.for_segment(segment_local_id, segment)?;
         let two = self.1.for_segment(segment_local_id, segment)?;
         let three = self.2.for_segment(segment_local_id, segment)?;
@@ -251,7 +258,7 @@ where
         self.0.requires_scoring() || self.1.requires_scoring() || self.2.requires_scoring()
     }
 
-    fn merge_fruits(&self, children: Vec<Self::Fruit>) -> Result<Self::Fruit> {
+    fn merge_fruits(&self, children: Vec<Self::Fruit>) -> crate::Result<Self::Fruit> {
         let mut one_fruits = vec![];
         let mut two_fruits = vec![];
         let mut three_fruits = vec![];
@@ -299,7 +306,11 @@ where
     type Fruit = (One::Fruit, Two::Fruit, Three::Fruit, Four::Fruit);
     type Child = (One::Child, Two::Child, Three::Child, Four::Child);
 
-    fn for_segment(&self, segment_local_id: u32, segment: &SegmentReader) -> Result<Self::Child> {
+    fn for_segment(
+        &self,
+        segment_local_id: u32,
+        segment: &SegmentReader,
+    ) -> crate::Result<Self::Child> {
         let one = self.0.for_segment(segment_local_id, segment)?;
         let two = self.1.for_segment(segment_local_id, segment)?;
         let three = self.2.for_segment(segment_local_id, segment)?;
@@ -314,7 +325,7 @@ where
             || self.3.requires_scoring()
     }
 
-    fn merge_fruits(&self, children: Vec<Self::Fruit>) -> Result<Self::Fruit> {
+    fn merge_fruits(&self, children: Vec<Self::Fruit>) -> crate::Result<Self::Fruit> {
         let mut one_fruits = vec![];
         let mut two_fruits = vec![];
         let mut three_fruits = vec![];

src/collector/multi_collector.rs

@@ -2,7 +2,6 @@ use super::Collector;
 use super::SegmentCollector;
 use crate::collector::Fruit;
 use crate::DocId;
-use crate::Result;
 use crate::Score;
 use crate::SegmentLocalId;
 use crate::SegmentReader;
@@ -24,7 +23,7 @@ impl<TCollector: Collector> Collector for CollectorWrapper<TCollector> {
         &self,
         segment_local_id: u32,
         reader: &SegmentReader,
-    ) -> Result<Box<dyn BoxableSegmentCollector>> {
+    ) -> crate::Result<Box<dyn BoxableSegmentCollector>> {
         let child = self.0.for_segment(segment_local_id, reader)?;
         Ok(Box::new(SegmentCollectorWrapper(child)))
     }
@@ -33,7 +32,10 @@ impl<TCollector: Collector> Collector for CollectorWrapper<TCollector> {
         self.0.requires_scoring()
     }
 
-    fn merge_fruits(&self, children: Vec<<Self as Collector>::Fruit>) -> Result<Box<dyn Fruit>> {
+    fn merge_fruits(
+        &self,
+        children: Vec<<Self as Collector>::Fruit>,
+    ) -> crate::Result<Box<dyn Fruit>> {
         let typed_fruit: Vec<TCollector::Fruit> = children
             .into_iter()
             .map(|untyped_fruit| {
@@ -44,7 +46,7 @@ impl<TCollector: Collector> Collector for CollectorWrapper<TCollector> {
                         TantivyError::InvalidArgument("Failed to cast child fruit.".to_string())
                     })
             })
-            .collect::<Result<_>>()?;
+            .collect::<crate::Result<_>>()?;
         let merged_fruit = self.0.merge_fruits(typed_fruit)?;
         Ok(Box::new(merged_fruit))
     }
@@ -175,12 +177,12 @@ impl<'a> Collector for MultiCollector<'a> {
         &self,
         segment_local_id: SegmentLocalId,
         segment: &SegmentReader,
-    ) -> Result<MultiCollectorChild> {
+    ) -> crate::Result<MultiCollectorChild> {
         let children = self
             .collector_wrappers
             .iter()
             .map(|collector_wrapper| collector_wrapper.for_segment(segment_local_id, segment))
-            .collect::<Result<Vec<_>>>()?;
+            .collect::<crate::Result<Vec<_>>>()?;
         Ok(MultiCollectorChild { children })
     }
 
@@ -191,7 +193,7 @@ impl<'a> Collector for MultiCollector<'a> {
             .any(Collector::requires_scoring)
     }
 
-    fn merge_fruits(&self, segments_multifruits: Vec<MultiFruit>) -> Result<MultiFruit> {
+    fn merge_fruits(&self, segments_multifruits: Vec<MultiFruit>) -> crate::Result<MultiFruit> {
         let mut segment_fruits_list: Vec<Vec<Box<dyn Fruit>>> = (0..self.collector_wrappers.len())
             .map(|_| Vec::with_capacity(segments_multifruits.len()))
             .collect::<Vec<_>>();
@@ -209,7 +211,7 @@ impl<'a> Collector for MultiCollector<'a> {
             .map(|(child_collector, segment_fruits)| {
                 Ok(Some(child_collector.merge_fruits(segment_fruits)?))
             })
-            .collect::<Result<_>>()?;
+            .collect::<crate::Result<_>>()?;
         Ok(MultiFruit { sub_fruits })
     }
 }

src/collector/tests.rs

@@ -55,7 +55,7 @@ impl Collector for TestCollector {
         &self,
         segment_id: SegmentLocalId,
         _reader: &SegmentReader,
-    ) -> Result<TestSegmentCollector> {
+    ) -> crate::Result<TestSegmentCollector> {
         Ok(TestSegmentCollector {
             segment_id,
             fruit: TestFruit::default(),
@@ -66,7 +66,7 @@ impl Collector for TestCollector {
         self.compute_score
     }
 
-    fn merge_fruits(&self, mut children: Vec<TestFruit>) -> Result<TestFruit> {
+    fn merge_fruits(&self, mut children: Vec<TestFruit>) -> crate::Result<TestFruit> {
         children.sort_by_key(|fruit| {
             if fruit.docs().is_empty() {
                 0
@@ -124,7 +124,7 @@ impl Collector for FastFieldTestCollector {
         &self,
         _: SegmentLocalId,
         segment_reader: &SegmentReader,
-    ) -> Result<FastFieldSegmentCollector> {
+    ) -> crate::Result<FastFieldSegmentCollector> {
         let reader = segment_reader
             .fast_fields()
             .u64(self.field)
@@ -139,7 +139,7 @@ impl Collector for FastFieldTestCollector {
         false
     }
 
-    fn merge_fruits(&self, children: Vec<Vec<u64>>) -> Result<Vec<u64>> {
+    fn merge_fruits(&self, children: Vec<Vec<u64>>) -> crate::Result<Vec<u64>> {
         Ok(children.into_iter().flat_map(|v| v.into_iter()).collect())
     }
 }
@@ -184,7 +184,7 @@ impl Collector for BytesFastFieldTestCollector {
         &self,
         _segment_local_id: u32,
         segment_reader: &SegmentReader,
-    ) -> Result<BytesFastFieldSegmentCollector> {
+    ) -> crate::Result<BytesFastFieldSegmentCollector> {
         Ok(BytesFastFieldSegmentCollector {
             vals: Vec::new(),
             reader: segment_reader
@@ -198,7 +198,7 @@ impl Collector for BytesFastFieldTestCollector {
         false
     }
 
-    fn merge_fruits(&self, children: Vec<Vec<u8>>) -> Result<Vec<u8>> {
+    fn merge_fruits(&self, children: Vec<Vec<u8>>) -> crate::Result<Vec<u8>> {
         Ok(children.into_iter().flat_map(|c| c.into_iter()).collect())
     }
 }

src/collector/top_collector.rs

@@ -1,6 +1,5 @@
 use crate::DocAddress;
 use crate::DocId;
-use crate::Result;
 use crate::SegmentLocalId;
 use crate::SegmentReader;
 use serde::export::PhantomData;
@@ -86,7 +85,7 @@ where
     pub fn merge_fruits(
         &self,
         children: Vec<Vec<(T, DocAddress)>>,
-    ) -> Result<Vec<(T, DocAddress)>> {
+    ) -> crate::Result<Vec<(T, DocAddress)>> {
         if self.limit == 0 {
             return Ok(Vec::new());
         }
@@ -113,7 +112,7 @@ where
         &self,
         segment_id: SegmentLocalId,
         _: &SegmentReader,
-    ) -> Result<TopSegmentCollector<F>> {
+    ) -> crate::Result<TopSegmentCollector<F>> {
         Ok(TopSegmentCollector::new(segment_id, self.limit))
     }
 }

src/collector/top_score_collector.rs

@@ -10,7 +10,6 @@ use crate::fastfield::FastFieldReader;
 use crate::schema::Field;
 use crate::DocAddress;
 use crate::DocId;
-use crate::Result;
 use crate::Score;
 use crate::SegmentLocalId;
 use crate::SegmentReader;
@@ -84,7 +83,10 @@ impl CustomScorer<u64> for ScorerByField {
             .fast_fields()
             .u64(self.field)
             .ok_or_else(|| {
-                crate::Error::SchemaError(format!("Field requested is not a i64/u64 fast field."))
+                crate::TantivyError::SchemaError(format!(
+                    "Field requested ({:?}) is not a i64/u64 fast field.",
+                    self.field
+                ))
             })?;
         Ok(ScorerByFastFieldReader { ff_reader })
     }
@@ -103,7 +105,7 @@ impl TopDocs {
     ///
     /// ```rust
     /// # use tantivy::schema::{Schema, FAST, TEXT};
-    /// # use tantivy::{doc, Index, Result, DocAddress};
+    /// # use tantivy::{doc, Index, DocAddress};
     /// # use tantivy::query::{Query, QueryParser};
     /// use tantivy::Searcher;
     /// use tantivy::collector::TopDocs;
@@ -140,7 +142,7 @@ impl TopDocs {
     /// fn docs_sorted_by_rating(searcher: &Searcher,
     ///                          query: &dyn Query,
     ///                          sort_by_field: Field)
-    ///     -> Result<Vec<(u64, DocAddress)>> {
+    ///     -> tantivy::Result<Vec<(u64, DocAddress)>> {
     ///
     ///     // This is where we build our topdocs collector
     ///     //
@@ -406,7 +408,7 @@ impl Collector for TopDocs {
         &self,
         segment_local_id: SegmentLocalId,
         reader: &SegmentReader,
-    ) -> Result<Self::Child> {
+    ) -> crate::Result<Self::Child> {
         let collector = self.0.for_segment(segment_local_id, reader)?;
         Ok(TopScoreSegmentCollector(collector))
     }
@@ -415,7 +417,10 @@ impl Collector for TopDocs {
         true
     }
 
-    fn merge_fruits(&self, child_fruits: Vec<Vec<(Score, DocAddress)>>) -> Result<Self::Fruit> {
+    fn merge_fruits(
+        &self,
+        child_fruits: Vec<Vec<(Score, DocAddress)>>,
+    ) -> crate::Result<Self::Fruit> {
         self.0.merge_fruits(child_fruits)
     }
 }
@@ -445,7 +450,6 @@ mod tests {
     use crate::Index;
     use crate::IndexWriter;
     use crate::Score;
-    use itertools::Itertools;
 
     fn make_index() -> Index {
         let mut schema_builder = Schema::builder();
@@ -519,8 +523,8 @@ mod tests {
 
         // precondition for the test to be meaningful: we did get documents
         // with the same score
-        assert!(page_1.iter().map(|result| result.0).all_equal());
-        assert!(page_2.iter().map(|result| result.0).all_equal());
+        assert!(page_1.iter().all(|result| result.0 == page_1[0].0));
+        assert!(page_2.iter().all(|result| result.0 == page_2[0].0));
 
         // sanity check since we're relying on make_index()
         assert_eq!(page_1.len(), 2);
@@ -609,8 +613,11 @@ mod tests {
         let segment = searcher.segment_reader(0);
         let top_collector = TopDocs::with_limit(4).order_by_u64_field(size);
         let err = top_collector.for_segment(0, segment);
-        if let Err(crate::Error::SchemaError(msg)) = err {
-            assert_eq!(msg, "Field requested is not a i64/u64 fast field.");
+        if let Err(crate::TantivyError::SchemaError(msg)) = err {
+            assert_eq!(
+                msg,
+                "Field requested (Field(1)) is not a i64/u64 fast field."
+            );
         } else {
             assert!(false);
         }

src/common/mod.rs

@@ -18,6 +18,19 @@ pub use byteorder::LittleEndian as Endianness;
 /// We do not allow segments with more than
 pub const MAX_DOC_LIMIT: u32 = 1 << 31;
 
+pub fn minmax<I, T>(mut vals: I) -> Option<(T, T)>
+where
+    I: Iterator<Item = T>,
+    T: Copy + Ord,
+{
+    if let Some(first_el) = vals.next() {
+        return Some(vals.fold((first_el, first_el), |(min_val, max_val), el| {
+            (min_val.min(el), max_val.max(el))
+        }));
+    }
+    None
+}
+
 /// Computes the number of bits that will be used for bitpacking.
 ///
 /// In general the target is the minimum number of bits
@@ -134,6 +147,7 @@ pub fn u64_to_f64(val: u64) -> f64 {
 #[cfg(test)]
 pub(crate) mod test {
 
+    pub use super::minmax;
     pub use super::serialize::test::fixed_size_test;
     use super::{compute_num_bits, f64_to_u64, i64_to_u64, u64_to_f64, u64_to_i64};
     use std::f64;
@@ -199,4 +213,21 @@ pub(crate) mod test {
         assert!(((super::MAX_DOC_LIMIT - 1) as i32) >= 0);
         assert!((super::MAX_DOC_LIMIT as i32) < 0);
     }
+
+    #[test]
+    fn test_minmax_empty() {
+        let vals: Vec<u32> = vec![];
+        assert_eq!(minmax(vals.into_iter()), None);
+    }
+
+    #[test]
+    fn test_minmax_one() {
+        assert_eq!(minmax(vec![1].into_iter()), Some((1, 1)));
+    }
+
+    #[test]
+    fn test_minmax_two() {
+        assert_eq!(minmax(vec![1, 2].into_iter()), Some((1, 2)));
+        assert_eq!(minmax(vec![2, 1].into_iter()), Some((1, 2)));
+    }
 }

src/core/executor.rs

@@ -1,4 +1,3 @@
-use crate::Result;
 use crossbeam::channel;
 use rayon::{ThreadPool, ThreadPoolBuilder};
 
@@ -23,7 +22,7 @@ impl Executor {
     }
 
     /// Creates an Executor that dispatches the tasks in a thread pool.
-    pub fn multi_thread(num_threads: usize, prefix: &'static str) -> Result<Executor> {
+    pub fn multi_thread(num_threads: usize, prefix: &'static str) -> crate::Result<Executor> {
         let pool = ThreadPoolBuilder::new()
             .num_threads(num_threads)
             .thread_name(move |num| format!("{}{}", prefix, num))
@@ -39,14 +38,14 @@ impl Executor {
         A: Send,
         R: Send,
         AIterator: Iterator<Item = A>,
-        F: Sized + Sync + Fn(A) -> Result<R>,
+        F: Sized + Sync + Fn(A) -> crate::Result<R>,
     >(
         &self,
         f: F,
         args: AIterator,
-    ) -> Result<Vec<R>> {
+    ) -> crate::Result<Vec<R>> {
         match self {
-            Executor::SingleThread => args.map(f).collect::<Result<_>>(),
+            Executor::SingleThread => args.map(f).collect::<crate::Result<_>>(),
             Executor::ThreadPool(pool) => {
                 let args_with_indices: Vec<(usize, A)> = args.enumerate().collect();
                 let num_fruits = args_with_indices.len();

src/core/index.rs

@@ -1,4 +1,3 @@
-use super::segment::create_segment;
 use super::segment::Segment;
 use crate::core::Executor;
 use crate::core::IndexMeta;
@@ -22,7 +21,6 @@ use crate::schema::FieldType;
 use crate::schema::Schema;
 use crate::tokenizer::{TextAnalyzer, TokenizerManager};
 use crate::IndexWriter;
-use crate::Result;
 use num_cpus;
 use std::borrow::BorrowMut;
 use std::collections::HashSet;
@@ -31,7 +29,10 @@ use std::fmt;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
-fn load_metas(directory: &dyn Directory, inventory: &SegmentMetaInventory) -> Result<IndexMeta> {
+fn load_metas(
+    directory: &dyn Directory,
+    inventory: &SegmentMetaInventory,
+) -> crate::Result<IndexMeta> {
     let meta_data = directory.atomic_read(&META_FILEPATH)?;
     let meta_string = String::from_utf8_lossy(&meta_data);
     IndexMeta::deserialize(&meta_string, &inventory)
@@ -72,14 +73,14 @@ impl Index {
 
     /// Replace the default single thread search executor pool
     /// by a thread pool with a given number of threads.
-    pub fn set_multithread_executor(&mut self, num_threads: usize) -> Result<()> {
+    pub fn set_multithread_executor(&mut self, num_threads: usize) -> crate::Result<()> {
         self.executor = Arc::new(Executor::multi_thread(num_threads, "thrd-tantivy-search-")?);
         Ok(())
     }
 
     /// Replace the default single thread search executor pool
     /// by a thread pool with a given number of threads.
-    pub fn set_default_multithread_executor(&mut self) -> Result<()> {
+    pub fn set_default_multithread_executor(&mut self) -> crate::Result<()> {
         let default_num_threads = num_cpus::get();
         self.set_multithread_executor(default_num_threads)
     }
@@ -98,7 +99,10 @@ impl Index {
     ///
     /// If a previous index was in this directory, then its meta file will be destroyed.
     #[cfg(feature = "mmap")]
-    pub fn create_in_dir<P: AsRef<Path>>(directory_path: P, schema: Schema) -> Result<Index> {
+    pub fn create_in_dir<P: AsRef<Path>>(
+        directory_path: P,
+        schema: Schema,
+    ) -> crate::Result<Index> {
         let mmap_directory = MmapDirectory::open(directory_path)?;
         if Index::exists(&mmap_directory) {
             return Err(TantivyError::IndexAlreadyExists);
@@ -107,7 +111,7 @@ impl Index {
     }
 
     /// Opens or creates a new index in the provided directory
-    pub fn open_or_create<Dir: Directory>(dir: Dir, schema: Schema) -> Result<Index> {
+    pub fn open_or_create<Dir: Directory>(dir: Dir, schema: Schema) -> crate::Result<Index> {
         if !Index::exists(&dir) {
             return Index::create(dir, schema);
         }
@@ -130,13 +134,13 @@ impl Index {
     /// The temp directory is only used for testing the `MmapDirectory`.
     /// For other unit tests, prefer the `RAMDirectory`, see: `create_in_ram`.
     #[cfg(feature = "mmap")]
-    pub fn create_from_tempdir(schema: Schema) -> Result<Index> {
+    pub fn create_from_tempdir(schema: Schema) -> crate::Result<Index> {
         let mmap_directory = MmapDirectory::create_from_tempdir()?;
         Index::create(mmap_directory, schema)
     }
 
     /// Creates a new index given an implementation of the trait `Directory`
-    pub fn create<Dir: Directory>(dir: Dir, schema: Schema) -> Result<Index> {
+    pub fn create<Dir: Directory>(dir: Dir, schema: Schema) -> crate::Result<Index> {
         let directory = ManagedDirectory::wrap(dir)?;
         Index::from_directory(directory, schema)
     }
@@ -144,7 +148,7 @@ impl Index {
     /// Create a new index from a directory.
     ///
     /// This will overwrite existing meta.json
-    fn from_directory(mut directory: ManagedDirectory, schema: Schema) -> Result<Index> {
+    fn from_directory(mut directory: ManagedDirectory, schema: Schema) -> crate::Result<Index> {
         save_new_metas(schema.clone(), directory.borrow_mut())?;
         let metas = IndexMeta::with_schema(schema);
         Index::create_from_metas(directory, &metas, SegmentMetaInventory::default())
@@ -155,7 +159,7 @@ impl Index {
         directory: ManagedDirectory,
         metas: &IndexMeta,
         inventory: SegmentMetaInventory,
-    ) -> Result<Index> {
+    ) -> crate::Result<Index> {
         let schema = metas.schema.clone();
         Ok(Index {
             directory,
@@ -172,7 +176,7 @@ impl Index {
     }
 
     /// Helper to access the tokenizer associated to a specific field.
-    pub fn tokenizer_for_field(&self, field: Field) -> Result<TextAnalyzer> {
+    pub fn tokenizer_for_field(&self, field: Field) -> crate::Result<TextAnalyzer> {
         let field_entry = self.schema.get_field_entry(field);
         let field_type = field_entry.field_type();
         let tokenizer_manager: &TokenizerManager = self.tokenizers();
@@ -195,7 +199,7 @@ impl Index {
     /// Create a default `IndexReader` for the given index.
     ///
     /// See [`Index.reader_builder()`](#method.reader_builder).
-    pub fn reader(&self) -> Result<IndexReader> {
+    pub fn reader(&self) -> crate::Result<IndexReader> {
         self.reader_builder().try_into()
     }
 
@@ -210,7 +214,7 @@ impl Index {
 
     /// Opens a new directory from an index path.
     #[cfg(feature = "mmap")]
-    pub fn open_in_dir<P: AsRef<Path>>(directory_path: P) -> Result<Index> {
+    pub fn open_in_dir<P: AsRef<Path>>(directory_path: P) -> crate::Result<Index> {
         let mmap_directory = MmapDirectory::open(directory_path)?;
         Index::open(mmap_directory)
     }
@@ -234,7 +238,7 @@ impl Index {
     }
 
     /// Open the index using the provided directory
-    pub fn open<D: Directory>(directory: D) -> Result<Index> {
+    pub fn open<D: Directory>(directory: D) -> crate::Result<Index> {
         let directory = ManagedDirectory::wrap(directory)?;
         let inventory = SegmentMetaInventory::default();
         let metas = load_metas(&directory, &inventory)?;
@@ -242,7 +246,7 @@ impl Index {
     }
 
     /// Reads the index meta file from the directory.
-    pub fn load_metas(&self) -> Result<IndexMeta> {
+    pub fn load_metas(&self) -> crate::Result<IndexMeta> {
         load_metas(self.directory(), &self.inventory)
     }
 
@@ -270,7 +274,7 @@ impl Index {
         &self,
         num_threads: usize,
         overall_heap_size_in_bytes: usize,
-    ) -> Result<IndexWriter> {
+    ) -> crate::Result<IndexWriter> {
         let directory_lock = self
             .directory
             .acquire_lock(&INDEX_WRITER_LOCK)
@@ -305,7 +309,7 @@ impl Index {
     /// If the lockfile already exists, returns `Error::FileAlreadyExists`.
     /// # Panics
     /// If the heap size per thread is too small, panics.
-    pub fn writer(&self, overall_heap_size_in_bytes: usize) -> Result<IndexWriter> {
+    pub fn writer(&self, overall_heap_size_in_bytes: usize) -> crate::Result<IndexWriter> {
         let mut num_threads = num_cpus::get();
         let heap_size_in_bytes_per_thread = overall_heap_size_in_bytes / num_threads;
         if heap_size_in_bytes_per_thread < HEAP_SIZE_MIN {
@@ -322,7 +326,7 @@ impl Index {
     }
 
     /// Returns the list of segments that are searchable
-    pub fn searchable_segments(&self) -> Result<Vec<Segment>> {
+    pub fn searchable_segments(&self) -> crate::Result<Vec<Segment>> {
         Ok(self
             .searchable_segment_metas()?
             .into_iter()
@@ -332,7 +336,7 @@ impl Index {
 
     #[doc(hidden)]
     pub fn segment(&self, segment_meta: SegmentMeta) -> Segment {
-        create_segment(self.clone(), segment_meta)
+        Segment::for_index(self.clone(), segment_meta)
     }
 
     /// Creates a new segment.
@@ -355,12 +359,12 @@ impl Index {
 
     /// Reads the meta.json and returns the list of
     /// `SegmentMeta` from the last commit.
-    pub fn searchable_segment_metas(&self) -> Result<Vec<SegmentMeta>> {
+    pub fn searchable_segment_metas(&self) -> crate::Result<Vec<SegmentMeta>> {
         Ok(self.load_metas()?.segments)
     }
 
     /// Returns the list of segment ids that are searchable.
-    pub fn searchable_segment_ids(&self) -> Result<Vec<SegmentId>> {
+    pub fn searchable_segment_ids(&self) -> crate::Result<Vec<SegmentId>> {
         Ok(self
             .searchable_segment_metas()?
             .iter()
@@ -369,7 +373,7 @@ impl Index {
     }
 
     /// Returns the set of corrupted files
-    pub fn validate_checksum(&self) -> Result<HashSet<PathBuf>> {
+    pub fn validate_checksum(&self) -> crate::Result<HashSet<PathBuf>> {
         self.directory.list_damaged().map_err(Into::into)
     }
 }

src/core/index_meta.rs

@@ -4,6 +4,7 @@ use crate::schema::Schema;
 use crate::Opstamp;
 use census::{Inventory, TrackedObject};
 use serde;
+use serde::{Deserialize, Serialize};
 use serde_json;
 use std::collections::HashSet;
 use std::fmt;

src/core/searcher.rs

@@ -14,7 +14,6 @@ use crate::store::StoreReader;
 use crate::termdict::TermMerger;
 use crate::DocAddress;
 use crate::Index;
-use crate::Result;
 use std::fmt;
 use std::sync::Arc;
 
@@ -23,8 +22,8 @@ fn collect_segment<C: Collector>(
     weight: &dyn Weight,
     segment_ord: u32,
     segment_reader: &SegmentReader,
-) -> Result<C::Fruit> {
-    let mut scorer = weight.scorer(segment_reader)?;
+) -> crate::Result<C::Fruit> {
+    let mut scorer = weight.scorer(segment_reader, 1.0f32)?;
     let mut segment_collector = collector.for_segment(segment_ord as u32, segment_reader)?;
     if let Some(delete_bitset) = segment_reader.delete_bitset() {
         scorer.for_each(&mut |doc, score| {
@@ -78,7 +77,7 @@ impl Searcher {
     ///
     /// The searcher uses the segment ordinal to route the
     /// the request to the right `Segment`.
-    pub fn doc(&self, doc_address: DocAddress) -> Result<Document> {
+    pub fn doc(&self, doc_address: DocAddress) -> crate::Result<Document> {
         let DocAddress(segment_local_id, doc_id) = doc_address;
         let store_reader = &self.store_readers[segment_local_id as usize];
         store_reader.get(doc_id)
@@ -132,7 +131,11 @@ impl Searcher {
     ///
     ///  Finally, the Collector merges each of the child collectors into itself for result usability
     ///  by the caller.
-    pub fn search<C: Collector>(&self, query: &dyn Query, collector: &C) -> Result<C::Fruit> {
+    pub fn search<C: Collector>(
+        &self,
+        query: &dyn Query,
+        collector: &C,
+    ) -> crate::Result<C::Fruit> {
         let executor = self.index.search_executor();
         self.search_with_executor(query, collector, executor)
     }
@@ -154,7 +157,7 @@ impl Searcher {
         query: &dyn Query,
         collector: &C,
         executor: &Executor,
-    ) -> Result<C::Fruit> {
+    ) -> crate::Result<C::Fruit> {
         let scoring_enabled = collector.requires_scoring();
         let weight = query.weight(self, scoring_enabled)?;
         let segment_readers = self.segment_readers();

src/core/segment.rs

@@ -8,10 +8,8 @@ use crate::directory::{ReadOnlySource, WritePtr};
 use crate::indexer::segment_serializer::SegmentSerializer;
 use crate::schema::Schema;
 use crate::Opstamp;
-use crate::Result;
 use std::fmt;
 use std::path::PathBuf;
-use std::result;
 
 /// A segment is a piece of the index.
 #[derive(Clone)]
@@ -26,15 +24,12 @@ impl fmt::Debug for Segment {
     }
 }
 
-/// Creates a new segment given an `Index` and a `SegmentId`
-///
-/// The function is here to make it private outside `tantivy`.
-/// #[doc(hidden)]
-pub fn create_segment(index: Index, meta: SegmentMeta) -> Segment {
-    Segment { index, meta }
-}
-
 impl Segment {
+    /// Creates a new segment given an `Index` and a `SegmentId`
+    pub(crate) fn for_index(index: Index, meta: SegmentMeta) -> Segment {
+        Segment { index, meta }
+    }
+
     /// Returns the index the segment belongs to.
     pub fn index(&self) -> &Index {
         &self.index
@@ -83,20 +78,14 @@ impl Segment {
     }
 
     /// Open one of the component file for a *regular* read.
-    pub fn open_read(
-        &self,
-        component: SegmentComponent,
-    ) -> result::Result<ReadOnlySource, OpenReadError> {
+    pub fn open_read(&self, component: SegmentComponent) -> Result<ReadOnlySource, OpenReadError> {
         let path = self.relative_path(component);
         let source = self.index.directory().open_read(&path)?;
         Ok(source)
     }
 
     /// Open one of the component file for *regular* write.
-    pub fn open_write(
-        &mut self,
-        component: SegmentComponent,
-    ) -> result::Result<WritePtr, OpenWriteError> {
+    pub fn open_write(&mut self, component: SegmentComponent) -> Result<WritePtr, OpenWriteError> {
         let path = self.relative_path(component);
         let write = self.index.directory_mut().open_write(&path)?;
         Ok(write)
@@ -109,5 +98,5 @@ pub trait SerializableSegment {
     ///
     /// # Returns
     /// The number of documents in the segment.
-    fn write(&self, serializer: SegmentSerializer) -> Result<u32>;
+    fn write(&self, serializer: SegmentSerializer) -> crate::Result<u32>;
 }

src/core/segment_id.rs

@@ -4,6 +4,7 @@ use uuid::Uuid;
 
 #[cfg(test)]
 use once_cell::sync::Lazy;
+use serde::{Deserialize, Serialize};
 use std::error::Error;
 use std::str::FromStr;
 #[cfg(test)]

src/core/segment_reader.rs

@@ -16,7 +16,6 @@ use crate::space_usage::SegmentSpaceUsage;
 use crate::store::StoreReader;
 use crate::termdict::TermDictionary;
 use crate::DocId;
-use crate::Result;
 use fail::fail_point;
 use std::collections::HashMap;
 use std::fmt;
@@ -145,7 +144,7 @@ impl SegmentReader {
     }
 
     /// Open a new segment for reading.
-    pub fn open(segment: &Segment) -> Result<SegmentReader> {
+    pub fn open(segment: &Segment) -> crate::Result<SegmentReader> {
         let termdict_source = segment.open_read(SegmentComponent::TERMS)?;
         let termdict_composite = CompositeFile::open(&termdict_source)?;
 

src/directory/footer.rs

@@ -8,6 +8,8 @@ use crc32fast::Hasher;
 use std::io;
 use std::io::Write;
 
+const FOOTER_MAX_LEN: usize = 10_000;
+
 type CrcHashU32 = u32;
 
 #[derive(Debug, Clone, PartialEq)]
@@ -143,12 +145,23 @@ impl BinarySerializable for VersionedFooter {
             }
         }
         BinarySerializable::serialize(&VInt(buf.len() as u64), writer)?;
+        assert!(buf.len() <= FOOTER_MAX_LEN);
         writer.write_all(&buf[..])?;
         Ok(())
     }
 
     fn deserialize<R: io::Read>(reader: &mut R) -> io::Result<Self> {
         let len = VInt::deserialize(reader)?.0 as usize;
+        if len > FOOTER_MAX_LEN {
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidData,
+                format!(
+                    "Footer seems invalid as it suggests a footer len of {}. File is corrupted, \
+            or the index was created with a different & old version of tantivy.",
+                    len
+                ),
+            ));
+        }
         let mut buf = vec![0u8; len];
         reader.read_exact(&mut buf[..])?;
         let mut cursor = &buf[..];
@@ -221,11 +234,12 @@ mod tests {
 
     use super::CrcHashU32;
     use super::FooterProxy;
-    use crate::common::BinarySerializable;
+    use crate::common::{BinarySerializable, VInt};
     use crate::directory::footer::{Footer, VersionedFooter};
     use crate::directory::TerminatingWrite;
     use byteorder::{ByteOrder, LittleEndian};
     use regex::Regex;
+    use std::io;
 
     #[test]
     fn test_versioned_footer() {
@@ -336,4 +350,20 @@ mod tests {
         let res = footer.is_compatible();
         assert!(res.is_err());
     }
+
+    #[test]
+    fn test_deserialize_too_large_footer() {
+        let mut buf = vec![];
+        assert!(FooterProxy::new(&mut buf).terminate().is_ok());
+        let mut long_len_buf = [0u8; 10];
+        let num_bytes = VInt(super::FOOTER_MAX_LEN as u64 + 1u64).serialize_into(&mut long_len_buf);
+        buf[0..num_bytes].copy_from_slice(&long_len_buf[..num_bytes]);
+        let err = Footer::deserialize(&mut &buf[..]).unwrap_err();
+        assert_eq!(err.kind(), io::ErrorKind::InvalidData);
+        assert_eq!(
+            err.to_string(),
+            "Footer seems invalid as it suggests a footer len of 10001. File is corrupted, \
+            or the index was created with a different & old version of tantivy."
+        );
+    }
 }

src/directory/managed_directory.rs

@@ -150,7 +150,7 @@ impl ManagedDirectory {
                 }
                 Err(err) => {
                     error!("Failed to acquire lock for GC");
-                    return Err(crate::Error::from(err));
+                    return Err(crate::TantivyError::from(err));
                 }
             }
         }

src/directory/mmap_directory.rs

@@ -22,6 +22,7 @@ use crate::directory::WatchHandle;
 use crate::directory::{TerminatingWrite, WritePtr};
 use atomicwrites;
 use memmap::Mmap;
+use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::convert::From;
 use std::fmt;

src/directory/ram_directory.rs

@@ -144,6 +144,22 @@ impl RAMDirectory {
     pub fn total_mem_usage(&self) -> usize {
         self.fs.read().unwrap().total_mem_usage()
     }
+
+    /// Write a copy of all of the files saved in the RAMDirectory in the target `Directory`.
+    ///
+    /// Files are all written using the `Directory::write` meaning, even if they were
+    /// written using the `atomic_write` api.
+    ///
+    /// If an error is encounterred, files may be persisted partially.
+    pub fn persist(&self, dest: &mut dyn Directory) -> crate::Result<()> {
+        let wlock = self.fs.write().unwrap();
+        for (path, source) in wlock.fs.iter() {
+            let mut dest_wrt = dest.open_write(path)?;
+            dest_wrt.write_all(source.as_slice())?;
+            dest_wrt.terminate()?;
+        }
+        Ok(())
+    }
 }
 
 impl Directory for RAMDirectory {
@@ -204,3 +220,28 @@ impl Directory for RAMDirectory {
         Ok(self.fs.write().unwrap().watch(watch_callback))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::RAMDirectory;
+    use crate::Directory;
+    use std::io::Write;
+    use std::path::Path;
+
+    #[test]
+    fn test_persist() {
+        let msg_atomic: &'static [u8] = b"atomic is the way";
+        let msg_seq: &'static [u8] = b"sequential is the way";
+        let path_atomic: &'static Path = Path::new("atomic");
+        let path_seq: &'static Path = Path::new("seq");
+        let mut directory = RAMDirectory::create();
+        assert!(directory.atomic_write(path_atomic, msg_atomic).is_ok());
+        let mut wrt = directory.open_write(path_seq).unwrap();
+        assert!(wrt.write_all(msg_seq).is_ok());
+        assert!(wrt.flush().is_ok());
+        let mut directory_copy = RAMDirectory::create();
+        assert!(directory.persist(&mut directory_copy).is_ok());
+        assert_eq!(directory_copy.atomic_read(path_atomic).unwrap(), msg_atomic);
+        assert_eq!(directory_copy.atomic_read(path_seq).unwrap(), msg_seq);
+    }
+}

src/fastfield/multivalued/writer.rs

@@ -6,7 +6,6 @@ use crate::schema::{Document, Field};
 use crate::termdict::TermOrdinal;
 use crate::DocId;
 use fnv::FnvHashMap;
-use itertools::Itertools;
 use std::io;
 
 /// Writer for multi-valued (as in, more than one value per document)
@@ -151,8 +150,8 @@ impl MultiValueIntFastFieldWriter {
                     }
                 }
                 None => {
-                    let val_min_max = self.vals.iter().cloned().minmax();
-                    let (val_min, val_max) = val_min_max.into_option().unwrap_or((0u64, 0u64));
+                    let val_min_max = crate::common::minmax(self.vals.iter().cloned());
+                    let (val_min, val_max) = val_min_max.unwrap_or((0u64, 0u64));
                     value_serializer =
                         serializer.new_u64_fast_field_with_idx(self.field, val_min, val_max, 1)?;
                     for &val in &self.vals {

src/fastfield/readers.rs

@@ -4,7 +4,6 @@ use crate::fastfield::MultiValueIntFastFieldReader;
 use crate::fastfield::{FastFieldNotAvailableError, FastFieldReader};
 use crate::schema::{Cardinality, Field, FieldType, Schema};
 use crate::space_usage::PerFieldSpaceUsage;
-use crate::Result;
 use std::collections::HashMap;
 
 /// Provides access to all of the FastFieldReader.
@@ -54,7 +53,7 @@ impl FastFieldReaders {
     pub(crate) fn load_all(
         schema: &Schema,
         fast_fields_composite: &CompositeFile,
-    ) -> Result<FastFieldReaders> {
+    ) -> crate::Result<FastFieldReaders> {
         let mut fast_field_readers = FastFieldReaders {
             fast_field_i64: Default::default(),
             fast_field_u64: Default::default(),

src/indexer/index_writer.rs

@@ -155,6 +155,8 @@ pub(crate) fn advance_deletes(
         None => BitSet::with_max_value(max_doc),
     };
 
+    let num_deleted_docs_before = segment.meta().num_deleted_docs();
+
     compute_deleted_bitset(
         &mut delete_bitset,
         &segment_reader,
@@ -164,6 +166,8 @@ pub(crate) fn advance_deletes(
     )?;
 
     // TODO optimize
+    // It should be possible to do something smarter by manipulation bitsets directly
+    // to compute this union.
     if let Some(seg_delete_bitset) = segment_reader.delete_bitset() {
         for doc in 0u32..max_doc {
             if seg_delete_bitset.is_deleted(doc) {
@@ -172,8 +176,9 @@ pub(crate) fn advance_deletes(
         }
     }
 
-    let num_deleted_docs = delete_bitset.len();
-    if num_deleted_docs > 0 {
+    let num_deleted_docs: u32 = delete_bitset.len() as u32;
+    if num_deleted_docs > num_deleted_docs_before {
+        // There are new deletes. We need to write a new delete file.
         segment = segment.with_delete_meta(num_deleted_docs as u32, target_opstamp);
         let mut delete_file = segment.open_write(SegmentComponent::DELETE)?;
         write_delete_bitset(&delete_bitset, max_doc, &mut delete_file)?;
@@ -803,6 +808,46 @@ mod tests {
         assert_eq!(batch_opstamp1, 2u64);
     }
 
+    #[test]
+    fn test_no_need_to_rewrite_delete_file_if_no_new_deletes() {
+        let mut schema_builder = schema::Schema::builder();
+        let text_field = schema_builder.add_text_field("text", schema::TEXT);
+        let index = Index::create_in_ram(schema_builder.build());
+
+        let mut index_writer = index.writer_with_num_threads(1, 3_000_000).unwrap();
+        index_writer.add_document(doc!(text_field => "hello1"));
+        index_writer.add_document(doc!(text_field => "hello2"));
+        assert!(index_writer.commit().is_ok());
+
+        let reader = index.reader().unwrap();
+        let searcher = reader.searcher();
+        assert_eq!(searcher.segment_readers().len(), 1);
+        assert_eq!(searcher.segment_reader(0u32).num_deleted_docs(), 0);
+
+        index_writer.delete_term(Term::from_field_text(text_field, "hello1"));
+        assert!(index_writer.commit().is_ok());
+
+        assert!(reader.reload().is_ok());
+        let searcher = reader.searcher();
+        assert_eq!(searcher.segment_readers().len(), 1);
+        assert_eq!(searcher.segment_reader(0u32).num_deleted_docs(), 1);
+
+        let previous_delete_opstamp = index.load_metas().unwrap().segments[0].delete_opstamp();
+
+        // All docs containing hello1 have been already removed.
+        // We should not update the delete meta.
+        index_writer.delete_term(Term::from_field_text(text_field, "hello1"));
+        assert!(index_writer.commit().is_ok());
+
+        assert!(reader.reload().is_ok());
+        let searcher = reader.searcher();
+        assert_eq!(searcher.segment_readers().len(), 1);
+        assert_eq!(searcher.segment_reader(0u32).num_deleted_docs(), 1);
+
+        let after_delete_opstamp = index.load_metas().unwrap().segments[0].delete_opstamp();
+        assert_eq!(after_delete_opstamp, previous_delete_opstamp);
+    }
+
     #[test]
     fn test_ordered_batched_operations() {
         // * one delete for `doc!(field=>"a")`

src/indexer/merger.rs

@@ -21,9 +21,6 @@ use crate::store::StoreWriter;
 use crate::termdict::TermMerger;
 use crate::termdict::TermOrdinal;
 use crate::DocId;
-use crate::Result;
-use crate::TantivyError;
-use itertools::Itertools;
 use std::cmp;
 use std::collections::HashMap;
 
@@ -72,11 +69,11 @@ fn compute_min_max_val(
             Some(delete_bitset) => {
                 // some deleted documents,
                 // we need to recompute the max / min
-                (0..max_doc)
-                    .filter(|doc_id| delete_bitset.is_alive(*doc_id))
-                    .map(|doc_id| u64_reader.get(doc_id))
-                    .minmax()
-                    .into_option()
+                crate::common::minmax(
+                    (0..max_doc)
+                        .filter(|doc_id| delete_bitset.is_alive(*doc_id))
+                        .map(|doc_id| u64_reader.get(doc_id)),
+                )
             }
             None => {
                 // no deleted documents,
@@ -143,7 +140,7 @@ impl DeltaComputer {
 }
 
 impl IndexMerger {
-    pub fn open(schema: Schema, segments: &[Segment]) -> Result<IndexMerger> {
+    pub fn open(schema: Schema, segments: &[Segment]) -> crate::Result<IndexMerger> {
         let mut readers = vec![];
         let mut max_doc: u32 = 0u32;
         for segment in segments {
@@ -159,7 +156,7 @@ impl IndexMerger {
                  which exceeds the limit {}.",
                 max_doc, MAX_DOC_LIMIT
             );
-            return Err(TantivyError::InvalidArgument(err_msg));
+            return Err(crate::TantivyError::InvalidArgument(err_msg));
         }
         Ok(IndexMerger {
             schema,
@@ -168,7 +165,10 @@ impl IndexMerger {
         })
     }
 
-    fn write_fieldnorms(&self, fieldnorms_serializer: &mut FieldNormsSerializer) -> Result<()> {
+    fn write_fieldnorms(
+        &self,
+        fieldnorms_serializer: &mut FieldNormsSerializer,
+    ) -> crate::Result<()> {
         let fields = FieldNormsWriter::fields_with_fieldnorm(&self.schema);
         let mut fieldnorms_data = Vec::with_capacity(self.max_doc as usize);
         for field in fields {
@@ -189,7 +189,7 @@ impl IndexMerger {
         &self,
         fast_field_serializer: &mut FastFieldSerializer,
         mut term_ord_mappings: HashMap<Field, TermOrdinalMapping>,
-    ) -> Result<()> {
+    ) -> crate::Result<()> {
         for (field, field_entry) in self.schema.fields() {
             let field_type = field_entry.field_type();
             match *field_type {
@@ -234,7 +234,7 @@ impl IndexMerger {
         &self,
         field: Field,
         fast_field_serializer: &mut FastFieldSerializer,
-    ) -> Result<()> {
+    ) -> crate::Result<()> {
         let mut u64_readers = vec![];
         let mut min_value = u64::max_value();
         let mut max_value = u64::min_value();
@@ -284,7 +284,7 @@ impl IndexMerger {
         &self,
         field: Field,
         fast_field_serializer: &mut FastFieldSerializer,
-    ) -> Result<()> {
+    ) -> crate::Result<()> {
         let mut total_num_vals = 0u64;
         let mut u64s_readers: Vec<MultiValueIntFastFieldReader<u64>> = Vec::new();
 
@@ -331,7 +331,7 @@ impl IndexMerger {
         field: Field,
         term_ordinal_mappings: &TermOrdinalMapping,
         fast_field_serializer: &mut FastFieldSerializer,
-    ) -> Result<()> {
+    ) -> crate::Result<()> {
         // Multifastfield consists in 2 fastfields.
         // The first serves as an index into the second one and is stricly increasing.
         // The second contains the actual values.
@@ -371,7 +371,7 @@ impl IndexMerger {
         &self,
         field: Field,
         fast_field_serializer: &mut FastFieldSerializer,
-    ) -> Result<()> {
+    ) -> crate::Result<()> {
         // Multifastfield consists in 2 fastfields.
         // The first serves as an index into the second one and is stricly increasing.
         // The second contains the actual values.
@@ -436,7 +436,7 @@ impl IndexMerger {
         &self,
         field: Field,
         fast_field_serializer: &mut FastFieldSerializer,
-    ) -> Result<()> {
+    ) -> crate::Result<()> {
         let mut total_num_vals = 0u64;
         let mut bytes_readers: Vec<BytesFastFieldReader> = Vec::new();
 
@@ -492,7 +492,7 @@ impl IndexMerger {
         indexed_field: Field,
         field_type: &FieldType,
         serializer: &mut InvertedIndexSerializer,
-    ) -> Result<Option<TermOrdinalMapping>> {
+    ) -> crate::Result<Option<TermOrdinalMapping>> {
         let mut positions_buffer: Vec<u32> = Vec::with_capacity(1_000);
         let mut delta_computer = DeltaComputer::new();
         let field_readers = self
@@ -646,7 +646,7 @@ impl IndexMerger {
     fn write_postings(
         &self,
         serializer: &mut InvertedIndexSerializer,
-    ) -> Result<HashMap<Field, TermOrdinalMapping>> {
+    ) -> crate::Result<HashMap<Field, TermOrdinalMapping>> {
         let mut term_ordinal_mappings = HashMap::new();
         for (field, field_entry) in self.schema.fields() {
             if field_entry.is_indexed() {
@@ -660,7 +660,7 @@ impl IndexMerger {
         Ok(term_ordinal_mappings)
     }
 
-    fn write_storable_fields(&self, store_writer: &mut StoreWriter) -> Result<()> {
+    fn write_storable_fields(&self, store_writer: &mut StoreWriter) -> crate::Result<()> {
         for reader in &self.readers {
             let store_reader = reader.get_store_reader();
             if reader.num_deleted_docs() > 0 {
@@ -677,7 +677,7 @@ impl IndexMerger {
 }
 
 impl SerializableSegment for IndexMerger {
-    fn write(&self, mut serializer: SegmentSerializer) -> Result<u32> {
+    fn write(&self, mut serializer: SegmentSerializer) -> crate::Result<u32> {
         let term_ord_mappings = self.write_postings(serializer.get_postings_serializer())?;
         self.write_fieldnorms(serializer.get_fieldnorms_serializer())?;
         self.write_fast_fields(serializer.get_fast_field_serializer(), term_ord_mappings)?;

src/indexer/prepared_commit.rs

@@ -1,6 +1,5 @@
 use super::IndexWriter;
 use crate::Opstamp;
-use crate::Result;
 use futures::executor::block_on;
 
 /// A prepared commit
@@ -27,11 +26,11 @@ impl<'a> PreparedCommit<'a> {
         self.payload = Some(payload.to_string())
     }
 
-    pub fn abort(self) -> Result<Opstamp> {
+    pub fn abort(self) -> crate::Result<Opstamp> {
         self.index_writer.rollback()
     }
 
-    pub fn commit(self) -> Result<Opstamp> {
+    pub fn commit(self) -> crate::Result<Opstamp> {
         info!("committing {}", self.opstamp);
         let _ = block_on(
             self.index_writer

src/indexer/segment_manager.rs

@@ -4,7 +4,6 @@ use crate::core::SegmentMeta;
 use crate::error::TantivyError;
 use crate::indexer::delete_queue::DeleteCursor;
 use crate::indexer::SegmentEntry;
-use crate::Result as TantivyResult;
 use std::collections::hash_set::HashSet;
 use std::fmt::{self, Debug, Formatter};
 use std::sync::RwLock;
@@ -49,7 +48,7 @@ pub struct SegmentManager {
 }
 
 impl Debug for SegmentManager {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         let lock = self.read();
         write!(
             f,
@@ -145,7 +144,7 @@ impl SegmentManager {
     /// Returns an error if some segments are missing, or if
     /// the `segment_ids` are not either all committed or all
     /// uncommitted.
-    pub fn start_merge(&self, segment_ids: &[SegmentId]) -> TantivyResult<Vec<SegmentEntry>> {
+    pub fn start_merge(&self, segment_ids: &[SegmentId]) -> crate::Result<Vec<SegmentEntry>> {
         let registers_lock = self.read();
         let mut segment_entries = vec![];
         if registers_lock.uncommitted.contains_all(segment_ids) {
@@ -188,7 +187,7 @@ impl SegmentManager {
             .segments_status(before_merge_segment_ids)
             .ok_or_else(|| {
                 warn!("couldn't find segment in SegmentManager");
-                crate::Error::InvalidArgument(
+                crate::TantivyError::InvalidArgument(
                     "The segments that were merged could not be found in the SegmentManager. \
                      This is not necessarily a bug, and can happen after a rollback for instance."
                         .to_string(),

src/indexer/segment_serializer.rs

@@ -1,5 +1,3 @@
-use crate::Result;
-
 use crate::core::Segment;
 use crate::core::SegmentComponent;
 use crate::fastfield::FastFieldSerializer;
@@ -18,7 +16,7 @@ pub struct SegmentSerializer {
 
 impl SegmentSerializer {
     /// Creates a new `SegmentSerializer`.
-    pub fn for_segment(segment: &mut Segment) -> Result<SegmentSerializer> {
+    pub fn for_segment(segment: &mut Segment) -> crate::Result<SegmentSerializer> {
         let store_write = segment.open_write(SegmentComponent::STORE)?;
 
         let fast_field_write = segment.open_write(SegmentComponent::FASTFIELDS)?;
@@ -57,7 +55,7 @@ impl SegmentSerializer {
     }
 
     /// Finalize the segment serialization.
-    pub fn close(self) -> Result<()> {
+    pub fn close(self) -> crate::Result<()> {
         self.fast_field_serializer.close()?;
         self.postings_serializer.close()?;
         self.store_writer.close()?;

src/indexer/segment_updater.rs

@@ -173,14 +173,18 @@ impl SegmentUpdater {
             .pool_size(1)
             .create()
             .map_err(|_| {
-                crate::Error::SystemError("Failed to spawn segment updater thread".to_string())
+                crate::TantivyError::SystemError(
+                    "Failed to spawn segment updater thread".to_string(),
+                )
             })?;
         let merge_thread_pool = ThreadPoolBuilder::new()
             .name_prefix("merge_thread")
             .pool_size(NUM_MERGE_THREADS)
             .create()
             .map_err(|_| {
-                crate::Error::SystemError("Failed to spawn segment merging thread".to_string())
+                crate::TantivyError::SystemError(
+                    "Failed to spawn segment merging thread".to_string(),
+                )
             })?;
         let index_meta = index.load_metas()?;
         Ok(SegmentUpdater(Arc::new(InnerSegmentUpdater {
@@ -222,7 +226,7 @@ impl SegmentUpdater {
         receiver.unwrap_or_else(|_| {
             let err_msg =
                 "A segment_updater future did not success. This should never happen.".to_string();
-            Err(crate::Error::SystemError(err_msg))
+            Err(crate::TantivyError::SystemError(err_msg))
         })
     }
 
@@ -419,7 +423,7 @@ impl SegmentUpdater {
         });
 
         Ok(merging_future_recv
-            .unwrap_or_else(|_| Err(crate::Error::SystemError("Merge failed".to_string()))))
+            .unwrap_or_else(|_| Err(crate::TantivyError::SystemError("Merge failed".to_string()))))
     }
 
     async fn consider_merge_options(&self) {

src/indexer/segment_writer.rs

@@ -16,15 +16,13 @@ use crate::tokenizer::{FacetTokenizer, TextAnalyzer};
 use crate::tokenizer::{TokenStreamChain, Tokenizer};
 use crate::DocId;
 use crate::Opstamp;
-use crate::Result;
-use crate::TantivyError;
 use std::io;
 use std::str;
 
 /// Computes the initial size of the hash table.
 ///
 /// Returns a number of bit `b`, such that the recommended initial table size is 2^b.
-fn initial_table_size(per_thread_memory_budget: usize) -> Result<usize> {
+fn initial_table_size(per_thread_memory_budget: usize) -> crate::Result<usize> {
     let table_memory_upper_bound = per_thread_memory_budget / 3;
     if let Some(limit) = (10..)
         .take_while(|num_bits: &usize| compute_table_size(*num_bits) < table_memory_upper_bound)
@@ -32,7 +30,7 @@ fn initial_table_size(per_thread_memory_budget: usize) -> Result<usize> {
     {
         Ok(limit.min(19)) // we cap it at 2^19 = 512K.
     } else {
-        Err(TantivyError::InvalidArgument(
+        Err(crate::TantivyError::InvalidArgument(
             format!("per thread memory budget (={}) is too small. Raise the memory budget or lower the number of threads.", per_thread_memory_budget)))
     }
 }
@@ -66,7 +64,7 @@ impl SegmentWriter {
         memory_budget: usize,
         mut segment: Segment,
         schema: &Schema,
-    ) -> Result<SegmentWriter> {
+    ) -> crate::Result<SegmentWriter> {
         let table_num_bits = initial_table_size(memory_budget)?;
         let segment_serializer = SegmentSerializer::for_segment(&mut segment)?;
         let multifield_postings = MultiFieldPostingsWriter::new(schema, table_num_bits);
@@ -99,7 +97,7 @@ impl SegmentWriter {
     ///
     /// Finalize consumes the `SegmentWriter`, so that it cannot
     /// be used afterwards.
-    pub fn finalize(mut self) -> Result<Vec<u64>> {
+    pub fn finalize(mut self) -> crate::Result<Vec<u64>> {
         self.fieldnorms_writer.fill_up_to_max_doc(self.max_doc);
         write(
             &self.multifield_postings,
@@ -281,7 +279,7 @@ fn write(
     fast_field_writers: &FastFieldsWriter,
     fieldnorms_writer: &FieldNormsWriter,
     mut serializer: SegmentSerializer,
-) -> Result<()> {
+) -> crate::Result<()> {
     let term_ord_map = multifield_postings.serialize(serializer.get_postings_serializer())?;
     fast_field_writers.serialize(serializer.get_fast_field_serializer(), &term_ord_map)?;
     fieldnorms_writer.serialize(serializer.get_fieldnorms_serializer())?;
@@ -290,7 +288,7 @@ fn write(
 }
 
 impl SerializableSegment for SegmentWriter {
-    fn write(&self, serializer: SegmentSerializer) -> Result<u32> {
+    fn write(&self, serializer: SegmentSerializer) -> crate::Result<u32> {
         let max_doc = self.max_doc;
         write(
             &self.multifield_postings,

src/lib.rs

@@ -98,9 +98,6 @@
 //! [literate programming](https://tantivy-search.github.io/examples/basic_search.html) /
 //! [source code](https://github.com/tantivy-search/tantivy/blob/master/examples/basic_search.rs))
 
-#[macro_use]
-extern crate serde_derive;
-
 #[cfg_attr(test, macro_use)]
 extern crate serde_json;
 
@@ -121,13 +118,13 @@ mod functional_test;
 mod macros;
 
 pub use crate::error::TantivyError;
-
-#[deprecated(since = "0.7.0", note = "please use `tantivy::TantivyError` instead")]
-pub use crate::error::TantivyError as Error;
 pub use chrono;
 
 /// Tantivy result.
-pub type Result<T> = std::result::Result<T, error::TantivyError>;
+///
+/// Within tantivy, please avoid importing `Result` using `use crate::Result`
+/// and instead, refer to this as `crate::Result<T>`.
+pub type Result<T> = std::result::Result<T, TantivyError>;
 
 /// Tantivy DateTime
 pub type DateTime = chrono::DateTime<chrono::Utc>;
@@ -173,6 +170,7 @@ pub use crate::schema::{Document, Term};
 use std::fmt;
 
 use once_cell::sync::Lazy;
+use serde::{Deserialize, Serialize};
 
 /// Index format version.
 const INDEX_FORMAT_VERSION: u32 = 1;
@@ -271,6 +269,144 @@ impl DocAddress {
     }
 }
 
+
+
+mod sse2 {
+    use crate::postings::compression::{AlignedBuffer, COMPRESSION_BLOCK_SIZE};
+    use std::arch::x86_64::__m128i as DataType;
+    use std::arch::x86_64::_mm_add_epi32 as op_add;
+    use std::arch::x86_64::_mm_cmplt_epi32 as op_lt;
+    use std::arch::x86_64::_mm_load_si128 as op_load;
+    // requires 128-bits alignment
+    use std::arch::x86_64::_mm_set1_epi32 as set1;
+    use std::arch::x86_64::_mm_setzero_si128 as set0;
+    use std::arch::x86_64::_mm_sub_epi32 as op_sub;
+    use std::arch::x86_64::{_mm_cvtsi128_si32, _mm_shuffle_epi32};
+
+    const MASK1: i32 = 78;
+    const MASK2: i32 = 177;
+
+    /// Performs an exhaustive linear search over the
+    ///
+    /// There is no early exit here. We simply count the
+    /// number of elements that are `< target`.
+    pub unsafe fn linear_search_sse2_128(arr: &AlignedBuffer, target: u32) -> usize {
+        let ptr = arr as *const AlignedBuffer as *const DataType;
+        let vkey = set1(target as i32);
+        let mut cnt = set0();
+        // We work over 4 `__m128i` at a time.
+        // A single `__m128i` actual contains 4 `u32`.
+        for i in 0..(COMPRESSION_BLOCK_SIZE as isize) / (4 * 4) {
+            let cmp1 = op_lt(op_load(ptr.offset(i * 4)), vkey);
+            let cmp2 = op_lt(op_load(ptr.offset(i * 4 + 1)), vkey);
+            let cmp3 = op_lt(op_load(ptr.offset(i * 4 + 2)), vkey);
+            let cmp4 = op_lt(op_load(ptr.offset(i * 4 + 3)), vkey);
+            let sum = op_add(op_add(cmp1, cmp2), op_add(cmp3, cmp4));
+            cnt = op_sub(cnt, sum);
+        }
+        cnt = op_add(cnt, _mm_shuffle_epi32(cnt, MASK1));
+        cnt = op_add(cnt, _mm_shuffle_epi32(cnt, MASK2));
+        _mm_cvtsi128_si32(cnt) as usize
+    }
+}
+
+
+const MAX_DOC: u32 = 2_000_000_000u32;
+
+use sse2::linear_search_sse2_128;
+use crate::postings::BlockSegmentPostings;
+use crate::schema::IndexRecordOption;
+
+struct DocCursor {
+    block_segment_postings: BlockSegmentPostings,
+    cursor: usize,
+}
+
+impl DocCursor {
+    fn new(mut block_segment_postings: BlockSegmentPostings) -> DocCursor {
+        block_segment_postings.advance();
+        DocCursor {
+            block_segment_postings,
+            cursor: 0,
+        }
+    }
+    fn doc(&self,) -> DocId {
+        self.block_segment_postings.doc(self.cursor)
+    }
+
+    fn len(&self,) -> usize {
+        self.block_segment_postings.doc_freq()
+    }
+
+    fn advance(&mut self) {
+        if self.cursor == 127 {
+            self.block_segment_postings.advance();
+            self.cursor = 0;
+        } else {
+            self.cursor += 1;
+        }
+    }
+
+    fn skip_to(&mut self, target: DocId) {
+        if self.block_segment_postings.skip_reader.doc() >= target {
+            unsafe {
+                let mut ptr = self.block_segment_postings.docs_aligned_b().0.get_unchecked(self.cursor) as *const u32;
+                while *ptr < target {
+                    self.cursor += 1;
+                    ptr = ptr.offset(1);
+                }
+            }
+            return;
+        }
+        self.block_segment_postings.skip_to_b(target);
+        let block= self.block_segment_postings.docs_aligned_b();
+        self.cursor = unsafe { linear_search_sse2_128(&block, target) };
+
+    }
+}
+
+pub fn intersection(idx: &InvertedIndexReader, terms: &[Term]) -> crate::Result<u32> {
+    let mut posting_lists: Vec<DocCursor> = Vec::with_capacity(terms.len());
+    for term in terms {
+        if let Some(mut block_postings) = idx.read_block_postings(term, IndexRecordOption::Basic) {
+            posting_lists.push(DocCursor::new(block_postings ));
+        } else {
+            return Ok(0);
+        }
+    }
+    posting_lists.sort_by_key(|posting_list| posting_list.len());
+    Ok({ intersection_idx(&mut posting_lists[..]) })
+}
+
+fn intersection_idx(posting_lists: &mut [DocCursor]) -> DocId {
+    let mut candidate = posting_lists[0].doc();
+    let mut i = 1;
+
+    let mut count = 0u32;
+
+    let num_posting_lists = posting_lists.len();
+    loop {
+        while i < num_posting_lists {
+            posting_lists[i].skip_to(candidate);
+            if posting_lists[i].doc() != candidate {
+                candidate = posting_lists[i].doc();
+                i = 0;
+                continue;
+            }
+            i += 1;
+        }
+        count += 1;
+        if candidate == MAX_DOC {
+            break;
+        }
+        posting_lists[0].advance();
+        candidate = posting_lists[0].doc();
+        i = 1;
+    }
+    count - 1u32
+}
+
+
 /// `DocAddress` contains all the necessary information
 /// to identify a document given a `Searcher` object.
 ///

src/postings/block_search.rs

@@ -25,7 +25,7 @@ mod sse2 {
     ///
     /// There is no early exit here. We simply count the
     /// number of elements that are `< target`.
-    pub(crate) fn linear_search_sse2_128(arr: &AlignedBuffer, target: u32) -> usize {
+    pub fn linear_search_sse2_128(arr: &AlignedBuffer, target: u32) -> usize {
         unsafe {
             let ptr = arr as *const AlignedBuffer as *const DataType;
             let vkey = set1(target as i32);
@@ -63,6 +63,8 @@ mod sse2 {
     }
 }
 
+pub use self::sse2::linear_search_sse2_128;
+
 /// This `linear search` browser exhaustively through the array.
 /// but the early exit is very difficult to predict.
 ///
@@ -106,7 +108,7 @@ impl BlockSearcher {
     /// the target.
     ///
     /// The results should be equivalent to
-    /// ```ignore
+    /// ```compile_fail
     /// block[..]
     //       .iter()
     //       .take_while(|&&val| val < target)

src/postings/compression/mod.rs

@@ -46,7 +46,7 @@ impl BlockEncoder {
 /// We ensure that the OutputBuffer is align on 128 bits
 /// in order to run SSE2 linear search on it.
 #[repr(align(128))]
-pub(crate) struct AlignedBuffer(pub [u32; COMPRESSION_BLOCK_SIZE]);
+pub struct AlignedBuffer(pub [u32; COMPRESSION_BLOCK_SIZE]);
 
 pub struct BlockDecoder {
     bitpacker: BitPacker4x,
@@ -67,6 +67,18 @@ impl BlockDecoder {
         }
     }
 
+    pub fn uncompress_vint_sorted_b<'a>(
+        &mut self,
+        compressed_data: &'a [u8],
+        offset: u32,
+        num_els: usize,
+    ) {
+        if num_els > 0 {
+            vint::uncompress_sorted(compressed_data, &mut self.output.0[..num_els], offset);
+        }
+        self.output.0[num_els..].iter_mut().for_each(|val| *val = 2_000_000_000u32);
+    }
+
     pub fn uncompress_block_sorted(
         &mut self,
         compressed_data: &[u8],
@@ -94,6 +106,11 @@ impl BlockDecoder {
         (&self.output, self.output_len)
     }
 
+    #[inline]
+    pub(crate) fn output_aligned_2(&self) -> &AlignedBuffer {
+        &self.output
+    }
+
     #[inline]
     pub fn output(&self, idx: usize) -> u32 {
         self.output.0[idx]

src/postings/mod.rs

@@ -3,7 +3,7 @@ Postings module (also called inverted index)
 */
 
 mod block_search;
-pub(crate) mod compression;
+pub mod compression;
 /// Postings module
 ///
 /// Postings, also called inverted lists, is the key datastructure

src/postings/postings_writer.rs

@@ -11,7 +11,6 @@ use crate::termdict::TermOrdinal;
 use crate::tokenizer::TokenStream;
 use crate::tokenizer::{Token, MAX_TOKEN_LEN};
 use crate::DocId;
-use crate::Result;
 use fnv::FnvHashMap;
 use std::collections::HashMap;
 use std::io;
@@ -129,7 +128,7 @@ impl MultiFieldPostingsWriter {
     pub fn serialize(
         &self,
         serializer: &mut InvertedIndexSerializer,
-    ) -> Result<HashMap<Field, FnvHashMap<UnorderedTermId, TermOrdinal>>> {
+    ) -> crate::Result<HashMap<Field, FnvHashMap<UnorderedTermId, TermOrdinal>>> {
         let mut term_offsets: Vec<(&[u8], Addr, UnorderedTermId)> =
             self.term_index.iter().collect();
         term_offsets.sort_unstable_by_key(|&(k, _, _)| k);

src/postings/segment_postings.rs

@@ -317,7 +317,7 @@ pub struct BlockSegmentPostings {
     num_vint_docs: usize,
 
     remaining_data: OwnedRead,
-    skip_reader: SkipReader,
+    pub skip_reader: SkipReader,
 }
 
 fn split_into_skips_and_postings(
@@ -414,7 +414,12 @@ impl BlockSegmentPostings {
         self.doc_decoder.output_array()
     }
 
-    pub(crate) fn docs_aligned(&self) -> (&AlignedBuffer, usize) {
+    #[inline(always)]
+    pub fn docs_aligned_b(&self) -> &AlignedBuffer {
+        self.doc_decoder.output_aligned_2()
+    }
+
+    pub fn docs_aligned(&self) -> (&AlignedBuffer, usize) {
         self.doc_decoder.output_aligned()
     }
 
@@ -486,6 +491,7 @@ impl BlockSegmentPostings {
                     }
                 }
                 self.doc_offset = self.skip_reader.doc();
+                unsafe { core::arch::x86_64::_mm_prefetch(self.remaining_data.as_ref() as *mut i8, _MM_HINT_T1) };
                 return BlockSegmentPostingsSkipResult::Success(skip_freqs);
             } else {
                 skip_freqs += self.skip_reader.tf_sum();
@@ -526,6 +532,41 @@ impl BlockSegmentPostings {
         BlockSegmentPostingsSkipResult::Terminated
     }
 
+    /// Ensure we are located on the right block.
+    #[inline(never)]
+    pub fn skip_to_b(&mut self, target_doc: DocId) {
+       while self.skip_reader.advance() {
+            if self.skip_reader.doc() >= target_doc {
+                // the last document of the current block is larger
+                // than the target.
+                //
+                // We found our block!
+                let num_bits = self.skip_reader.doc_num_bits();
+                let num_consumed_bytes = self.doc_decoder.uncompress_block_sorted(
+                    self.remaining_data.as_ref(),
+                    self.doc_offset,
+                    num_bits,
+                );
+                let tf_num_bits = self.skip_reader.tf_num_bits();
+                let num_bytes_to_skip = compressed_block_size(tf_num_bits);
+                self.remaining_data.advance(num_consumed_bytes + num_bytes_to_skip);
+                self.doc_offset = self.skip_reader.doc();
+                return;
+            } else {
+                let advance_len = self.skip_reader.total_block_len();
+                self.doc_offset = self.skip_reader.doc();
+                self.remaining_data.advance(advance_len);
+            }
+        }
+
+        // we are now on the last, incomplete, variable encoded block.
+        self.doc_decoder.uncompress_vint_sorted_b(
+           self.remaining_data.as_ref(),
+           self.doc_offset,
+          self.num_vint_docs
+        );
+    }
+
     /// Advance to the next block.
     ///
     /// Returns false iff there was no remaining blocks.

src/postings/serializer.rs

@@ -11,7 +11,6 @@ use crate::schema::Schema;
 use crate::schema::{Field, FieldEntry, FieldType};
 use crate::termdict::{TermDictionaryBuilder, TermOrdinal};
 use crate::DocId;
-use crate::Result;
 use std::io::{self, Write};
 
 /// `InvertedIndexSerializer` is in charge of serializing
@@ -61,7 +60,7 @@ impl InvertedIndexSerializer {
         positions_write: CompositeWrite<WritePtr>,
         positionsidx_write: CompositeWrite<WritePtr>,
         schema: Schema,
-    ) -> Result<InvertedIndexSerializer> {
+    ) -> crate::Result<InvertedIndexSerializer> {
         Ok(InvertedIndexSerializer {
             terms_write,
             postings_write,
@@ -72,7 +71,7 @@ impl InvertedIndexSerializer {
     }
 
     /// Open a new `PostingsSerializer` for the given segment
-    pub fn open(segment: &mut Segment) -> Result<InvertedIndexSerializer> {
+    pub fn open(segment: &mut Segment) -> crate::Result<InvertedIndexSerializer> {
         use crate::SegmentComponent::{POSITIONS, POSITIONSSKIP, POSTINGS, TERMS};
         InvertedIndexSerializer::create(
             CompositeWrite::wrap(segment.open_write(TERMS)?),

src/postings/skip.rs

@@ -49,7 +49,7 @@ impl SkipSerializer {
     }
 }
 
-pub(crate) struct SkipReader {
+pub struct SkipReader {
     doc: DocId,
     owned_read: OwnedRead,
     doc_num_bits: u8,

src/query/all_query.rs

@@ -1,10 +1,10 @@
 use crate::core::Searcher;
 use crate::core::SegmentReader;
 use crate::docset::DocSet;
+use crate::query::boost_query::BoostScorer;
 use crate::query::explanation::does_not_match;
 use crate::query::{Explanation, Query, Scorer, Weight};
 use crate::DocId;
-use crate::Result;
 use crate::Score;
 
 /// Query that matches all of the documents.
@@ -14,7 +14,7 @@ use crate::Score;
 pub struct AllQuery;
 
 impl Query for AllQuery {
-    fn weight(&self, _: &Searcher, _: bool) -> Result<Box<dyn Weight>> {
+    fn weight(&self, _: &Searcher, _: bool) -> crate::Result<Box<dyn Weight>> {
         Ok(Box::new(AllWeight))
     }
 }
@@ -23,15 +23,16 @@ impl Query for AllQuery {
 pub struct AllWeight;
 
 impl Weight for AllWeight {
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
-        Ok(Box::new(AllScorer {
+    fn scorer(&self, reader: &SegmentReader, boost: f32) -> crate::Result<Box<dyn Scorer>> {
+        let all_scorer = AllScorer {
             state: State::NotStarted,
             doc: 0u32,
             max_doc: reader.max_doc(),
-        }))
+        };
+        Ok(Box::new(BoostScorer::new(all_scorer, boost)))
     }
 
-    fn explain(&self, reader: &SegmentReader, doc: DocId) -> Result<Explanation> {
+    fn explain(&self, reader: &SegmentReader, doc: DocId) -> crate::Result<Explanation> {
         if doc >= reader.max_doc() {
             return Err(does_not_match(doc));
         }
@@ -91,14 +92,12 @@ impl Scorer for AllScorer {
 
 #[cfg(test)]
 mod tests {
-
     use super::AllQuery;
     use crate::query::Query;
     use crate::schema::{Schema, TEXT};
     use crate::Index;
 
-    #[test]
-    fn test_all_query() {
+    fn create_test_index() -> Index {
         let mut schema_builder = Schema::builder();
         let field = schema_builder.add_text_field("text", TEXT);
         let schema = schema_builder.build();
@@ -109,13 +108,18 @@ mod tests {
         index_writer.commit().unwrap();
         index_writer.add_document(doc!(field=>"ccc"));
         index_writer.commit().unwrap();
+        index
+    }
+
+    #[test]
+    fn test_all_query() {
+        let index = create_test_index();
         let reader = index.reader().unwrap();
-        reader.reload().unwrap();
         let searcher = reader.searcher();
         let weight = AllQuery.weight(&searcher, false).unwrap();
         {
             let reader = searcher.segment_reader(0);
-            let mut scorer = weight.scorer(reader).unwrap();
+            let mut scorer = weight.scorer(reader, 1.0f32).unwrap();
             assert!(scorer.advance());
             assert_eq!(scorer.doc(), 0u32);
             assert!(scorer.advance());
@@ -124,10 +128,31 @@ mod tests {
         }
         {
             let reader = searcher.segment_reader(1);
-            let mut scorer = weight.scorer(reader).unwrap();
+            let mut scorer = weight.scorer(reader, 1.0f32).unwrap();
             assert!(scorer.advance());
             assert_eq!(scorer.doc(), 0u32);
             assert!(!scorer.advance());
         }
     }
+
+    #[test]
+    fn test_all_query_with_boost() {
+        let index = create_test_index();
+        let reader = index.reader().unwrap();
+        let searcher = reader.searcher();
+        let weight = AllQuery.weight(&searcher, false).unwrap();
+        let reader = searcher.segment_reader(0);
+        {
+            let mut scorer = weight.scorer(reader, 2.0f32).unwrap();
+            assert!(scorer.advance());
+            assert_eq!(scorer.doc(), 0u32);
+            assert_eq!(scorer.score(), 2.0f32);
+        }
+        {
+            let mut scorer = weight.scorer(reader, 1.5f32).unwrap();
+            assert!(scorer.advance());
+            assert_eq!(scorer.doc(), 0u32);
+            assert_eq!(scorer.score(), 1.5f32);
+        }
+    }
 }

src/query/automaton_weight.rs

@@ -40,7 +40,7 @@ impl<A> Weight for AutomatonWeight<A>
 where
     A: Automaton + Send + Sync + 'static,
 {
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
+    fn scorer(&self, reader: &SegmentReader, boost: f32) -> Result<Box<dyn Scorer>> {
         let max_doc = reader.max_doc();
         let mut doc_bitset = BitSet::with_max_value(max_doc);
 
@@ -58,11 +58,12 @@ where
             }
         }
         let doc_bitset = BitSetDocSet::from(doc_bitset);
-        Ok(Box::new(ConstScorer::new(doc_bitset)))
+        let const_scorer = ConstScorer::new(doc_bitset, boost);
+        Ok(Box::new(const_scorer))
     }
 
     fn explain(&self, reader: &SegmentReader, doc: DocId) -> Result<Explanation> {
-        let mut scorer = self.scorer(reader)?;
+        let mut scorer = self.scorer(reader, 1.0f32)?;
         if scorer.skip_next(doc) == SkipResult::Reached {
             Ok(Explanation::new("AutomatonScorer", 1.0f32))
         } else {
@@ -72,3 +73,95 @@ where
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::AutomatonWeight;
+    use crate::query::Weight;
+    use crate::schema::{Schema, STRING};
+    use crate::Index;
+    use tantivy_fst::Automaton;
+
+    fn create_index() -> Index {
+        let mut schema = Schema::builder();
+        let title = schema.add_text_field("title", STRING);
+        let index = Index::create_in_ram(schema.build());
+        let mut index_writer = index.writer_with_num_threads(1, 3_000_000).unwrap();
+        index_writer.add_document(doc!(title=>"abc"));
+        index_writer.add_document(doc!(title=>"bcd"));
+        index_writer.add_document(doc!(title=>"abcd"));
+        assert!(index_writer.commit().is_ok());
+        index
+    }
+
+    enum State {
+        Start,
+        NotMatching,
+        AfterA,
+    }
+
+    struct PrefixedByA;
+
+    impl Automaton for PrefixedByA {
+        type State = State;
+
+        fn start(&self) -> Self::State {
+            State::Start
+        }
+
+        fn is_match(&self, state: &Self::State) -> bool {
+            match *state {
+                State::AfterA => true,
+                _ => false,
+            }
+        }
+
+        fn accept(&self, state: &Self::State, byte: u8) -> Self::State {
+            match *state {
+                State::Start => {
+                    if byte == b'a' {
+                        State::AfterA
+                    } else {
+                        State::NotMatching
+                    }
+                }
+                State::AfterA => State::AfterA,
+                State::NotMatching => State::NotMatching,
+            }
+        }
+    }
+
+    #[test]
+    fn test_automaton_weight() {
+        let index = create_index();
+        let field = index.schema().get_field("title").unwrap();
+        let automaton_weight = AutomatonWeight::new(field, PrefixedByA);
+        let reader = index.reader().unwrap();
+        let searcher = reader.searcher();
+        let mut scorer = automaton_weight
+            .scorer(searcher.segment_reader(0u32), 1.0f32)
+            .unwrap();
+        assert!(scorer.advance());
+        assert_eq!(scorer.doc(), 0u32);
+        assert_eq!(scorer.score(), 1.0f32);
+        assert!(scorer.advance());
+        assert_eq!(scorer.doc(), 2u32);
+        assert_eq!(scorer.score(), 1.0f32);
+        assert!(!scorer.advance());
+    }
+
+    #[test]
+    fn test_automaton_weight_boost() {
+        let index = create_index();
+        let field = index.schema().get_field("title").unwrap();
+        let automaton_weight = AutomatonWeight::new(field, PrefixedByA);
+        let reader = index.reader().unwrap();
+        let searcher = reader.searcher();
+        let mut scorer = automaton_weight
+            .scorer(searcher.segment_reader(0u32), 1.32f32)
+            .unwrap();
+        assert!(scorer.advance());
+        assert_eq!(scorer.doc(), 0u32);
+        assert_eq!(scorer.score(), 1.32f32);
+    }
+}

src/query/bm25.rs

@@ -25,7 +25,6 @@ fn compute_tf_cache(average_fieldnorm: f32) -> [f32; 256] {
     cache
 }
 
-#[derive(Clone)]
 pub struct BM25Weight {
     idf_explain: Explanation,
     weight: f32,
@@ -34,6 +33,15 @@ pub struct BM25Weight {
 }
 
 impl BM25Weight {
+    pub fn boost_by(&self, boost: f32) -> BM25Weight {
+        BM25Weight {
+            idf_explain: self.idf_explain.clone(),
+            weight: self.weight * boost,
+            cache: self.cache,
+            average_fieldnorm: self.average_fieldnorm,
+        }
+    }
+
     pub fn for_terms(searcher: &Searcher, terms: &[Term]) -> BM25Weight {
         assert!(!terms.is_empty(), "BM25 requires at least one term");
         let field = terms[0].field();

src/query/boolean_query/boolean_query.rs

@@ -5,7 +5,6 @@ use crate::query::TermQuery;
 use crate::query::Weight;
 use crate::schema::IndexRecordOption;
 use crate::schema::Term;
-use crate::Result;
 use crate::Searcher;
 use std::collections::BTreeSet;
 
@@ -30,9 +29,9 @@ use std::collections::BTreeSet;
 ///use tantivy::query::{BooleanQuery, Occur, PhraseQuery, Query, TermQuery};
 ///use tantivy::schema::{IndexRecordOption, Schema, TEXT};
 ///use tantivy::Term;
-///use tantivy::{Index, Result};
+///use tantivy::Index;
 ///
-///fn main() -> Result<()> {
+///fn main() -> tantivy::Result<()> {
 ///    let mut schema_builder = Schema::builder();
 ///    let title = schema_builder.add_text_field("title", TEXT);
 ///    let body = schema_builder.add_text_field("body", TEXT);
@@ -149,14 +148,14 @@ impl From<Vec<(Occur, Box<dyn Query>)>> for BooleanQuery {
 }
 
 impl Query for BooleanQuery {
-    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> Result<Box<dyn Weight>> {
+    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> crate::Result<Box<dyn Weight>> {
         let sub_weights = self
             .subqueries
             .iter()
             .map(|&(ref occur, ref subquery)| {
                 Ok((*occur, subquery.weight(searcher, scoring_enabled)?))
             })
-            .collect::<Result<_>>()?;
+            .collect::<crate::Result<_>>()?;
         Ok(Box::new(BooleanWeight::new(sub_weights, scoring_enabled)))
     }
 

src/query/boolean_query/boolean_weight.rs

@@ -10,7 +10,6 @@ use crate::query::Scorer;
 use crate::query::Union;
 use crate::query::Weight;
 use crate::query::{intersect_scorers, Explanation};
-use crate::Result;
 use crate::{DocId, SkipResult};
 use std::collections::HashMap;
 
@@ -56,10 +55,11 @@ impl BooleanWeight {
     fn per_occur_scorers(
         &self,
         reader: &SegmentReader,
-    ) -> Result<HashMap<Occur, Vec<Box<dyn Scorer>>>> {
+        boost: f32,
+    ) -> crate::Result<HashMap<Occur, Vec<Box<dyn Scorer>>>> {
         let mut per_occur_scorers: HashMap<Occur, Vec<Box<dyn Scorer>>> = HashMap::new();
         for &(ref occur, ref subweight) in &self.weights {
-            let sub_scorer: Box<dyn Scorer> = subweight.scorer(reader)?;
+            let sub_scorer: Box<dyn Scorer> = subweight.scorer(reader, boost)?;
             per_occur_scorers
                 .entry(*occur)
                 .or_insert_with(Vec::new)
@@ -71,8 +71,9 @@ impl BooleanWeight {
     fn complex_scorer<TScoreCombiner: ScoreCombiner>(
         &self,
         reader: &SegmentReader,
-    ) -> Result<Box<dyn Scorer>> {
-        let mut per_occur_scorers = self.per_occur_scorers(reader)?;
+        boost: f32,
+    ) -> crate::Result<Box<dyn Scorer>> {
+        let mut per_occur_scorers = self.per_occur_scorers(reader, boost)?;
 
         let should_scorer_opt: Option<Box<dyn Scorer>> = per_occur_scorers
             .remove(&Occur::Should)
@@ -113,7 +114,7 @@ impl BooleanWeight {
 }
 
 impl Weight for BooleanWeight {
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
+    fn scorer(&self, reader: &SegmentReader, boost: f32) -> crate::Result<Box<dyn Scorer>> {
         if self.weights.is_empty() {
             Ok(Box::new(EmptyScorer))
         } else if self.weights.len() == 1 {
@@ -121,17 +122,17 @@ impl Weight for BooleanWeight {
             if occur == Occur::MustNot {
                 Ok(Box::new(EmptyScorer))
             } else {
-                weight.scorer(reader)
+                weight.scorer(reader, boost)
             }
         } else if self.scoring_enabled {
-            self.complex_scorer::<SumWithCoordsCombiner>(reader)
+            self.complex_scorer::<SumWithCoordsCombiner>(reader, boost)
         } else {
-            self.complex_scorer::<DoNothingCombiner>(reader)
+            self.complex_scorer::<DoNothingCombiner>(reader, boost)
         }
     }
 
-    fn explain(&self, reader: &SegmentReader, doc: DocId) -> Result<Explanation> {
-        let mut scorer = self.scorer(reader)?;
+    fn explain(&self, reader: &SegmentReader, doc: DocId) -> crate::Result<Explanation> {
+        let mut scorer = self.scorer(reader, 1.0f32)?;
         if scorer.skip_next(doc) != SkipResult::Reached {
             return Err(does_not_match(doc));
         }

src/query/boolean_query/mod.rs

@@ -18,6 +18,7 @@ mod tests {
     use crate::query::Scorer;
     use crate::query::TermQuery;
     use crate::schema::*;
+    use crate::tests::assert_nearly_equals;
     use crate::Index;
     use crate::{DocAddress, DocId};
 
@@ -30,24 +31,11 @@ mod tests {
             // writing the segment
             let mut index_writer = index.writer_with_num_threads(1, 3_000_000).unwrap();
             {
-                let doc = doc!(text_field => "a b c");
-                index_writer.add_document(doc);
-            }
-            {
-                let doc = doc!(text_field => "a c");
-                index_writer.add_document(doc);
-            }
-            {
-                let doc = doc!(text_field => "b c");
-                index_writer.add_document(doc);
-            }
-            {
-                let doc = doc!(text_field => "a b c d");
-                index_writer.add_document(doc);
-            }
-            {
-                let doc = doc!(text_field => "d");
-                index_writer.add_document(doc);
+                index_writer.add_document(doc!(text_field => "a b c"));
+                index_writer.add_document(doc!(text_field => "a c"));
+                index_writer.add_document(doc!(text_field => "b c"));
+                index_writer.add_document(doc!(text_field => "a b c d"));
+                index_writer.add_document(doc!(text_field => "d"));
             }
             assert!(index_writer.commit().is_ok());
         }
@@ -70,7 +58,9 @@ mod tests {
         let query = query_parser.parse_query("+a").unwrap();
         let searcher = index.reader().unwrap().searcher();
         let weight = query.weight(&searcher, true).unwrap();
-        let scorer = weight.scorer(searcher.segment_reader(0u32)).unwrap();
+        let scorer = weight
+            .scorer(searcher.segment_reader(0u32), 1.0f32)
+            .unwrap();
         assert!(scorer.is::<TermScorer>());
     }
 
@@ -82,13 +72,17 @@ mod tests {
         {
             let query = query_parser.parse_query("+a +b +c").unwrap();
             let weight = query.weight(&searcher, true).unwrap();
-            let scorer = weight.scorer(searcher.segment_reader(0u32)).unwrap();
+            let scorer = weight
+                .scorer(searcher.segment_reader(0u32), 1.0f32)
+                .unwrap();
             assert!(scorer.is::<Intersection<TermScorer>>());
         }
         {
             let query = query_parser.parse_query("+a +(b c)").unwrap();
             let weight = query.weight(&searcher, true).unwrap();
-            let scorer = weight.scorer(searcher.segment_reader(0u32)).unwrap();
+            let scorer = weight
+                .scorer(searcher.segment_reader(0u32), 1.0f32)
+                .unwrap();
             assert!(scorer.is::<Intersection<Box<dyn Scorer>>>());
         }
     }
@@ -101,7 +95,9 @@ mod tests {
         {
             let query = query_parser.parse_query("+a b").unwrap();
             let weight = query.weight(&searcher, true).unwrap();
-            let scorer = weight.scorer(searcher.segment_reader(0u32)).unwrap();
+            let scorer = weight
+                .scorer(searcher.segment_reader(0u32), 1.0f32)
+                .unwrap();
             assert!(scorer.is::<RequiredOptionalScorer<
                 Box<dyn Scorer>,
                 Box<dyn Scorer>,
@@ -111,7 +107,9 @@ mod tests {
         {
             let query = query_parser.parse_query("+a b").unwrap();
             let weight = query.weight(&searcher, false).unwrap();
-            let scorer = weight.scorer(searcher.segment_reader(0u32)).unwrap();
+            let scorer = weight
+                .scorer(searcher.segment_reader(0u32), 1.0f32)
+                .unwrap();
             assert!(scorer.is::<TermScorer>());
         }
     }
@@ -179,6 +177,50 @@ mod tests {
         }
     }
 
+    #[test]
+    pub fn test_boolean_query_with_weight() {
+        let mut schema_builder = Schema::builder();
+        let text_field = schema_builder.add_text_field("text", TEXT);
+        let schema = schema_builder.build();
+        let index = Index::create_in_ram(schema);
+        {
+            let mut index_writer = index.writer_with_num_threads(1, 3_000_000).unwrap();
+            index_writer.add_document(doc!(text_field => "a b c"));
+            index_writer.add_document(doc!(text_field => "a c"));
+            index_writer.add_document(doc!(text_field => "b c"));
+            assert!(index_writer.commit().is_ok());
+        }
+        let term_a: Box<dyn Query> = Box::new(TermQuery::new(
+            Term::from_field_text(text_field, "a"),
+            IndexRecordOption::WithFreqs,
+        ));
+        let term_b: Box<dyn Query> = Box::new(TermQuery::new(
+            Term::from_field_text(text_field, "b"),
+            IndexRecordOption::WithFreqs,
+        ));
+        let reader = index.reader().unwrap();
+        let searcher = reader.searcher();
+        let boolean_query =
+            BooleanQuery::from(vec![(Occur::Should, term_a), (Occur::Should, term_b)]);
+        let boolean_weight = boolean_query.weight(&searcher, true).unwrap();
+        {
+            let mut boolean_scorer = boolean_weight
+                .scorer(searcher.segment_reader(0u32), 1.0f32)
+                .unwrap();
+            assert!(boolean_scorer.advance());
+            assert_eq!(boolean_scorer.doc(), 0u32);
+            assert_nearly_equals(boolean_scorer.score(), 0.84163445f32);
+        }
+        {
+            let mut boolean_scorer = boolean_weight
+                .scorer(searcher.segment_reader(0u32), 2.0f32)
+                .unwrap();
+            assert!(boolean_scorer.advance());
+            assert_eq!(boolean_scorer.doc(), 0u32);
+            assert_nearly_equals(boolean_scorer.score(), 1.6832689f32);
+        }
+    }
+
     #[test]
     pub fn test_intersection_score() {
         let (index, text_field) = aux_test_helper();
@@ -249,7 +291,9 @@ mod tests {
         let query_parser = QueryParser::for_index(&index, vec![title, text]);
         let query = query_parser.parse_query("Оксана Лифенко").unwrap();
         let weight = query.weight(&searcher, true).unwrap();
-        let mut scorer = weight.scorer(searcher.segment_reader(0u32)).unwrap();
+        let mut scorer = weight
+            .scorer(searcher.segment_reader(0u32), 1.0f32)
+            .unwrap();
         scorer.advance();
 
         let explanation = query.explain(&searcher, DocAddress(0u32, 0u32)).unwrap();

src/query/boost_query.rs

@@ -0,0 +1,164 @@
+use crate::common::BitSet;
+use crate::fastfield::DeleteBitSet;
+use crate::query::explanation::does_not_match;
+use crate::query::{Explanation, Query, Scorer, Weight};
+use crate::{DocId, DocSet, Searcher, SegmentReader, SkipResult, Term};
+use std::collections::BTreeSet;
+use std::fmt;
+
+/// `BoostQuery` is a wrapper over a query used to boost its score.
+///
+/// The document set matched by the `BoostQuery` is strictly the same as the underlying query.
+/// The score of each document, is the score of the underlying query multiplied by the `boost`
+/// factor.
+pub struct BoostQuery {
+    query: Box<dyn Query>,
+    boost: f32,
+}
+
+impl BoostQuery {
+    /// Builds a boost query.
+    pub fn new(query: Box<dyn Query>, boost: f32) -> BoostQuery {
+        BoostQuery { query, boost }
+    }
+}
+
+impl Clone for BoostQuery {
+    fn clone(&self) -> Self {
+        BoostQuery {
+            query: self.query.box_clone(),
+            boost: self.boost,
+        }
+    }
+}
+
+impl fmt::Debug for BoostQuery {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Boost(query={:?}, boost={})", self.query, self.boost)
+    }
+}
+
+impl Query for BoostQuery {
+    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> crate::Result<Box<dyn Weight>> {
+        let weight_without_boost = self.query.weight(searcher, scoring_enabled)?;
+        let boosted_weight = if scoring_enabled {
+            Box::new(BoostWeight::new(weight_without_boost, self.boost))
+        } else {
+            weight_without_boost
+        };
+        Ok(boosted_weight)
+    }
+
+    fn query_terms(&self, term_set: &mut BTreeSet<Term>) {
+        self.query.query_terms(term_set)
+    }
+}
+
+pub(crate) struct BoostWeight {
+    weight: Box<dyn Weight>,
+    boost: f32,
+}
+
+impl BoostWeight {
+    pub fn new(weight: Box<dyn Weight>, boost: f32) -> Self {
+        BoostWeight { weight, boost }
+    }
+}
+
+impl Weight for BoostWeight {
+    fn scorer(&self, reader: &SegmentReader, boost: f32) -> crate::Result<Box<dyn Scorer>> {
+        self.weight.scorer(reader, boost * self.boost)
+    }
+
+    fn explain(&self, reader: &SegmentReader, doc: u32) -> crate::Result<Explanation> {
+        let mut scorer = self.scorer(reader, 1.0f32)?;
+        if scorer.skip_next(doc) != SkipResult::Reached {
+            return Err(does_not_match(doc));
+        }
+        let mut explanation =
+            Explanation::new(format!("Boost x{} of ...", self.boost), scorer.score());
+        let underlying_explanation = self.weight.explain(reader, doc)?;
+        explanation.add_detail(underlying_explanation);
+        Ok(explanation)
+    }
+
+    fn count(&self, reader: &SegmentReader) -> crate::Result<u32> {
+        self.weight.count(reader)
+    }
+}
+
+pub(crate) struct BoostScorer<S: Scorer> {
+    underlying: S,
+    boost: f32,
+}
+
+impl<S: Scorer> BoostScorer<S> {
+    pub fn new(underlying: S, boost: f32) -> BoostScorer<S> {
+        BoostScorer { underlying, boost }
+    }
+}
+
+impl<S: Scorer> DocSet for BoostScorer<S> {
+    fn advance(&mut self) -> bool {
+        self.underlying.advance()
+    }
+
+    fn skip_next(&mut self, target: DocId) -> SkipResult {
+        self.underlying.skip_next(target)
+    }
+
+    fn fill_buffer(&mut self, buffer: &mut [DocId]) -> usize {
+        self.underlying.fill_buffer(buffer)
+    }
+
+    fn doc(&self) -> u32 {
+        self.underlying.doc()
+    }
+
+    fn size_hint(&self) -> u32 {
+        self.underlying.size_hint()
+    }
+
+    fn append_to_bitset(&mut self, bitset: &mut BitSet) {
+        self.underlying.append_to_bitset(bitset)
+    }
+
+    fn count(&mut self, delete_bitset: &DeleteBitSet) -> u32 {
+        self.underlying.count(delete_bitset)
+    }
+
+    fn count_including_deleted(&mut self) -> u32 {
+        self.underlying.count_including_deleted()
+    }
+}
+
+impl<S: Scorer> Scorer for BoostScorer<S> {
+    fn score(&mut self) -> f32 {
+        self.underlying.score() * self.boost
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::BoostQuery;
+    use crate::query::{AllQuery, Query};
+    use crate::schema::Schema;
+    use crate::{DocAddress, Document, Index};
+
+    #[test]
+    fn test_boost_query_explain() {
+        let schema = Schema::builder().build();
+        let index = Index::create_in_ram(schema);
+        let mut index_writer = index.writer_with_num_threads(1, 3_000_000).unwrap();
+        index_writer.add_document(Document::new());
+        assert!(index_writer.commit().is_ok());
+        let reader = index.reader().unwrap();
+        let searcher = reader.searcher();
+        let query = BoostQuery::new(Box::new(AllQuery), 0.2);
+        let explanation = query.explain(&searcher, DocAddress(0, 0u32)).unwrap();
+        assert_eq!(
+            explanation.to_pretty_json(),
+            "{\n  \"value\": 0.2,\n  \"description\": \"Boost x0.2 of ...\",\n  \"details\": [\n    {\n      \"value\": 1.0,\n      \"description\": \"AllQuery\"\n    }\n  ]\n}"
+        )
+    }
+}

src/query/empty_query.rs

@@ -4,7 +4,6 @@ use crate::query::Weight;
 use crate::query::{Explanation, Query};
 use crate::DocId;
 use crate::DocSet;
-use crate::Result;
 use crate::Score;
 use crate::Searcher;
 use crate::SegmentReader;
@@ -16,11 +15,15 @@ use crate::SegmentReader;
 pub struct EmptyQuery;
 
 impl Query for EmptyQuery {
-    fn weight(&self, _searcher: &Searcher, _scoring_enabled: bool) -> Result<Box<dyn Weight>> {
+    fn weight(
+        &self,
+        _searcher: &Searcher,
+        _scoring_enabled: bool,
+    ) -> crate::Result<Box<dyn Weight>> {
         Ok(Box::new(EmptyWeight))
     }
 
-    fn count(&self, _searcher: &Searcher) -> Result<usize> {
+    fn count(&self, _searcher: &Searcher) -> crate::Result<usize> {
         Ok(0)
     }
 }
@@ -30,11 +33,11 @@ impl Query for EmptyQuery {
 /// It is useful for tests and handling edge cases.
 pub struct EmptyWeight;
 impl Weight for EmptyWeight {
-    fn scorer(&self, _reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
+    fn scorer(&self, _reader: &SegmentReader, _boost: f32) -> crate::Result<Box<dyn Scorer>> {
         Ok(Box::new(EmptyScorer))
     }
 
-    fn explain(&self, _reader: &SegmentReader, doc: DocId) -> Result<Explanation> {
+    fn explain(&self, _reader: &SegmentReader, doc: DocId) -> crate::Result<Explanation> {
         Err(does_not_match(doc))
     }
 }

src/query/explanation.rs

@@ -1,4 +1,5 @@
 use crate::{DocId, TantivyError};
+use serde::Serialize;
 
 pub(crate) fn does_not_match(doc: DocId) -> TantivyError {
     TantivyError::InvalidArgument(format!("Document #({}) does not match", doc))

src/query/fuzzy_query.rs

@@ -1,16 +1,41 @@
-use crate::error::TantivyError::InvalidArgument;
 use crate::query::{AutomatonWeight, Query, Weight};
 use crate::schema::Term;
-use crate::Result;
 use crate::Searcher;
-use levenshtein_automata::{LevenshteinAutomatonBuilder, DFA};
+use crate::TantivyError::InvalidArgument;
+use levenshtein_automata::{Distance, LevenshteinAutomatonBuilder, DFA};
 use once_cell::sync::Lazy;
 use std::collections::HashMap;
 use std::ops::Range;
+use tantivy_fst::Automaton;
+
+pub(crate) struct DFAWrapper(pub DFA);
+
+impl Automaton for DFAWrapper {
+    type State = u32;
+
+    fn start(&self) -> Self::State {
+        self.0.initial_state()
+    }
+
+    fn is_match(&self, state: &Self::State) -> bool {
+        match self.0.distance(*state) {
+            Distance::Exact(_) => true,
+            Distance::AtLeast(_) => false,
+        }
+    }
+
+    fn can_match(&self, state: &u32) -> bool {
+        *state != levenshtein_automata::SINK_STATE
+    }
+
+    fn accept(&self, state: &Self::State, byte: u8) -> Self::State {
+        self.0.transition(*state, byte)
+    }
+}
 
 /// A range of Levenshtein distances that we will build DFAs for our terms
 /// The computation is exponential, so best keep it to low single digits
-const VALID_LEVENSHTEIN_DISTANCE_RANGE: Range<u8> = (0..3);
+const VALID_LEVENSHTEIN_DISTANCE_RANGE: Range<u8> = 0..3;
 
 static LEV_BUILDER: Lazy<HashMap<(u8, bool), LevenshteinAutomatonBuilder>> = Lazy::new(|| {
     let mut lev_builder_cache = HashMap::new();
@@ -31,9 +56,9 @@ static LEV_BUILDER: Lazy<HashMap<(u8, bool), LevenshteinAutomatonBuilder>> = Laz
 /// use tantivy::collector::{Count, TopDocs};
 /// use tantivy::query::FuzzyTermQuery;
 /// use tantivy::schema::{Schema, TEXT};
-/// use tantivy::{doc, Index, Result, Term};
+/// use tantivy::{doc, Index, Term};
 ///
-/// fn example() -> Result<()> {
+/// fn example() -> tantivy::Result<()> {
 ///     let mut schema_builder = Schema::builder();
 ///     let title = schema_builder.add_text_field("title", TEXT);
 ///     let schema = schema_builder.build();
@@ -102,13 +127,20 @@ impl FuzzyTermQuery {
         }
     }
 
-    fn specialized_weight(&self) -> Result<AutomatonWeight<DFA>> {
+    fn specialized_weight(&self) -> crate::Result<AutomatonWeight<DFAWrapper>> {
         // LEV_BUILDER is a HashMap, whose `get` method returns an Option
         match LEV_BUILDER.get(&(self.distance, false)) {
             // Unwrap the option and build the Ok(AutomatonWeight)
             Some(automaton_builder) => {
-                let automaton = automaton_builder.build_dfa(self.term.text());
-                Ok(AutomatonWeight::new(self.term.field(), automaton))
+                let automaton = if self.prefix {
+                    automaton_builder.build_prefix_dfa(self.term.text())
+                } else {
+                    automaton_builder.build_dfa(self.term.text())
+                };
+                Ok(AutomatonWeight::new(
+                    self.term.field(),
+                    DFAWrapper(automaton),
+                ))
             }
             None => Err(InvalidArgument(format!(
                 "Levenshtein distance of {} is not allowed. Choose a value in the {:?} range",
@@ -119,7 +151,11 @@ impl FuzzyTermQuery {
 }
 
 impl Query for FuzzyTermQuery {
-    fn weight(&self, _searcher: &Searcher, _scoring_enabled: bool) -> Result<Box<dyn Weight>> {
+    fn weight(
+        &self,
+        _searcher: &Searcher,
+        _scoring_enabled: bool,
+    ) -> crate::Result<Box<dyn Weight>> {
         Ok(Box::new(self.specialized_weight()?))
     }
 }
@@ -163,5 +199,17 @@ mod test {
             let (score, _) = top_docs[0];
             assert_nearly_equals(1f32, score);
         }
+
+        {
+            let term = Term::from_field_text(country_field, "jap");
+
+            let fuzzy_query = FuzzyTermQuery::new_prefix(term, 1, true);
+            let top_docs = searcher
+                .search(&fuzzy_query, &TopDocs::with_limit(2))
+                .unwrap();
+            assert_eq!(top_docs.len(), 1, "Expected only 1 document");
+            let (score, _) = top_docs[0];
+            assert_nearly_equals(1f32, score);
+        }
     }
 }

src/query/mod.rs

@@ -7,6 +7,7 @@ mod automaton_weight;
 mod bitset;
 mod bm25;
 mod boolean_query;
+mod boost_query;
 mod empty_query;
 mod exclude;
 mod explanation;
@@ -23,6 +24,7 @@ mod term_query;
 mod union;
 mod weight;
 
+
 #[cfg(test)]
 mod vec_docset;
 
@@ -37,10 +39,12 @@ pub use self::all_query::{AllQuery, AllScorer, AllWeight};
 pub use self::automaton_weight::AutomatonWeight;
 pub use self::bitset::BitSetDocSet;
 pub use self::boolean_query::BooleanQuery;
+pub use self::boost_query::BoostQuery;
 pub use self::empty_query::{EmptyQuery, EmptyScorer, EmptyWeight};
 pub use self::exclude::Exclude;
 pub use self::explanation::Explanation;
 pub use self::fuzzy_query::FuzzyTermQuery;
+pub(crate) use self::fuzzy_query::DFAWrapper;
 pub use self::intersection::intersect_scorers;
 pub use self::phrase_query::PhraseQuery;
 pub use self::query::Query;

src/query/phrase_query/mod.rs

@@ -7,18 +7,17 @@ pub use self::phrase_scorer::PhraseScorer;
 pub use self::phrase_weight::PhraseWeight;
 
 #[cfg(test)]
-mod tests {
+pub mod tests {
 
     use super::*;
     use crate::collector::tests::{TEST_COLLECTOR_WITHOUT_SCORE, TEST_COLLECTOR_WITH_SCORE};
     use crate::core::Index;
-    use crate::error::TantivyError;
     use crate::schema::{Schema, Term, TEXT};
     use crate::tests::assert_nearly_equals;
+    use crate::DocAddress;
     use crate::DocId;
-    use crate::{DocAddress, DocSet};
 
-    fn create_index(texts: &[&'static str]) -> Index {
+    pub fn create_index(texts: &[&'static str]) -> Index {
         let mut schema_builder = Schema::builder();
         let text_field = schema_builder.add_text_field("text", TEXT);
         let schema = schema_builder.build();
@@ -102,30 +101,6 @@ mod tests {
         assert!(test_query(vec!["g", "a"]).is_empty());
     }
 
-    #[test]
-    pub fn test_phrase_count() {
-        let index = create_index(&["a c", "a a b d a b c", " a b"]);
-        let schema = index.schema();
-        let text_field = schema.get_field("text").unwrap();
-        let searcher = index.reader().unwrap().searcher();
-        let phrase_query = PhraseQuery::new(vec![
-            Term::from_field_text(text_field, "a"),
-            Term::from_field_text(text_field, "b"),
-        ]);
-        let phrase_weight = phrase_query.phrase_weight(&searcher, true).unwrap();
-        let mut phrase_scorer = phrase_weight
-            .phrase_scorer(searcher.segment_reader(0u32))
-            .unwrap()
-            .unwrap();
-        assert!(phrase_scorer.advance());
-        assert_eq!(phrase_scorer.doc(), 1);
-        assert_eq!(phrase_scorer.phrase_count(), 2);
-        assert!(phrase_scorer.advance());
-        assert_eq!(phrase_scorer.doc(), 2);
-        assert_eq!(phrase_scorer.phrase_count(), 1);
-        assert!(!phrase_scorer.advance());
-    }
-
     #[test]
     pub fn test_phrase_query_no_positions() {
         let mut schema_builder = Schema::builder();
@@ -151,21 +126,16 @@ mod tests {
             Term::from_field_text(text_field, "a"),
             Term::from_field_text(text_field, "b"),
         ]);
-        match searcher
+
+        let search_result = searcher
             .search(&phrase_query, &TEST_COLLECTOR_WITH_SCORE)
-            .map(|_| ())
-            .unwrap_err()
-        {
-            TantivyError::SchemaError(ref msg) => {
-                assert_eq!(
-                    "Applied phrase query on field \"text\", which does not have positions indexed",
-                    msg.as_str()
-                );
-            }
-            _ => {
-                panic!("Should have returned an error");
-            }
-        }
+            .map(|_| ());
+        assert!(matches!(
+            search_result,
+            Err(crate::TantivyError::SchemaError(msg))
+            if msg == "Applied phrase query on field \"text\", which does not have positions \
+            indexed"
+        ));
     }
 
     #[test]

src/query/phrase_query/phrase_query.rs

@@ -1,12 +1,10 @@
 use super::PhraseWeight;
 use crate::core::searcher::Searcher;
-use crate::error::TantivyError;
 use crate::query::bm25::BM25Weight;
 use crate::query::Query;
 use crate::query::Weight;
 use crate::schema::IndexRecordOption;
 use crate::schema::{Field, Term};
-use crate::Result;
 use std::collections::BTreeSet;
 
 /// `PhraseQuery` matches a specific sequence of words.
@@ -81,7 +79,7 @@ impl PhraseQuery {
         &self,
         searcher: &Searcher,
         scoring_enabled: bool,
-    ) -> Result<PhraseWeight> {
+    ) -> crate::Result<PhraseWeight> {
         let schema = searcher.schema();
         let field_entry = schema.get_field_entry(self.field);
         let has_positions = field_entry
@@ -91,7 +89,7 @@ impl PhraseQuery {
             .unwrap_or(false);
         if !has_positions {
             let field_name = field_entry.name();
-            return Err(TantivyError::SchemaError(format!(
+            return Err(crate::TantivyError::SchemaError(format!(
                 "Applied phrase query on field {:?}, which does not have positions indexed",
                 field_name
             )));
@@ -110,7 +108,7 @@ impl Query for PhraseQuery {
     /// Create the weight associated to a query.
     ///
     /// See [`Weight`](./trait.Weight.html).
-    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> Result<Box<dyn Weight>> {
+    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> crate::Result<Box<dyn Weight>> {
         let phrase_weight = self.phrase_weight(searcher, scoring_enabled)?;
         Ok(Box::new(phrase_weight))
     }

src/query/phrase_query/phrase_weight.rs

@@ -37,11 +37,12 @@ impl PhraseWeight {
         reader.get_fieldnorms_reader(field)
     }
 
-    pub fn phrase_scorer(
+    fn phrase_scorer(
         &self,
         reader: &SegmentReader,
+        boost: f32,
     ) -> Result<Option<PhraseScorer<SegmentPostings>>> {
-        let similarity_weight = self.similarity_weight.clone();
+        let similarity_weight = self.similarity_weight.boost_by(boost);
         let fieldnorm_reader = self.fieldnorm_reader(reader);
         if reader.has_deletes() {
             let mut term_postings_list = Vec::new();
@@ -84,8 +85,8 @@ impl PhraseWeight {
 }
 
 impl Weight for PhraseWeight {
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
-        if let Some(scorer) = self.phrase_scorer(reader)? {
+    fn scorer(&self, reader: &SegmentReader, boost: f32) -> Result<Box<dyn Scorer>> {
+        if let Some(scorer) = self.phrase_scorer(reader, boost)? {
             Ok(Box::new(scorer))
         } else {
             Ok(Box::new(EmptyScorer))
@@ -93,7 +94,7 @@ impl Weight for PhraseWeight {
     }
 
     fn explain(&self, reader: &SegmentReader, doc: DocId) -> Result<Explanation> {
-        let scorer_opt = self.phrase_scorer(reader)?;
+        let scorer_opt = self.phrase_scorer(reader, 1.0f32)?;
         if scorer_opt.is_none() {
             return Err(does_not_match(doc));
         }
@@ -109,3 +110,34 @@ impl Weight for PhraseWeight {
         Ok(explanation)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::super::tests::create_index;
+    use crate::query::PhraseQuery;
+    use crate::{DocSet, Term};
+
+    #[test]
+    pub fn test_phrase_count() {
+        let index = create_index(&["a c", "a a b d a b c", " a b"]);
+        let schema = index.schema();
+        let text_field = schema.get_field("text").unwrap();
+        let searcher = index.reader().unwrap().searcher();
+        let phrase_query = PhraseQuery::new(vec![
+            Term::from_field_text(text_field, "a"),
+            Term::from_field_text(text_field, "b"),
+        ]);
+        let phrase_weight = phrase_query.phrase_weight(&searcher, true).unwrap();
+        let mut phrase_scorer = phrase_weight
+            .phrase_scorer(searcher.segment_reader(0u32), 1.0f32)
+            .unwrap()
+            .unwrap();
+        assert!(phrase_scorer.advance());
+        assert_eq!(phrase_scorer.doc(), 1);
+        assert_eq!(phrase_scorer.phrase_count(), 2);
+        assert!(phrase_scorer.advance());
+        assert_eq!(phrase_scorer.doc(), 2);
+        assert_eq!(phrase_scorer.phrase_count(), 1);
+        assert!(!phrase_scorer.advance());
+    }
+}

src/query/query.rs

@@ -1,12 +1,17 @@
 use super::Weight;
 use crate::core::searcher::Searcher;
 use crate::query::Explanation;
-use crate::DocAddress;
-use crate::Result;
+use crate::{DocAddress, Score};
 use crate::Term;
 use downcast_rs::impl_downcast;
 use std::collections::BTreeSet;
 use std::fmt;
+use crate::collector::{TopDocs, Collector, SegmentCollector, Count};
+
+pub struct TopKResult {
+    pub count: u64,
+    docs: Vec<(Score, DocAddress)>
+}
 
 /// The `Query` trait defines a set of documents and a scoring method
 /// for those documents.
@@ -48,17 +53,38 @@ pub trait Query: QueryClone + downcast_rs::Downcast + fmt::Debug {
     /// can increase performances.
     ///
     /// See [`Weight`](./trait.Weight.html).
-    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> Result<Box<dyn Weight>>;
+    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> crate::Result<Box<dyn Weight>>;
 
     /// Returns an `Explanation` for the score of the document.
-    fn explain(&self, searcher: &Searcher, doc_address: DocAddress) -> Result<Explanation> {
+    fn explain(&self, searcher: &Searcher, doc_address: DocAddress) -> crate::Result<Explanation> {
         let reader = searcher.segment_reader(doc_address.segment_ord());
         let weight = self.weight(searcher, true)?;
         weight.explain(reader, doc_address.doc())
     }
 
+    fn top_k(&self, searcher: &Searcher, num_hits: usize) -> crate::Result<TopKResult> {
+        let top_docs = TopDocs::with_limit(num_hits);
+        let collector = (Count, top_docs);
+        let weight = self.weight(searcher, false)?;
+        let mut count = 0u64;
+        let mut result = 0;
+        let mut child_fruits = Vec::with_capacity(searcher.segment_readers().len());
+        for (segment_ord, reader) in searcher.segment_readers().iter().enumerate() {
+            let mut child_top_k = collector.for_segment(segment_ord as u32, reader)?;
+            let mut scorer = weight.scorer(reader, 1.0f32)?;
+            // handle deletes
+            scorer.top_k(&mut child_top_k);
+            child_fruits.push(child_top_k.harvest());
+        }
+        let (count, docs) = collector.merge_fruits(child_fruits)?;
+        Ok(TopKResult {
+            count: count as u64,
+            docs
+        })
+    }
+
     /// Returns the number of documents matching the query.
-    fn count(&self, searcher: &Searcher) -> Result<usize> {
+    fn count(&self, searcher: &Searcher) -> crate::Result<usize> {
         let weight = self.weight(searcher, false)?;
         let mut result = 0;
         for reader in searcher.segment_readers() {
@@ -86,11 +112,11 @@ where
 }
 
 impl Query for Box<dyn Query> {
-    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> Result<Box<dyn Weight>> {
+    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> crate::Result<Box<dyn Weight>> {
         self.as_ref().weight(searcher, scoring_enabled)
     }
 
-    fn count(&self, searcher: &Searcher) -> Result<usize> {
+    fn count(&self, searcher: &Searcher) -> crate::Result<usize> {
         self.as_ref().count(searcher)
     }
 

src/query/query_parser/logical_ast.rs

@@ -21,6 +21,17 @@ pub enum LogicalLiteral {
 pub enum LogicalAST {
     Clause(Vec<(Occur, LogicalAST)>),
     Leaf(Box<LogicalLiteral>),
+    Boost(Box<LogicalAST>, f32),
+}
+
+impl LogicalAST {
+    pub fn boost(self, boost: f32) -> LogicalAST {
+        if (boost - 1.0f32).abs() < std::f32::EPSILON {
+            self
+        } else {
+            LogicalAST::Boost(Box::new(self), boost)
+        }
+    }
 }
 
 fn occur_letter(occur: Occur) -> &'static str {
@@ -47,6 +58,7 @@ impl fmt::Debug for LogicalAST {
                 }
                 Ok(())
             }
+            LogicalAST::Boost(ref ast, boost) => write!(formatter, "{:?}^{}", ast, boost),
             LogicalAST::Leaf(ref literal) => write!(formatter, "{:?}", literal),
         }
     }

src/query/query_parser/query_parser.rs

@@ -1,6 +1,5 @@
 use super::logical_ast::*;
 use crate::core::Index;
-use crate::query::AllQuery;
 use crate::query::BooleanQuery;
 use crate::query::EmptyQuery;
 use crate::query::Occur;
@@ -8,11 +7,13 @@ use crate::query::PhraseQuery;
 use crate::query::Query;
 use crate::query::RangeQuery;
 use crate::query::TermQuery;
+use crate::query::{AllQuery, BoostQuery};
 use crate::schema::{Facet, IndexRecordOption};
 use crate::schema::{Field, Schema};
 use crate::schema::{FieldType, Term};
 use crate::tokenizer::TokenizerManager;
 use std::borrow::Cow;
+use std::collections::HashMap;
 use std::num::{ParseFloatError, ParseIntError};
 use std::ops::Bound;
 use std::str::FromStr;
@@ -144,7 +145,6 @@ fn trim_ast(logical_ast: LogicalAST) -> Option<LogicalAST> {
 ///
 /// * must terms: By prepending a term by a `+`, a term can be made required for the search.
 ///
-///
 /// * phrase terms: Quoted terms become phrase searches on fields that have positions indexed.
 ///   e.g., `title:"Barack Obama"` will only find documents that have "barack" immediately followed
 ///   by "obama".
@@ -158,12 +158,30 @@ fn trim_ast(logical_ast: LogicalAST) -> Option<LogicalAST> {
 ///
 /// *  all docs query: A plain `*` will match all documents in the index.
 ///
+/// Parts of the queries can be boosted by appending `^boostfactor`.
+/// For instance, `"SRE"^2.0 OR devops^0.4` will boost documents containing `SRE` instead of
+/// devops. Negative boosts are not allowed.
+///
+/// It is also possible to define a boost for a some specific field, at the query parser level.
+/// (See [`set_boost(...)`](#method.set_field_boost) ). Typically you may want to boost a title
+/// field.
 #[derive(Clone)]
 pub struct QueryParser {
     schema: Schema,
     default_fields: Vec<Field>,
     conjunction_by_default: bool,
     tokenizer_manager: TokenizerManager,
+    boost: HashMap<Field, f32>,
+}
+
+fn all_negative(ast: &LogicalAST) -> bool {
+    match ast {
+        LogicalAST::Leaf(_) => false,
+        LogicalAST::Boost(ref child_ast, _) => all_negative(&*child_ast),
+        LogicalAST::Clause(children) => children
+            .iter()
+            .all(|(ref occur, child)| (*occur == Occur::MustNot) || all_negative(child)),
+    }
 }
 
 impl QueryParser {
@@ -181,6 +199,7 @@ impl QueryParser {
             default_fields,
             tokenizer_manager,
             conjunction_by_default: false,
+            boost: Default::default(),
         }
     }
 
@@ -201,6 +220,17 @@ impl QueryParser {
         self.conjunction_by_default = true;
     }
 
+    /// Sets a boost for a specific field.
+    ///
+    /// The parse query will automatically boost this field.
+    ///
+    /// If the query defines a query boost through the query language (e.g: `country:France^3.0`),
+    /// the two boosts (the one defined in the query, and the one defined in the `QueryParser`)
+    /// are multiplied together.
+    pub fn set_field_boost(&mut self, field: Field, boost: f32) {
+        self.boost.insert(field, boost);
+    }
+
     /// Parse a query
     ///
     /// Note that `parse_query` returns an error if the input
@@ -233,8 +263,13 @@ impl QueryParser {
         &self,
         user_input_ast: UserInputAST,
     ) -> Result<LogicalAST, QueryParserError> {
-        let (occur, ast) = self.compute_logical_ast_with_occur(user_input_ast)?;
-        if occur == Occur::MustNot {
+        let ast = self.compute_logical_ast_with_occur(user_input_ast)?;
+        if let LogicalAST::Clause(children) = &ast {
+            if children.is_empty() {
+                return Ok(ast);
+            }
+        }
+        if all_negative(&ast) {
             return Err(QueryParserError::AllButQueryForbidden);
         }
         Ok(ast)
@@ -390,30 +425,30 @@ impl QueryParser {
     fn compute_logical_ast_with_occur(
         &self,
         user_input_ast: UserInputAST,
-    ) -> Result<(Occur, LogicalAST), QueryParserError> {
+    ) -> Result<LogicalAST, QueryParserError> {
         match user_input_ast {
             UserInputAST::Clause(sub_queries) => {
                 let default_occur = self.default_occur();
                 let mut logical_sub_queries: Vec<(Occur, LogicalAST)> = Vec::new();
-                for sub_query in sub_queries {
-                    let (occur, sub_ast) = self.compute_logical_ast_with_occur(sub_query)?;
-                    let new_occur = Occur::compose(default_occur, occur);
-                    logical_sub_queries.push((new_occur, sub_ast));
+                for (occur_opt, sub_ast) in sub_queries {
+                    let sub_ast = self.compute_logical_ast_with_occur(sub_ast)?;
+                    let occur = occur_opt.unwrap_or(default_occur);
+                    logical_sub_queries.push((occur, sub_ast));
                 }
-                Ok((Occur::Should, LogicalAST::Clause(logical_sub_queries)))
+                Ok(LogicalAST::Clause(logical_sub_queries))
             }
-            UserInputAST::Unary(left_occur, subquery) => {
-                let (right_occur, logical_sub_queries) =
-                    self.compute_logical_ast_with_occur(*subquery)?;
-                Ok((Occur::compose(left_occur, right_occur), logical_sub_queries))
-            }
-            UserInputAST::Leaf(leaf) => {
-                let result_ast = self.compute_logical_ast_from_leaf(*leaf)?;
-                Ok((Occur::Should, result_ast))
+            UserInputAST::Boost(ast, boost) => {
+                let ast = self.compute_logical_ast_with_occur(*ast)?;
+                Ok(ast.boost(boost))
             }
+            UserInputAST::Leaf(leaf) => self.compute_logical_ast_from_leaf(*leaf),
         }
     }
 
+    fn field_boost(&self, field: Field) -> f32 {
+        self.boost.get(&field).cloned().unwrap_or(1.0f32)
+    }
+
     fn compute_logical_ast_from_leaf(
         &self,
         leaf: UserInputLeaf,
@@ -439,7 +474,9 @@ impl QueryParser {
                 let mut asts: Vec<LogicalAST> = Vec::new();
                 for (field, phrase) in term_phrases {
                     if let Some(ast) = self.compute_logical_ast_for_leaf(field, &phrase)? {
-                        asts.push(LogicalAST::Leaf(Box::new(ast)));
+                        // Apply some field specific boost defined at the query parser level.
+                        let boost = self.field_boost(field);
+                        asts.push(LogicalAST::Leaf(Box::new(ast)).boost(boost));
                     }
                 }
                 let result_ast: LogicalAST = if asts.len() == 1 {
@@ -459,14 +496,16 @@ impl QueryParser {
                 let mut clauses = fields
                     .iter()
                     .map(|&field| {
+                        let boost = self.field_boost(field);
                         let field_entry = self.schema.get_field_entry(field);
                         let value_type = field_entry.field_type().value_type();
-                        Ok(LogicalAST::Leaf(Box::new(LogicalLiteral::Range {
+                        let logical_ast = LogicalAST::Leaf(Box::new(LogicalLiteral::Range {
                             field,
                             value_type,
                             lower: self.resolve_bound(field, &lower)?,
                             upper: self.resolve_bound(field, &upper)?,
-                        })))
+                        }));
+                        Ok(logical_ast.boost(boost))
                     })
                     .collect::<Result<Vec<_>, QueryParserError>>()?;
                 let result_ast = if clauses.len() == 1 {
@@ -519,6 +558,11 @@ fn convert_to_query(logical_ast: LogicalAST) -> Box<dyn Query> {
         Some(LogicalAST::Leaf(trimmed_logical_literal)) => {
             convert_literal_to_query(*trimmed_logical_literal)
         }
+        Some(LogicalAST::Boost(ast, boost)) => {
+            let query = convert_to_query(*ast);
+            let boosted_query = BoostQuery::new(query, boost);
+            Box::new(boosted_query)
+        }
         None => Box::new(EmptyQuery),
     }
 }
@@ -538,7 +582,7 @@ mod test {
     use crate::Index;
     use matches::assert_matches;
 
-    fn make_query_parser() -> QueryParser {
+    fn make_schema() -> Schema {
         let mut schema_builder = Schema::builder();
         let text_field_indexing = TextFieldIndexing::default()
             .set_tokenizer("en_with_stop_words")
@@ -546,8 +590,8 @@ mod test {
         let text_options = TextOptions::default()
             .set_indexing_options(text_field_indexing)
             .set_stored();
-        let title = schema_builder.add_text_field("title", TEXT);
-        let text = schema_builder.add_text_field("text", TEXT);
+        schema_builder.add_text_field("title", TEXT);
+        schema_builder.add_text_field("text", TEXT);
         schema_builder.add_i64_field("signed", INDEXED);
         schema_builder.add_u64_field("unsigned", INDEXED);
         schema_builder.add_text_field("notindexed_text", STORED);
@@ -558,8 +602,15 @@ mod test {
         schema_builder.add_date_field("date", INDEXED);
         schema_builder.add_f64_field("float", INDEXED);
         schema_builder.add_facet_field("facet");
-        let schema = schema_builder.build();
-        let default_fields = vec![title, text];
+        schema_builder.build()
+    }
+
+    fn make_query_parser() -> QueryParser {
+        let schema = make_schema();
+        let default_fields: Vec<Field> = vec!["title", "text"]
+            .into_iter()
+            .flat_map(|field_name| schema.get_field(field_name))
+            .collect();
         let tokenizer_manager = TokenizerManager::default();
         tokenizer_manager.register(
             "en_with_stop_words",
@@ -601,6 +652,45 @@ mod test {
         );
     }
 
+    #[test]
+    pub fn test_parse_query_with_boost() {
+        let mut query_parser = make_query_parser();
+        let schema = make_schema();
+        let text_field = schema.get_field("text").unwrap();
+        query_parser.set_field_boost(text_field, 2.0f32);
+        let query = query_parser.parse_query("text:hello").unwrap();
+        assert_eq!(
+            format!("{:?}", query),
+            "Boost(query=TermQuery(Term(field=1,bytes=[104, 101, 108, 108, 111])), boost=2)"
+        );
+    }
+
+    #[test]
+    pub fn test_parse_query_range_with_boost() {
+        let mut query_parser = make_query_parser();
+        let schema = make_schema();
+        let title_field = schema.get_field("title").unwrap();
+        query_parser.set_field_boost(title_field, 2.0f32);
+        let query = query_parser.parse_query("title:[A TO B]").unwrap();
+        assert_eq!(
+            format!("{:?}", query),
+            "Boost(query=RangeQuery { field: Field(0), value_type: Str, left_bound: Included([97]), right_bound: Included([98]) }, boost=2)"
+        );
+    }
+
+    #[test]
+    pub fn test_parse_query_with_default_boost_and_custom_boost() {
+        let mut query_parser = make_query_parser();
+        let schema = make_schema();
+        let text_field = schema.get_field("text").unwrap();
+        query_parser.set_field_boost(text_field, 2.0f32);
+        let query = query_parser.parse_query("text:hello^2").unwrap();
+        assert_eq!(
+            format!("{:?}", query),
+            "Boost(query=Boost(query=TermQuery(Term(field=1,bytes=[104, 101, 108, 108, 111])), boost=2), boost=2)"
+        );
+    }
+
     #[test]
     pub fn test_parse_nonindexed_field_yields_error() {
         let query_parser = make_query_parser();
@@ -699,6 +789,20 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_parse_query_to_ast_ab_c() {
+        test_parse_query_to_logical_ast_helper(
+            "(+title:a +title:b) title:c",
+            "((+Term(field=0,bytes=[97]) +Term(field=0,bytes=[98])) Term(field=0,bytes=[99]))",
+            false,
+        );
+        test_parse_query_to_logical_ast_helper(
+            "(+title:a +title:b) title:c",
+            "(+(+Term(field=0,bytes=[97]) +Term(field=0,bytes=[98])) +Term(field=0,bytes=[99]))",
+            true,
+        );
+    }
+
     #[test]
     pub fn test_parse_query_to_ast_single_term() {
         test_parse_query_to_logical_ast_helper(
@@ -718,11 +822,13 @@ mod test {
              Term(field=1,bytes=[116, 105, 116, 105])))",
             false,
         );
-        assert_eq!(
-            parse_query_to_logical_ast("-title:toto", false)
-                .err()
-                .unwrap(),
-            QueryParserError::AllButQueryForbidden
+    }
+
+    #[test]
+    fn test_single_negative_term() {
+        assert_matches!(
+            parse_query_to_logical_ast("-title:toto", false),
+            Err(QueryParserError::AllButQueryForbidden)
         );
     }
 
@@ -882,6 +988,18 @@ mod test {
         assert!(query_parser.parse_query("with_stop_words:the").is_ok());
     }
 
+    #[test]
+    pub fn test_parse_query_single_negative_term_through_error() {
+        assert_matches!(
+            parse_query_to_logical_ast("-title:toto", true),
+            Err(QueryParserError::AllButQueryForbidden)
+        );
+        assert_matches!(
+            parse_query_to_logical_ast("-title:toto", false),
+            Err(QueryParserError::AllButQueryForbidden)
+        );
+    }
+
     #[test]
     pub fn test_parse_query_to_ast_conjunction() {
         test_parse_query_to_logical_ast_helper(
@@ -901,12 +1019,6 @@ mod test {
              Term(field=1,bytes=[116, 105, 116, 105])))",
             true,
         );
-        assert_eq!(
-            parse_query_to_logical_ast("-title:toto", true)
-                .err()
-                .unwrap(),
-            QueryParserError::AllButQueryForbidden
-        );
         test_parse_query_to_logical_ast_helper(
             "title:a b",
             "(+Term(field=0,bytes=[97]) \
@@ -930,4 +1042,26 @@ mod test {
             false
         );
     }
+
+    #[test]
+    fn test_and_default_regardless_of_default_conjunctive() {
+        for &default_conjunction in &[false, true] {
+            test_parse_query_to_logical_ast_helper(
+                "title:a AND title:b",
+                "(+Term(field=0,bytes=[97]) +Term(field=0,bytes=[98]))",
+                default_conjunction,
+            );
+        }
+    }
+
+    #[test]
+    fn test_or_default_conjunctive() {
+        for &default_conjunction in &[false, true] {
+            test_parse_query_to_logical_ast_helper(
+                "title:a OR title:b",
+                "(Term(field=0,bytes=[97]) Term(field=0,bytes=[98]))",
+                default_conjunction,
+            );
+        }
+    }
 }

src/query/range_query.rs

@@ -289,7 +289,7 @@ impl RangeWeight {
 }
 
 impl Weight for RangeWeight {
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
+    fn scorer(&self, reader: &SegmentReader, boost: f32) -> Result<Box<dyn Scorer>> {
         let max_doc = reader.max_doc();
         let mut doc_bitset = BitSet::with_max_value(max_doc);
 
@@ -307,11 +307,11 @@ impl Weight for RangeWeight {
             }
         }
         let doc_bitset = BitSetDocSet::from(doc_bitset);
-        Ok(Box::new(ConstScorer::new(doc_bitset)))
+        Ok(Box::new(ConstScorer::new(doc_bitset, boost)))
     }
 
     fn explain(&self, reader: &SegmentReader, doc: DocId) -> Result<Explanation> {
-        let mut scorer = self.scorer(reader)?;
+        let mut scorer = self.scorer(reader, 1.0f32)?;
         if scorer.skip_next(doc) != SkipResult::Reached {
             return Err(does_not_match(doc));
         }

src/query/regex_query.rs

@@ -1,7 +1,6 @@
 use crate::error::TantivyError;
 use crate::query::{AutomatonWeight, Query, Weight};
 use crate::schema::Field;
-use crate::Result;
 use crate::Searcher;
 use std::clone::Clone;
 use std::sync::Arc;
@@ -58,7 +57,7 @@ pub struct RegexQuery {
 
 impl RegexQuery {
     /// Creates a new RegexQuery from a given pattern
-    pub fn from_pattern(regex_pattern: &str, field: Field) -> Result<Self> {
+    pub fn from_pattern(regex_pattern: &str, field: Field) -> crate::Result<Self> {
         let regex = Regex::new(&regex_pattern)
             .map_err(|_| TantivyError::InvalidArgument(regex_pattern.to_string()))?;
         Ok(RegexQuery::from_regex(regex, field))
@@ -78,7 +77,11 @@ impl RegexQuery {
 }
 
 impl Query for RegexQuery {
-    fn weight(&self, _searcher: &Searcher, _scoring_enabled: bool) -> Result<Box<dyn Weight>> {
+    fn weight(
+        &self,
+        _searcher: &Searcher,
+        _scoring_enabled: bool,
+    ) -> crate::Result<Box<dyn Weight>> {
         Ok(Box::new(self.specialized_weight()))
     }
 }

src/query/reqopt_scorer.rs

@@ -115,8 +115,8 @@ mod tests {
         let req = vec![1, 3, 7];
         let mut reqoptscorer: RequiredOptionalScorer<_, _, SumCombiner> =
             RequiredOptionalScorer::new(
-                ConstScorer::new(VecDocSet::from(req.clone())),
-                ConstScorer::new(VecDocSet::from(vec![])),
+                ConstScorer::from(VecDocSet::from(req.clone())),
+                ConstScorer::from(VecDocSet::from(vec![])),
             );
         let mut docs = vec![];
         while reqoptscorer.advance() {
@@ -129,8 +129,8 @@ mod tests {
     fn test_reqopt_scorer() {
         let mut reqoptscorer: RequiredOptionalScorer<_, _, SumCombiner> =
             RequiredOptionalScorer::new(
-                ConstScorer::new(VecDocSet::from(vec![1, 3, 7, 8, 9, 10, 13, 15])),
-                ConstScorer::new(VecDocSet::from(vec![1, 2, 7, 11, 12, 15])),
+                ConstScorer::new(VecDocSet::from(vec![1, 3, 7, 8, 9, 10, 13, 15]), 1.0f32),
+                ConstScorer::new(VecDocSet::from(vec![1, 2, 7, 11, 12, 15]), 1.0f32),
             );
         {
             assert!(reqoptscorer.advance());
@@ -183,8 +183,8 @@ mod tests {
         test_skip_against_unoptimized(
             || {
                 Box::new(RequiredOptionalScorer::<_, _, DoNothingCombiner>::new(
-                    ConstScorer::new(VecDocSet::from(req_docs.clone())),
-                    ConstScorer::new(VecDocSet::from(opt_docs.clone())),
+                    ConstScorer::from(VecDocSet::from(req_docs.clone())),
+                    ConstScorer::from(VecDocSet::from(opt_docs.clone())),
                 ))
             },
             skip_docs,

src/query/scorer.rs

@@ -4,6 +4,8 @@ use crate::DocId;
 use crate::Score;
 use downcast_rs::impl_downcast;
 use std::ops::DerefMut;
+use crate::collector::{SegmentCollector, Collector, TopDocs, Count};
+
 
 /// Scored set of documents matching a query within a specific segment.
 ///
@@ -21,6 +23,12 @@ pub trait Scorer: downcast_rs::Downcast + DocSet + 'static {
             callback(self.doc(), self.score());
         }
     }
+
+    fn top_k(&mut self, collector: &mut <(Count, TopDocs) as Collector>::Child) {
+        while self.advance() {
+            collector.collect(self.doc(), self.score());
+        }
+    }
 }
 
 impl_downcast!(Scorer);
@@ -49,16 +57,14 @@ pub struct ConstScorer<TDocSet: DocSet> {
 
 impl<TDocSet: DocSet> ConstScorer<TDocSet> {
     /// Creates a new `ConstScorer`.
-    pub fn new(docset: TDocSet) -> ConstScorer<TDocSet> {
-        ConstScorer {
-            docset,
-            score: 1f32,
-        }
+    pub fn new(docset: TDocSet, score: f32) -> ConstScorer<TDocSet> {
+        ConstScorer { docset, score }
     }
+}
 
-    /// Sets the constant score to a different value.
-    pub fn set_score(&mut self, score: Score) {
-        self.score = score;
+impl<TDocSet: DocSet> From<TDocSet> for ConstScorer<TDocSet> {
+    fn from(docset: TDocSet) -> Self {
+        ConstScorer::new(docset, 1.0f32)
     }
 }
 
@@ -90,6 +96,6 @@ impl<TDocSet: DocSet> DocSet for ConstScorer<TDocSet> {
 
 impl<TDocSet: DocSet + 'static> Scorer for ConstScorer<TDocSet> {
     fn score(&mut self) -> Score {
-        1f32
+        self.score
     }
 }

src/query/term_query/mod.rs

@@ -39,7 +39,7 @@ mod tests {
         );
         let term_weight = term_query.weight(&searcher, true).unwrap();
         let segment_reader = searcher.segment_reader(0);
-        let mut term_scorer = term_weight.scorer(segment_reader).unwrap();
+        let mut term_scorer = term_weight.scorer(segment_reader, 1.0f32).unwrap();
         assert!(term_scorer.advance());
         assert_eq!(term_scorer.doc(), 0);
         assert_eq!(term_scorer.score(), 0.28768212);

src/query/term_query/term_query.rs

@@ -3,7 +3,6 @@ use crate::query::bm25::BM25Weight;
 use crate::query::Query;
 use crate::query::Weight;
 use crate::schema::IndexRecordOption;
-use crate::Result;
 use crate::Searcher;
 use crate::Term;
 use std::collections::BTreeSet;
@@ -101,7 +100,7 @@ impl TermQuery {
 }
 
 impl Query for TermQuery {
-    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> Result<Box<dyn Weight>> {
+    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> crate::Result<Box<dyn Weight>> {
         Ok(Box::new(self.specialized_weight(searcher, scoring_enabled)))
     }
     fn query_terms(&self, term_set: &mut BTreeSet<Term>) {

src/query/term_query/term_weight.rs

@@ -18,13 +18,13 @@ pub struct TermWeight {
 }
 
 impl Weight for TermWeight {
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
-        let term_scorer = self.scorer_specialized(reader)?;
+    fn scorer(&self, reader: &SegmentReader, boost: f32) -> Result<Box<dyn Scorer>> {
+        let term_scorer = self.scorer_specialized(reader, boost)?;
         Ok(Box::new(term_scorer))
     }
 
     fn explain(&self, reader: &SegmentReader, doc: DocId) -> Result<Explanation> {
-        let mut scorer = self.scorer_specialized(reader)?;
+        let mut scorer = self.scorer_specialized(reader, 1.0f32)?;
         if scorer.skip_next(doc) != SkipResult::Reached {
             return Err(does_not_match(doc));
         }
@@ -33,7 +33,7 @@ impl Weight for TermWeight {
 
     fn count(&self, reader: &SegmentReader) -> Result<u32> {
         if let Some(delete_bitset) = reader.delete_bitset() {
-            Ok(self.scorer(reader)?.count(delete_bitset))
+            Ok(self.scorer(reader, 1.0f32)?.count(delete_bitset))
         } else {
             let field = self.term.field();
             Ok(reader
@@ -58,11 +58,11 @@ impl TermWeight {
         }
     }
 
-    fn scorer_specialized(&self, reader: &SegmentReader) -> Result<TermScorer> {
+    fn scorer_specialized(&self, reader: &SegmentReader, boost: f32) -> Result<TermScorer> {
         let field = self.term.field();
         let inverted_index = reader.inverted_index(field);
         let fieldnorm_reader = reader.get_fieldnorms_reader(field);
-        let similarity_weight = self.similarity_weight.clone();
+        let similarity_weight = self.similarity_weight.boost_by(boost);
         let postings_opt: Option<SegmentPostings> =
             inverted_index.read_postings(&self.term, self.index_record_option);
         if let Some(segment_postings) = postings_opt {

src/query/union.rs

@@ -145,26 +145,6 @@ where
         }
     }
 
-    fn count_including_deleted(&mut self) -> u32 {
-        let mut count = self.bitsets[self.cursor..HORIZON_NUM_TINYBITSETS]
-            .iter()
-            .map(|bitset| bitset.len())
-            .sum::<u32>();
-        for bitset in self.bitsets.iter_mut() {
-            bitset.clear();
-        }
-        while self.refill() {
-            count += self.bitsets.iter().map(|bitset| bitset.len()).sum::<u32>();
-            for bitset in self.bitsets.iter_mut() {
-                bitset.clear();
-            }
-        }
-        self.cursor = HORIZON_NUM_TINYBITSETS;
-        count
-    }
-
-    // TODO implement `count` efficiently.
-
     fn skip_next(&mut self, target: DocId) -> SkipResult {
         if !self.advance() {
             return SkipResult::End;
@@ -243,6 +223,8 @@ where
         }
     }
 
+    // TODO implement `count` efficiently.
+
     fn doc(&self) -> DocId {
         self.doc
     }
@@ -250,6 +232,24 @@ where
     fn size_hint(&self) -> u32 {
         0u32
     }
+
+    fn count_including_deleted(&mut self) -> u32 {
+        let mut count = self.bitsets[self.cursor..HORIZON_NUM_TINYBITSETS]
+            .iter()
+            .map(|bitset| bitset.len())
+            .sum::<u32>();
+        for bitset in self.bitsets.iter_mut() {
+            bitset.clear();
+        }
+        while self.refill() {
+            count += self.bitsets.iter().map(|bitset| bitset.len()).sum::<u32>();
+            for bitset in self.bitsets.iter_mut() {
+                bitset.clear();
+            }
+        }
+        self.cursor = HORIZON_NUM_TINYBITSETS;
+        count
+    }
 }
 
 impl<TScorer, TScoreCombiner> Scorer for Union<TScorer, TScoreCombiner>
@@ -290,7 +290,7 @@ mod tests {
                 vals.iter()
                     .cloned()
                     .map(VecDocSet::from)
-                    .map(ConstScorer::new)
+                    .map(|docset| ConstScorer::new(docset, 1.0f32))
                     .collect::<Vec<ConstScorer<VecDocSet>>>(),
             )
         };
@@ -339,7 +339,7 @@ mod tests {
                     .iter()
                     .map(|docs| docs.clone())
                     .map(VecDocSet::from)
-                    .map(ConstScorer::new)
+                    .map(|docset| ConstScorer::new(docset, 1.0f32))
                     .collect::<Vec<_>>(),
             ));
             res
@@ -369,8 +369,8 @@ mod tests {
     #[test]
     fn test_union_skip_corner_case3() {
         let mut docset = Union::<_, DoNothingCombiner>::from(vec![
-            ConstScorer::new(VecDocSet::from(vec![0u32, 5u32])),
-            ConstScorer::new(VecDocSet::from(vec![1u32, 4u32])),
+            ConstScorer::from(VecDocSet::from(vec![0u32, 5u32])),
+            ConstScorer::from(VecDocSet::from(vec![1u32, 4u32])),
         ]);
         assert!(docset.advance());
         assert_eq!(docset.doc(), 0u32);

src/query/weight.rs

@@ -1,7 +1,7 @@
 use super::Scorer;
 use crate::core::SegmentReader;
 use crate::query::Explanation;
-use crate::{DocId, Result};
+use crate::DocId;
 
 /// A Weight is the specialization of a Query
 /// for a given set of segments.
@@ -9,15 +9,18 @@ use crate::{DocId, Result};
 /// See [`Query`](./trait.Query.html).
 pub trait Weight: Send + Sync + 'static {
     /// Returns the scorer for the given segment.
+    ///
+    /// `boost` is a multiplier to apply to the score.
+    ///
     /// See [`Query`](./trait.Query.html).
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>>;
+    fn scorer(&self, reader: &SegmentReader, boost: f32) -> crate::Result<Box<dyn Scorer>>;
 
     /// Returns an `Explanation` for the given document.
-    fn explain(&self, reader: &SegmentReader, doc: DocId) -> Result<Explanation>;
+    fn explain(&self, reader: &SegmentReader, doc: DocId) -> crate::Result<Explanation>;
 
     /// Returns the number documents within the given `SegmentReader`.
-    fn count(&self, reader: &SegmentReader) -> Result<u32> {
-        let mut scorer = self.scorer(reader)?;
+    fn count(&self, reader: &SegmentReader) -> crate::Result<u32> {
+        let mut scorer = self.scorer(reader, 1.0f32)?;
         if let Some(delete_bitset) = reader.delete_bitset() {
             Ok(scorer.count(delete_bitset))
         } else {

src/reader/mod.rs

@@ -7,7 +7,6 @@ use crate::directory::Directory;
 use crate::directory::WatchHandle;
 use crate::directory::META_LOCK;
 use crate::Index;
-use crate::Result;
 use crate::Searcher;
 use crate::SegmentReader;
 use std::sync::Arc;
@@ -62,7 +61,7 @@ impl IndexReaderBuilder {
     /// to open different segment readers. It may take hundreds of milliseconds
     /// of time and it may return an error.
     /// TODO(pmasurel) Use the `TryInto` trait once it is available in stable.
-    pub fn try_into(self) -> Result<IndexReader> {
+    pub fn try_into(self) -> crate::Result<IndexReader> {
         let inner_reader = InnerIndexReader {
             index: self.index,
             num_searchers: self.num_searchers,
@@ -121,14 +120,14 @@ struct InnerIndexReader {
 }
 
 impl InnerIndexReader {
-    fn reload(&self) -> Result<()> {
+    fn reload(&self) -> crate::Result<()> {
         let segment_readers: Vec<SegmentReader> = {
             let _meta_lock = self.index.directory().acquire_lock(&META_LOCK)?;
             let searchable_segments = self.searchable_segments()?;
             searchable_segments
                 .iter()
                 .map(SegmentReader::open)
-                .collect::<Result<_>>()?
+                .collect::<crate::Result<_>>()?
         };
         let schema = self.index.schema();
         let searchers = (0..self.num_searchers)
@@ -139,7 +138,7 @@ impl InnerIndexReader {
     }
 
     /// Returns the list of segments that are searchable
-    fn searchable_segments(&self) -> Result<Vec<Segment>> {
+    fn searchable_segments(&self) -> crate::Result<Vec<Segment>> {
         self.index.searchable_segments()
     }
 
@@ -176,7 +175,7 @@ impl IndexReader {
     ///
     /// This automatic reload can take 10s of milliseconds to kick in however, and in unit tests
     /// it can be nice to deterministically force the reload of searchers.
-    pub fn reload(&self) -> Result<()> {
+    pub fn reload(&self) -> crate::Result<()> {
         self.inner.reload()
     }
 

src/reader/pool.rs

@@ -68,7 +68,9 @@ impl<T> Pool<T> {
     /// After publish, all new `Searcher` acquired will be
     /// of the new generation.
     pub fn publish_new_generation(&self, items: Vec<T>) {
+        assert!(!items.is_empty());
         let next_generation = self.next_generation.fetch_add(1, Ordering::SeqCst) + 1;
+        let num_items = items.len();
         for item in items {
             let gen_item = GenerationItem {
                 item,
@@ -77,6 +79,23 @@ impl<T> Pool<T> {
             self.queue.push(gen_item);
         }
         self.advertise_generation(next_generation);
+        // Purge possible previous searchers.
+        //
+        // Assuming at this point no searcher is held more than duration T by the user,
+        // this guarantees that an obsolete searcher will not be uselessly held (and its associated
+        // mmap) for more than duration T.
+        //
+        // Proof: At this point, obsolete searcher that are held by the user will be held for less
+        // than T. When released, they will be dropped as their generation is detected obsolete.
+        //
+        // We still need to ensure that the searcher that are obsolete and in the pool get removed.
+        // The queue currently contains up to 2n searchers, in any random order.
+        //
+        // Half of them are obsoletes. By requesting `(n+1)` fresh searchers, we ensure that all
+        // searcher will be inspected.
+        for _ in 0..=num_items {
+            let _ = self.acquire();
+        }
     }
 
     /// At the exit of this method,

src/schema/document.rs

@@ -3,8 +3,9 @@ use crate::common::BinarySerializable;
 use crate::common::VInt;
 use crate::tokenizer::PreTokenizedString;
 use crate::DateTime;
-use itertools::Itertools;
+use serde;
 use std::io::{self, Read, Write};
+use std::mem;
 
 /// Tantivy's Document is the object that can
 /// be indexed and then searched for.
@@ -16,7 +17,7 @@ use std::io::{self, Read, Write};
 
 /// Documents are really just a list of couple `(field, value)`.
 /// In this list, one field may appear more than once.
-#[derive(Clone, Debug, Serialize, Deserialize, Default)]
+#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, Default)]
 pub struct Document {
     field_values: Vec<FieldValue>,
 }
@@ -131,12 +132,34 @@ impl Document {
     pub fn get_sorted_field_values(&self) -> Vec<(Field, Vec<&FieldValue>)> {
         let mut field_values: Vec<&FieldValue> = self.field_values().iter().collect();
         field_values.sort_by_key(|field_value| field_value.field());
-        field_values
-            .into_iter()
-            .group_by(|field_value| field_value.field())
-            .into_iter()
-            .map(|(key, group)| (key, group.collect()))
-            .collect::<Vec<(Field, Vec<&FieldValue>)>>()
+
+        let mut grouped_field_values = vec![];
+
+        let mut current_field;
+        let mut current_group;
+
+        let mut field_values_it = field_values.into_iter();
+        if let Some(field_value) = field_values_it.next() {
+            current_field = field_value.field();
+            current_group = vec![field_value]
+        } else {
+            return grouped_field_values;
+        }
+
+        for field_value in field_values_it {
+            if field_value.field() == current_field {
+                current_group.push(field_value);
+            } else {
+                grouped_field_values.push((
+                    current_field,
+                    mem::replace(&mut current_group, vec![field_value]),
+                ));
+                current_field = field_value.field();
+            }
+        }
+
+        grouped_field_values.push((current_field, current_group));
+        grouped_field_values
     }
 
     /// Returns all of the `FieldValue`s associated the given field

src/schema/facet.rs

@@ -125,7 +125,7 @@ impl Facet {
 
     /// This function is the inverse of Facet::from(&str).
     pub fn to_path_string(&self) -> String {
-        format!("{}", self.to_string())
+        format!("{}", self)
     }
 }
 

src/schema/field.rs

@@ -1,11 +1,14 @@
 use crate::common::BinarySerializable;
+use serde;
 use std::io;
 use std::io::Read;
 use std::io::Write;
 
 /// `Field` is represented by an unsigned 32-bit integer type
 /// The schema holds the mapping between field names and `Field` objects.
-#[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Eq, Ord, Hash, Serialize, Deserialize)]
+#[derive(
+    Copy, Clone, Debug, PartialEq, PartialOrd, Eq, Ord, Hash, serde::Serialize, serde::Deserialize,
+)]
 pub struct Field(u32);
 
 impl Field {

src/schema/field_value.rs

@@ -1,12 +1,13 @@
 use crate::common::BinarySerializable;
 use crate::schema::Field;
 use crate::schema::Value;
+use serde;
 use std::io;
 use std::io::Read;
 use std::io::Write;
 
 /// `FieldValue` holds together a `Field` and its `Value`.
-#[derive(Debug, Clone, Ord, PartialEq, Eq, PartialOrd, Serialize, Deserialize)]
+#[derive(Debug, Clone, Ord, PartialEq, Eq, PartialOrd, serde::Serialize, serde::Deserialize)]
 pub struct FieldValue {
     field: Field,
     value: Value,

src/schema/index_record_option.rs

@@ -1,3 +1,5 @@
+use serde::{Deserialize, Serialize};
+
 /// `IndexRecordOption` describes an amount information associated
 /// to a given indexed field.
 ///

src/schema/int_options.rs

@@ -1,4 +1,5 @@
 use crate::schema::flags::{FastFlag, IndexedFlag, SchemaFlagList, StoredFlag};
+use serde::{Deserialize, Serialize};
 use std::ops::BitOr;
 
 /// Express whether a field is single-value or multi-valued.

src/schema/named_field_document.rs

@@ -1,4 +1,5 @@
 use crate::schema::Value;
+use serde::Serialize;
 use std::collections::BTreeMap;
 
 /// Internal representation of a document used for JSON

src/schema/text_options.rs

@@ -1,6 +1,7 @@
 use crate::schema::flags::SchemaFlagList;
 use crate::schema::flags::StoredFlag;
 use crate::schema::IndexRecordOption;
+use serde::{Deserialize, Serialize};
 use std::borrow::Cow;
 use std::ops::BitOr;
 
@@ -155,30 +156,17 @@ mod tests {
 
     #[test]
     fn test_field_options() {
-        {
-            let field_options = STORED | TEXT;
-            assert!(field_options.is_stored());
-            assert!(field_options.get_indexing_options().is_some());
-        }
-        {
-            let mut schema_builder = Schema::builder();
-            schema_builder.add_text_field("body", TEXT);
-            let schema = schema_builder.build();
-            let field = schema.get_field("body").unwrap();
-            let field_entry = schema.get_field_entry(field);
-            match field_entry.field_type() {
-                &FieldType::Str(ref text_options) => {
-                    assert!(text_options.get_indexing_options().is_some());
-                    assert_eq!(
-                        text_options.get_indexing_options().unwrap().tokenizer(),
-                        "default"
-                    );
-                }
-                _ => {
-                    panic!("");
-                }
-            }
-        }
+        let field_options = STORED | TEXT;
+        assert!(field_options.is_stored());
+        assert!(field_options.get_indexing_options().is_some());
+        let mut schema_builder = Schema::builder();
+        schema_builder.add_text_field("body", TEXT);
+        let schema = schema_builder.build();
+        let field = schema.get_field("body").unwrap();
+        let field_entry = schema.get_field_entry(field);
+        assert!(matches!(field_entry.field_type(),
+                &FieldType::Str(ref text_options)
+                if text_options.get_indexing_options().unwrap().tokenizer() == "default"));
     }
 
     #[test]

src/snippet/mod.rs

@@ -3,7 +3,6 @@ use crate::schema::Field;
 use crate::schema::Value;
 use crate::tokenizer::{TextAnalyzer, Token};
 use crate::Document;
-use crate::Result;
 use crate::Searcher;
 use htmlescape::encode_minimal;
 use std::cmp::Ordering;
@@ -261,7 +260,7 @@ impl SnippetGenerator {
         searcher: &Searcher,
         query: &dyn Query,
         field: Field,
-    ) -> Result<SnippetGenerator> {
+    ) -> crate::Result<SnippetGenerator> {
         let mut terms = BTreeSet::new();
         query.query_terms(&mut terms);
         let terms_text: BTreeMap<String, f32> = terms

src/space_usage/mod.rs

@@ -11,6 +11,7 @@ under-count actual resultant space usage by up to 4095 bytes per file.
 
 use crate::schema::Field;
 use crate::SegmentComponent;
+use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 
 /// Indicates space usage in bytes

src/store/compression_snap.rs

@@ -9,7 +9,7 @@ pub const COMPRESSION: &str = "snappy";
 
 pub fn compress(uncompressed: &[u8], compressed: &mut Vec<u8>) -> io::Result<()> {
     compressed.clear();
-    let mut encoder = snap::Writer::new(compressed);
+    let mut encoder = snap::write::FrameEncoder::new(compressed);
     encoder.write_all(&uncompressed)?;
     encoder.flush()?;
     Ok(())
@@ -17,6 +17,6 @@ pub fn compress(uncompressed: &[u8], compressed: &mut Vec<u8>) -> io::Result<()>
 
 pub fn decompress(compressed: &[u8], decompressed: &mut Vec<u8>) -> io::Result<()> {
     decompressed.clear();
-    snap::Reader::new(compressed).read_to_end(decompressed)?;
+    snap::read::FrameDecoder::new(compressed).read_to_end(decompressed)?;
     Ok(())
 }

src/store/reader.rs

@@ -1,5 +1,3 @@
-use crate::Result;
-
 use super::decompress;
 use super::skiplist::SkipList;
 use crate::common::BinarySerializable;
@@ -75,7 +73,7 @@ impl StoreReader {
     ///
     /// It should not be called to score documents
     /// for instance.
-    pub fn get(&self, doc_id: DocId) -> Result<Document> {
+    pub fn get(&self, doc_id: DocId) -> crate::Result<Document> {
         let (first_doc_id, block_offset) = self.block_offset(doc_id);
         self.read_block(block_offset as usize)?;
         let current_block_mut = self.current_block.borrow_mut();

src/termdict/mod.rs

@@ -435,6 +435,7 @@ mod tests {
     #[test]
     fn test_automaton_search() {
         use levenshtein_automata::LevenshteinAutomatonBuilder;
+        use crate::query::DFAWrapper;
 
         const COUNTRIES: [&'static str; 7] = [
             "San Marino",
@@ -463,7 +464,7 @@ mod tests {
 
         // We can now build an entire dfa.
         let lev_automaton_builder = LevenshteinAutomatonBuilder::new(2, true);
-        let automaton = lev_automaton_builder.build_dfa("Spaen");
+        let automaton = DFAWrapper(lev_automaton_builder.build_dfa("Spaen"));
 
         let mut range = term_dict.search(automaton).into_stream();
 

src/tokenizer/stemmer.rs

@@ -1,6 +1,7 @@
 use super::{Token, TokenFilter, TokenStream};
 use crate::tokenizer::BoxTokenStream;
 use rust_stemmers::{self, Algorithm};
+use serde::{Deserialize, Serialize};
 
 /// Available stemmer languages.
 #[derive(Debug, Serialize, Deserialize, Eq, PartialEq, Copy, Clone)]

src/tokenizer/tokenized_string.rs

@@ -1,4 +1,5 @@
 use crate::tokenizer::{BoxTokenStream, Token, TokenStream, TokenStreamChain};
+use serde::{Deserialize, Serialize};
 use std::cmp::Ordering;
 
 /// Struct representing pre-tokenized text

src/tokenizer/tokenizer.rs

@@ -1,4 +1,5 @@
 use crate::tokenizer::TokenStreamChain;
+use serde::{Deserialize, Serialize};
 /// The tokenizer module contains all of the tools used to process
 /// text in `tantivy`.
 use std::borrow::{Borrow, BorrowMut};