Removed temporary comment

* Make Executor public so Searcher::search_in_executor method now can be used

* Fixed cargo fmt

CHANGELOG.md

@@ -1,3 +1,25 @@
+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) 
+
+## How to update?
+
+Crates relying on custom tokenizer, or registering tokenizer in the manager will require some 
+minor changes. Check https://github.com/tantivy-search/tantivy/blob/master/examples/custom_tokenizer.rs
+to check for some code sample.
+
+Tantivy 0.11.3
+=======================
+- Fixed DateTime as a fast field (#735)
+
+Tantivy 0.11.2
+=======================
+- The future returned by `IndexWriter::merge` does not borrow `self` mutably anymore (#732)
+- Exposing a constructor for `WatchHandle` (#731)
+
 Tantivy 0.11.1
 =====================
 - Bug fix #729

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "tantivy"
-version = "0.11.1"
+version = "0.12.0"
 authors = ["Paul Masurel <paul.masurel@gmail.com>"]
 license = "MIT"
 categories = ["database-implementations", "data-structures"]
@@ -18,7 +18,7 @@ byteorder = "1.0"
 crc32fast = "1.2.0"
 once_cell = "1.0"
 regex ={version = "1.3.0", default-features = false, features = ["std"]}
-tantivy-fst = "0.1"
+tantivy-fst = "0.2.1"
 memmap = {version = "0.7", optional=true}
 lz4 = {version="1.20", optional=true}
 snap = {version="0.2"}
@@ -60,7 +60,6 @@ winapi = "0.3"
 rand = "0.7"
 maplit = "1"
 matches = "0.1.8"
-time = "0.1.42"
 
 [dev-dependencies.fail]
 version = "0.3"

examples/faceted_search.rs

@@ -13,63 +13,100 @@
 // ---
 // Importing tantivy...
 use tantivy::collector::FacetCollector;
-use tantivy::query::AllQuery;
+use tantivy::query::{AllQuery, TermQuery};
 use tantivy::schema::*;
 use tantivy::{doc, Index};
-use tempfile::TempDir;
 
 fn main() -> tantivy::Result<()> {
-    // Let's create a temporary directory for the
-    // sake of this example
-    let index_path = TempDir::new()?;
+    // Let's create a temporary directory for the sake of this example
     let mut schema_builder = Schema::builder();
 
-    schema_builder.add_text_field("name", TEXT | STORED);
-
-    // this is our faceted field
-    schema_builder.add_facet_field("tags");
+    let name = schema_builder.add_text_field("felin_name", TEXT | STORED);
+    // this is our faceted field: its scientific classification
+    let classification = schema_builder.add_facet_field("classification");
 
     let schema = schema_builder.build();
+    let index = Index::create_in_ram(schema);
 
-    let index = Index::create_in_dir(&index_path, schema.clone())?;
-
-    let mut index_writer = index.writer(50_000_000)?;
-
-    let name = schema.get_field("name").unwrap();
-    let tags = schema.get_field("tags").unwrap();
+    let mut index_writer = index.writer(30_000_000)?;
 
     // For convenience, tantivy also comes with a macro to
     // reduce the boilerplate above.
     index_writer.add_document(doc!(
-        name => "the ditch",
-        tags => Facet::from("/pools/north")
+        name => "Cat",
+        classification => Facet::from("/Felidae/Felinae/Felis")
     ));
-
     index_writer.add_document(doc!(
-        name => "little stacey",
-        tags => Facet::from("/pools/south")
+        name => "Canada lynx",
+        classification => Facet::from("/Felidae/Felinae/Lynx")
+    ));
+    index_writer.add_document(doc!(
+        name => "Cheetah",
+        classification => Facet::from("/Felidae/Felinae/Acinonyx")
+    ));
+    index_writer.add_document(doc!(
+        name => "Tiger",
+        classification => Facet::from("/Felidae/Pantherinae/Panthera")
+    ));
+    index_writer.add_document(doc!(
+        name => "Lion",
+        classification => Facet::from("/Felidae/Pantherinae/Panthera")
+    ));
+    index_writer.add_document(doc!(
+        name => "Jaguar",
+        classification => Facet::from("/Felidae/Pantherinae/Panthera")
+    ));
+    index_writer.add_document(doc!(
+        name => "Sunda clouded leopard",
+        classification => Facet::from("/Felidae/Pantherinae/Neofelis")
+    ));
+    index_writer.add_document(doc!(
+        name => "Fossa",
+        classification => Facet::from("/Eupleridae/Cryptoprocta")
     ));
-
     index_writer.commit()?;
 
     let reader = index.reader()?;
-
     let searcher = reader.searcher();
+    {
+        let mut facet_collector = FacetCollector::for_field(classification);
+        facet_collector.add_facet("/Felidae");
+        let facet_counts = searcher.search(&AllQuery, &facet_collector)?;
+        // This lists all of the facet counts, right below "/Felidae".
+        let facets: Vec<(&Facet, u64)> = facet_counts.get("/Felidae").collect();
+        assert_eq!(
+            facets,
+            vec![
+                (&Facet::from("/Felidae/Felinae"), 3),
+                (&Facet::from("/Felidae/Pantherinae"), 4),
+            ]
+        );
+    }
 
-    let mut facet_collector = FacetCollector::for_field(tags);
-    facet_collector.add_facet("/pools");
+    // Facets are also searchable.
+    //
+    // For instance a common UI pattern is to allow the user someone to click on a facet link
+    // (e.g: `Pantherinae`) to drill down and filter the current result set with this subfacet.
+    //
+    // The search would then look as follows.
 
-    let facet_counts = searcher.search(&AllQuery, &facet_collector).unwrap();
-
-    // This lists all of the facet counts
-    let facets: Vec<(&Facet, u64)> = facet_counts.get("/pools").collect();
-    assert_eq!(
-        facets,
-        vec![
-            (&Facet::from("/pools/north"), 1),
-            (&Facet::from("/pools/south"), 1),
-        ]
-    );
+    // Check the reference doc for different ways to create a `Facet` object.
+    {
+        let facet = Facet::from_text("/Felidae/Pantherinae");
+        let facet_term = Term::from_facet(classification, &facet);
+        let facet_term_query = TermQuery::new(facet_term, IndexRecordOption::Basic);
+        let mut facet_collector = FacetCollector::for_field(classification);
+        facet_collector.add_facet("/Felidae/Pantherinae");
+        let facet_counts = searcher.search(&facet_term_query, &facet_collector)?;
+        let facets: Vec<(&Facet, u64)> = facet_counts.get("/Felidae/Pantherinae").collect();
+        assert_eq!(
+            facets,
+            vec![
+                (&Facet::from("/Felidae/Pantherinae/Neofelis"), 1),
+                (&Facet::from("/Felidae/Pantherinae/Panthera"), 3),
+            ]
+        );
+    }
 
     Ok(())
 }

examples/pre_tokenized_text.rs

@@ -9,7 +9,7 @@
 // - import tokenized text straight from json,
 // - perform a search on documents with pre-tokenized text
 
-use tantivy::tokenizer::{PreTokenizedString, SimpleTokenizer, Token, TokenStream, Tokenizer};
+use tantivy::tokenizer::{PreTokenizedString, SimpleTokenizer, Token, Tokenizer};
 
 use tantivy::collector::{Count, TopDocs};
 use tantivy::query::TermQuery;

examples/stop_words.rs

@@ -50,7 +50,7 @@ fn main() -> tantivy::Result<()> {
 
     // This tokenizer lowers all of the text (to help with stop word matching)
     // then removes all instances of `the` and `and` from the corpus
-    let tokenizer = SimpleTokenizer
+    let tokenizer = TextAnalyzer::from(SimpleTokenizer)
         .filter(LowerCaser)
         .filter(StopWordFilter::remove(vec![
             "the".to_string(),

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 {
@@ -452,9 +451,11 @@ impl FacetCounts {
 #[cfg(test)]
 mod tests {
     use super::{FacetCollector, FacetCounts};
+    use crate::collector::Count;
     use crate::core::Index;
-    use crate::query::AllQuery;
-    use crate::schema::{Document, Facet, Field, Schema};
+    use crate::query::{AllQuery, QueryParser, TermQuery};
+    use crate::schema::{Document, Facet, Field, IndexRecordOption, Schema};
+    use crate::Term;
     use rand::distributions::Uniform;
     use rand::prelude::SliceRandom;
     use rand::{thread_rng, Rng};
@@ -544,6 +545,56 @@ mod tests {
         assert_eq!(facets[0].1, 1);
     }
 
+    #[test]
+    fn test_doc_search_by_facet() {
+        let mut schema_builder = Schema::builder();
+        let facet_field = schema_builder.add_facet_field("facet");
+        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!(
+            facet_field => Facet::from_text(&"/A/A"),
+        ));
+        index_writer.add_document(doc!(
+            facet_field => Facet::from_text(&"/A/B"),
+        ));
+        index_writer.add_document(doc!(
+            facet_field => Facet::from_text(&"/A/C/A"),
+        ));
+        index_writer.add_document(doc!(
+            facet_field => Facet::from_text(&"/D/C/A"),
+        ));
+        index_writer.commit().unwrap();
+        let reader = index.reader().unwrap();
+        let searcher = reader.searcher();
+        assert_eq!(searcher.num_docs(), 4);
+
+        let count_facet = |facet_str: &str| {
+            let term = Term::from_facet(facet_field, &Facet::from_text(facet_str));
+            searcher
+                .search(&TermQuery::new(term, IndexRecordOption::Basic), &Count)
+                .unwrap()
+        };
+
+        assert_eq!(count_facet("/"), 4);
+        assert_eq!(count_facet("/A"), 3);
+        assert_eq!(count_facet("/A/B"), 1);
+        assert_eq!(count_facet("/A/C"), 1);
+        assert_eq!(count_facet("/A/C/A"), 1);
+        assert_eq!(count_facet("/C/A"), 0);
+        {
+            let query_parser = QueryParser::for_index(&index, vec![]);
+            {
+                let query = query_parser.parse_query("facet:/A/B").unwrap();
+                assert_eq!(1, searcher.search(&query, &Count).unwrap());
+            }
+            {
+                let query = query_parser.parse_query("facet:/A").unwrap();
+                assert_eq!(3, searcher.search(&query, &Count).unwrap());
+            }
+        }
+    }
+
     #[test]
     fn test_non_used_facet_collector() {
         let mut facet_collector = FacetCollector::for_field(Field::from_field_id(0));

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

@@ -6,10 +6,10 @@ use crate::collector::tweak_score_top_collector::TweakedScoreTopCollector;
 use crate::collector::{
     CustomScorer, CustomSegmentScorer, ScoreSegmentTweaker, ScoreTweaker, SegmentCollector,
 };
+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;
@@ -61,6 +61,36 @@ impl fmt::Debug for TopDocs {
     }
 }
 
+struct ScorerByFastFieldReader {
+    ff_reader: FastFieldReader<u64>,
+}
+
+impl CustomSegmentScorer<u64> for ScorerByFastFieldReader {
+    fn score(&self, doc: DocId) -> u64 {
+        self.ff_reader.get_u64(u64::from(doc))
+    }
+}
+
+struct ScorerByField {
+    field: Field,
+}
+
+impl CustomScorer<u64> for ScorerByField {
+    type Child = ScorerByFastFieldReader;
+
+    fn segment_scorer(&self, segment_reader: &SegmentReader) -> crate::Result<Self::Child> {
+        let ff_reader = segment_reader
+            .fast_fields()
+            .u64(self.field)
+            .ok_or_else(|| {
+                crate::TantivyError::SchemaError(format!(
+                    "Field requested is not a i64/u64 fast field."
+                ))
+            })?;
+        Ok(ScorerByFastFieldReader { ff_reader })
+    }
+}
+
 impl TopDocs {
     /// Creates a top score collector, with a number of documents equal to "limit".
     ///
@@ -74,7 +104,7 @@ 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;
@@ -111,7 +141,7 @@ 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
     ///     //
@@ -143,14 +173,7 @@ impl TopDocs {
         self,
         field: Field,
     ) -> impl Collector<Fruit = Vec<(u64, DocAddress)>> {
-        self.custom_score(move |segment_reader: &SegmentReader| {
-            let ff_reader = segment_reader
-                .fast_fields()
-                .u64(field)
-                .expect("Field requested is not a i64/u64 fast field.");
-            //TODO error message missmatch actual behavior for i64
-            move |doc: DocId| ff_reader.get(doc)
-        })
+        self.custom_score(ScorerByField { field })
     }
 
     /// Ranks the documents using a custom score.
@@ -384,7 +407,7 @@ 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))
     }
@@ -393,7 +416,10 @@ 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)
     }
 }
@@ -572,7 +598,6 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "Field requested is not a i64/u64 fast field")]
     fn test_field_not_fast_field() {
         let mut schema_builder = Schema::builder();
         let title = schema_builder.add_text_field(TITLE, TEXT);
@@ -587,7 +612,12 @@ mod tests {
         let searcher = index.reader().unwrap().searcher();
         let segment = searcher.segment_reader(0);
         let top_collector = TopDocs::with_limit(4).order_by_u64_field(size);
-        assert!(top_collector.for_segment(0, segment).is_ok());
+        let err = top_collector.for_segment(0, segment);
+        if let Err(crate::TantivyError::SchemaError(msg)) = err {
+            assert_eq!(msg, "Field requested is not a i64/u64 fast field.");
+        } else {
+            assert!(false);
+        }
     }
 
     fn index(

src/core/executor.rs

@@ -1,4 +1,3 @@
-use crate::Result;
 use crossbeam::channel;
 use rayon::{ThreadPool, ThreadPoolBuilder};
 
@@ -10,7 +9,9 @@ use rayon::{ThreadPool, ThreadPoolBuilder};
 /// API of a dependency, knowing it might conflict with a different version
 /// used by the client. Second, we may stop using rayon in the future.
 pub enum Executor {
+    /// Single thread variant of an Executor
     SingleThread,
+    /// Thread pool variant of an Executor
     ThreadPool(ThreadPool),
 }
 
@@ -20,8 +21,8 @@ impl Executor {
         Executor::SingleThread
     }
 
-    // Creates an Executor that dispatches the tasks in a thread pool.
-    pub fn multi_thread(num_threads: usize, prefix: &'static str) -> Result<Executor> {
+    /// Creates an Executor that dispatches the tasks in a thread pool.
+    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))
@@ -29,22 +30,22 @@ impl Executor {
         Ok(Executor::ThreadPool(pool))
     }
 
-    // Perform a map in the thread pool.
-    //
-    // Regardless of the executor (`SingleThread` or `ThreadPool`), panics in the task
-    // will propagate to the caller.
+    /// Perform a map in the thread pool.
+    ///
+    /// Regardless of the executor (`SingleThread` or `ThreadPool`), panics in the task
+    /// will propagate to the caller.
     pub fn map<
         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

@@ -20,10 +20,8 @@ use crate::reader::IndexReaderBuilder;
 use crate::schema::Field;
 use crate::schema::FieldType;
 use crate::schema::Schema;
-use crate::tokenizer::BoxedTokenizer;
-use crate::tokenizer::TokenizerManager;
+use crate::tokenizer::{TextAnalyzer, TokenizerManager};
 use crate::IndexWriter;
-use crate::Result;
 use num_cpus;
 use std::borrow::BorrowMut;
 use std::collections::HashSet;
@@ -32,7 +30,10 @@ 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)
@@ -73,14 +74,14 @@ 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)
     }
@@ -99,7 +100,10 @@ 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);
@@ -108,7 +112,7 @@ 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);
         }
@@ -131,13 +135,13 @@ 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)
     }
@@ -145,7 +149,7 @@ 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())
@@ -156,7 +160,7 @@ impl Index {
         directory: ManagedDirectory,
         metas: &IndexMeta,
         inventory: SegmentMetaInventory,
-    ) -> Result<Index> {
+    ) -> crate::Result<Index> {
         let schema = metas.schema.clone();
         Ok(Index {
             directory,
@@ -173,11 +177,11 @@ impl Index {
     }
 
     /// Helper to access the tokenizer associated to a specific field.
-    pub fn tokenizer_for_field(&self, field: Field) -> Result<BoxedTokenizer> {
+    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();
-        let tokenizer_name_opt: Option<BoxedTokenizer> = match field_type {
+        let tokenizer_name_opt: Option<TextAnalyzer> = match field_type {
             FieldType::Str(text_options) => text_options
                 .get_indexing_options()
                 .map(|text_indexing_options| text_indexing_options.tokenizer().to_string())
@@ -196,7 +200,7 @@ 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()
     }
 
@@ -211,7 +215,7 @@ 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)
     }
@@ -235,7 +239,7 @@ 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)?;
@@ -243,7 +247,7 @@ 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)
     }
 
@@ -271,7 +275,7 @@ 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)
@@ -306,7 +310,7 @@ 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 {
@@ -323,7 +327,7 @@ 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()
@@ -356,12 +360,12 @@ 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()
@@ -370,7 +374,7 @@ 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/inverted_index_reader.rs

@@ -60,7 +60,7 @@ impl InvertedIndexReader {
             .get_index_record_option()
             .unwrap_or(IndexRecordOption::Basic);
         InvertedIndexReader {
-            termdict: TermDictionary::empty(&field_type),
+            termdict: TermDictionary::empty(),
             postings_source: ReadOnlySource::empty(),
             positions_source: ReadOnlySource::empty(),
             positions_idx_source: ReadOnlySource::empty(),

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;
 
@@ -23,7 +22,7 @@ fn collect_segment<C: Collector>(
     weight: &dyn Weight,
     segment_ord: u32,
     segment_reader: &SegmentReader,
-) -> Result<C::Fruit> {
+) -> crate::Result<C::Fruit> {
     let mut scorer = weight.scorer(segment_reader)?;
     let mut segment_collector = collector.for_segment(segment_ord as u32, segment_reader)?;
     if let Some(delete_bitset) = segment_reader.delete_bitset() {
@@ -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)]
@@ -83,20 +81,14 @@ 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 +101,5 @@ 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_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/directory.rs

@@ -119,7 +119,7 @@ pub trait Directory: DirectoryClone + fmt::Debug + Send + Sync + 'static {
     /// Specifically, subsequent writes or flushes should
     /// have no effect on the returned `ReadOnlySource` object.
     ///
-    /// You should only use this to read files create with [`open_write`]
+    /// You should only use this to read files create with [Directory::open_write].
     fn open_read(&self, path: &Path) -> result::Result<ReadOnlySource, OpenReadError>;
 
     /// Removes a file
@@ -160,7 +160,7 @@ pub trait Directory: DirectoryClone + fmt::Debug + Send + Sync + 'static {
     ///
     /// This should only be used for small files.
     ///
-    /// You should only use this to read files create with [`atomic_write`]
+    /// You should only use this to read files create with [Directory::atomic_write].
     fn atomic_read(&self, path: &Path) -> Result<Vec<u8>, OpenReadError>;
 
     /// Atomically replace the content of a file with data.
@@ -197,7 +197,7 @@ pub trait Directory: DirectoryClone + fmt::Debug + Send + Sync + 'static {
     /// Registers a callback that will be called whenever a change on the `meta.json`
     /// using the `atomic_write` API is detected.
     ///
-    /// The behavior when using `.watch()` on a file using `.open_write(...)` is, on the other
+    /// The behavior when using `.watch()` on a file using [Directory::open_write] is, on the other
     /// hand, undefined.
     ///
     /// The file will be watched for the lifetime of the returned `WatchHandle`. The caller is

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

@@ -131,19 +131,18 @@ impl MmapCache {
         }
         self.cache.remove(full_path);
         self.counters.miss += 1;
-        Ok(if let Some(mmap) = open_mmap(full_path)? {
+        let mmap_opt = open_mmap(full_path)?;
+        Ok(mmap_opt.map(|mmap| {
             let mmap_arc: Arc<BoxedData> = Arc::new(Box::new(mmap));
             let mmap_weak = Arc::downgrade(&mmap_arc);
             self.cache.insert(full_path.to_owned(), mmap_weak);
-            Some(mmap_arc)
-        } else {
-            None
-        })
+            mmap_arc
+        }))
     }
 }
 
 struct WatcherWrapper {
-    _watcher: Mutex<notify::RecommendedWatcher>,
+    _watcher: Mutex<notify::PollWatcher>,
     watcher_router: Arc<WatchCallbackList>,
 }
 
@@ -151,7 +150,7 @@ impl WatcherWrapper {
     pub fn new(path: &Path) -> Result<Self, OpenDirectoryError> {
         let (tx, watcher_recv): (Sender<RawEvent>, Receiver<RawEvent>) = channel();
         // We need to initialize the
-        let watcher = notify::raw_watcher(tx)
+        let watcher = notify::poll::PollWatcher::with_delay_ms(tx, 1)
             .and_then(|mut watcher| {
                 watcher.watch(path, RecursiveMode::Recursive)?;
                 Ok(watcher)

src/directory/mod.rs

@@ -23,11 +23,9 @@ pub use self::directory::{Directory, DirectoryClone};
 pub use self::directory_lock::{Lock, INDEX_WRITER_LOCK, META_LOCK};
 pub use self::ram_directory::RAMDirectory;
 pub use self::read_only_source::ReadOnlySource;
-pub(crate) use self::watch_event_router::WatchCallbackList;
-pub use self::watch_event_router::{WatchCallback, WatchHandle};
+pub use self::watch_event_router::{WatchCallback, WatchCallbackList, WatchHandle};
 use std::io::{self, BufWriter, Write};
 use std::path::PathBuf;
-
 /// Outcome of the Garbage collection
 pub struct GarbageCollectionResult {
     /// List of files that were deleted in this cycle

src/directory/watch_event_router.rs

@@ -24,13 +24,20 @@ pub struct WatchCallbackList {
 #[derive(Clone)]
 pub struct WatchHandle(Arc<WatchCallback>);
 
+impl WatchHandle {
+    /// Create a WatchHandle handle.
+    pub fn new(watch_callback: Arc<WatchCallback>) -> WatchHandle {
+        WatchHandle(watch_callback)
+    }
+}
+
 impl WatchCallbackList {
     /// Suscribes a new callback and returns a handle that controls the lifetime of the callback.
     pub fn subscribe(&self, watch_callback: WatchCallback) -> WatchHandle {
         let watch_callback_arc = Arc::new(watch_callback);
         let watch_callback_weak = Arc::downgrade(&watch_callback_arc);
         self.router.write().unwrap().push(watch_callback_weak);
-        WatchHandle(watch_callback_arc)
+        WatchHandle::new(watch_callback_arc)
     }
 
     fn list_callback(&self) -> Vec<Arc<WatchCallback>> {

src/fastfield/mod.rs

@@ -33,6 +33,7 @@ pub use self::reader::FastFieldReader;
 pub use self::readers::FastFieldReaders;
 pub use self::serializer::FastFieldSerializer;
 pub use self::writer::{FastFieldsWriter, IntFastFieldWriter};
+use crate::chrono::{NaiveDateTime, Utc};
 use crate::common;
 use crate::schema::Cardinality;
 use crate::schema::FieldType;
@@ -49,7 +50,7 @@ mod serializer;
 mod writer;
 
 /// Trait for types that are allowed for fast fields: (u64, i64 and f64).
-pub trait FastValue: Default + Clone + Copy + Send + Sync + PartialOrd {
+pub trait FastValue: Clone + Copy + Send + Sync + PartialOrd {
     /// Converts a value from u64
     ///
     /// Internally all fast field values are encoded as u64.
@@ -69,6 +70,12 @@ pub trait FastValue: Default + Clone + Copy + Send + Sync + PartialOrd {
     /// Cast value to `u64`.
     /// The value is just reinterpreted in memory.
     fn as_u64(&self) -> u64;
+
+    /// Build a default value. This default value is never used, so the value does not
+    /// really matter.
+    fn make_zero() -> Self {
+        Self::from_u64(0i64.to_u64())
+    }
 }
 
 impl FastValue for u64 {
@@ -135,11 +142,34 @@ impl FastValue for f64 {
     }
 }
 
+impl FastValue for crate::DateTime {
+    fn from_u64(timestamp_u64: u64) -> Self {
+        let timestamp_i64 = i64::from_u64(timestamp_u64);
+        crate::DateTime::from_utc(NaiveDateTime::from_timestamp(timestamp_i64, 0), Utc)
+    }
+
+    fn to_u64(&self) -> u64 {
+        self.timestamp().to_u64()
+    }
+
+    fn fast_field_cardinality(field_type: &FieldType) -> Option<Cardinality> {
+        match *field_type {
+            FieldType::Date(ref integer_options) => integer_options.get_fastfield_cardinality(),
+            _ => None,
+        }
+    }
+
+    fn as_u64(&self) -> u64 {
+        self.timestamp().as_u64()
+    }
+}
+
 fn value_to_u64(value: &Value) -> u64 {
     match *value {
         Value::U64(ref val) => *val,
         Value::I64(ref val) => common::i64_to_u64(*val),
         Value::F64(ref val) => common::f64_to_u64(*val),
+        Value::Date(ref datetime) => common::i64_to_u64(datetime.timestamp()),
         _ => panic!("Expected a u64/i64/f64 field, got {:?} ", value),
     }
 }
@@ -151,10 +181,12 @@ mod tests {
     use crate::common::CompositeFile;
     use crate::directory::{Directory, RAMDirectory, WritePtr};
     use crate::fastfield::FastFieldReader;
-    use crate::schema::Document;
+    use crate::merge_policy::NoMergePolicy;
     use crate::schema::Field;
     use crate::schema::Schema;
     use crate::schema::FAST;
+    use crate::schema::{Document, IntOptions};
+    use crate::{Index, SegmentId, SegmentReader};
     use once_cell::sync::Lazy;
     use rand::prelude::SliceRandom;
     use rand::rngs::StdRng;
@@ -178,6 +210,12 @@ mod tests {
         assert_eq!(test_fastfield.get(2), 300);
     }
 
+    #[test]
+    pub fn test_fastfield_i64_u64() {
+        let datetime = crate::DateTime::from_utc(NaiveDateTime::from_timestamp(0i64, 0), Utc);
+        assert_eq!(i64::from_u64(datetime.to_u64()), 0i64);
+    }
+
     #[test]
     fn test_intfastfield_small() {
         let path = Path::new("test");
@@ -429,6 +467,93 @@ mod tests {
             }
         }
     }
+
+    #[test]
+    fn test_merge_missing_date_fast_field() {
+        let mut schema_builder = Schema::builder();
+        let date_field = schema_builder.add_date_field("date", FAST);
+        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.set_merge_policy(Box::new(NoMergePolicy));
+        index_writer.add_document(doc!(date_field =>crate::chrono::prelude::Utc::now()));
+        index_writer.commit().unwrap();
+        index_writer.add_document(doc!());
+        index_writer.commit().unwrap();
+        let reader = index.reader().unwrap();
+        let segment_ids: Vec<SegmentId> = reader
+            .searcher()
+            .segment_readers()
+            .iter()
+            .map(SegmentReader::segment_id)
+            .collect();
+        assert_eq!(segment_ids.len(), 2);
+        let merge_future = index_writer.merge(&segment_ids[..]);
+        let merge_res = futures::executor::block_on(merge_future);
+        assert!(merge_res.is_ok());
+        assert!(reader.reload().is_ok());
+        assert_eq!(reader.searcher().segment_readers().len(), 1);
+    }
+
+    #[test]
+    fn test_default_datetime() {
+        assert_eq!(crate::DateTime::make_zero().timestamp(), 0i64);
+    }
+
+    #[test]
+    fn test_datefastfield() {
+        use crate::fastfield::FastValue;
+        let mut schema_builder = Schema::builder();
+        let date_field = schema_builder.add_date_field("date", FAST);
+        let multi_date_field = schema_builder.add_date_field(
+            "multi_date",
+            IntOptions::default().set_fast(Cardinality::MultiValues),
+        );
+        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.set_merge_policy(Box::new(NoMergePolicy));
+        index_writer.add_document(doc!(
+            date_field => crate::DateTime::from_u64(1i64.to_u64()),
+            multi_date_field => crate::DateTime::from_u64(2i64.to_u64()),
+            multi_date_field => crate::DateTime::from_u64(3i64.to_u64())
+        ));
+        index_writer.add_document(doc!(
+            date_field => crate::DateTime::from_u64(4i64.to_u64())
+        ));
+        index_writer.add_document(doc!(
+            multi_date_field => crate::DateTime::from_u64(5i64.to_u64()),
+            multi_date_field => crate::DateTime::from_u64(6i64.to_u64())
+        ));
+        index_writer.commit().unwrap();
+        let reader = index.reader().unwrap();
+        let searcher = reader.searcher();
+        assert_eq!(searcher.segment_readers().len(), 1);
+        let segment_reader = searcher.segment_reader(0);
+        let fast_fields = segment_reader.fast_fields();
+        let date_fast_field = fast_fields.date(date_field).unwrap();
+        let dates_fast_field = fast_fields.dates(multi_date_field).unwrap();
+        let mut dates = vec![];
+        {
+            assert_eq!(date_fast_field.get(0u32).timestamp(), 1i64);
+            dates_fast_field.get_vals(0u32, &mut dates);
+            assert_eq!(dates.len(), 2);
+            assert_eq!(dates[0].timestamp(), 2i64);
+            assert_eq!(dates[1].timestamp(), 3i64);
+        }
+        {
+            assert_eq!(date_fast_field.get(1u32).timestamp(), 4i64);
+            dates_fast_field.get_vals(1u32, &mut dates);
+            assert!(dates.is_empty());
+        }
+        {
+            assert_eq!(date_fast_field.get(2u32).timestamp(), 0i64);
+            dates_fast_field.get_vals(2u32, &mut dates);
+            assert_eq!(dates.len(), 2);
+            assert_eq!(dates[0].timestamp(), 5i64);
+            assert_eq!(dates[1].timestamp(), 6i64);
+        }
+    }
 }
 
 #[cfg(all(test, feature = "unstable"))]

src/fastfield/multivalued/mod.rs

@@ -7,9 +7,6 @@ pub use self::writer::MultiValueIntFastFieldWriter;
 #[cfg(test)]
 mod tests {
 
-    use time;
-
-    use self::time::Duration;
     use crate::collector::TopDocs;
     use crate::query::QueryParser;
     use crate::schema::Cardinality;
@@ -17,6 +14,7 @@ mod tests {
     use crate::schema::IntOptions;
     use crate::schema::Schema;
     use crate::Index;
+    use chrono::Duration;
 
     #[test]
     fn test_multivalued_u64() {

src/fastfield/multivalued/reader.rs

@@ -45,7 +45,7 @@ impl<Item: FastValue> MultiValueIntFastFieldReader<Item> {
     pub fn get_vals(&self, doc: DocId, vals: &mut Vec<Item>) {
         let (start, stop) = self.range(doc);
         let len = (stop - start) as usize;
-        vals.resize(len, Item::default());
+        vals.resize(len, Item::make_zero());
         self.vals_reader.get_range_u64(start, &mut 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.
@@ -15,9 +14,11 @@ pub struct FastFieldReaders {
     fast_field_i64: HashMap<Field, FastFieldReader<i64>>,
     fast_field_u64: HashMap<Field, FastFieldReader<u64>>,
     fast_field_f64: HashMap<Field, FastFieldReader<f64>>,
+    fast_field_date: HashMap<Field, FastFieldReader<crate::DateTime>>,
     fast_field_i64s: HashMap<Field, MultiValueIntFastFieldReader<i64>>,
     fast_field_u64s: HashMap<Field, MultiValueIntFastFieldReader<u64>>,
     fast_field_f64s: HashMap<Field, MultiValueIntFastFieldReader<f64>>,
+    fast_field_dates: HashMap<Field, MultiValueIntFastFieldReader<crate::DateTime>>,
     fast_bytes: HashMap<Field, BytesFastFieldReader>,
     fast_fields_composite: CompositeFile,
 }
@@ -26,6 +27,7 @@ enum FastType {
     I64,
     U64,
     F64,
+    Date,
 }
 
 fn type_and_cardinality(field_type: &FieldType) -> Option<(FastType, Cardinality)> {
@@ -39,6 +41,9 @@ fn type_and_cardinality(field_type: &FieldType) -> Option<(FastType, Cardinality
         FieldType::F64(options) => options
             .get_fastfield_cardinality()
             .map(|cardinality| (FastType::F64, cardinality)),
+        FieldType::Date(options) => options
+            .get_fastfield_cardinality()
+            .map(|cardinality| (FastType::Date, cardinality)),
         FieldType::HierarchicalFacet => Some((FastType::U64, Cardinality::MultiValues)),
         _ => None,
     }
@@ -48,14 +53,16 @@ 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(),
             fast_field_f64: Default::default(),
+            fast_field_date: Default::default(),
             fast_field_i64s: Default::default(),
             fast_field_u64s: Default::default(),
             fast_field_f64s: Default::default(),
+            fast_field_dates: Default::default(),
             fast_bytes: Default::default(),
             fast_fields_composite: fast_fields_composite.clone(),
         };
@@ -95,6 +102,12 @@ impl FastFieldReaders {
                                         FastFieldReader::open(fast_field_data.clone()),
                                     );
                                 }
+                                FastType::Date => {
+                                    fast_field_readers.fast_field_date.insert(
+                                        field,
+                                        FastFieldReader::open(fast_field_data.clone()),
+                                    );
+                                }
                             }
                         } else {
                             return Err(From::from(FastFieldNotAvailableError::new(field_entry)));
@@ -130,6 +143,14 @@ impl FastFieldReaders {
                                         .fast_field_f64s
                                         .insert(field, multivalued_int_fast_field);
                                 }
+                                FastType::Date => {
+                                    let vals_reader = FastFieldReader::open(fast_field_data);
+                                    let multivalued_int_fast_field =
+                                        MultiValueIntFastFieldReader::open(idx_reader, vals_reader);
+                                    fast_field_readers
+                                        .fast_field_dates
+                                        .insert(field, multivalued_int_fast_field);
+                                }
                             }
                         } else {
                             return Err(From::from(FastFieldNotAvailableError::new(field_entry)));
@@ -167,6 +188,9 @@ impl FastFieldReaders {
         if let Some(f64_ff_reader) = self.f64(field) {
             return Some(f64_ff_reader.into_u64_reader());
         }
+        if let Some(date_ff_reader) = self.date(field) {
+            return Some(date_ff_reader.into_u64_reader());
+        }
         None
     }
 
@@ -177,6 +201,13 @@ impl FastFieldReaders {
         self.fast_field_i64.get(&field).cloned()
     }
 
+    /// Returns the `i64` fast field reader reader associated to `field`.
+    ///
+    /// If `field` is not a i64 fast field, this method returns `None`.
+    pub fn date(&self, field: Field) -> Option<FastFieldReader<crate::DateTime>> {
+        self.fast_field_date.get(&field).cloned()
+    }
+
     /// Returns the `f64` fast field reader reader associated to `field`.
     ///
     /// If `field` is not a f64 fast field, this method returns `None`.
@@ -223,6 +254,13 @@ impl FastFieldReaders {
         self.fast_field_f64s.get(&field).cloned()
     }
 
+    /// Returns a `crate::DateTime` multi-valued fast field reader reader associated to `field`.
+    ///
+    /// If `field` is not a `crate::DateTime` multi-valued fast field, this method returns `None`.
+    pub fn dates(&self, field: Field) -> Option<MultiValueIntFastFieldReader<crate::DateTime>> {
+        self.fast_field_dates.get(&field).cloned()
+    }
+
     /// Returns the `bytes` fast field reader associated to `field`.
     ///
     /// If `field` is not a bytes fast field, returns `None`.

src/fastfield/writer.rs

@@ -4,7 +4,7 @@ use crate::common::BinarySerializable;
 use crate::common::VInt;
 use crate::fastfield::{BytesFastFieldWriter, FastFieldSerializer};
 use crate::postings::UnorderedTermId;
-use crate::schema::{Cardinality, Document, Field, FieldType, Schema};
+use crate::schema::{Cardinality, Document, Field, FieldEntry, FieldType, Schema};
 use crate::termdict::TermOrdinal;
 use fnv::FnvHashMap;
 use std::collections::HashMap;
@@ -17,6 +17,14 @@ pub struct FastFieldsWriter {
     bytes_value_writers: Vec<BytesFastFieldWriter>,
 }
 
+fn fast_field_default_value(field_entry: &FieldEntry) -> u64 {
+    match *field_entry.field_type() {
+        FieldType::I64(_) | FieldType::Date(_) => common::i64_to_u64(0i64),
+        FieldType::F64(_) => common::f64_to_u64(0.0f64),
+        _ => 0u64,
+    }
+}
+
 impl FastFieldsWriter {
     /// Create all `FastFieldWriter` required by the schema.
     pub fn from_schema(schema: &Schema) -> FastFieldsWriter {
@@ -25,18 +33,15 @@ impl FastFieldsWriter {
         let mut bytes_value_writers = Vec::new();
 
         for (field, field_entry) in schema.fields() {
-            let default_value = match *field_entry.field_type() {
-                FieldType::I64(_) => common::i64_to_u64(0i64),
-                FieldType::F64(_) => common::f64_to_u64(0.0f64),
-                _ => 0u64,
-            };
             match *field_entry.field_type() {
                 FieldType::I64(ref int_options)
                 | FieldType::U64(ref int_options)
-                | FieldType::F64(ref int_options) => {
+                | FieldType::F64(ref int_options)
+                | FieldType::Date(ref int_options) => {
                     match int_options.get_fastfield_cardinality() {
                         Some(Cardinality::SingleValue) => {
                             let mut fast_field_writer = IntFastFieldWriter::new(field);
+                            let default_value = fast_field_default_value(field_entry);
                             fast_field_writer.set_val_if_missing(default_value);
                             single_value_writers.push(fast_field_writer);
                         }

src/indexer/index_writer.rs

@@ -514,9 +514,13 @@ impl IndexWriter {
     /// Merges a given list of segments
     ///
     /// `segment_ids` is required to be non-empty.
-    pub async fn merge(&mut self, segment_ids: &[SegmentId]) -> crate::Result<SegmentMeta> {
+    pub fn merge(
+        &mut self,
+        segment_ids: &[SegmentId],
+    ) -> impl Future<Output = crate::Result<SegmentMeta>> {
         let merge_operation = self.segment_updater.make_merge_operation(segment_ids);
-        self.segment_updater.start_merge(merge_operation)?.await
+        let segment_updater = self.segment_updater.clone();
+        async move { segment_updater.start_merge(merge_operation)?.await }
     }
 
     /// Closes the current document channel send.
@@ -893,7 +897,7 @@ mod tests {
         let index_writer = index.writer(3_000_000).unwrap();
         assert_eq!(
             format!("{:?}", index_writer.get_merge_policy()),
-            "LogMergePolicy { min_merge_size: 8, min_layer_size: 10000, \
+            "LogMergePolicy { min_merge_size: 8, max_merge_size: 10000000, min_layer_size: 10000, \
              level_log_size: 0.75 }"
         );
         let merge_policy = Box::new(NoMergePolicy::default());

src/indexer/log_merge_policy.rs

@@ -6,12 +6,14 @@ use std::f64;
 const DEFAULT_LEVEL_LOG_SIZE: f64 = 0.75;
 const DEFAULT_MIN_LAYER_SIZE: u32 = 10_000;
 const DEFAULT_MIN_MERGE_SIZE: usize = 8;
+const DEFAULT_MAX_MERGE_SIZE: usize = 10_000_000;
 
 /// `LogMergePolicy` tries tries to merge segments that have a similar number of
 /// documents.
 #[derive(Debug, Clone)]
 pub struct LogMergePolicy {
     min_merge_size: usize,
+    max_merge_size: usize,
     min_layer_size: u32,
     level_log_size: f64,
 }
@@ -26,6 +28,12 @@ impl LogMergePolicy {
         self.min_merge_size = min_merge_size;
     }
 
+    /// Set the maximum number docs in a segment for it to be considered for
+    /// merging.
+    pub fn set_max_merge_size(&mut self, max_merge_size: usize) {
+        self.max_merge_size = max_merge_size;
+    }
+
     /// Set the minimum segment size under which all segment belong
     /// to the same level.
     pub fn set_min_layer_size(&mut self, min_layer_size: u32) {
@@ -53,6 +61,7 @@ impl MergePolicy for LogMergePolicy {
         let mut size_sorted_tuples = segments
             .iter()
             .map(SegmentMeta::num_docs)
+            .filter(|s| s <= &(self.max_merge_size as u32))
             .enumerate()
             .collect::<Vec<(usize, u32)>>();
 
@@ -86,6 +95,7 @@ impl Default for LogMergePolicy {
     fn default() -> LogMergePolicy {
         LogMergePolicy {
             min_merge_size: DEFAULT_MIN_MERGE_SIZE,
+            max_merge_size: DEFAULT_MAX_MERGE_SIZE,
             min_layer_size: DEFAULT_MIN_LAYER_SIZE,
             level_log_size: DEFAULT_LEVEL_LOG_SIZE,
         }
@@ -104,6 +114,7 @@ mod tests {
     fn test_merge_policy() -> LogMergePolicy {
         let mut log_merge_policy = LogMergePolicy::default();
         log_merge_policy.set_min_merge_size(3);
+        log_merge_policy.set_max_merge_size(100_000);
         log_merge_policy.set_min_layer_size(2);
         log_merge_policy
     }
@@ -141,11 +152,11 @@ mod tests {
             create_random_segment_meta(10),
             create_random_segment_meta(10),
             create_random_segment_meta(10),
-            create_random_segment_meta(1000),
-            create_random_segment_meta(1000),
-            create_random_segment_meta(1000),
-            create_random_segment_meta(10000),
-            create_random_segment_meta(10000),
+            create_random_segment_meta(1_000),
+            create_random_segment_meta(1_000),
+            create_random_segment_meta(1_000),
+            create_random_segment_meta(10_000),
+            create_random_segment_meta(10_000),
             create_random_segment_meta(10),
             create_random_segment_meta(10),
             create_random_segment_meta(10),
@@ -182,4 +193,19 @@ mod tests {
         let result_list = test_merge_policy().compute_merge_candidates(&test_input);
         assert_eq!(result_list.len(), 1);
     }
+
+    #[test]
+    fn test_large_merge_segments() {
+        let test_input = vec![
+            create_random_segment_meta(1_000_000),
+            create_random_segment_meta(100_001),
+            create_random_segment_meta(100_000),
+            create_random_segment_meta(100_000),
+            create_random_segment_meta(100_000),
+        ];
+        let result_list = test_merge_policy().compute_merge_candidates(&test_input);
+        // Do not include large segments
+        assert_eq!(result_list.len(), 1);
+        assert_eq!(result_list[0].0.len(), 3)
+    }
 }

src/indexer/merger.rs

@@ -21,8 +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;
@@ -143,7 +141,7 @@ 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 +157,7 @@ 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 +166,10 @@ 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 +190,7 @@ 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 +235,7 @@ 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 +285,7 @@ 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 +332,7 @@ 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 +372,7 @@ 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 +437,7 @@ 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 +493,7 @@ 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 +647,7 @@ 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 +661,7 @@ 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 +678,7 @@ 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/mod.rs

@@ -33,6 +33,7 @@ pub type DefaultMergePolicy = LogMergePolicy;
 mod tests {
     use crate::schema::{self, Schema};
     use crate::{Index, Term};
+
     #[test]
     fn test_advance_delete_bug() {
         let mut schema_builder = Schema::builder();

src/indexer/operation.rs

@@ -19,6 +19,8 @@ pub struct AddOperation {
 /// UserOperation is an enum type that encapsulates other operation types.
 #[derive(Eq, PartialEq, Debug)]
 pub enum UserOperation {
+    /// Add operation
     Add(Document),
+    /// Delete operation
     Delete(Term),
 }

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

@@ -11,21 +11,18 @@ use crate::schema::Schema;
 use crate::schema::Term;
 use crate::schema::Value;
 use crate::schema::{Field, FieldEntry};
-use crate::tokenizer::BoxedTokenizer;
-use crate::tokenizer::FacetTokenizer;
-use crate::tokenizer::PreTokenizedStream;
-use crate::tokenizer::{TokenStream, TokenStreamChain, Tokenizer};
+use crate::tokenizer::{BoxTokenStream, PreTokenizedStream};
+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)
@@ -33,7 +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)))
     }
 }
@@ -50,7 +47,7 @@ pub struct SegmentWriter {
     fast_field_writers: FastFieldsWriter,
     fieldnorms_writer: FieldNormsWriter,
     doc_opstamps: Vec<Opstamp>,
-    tokenizers: Vec<Option<BoxedTokenizer>>,
+    tokenizers: Vec<Option<TextAnalyzer>>,
 }
 
 impl SegmentWriter {
@@ -67,7 +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);
@@ -100,7 +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,
@@ -159,7 +156,7 @@ impl SegmentWriter {
                     }
                 }
                 FieldType::Str(_) => {
-                    let mut token_streams: Vec<Box<dyn TokenStream>> = vec![];
+                    let mut token_streams: Vec<BoxTokenStream> = vec![];
                     let mut offsets = vec![];
                     let mut total_offset = 0;
 
@@ -172,7 +169,7 @@ impl SegmentWriter {
                                 }
 
                                 token_streams
-                                    .push(Box::new(PreTokenizedStream::from(tok_str.clone())));
+                                    .push(PreTokenizedStream::from(tok_str.clone()).into());
                             }
                             Value::Str(ref text) => {
                                 if let Some(ref mut tokenizer) =
@@ -191,8 +188,7 @@ impl SegmentWriter {
                     let num_tokens = if token_streams.is_empty() {
                         0
                     } else {
-                        let mut token_stream: Box<dyn TokenStream> =
-                            Box::new(TokenStreamChain::new(offsets, token_streams));
+                        let mut token_stream = TokenStreamChain::new(offsets, token_streams);
                         self.multifield_postings
                             .index_text(doc_id, field, &mut token_stream)
                     };
@@ -283,7 +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())?;
@@ -292,7 +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/indexer/stamper.rs

@@ -1,18 +1,76 @@
 use crate::Opstamp;
 use std::ops::Range;
-use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::atomic::Ordering;
 use std::sync::Arc;
 
+#[cfg(not(target_arch = "arm"))]
+mod atomic_impl {
+
+    use crate::Opstamp;
+    use std::sync::atomic::{AtomicU64, Ordering};
+
+    #[derive(Default)]
+    pub struct AtomicU64Wrapper(AtomicU64);
+
+    impl AtomicU64Wrapper {
+        pub fn new(first_opstamp: Opstamp) -> AtomicU64Wrapper {
+            AtomicU64Wrapper(AtomicU64::new(first_opstamp as u64))
+        }
+
+        pub fn fetch_add(&self, val: u64, order: Ordering) -> u64 {
+            self.0.fetch_add(val as u64, order) as u64
+        }
+
+        pub fn revert(&self, val: u64, order: Ordering) -> u64 {
+            self.0.store(val, order);
+            val
+        }
+    }
+}
+
+#[cfg(target_arch = "arm")]
+mod atomic_impl {
+
+    use crate::Opstamp;
+    /// Under other architecture, we rely on a mutex.
+    use std::sync::atomic::Ordering;
+    use std::sync::RwLock;
+
+    #[derive(Default)]
+    pub struct AtomicU64Wrapper(RwLock<u64>);
+
+    impl AtomicU64Wrapper {
+        pub fn new(first_opstamp: Opstamp) -> AtomicU64Wrapper {
+            AtomicU64Wrapper(RwLock::new(first_opstamp))
+        }
+
+        pub fn fetch_add(&self, incr: u64, _order: Ordering) -> u64 {
+            let mut lock = self.0.write().unwrap();
+            let previous_val = *lock;
+            *lock = previous_val + incr;
+            previous_val
+        }
+
+        pub fn revert(&self, val: u64, _order: Ordering) -> u64 {
+            let mut lock = self.0.write().unwrap();
+            *lock = val;
+            val
+        }
+    }
+}
+
+use self::atomic_impl::AtomicU64Wrapper;
+
 /// Stamper provides Opstamps, which is just an auto-increment id to label
 /// an operation.
 ///
 /// Cloning does not "fork" the stamp generation. The stamper actually wraps an `Arc`.
 #[derive(Clone, Default)]
-pub struct Stamper(Arc<AtomicU64>);
+pub struct Stamper(Arc<AtomicU64Wrapper>);
 
 impl Stamper {
     pub fn new(first_opstamp: Opstamp) -> Stamper {
-        Stamper(Arc::new(AtomicU64::new(first_opstamp)))
+        Stamper(Arc::new(AtomicU64Wrapper::new(first_opstamp)))
     }
 
     pub fn stamp(&self) -> Opstamp {
@@ -31,8 +89,7 @@ impl Stamper {
 
     /// Reverts the stamper to a given `Opstamp` value and returns it
     pub fn revert(&self, to_opstamp: Opstamp) -> Opstamp {
-        self.0.store(to_opstamp, Ordering::SeqCst);
-        to_opstamp
+        self.0.revert(to_opstamp, Ordering::SeqCst)
     }
 }
 

src/lib.rs

@@ -121,13 +121,13 @@ 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>;
@@ -161,10 +161,11 @@ pub use self::snippet::{Snippet, SnippetGenerator};
 mod docset;
 pub use self::docset::{DocSet, SkipResult};
 pub use crate::common::{f64_to_u64, i64_to_u64, u64_to_f64, u64_to_i64};
-pub use crate::core::SegmentComponent;
+pub use crate::core::{Executor, SegmentComponent};
 pub use crate::core::{Index, IndexMeta, Searcher, Segment, SegmentId, SegmentMeta};
 pub use crate::core::{InvertedIndexReader, SegmentReader};
 pub use crate::directory::Directory;
+pub use crate::indexer::operation::UserOperation;
 pub use crate::indexer::IndexWriter;
 pub use crate::postings::Postings;
 pub use crate::reader::LeasedItem;

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/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)?),
@@ -148,8 +147,7 @@ impl<'a> FieldSerializer<'a> {
             }
             _ => (false, false),
         };
-        let term_dictionary_builder =
-            TermDictionaryBuilder::create(term_dictionary_write, &field_type)?;
+        let term_dictionary_builder = TermDictionaryBuilder::create(term_dictionary_write)?;
         let postings_serializer =
             PostingsSerializer::new(postings_write, term_freq_enabled, position_enabled);
         let positions_serializer_opt = if position_enabled {

src/query/all_query.rs

@@ -4,7 +4,6 @@ use crate::docset::DocSet;
 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 +13,7 @@ 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))
     }
 }
@@ -23,7 +22,7 @@ impl Query for AllQuery {
 pub struct AllWeight;
 
 impl Weight for AllWeight {
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
+    fn scorer(&self, reader: &SegmentReader) -> crate::Result<Box<dyn Scorer>> {
         Ok(Box::new(AllScorer {
             state: State::NotStarted,
             doc: 0u32,
@@ -31,7 +30,7 @@ impl Weight for AllWeight {
         }))
     }
 
-    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));
         }

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;
 
@@ -56,7 +55,7 @@ impl BooleanWeight {
     fn per_occur_scorers(
         &self,
         reader: &SegmentReader,
-    ) -> Result<HashMap<Occur, Vec<Box<dyn Scorer>>>> {
+    ) -> 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)?;
@@ -71,7 +70,7 @@ impl BooleanWeight {
     fn complex_scorer<TScoreCombiner: ScoreCombiner>(
         &self,
         reader: &SegmentReader,
-    ) -> Result<Box<dyn Scorer>> {
+    ) -> crate::Result<Box<dyn Scorer>> {
         let mut per_occur_scorers = self.per_occur_scorers(reader)?;
 
         let should_scorer_opt: Option<Box<dyn Scorer>> = per_occur_scorers
@@ -113,7 +112,7 @@ impl BooleanWeight {
 }
 
 impl Weight for BooleanWeight {
-    fn scorer(&self, reader: &SegmentReader) -> Result<Box<dyn Scorer>> {
+    fn scorer(&self, reader: &SegmentReader) -> crate::Result<Box<dyn Scorer>> {
         if self.weights.is_empty() {
             Ok(Box::new(EmptyScorer))
         } else if self.weights.len() == 1 {
@@ -130,7 +129,7 @@ impl Weight for BooleanWeight {
         }
     }
 
-    fn explain(&self, reader: &SegmentReader, doc: DocId) -> Result<Explanation> {
+    fn explain(&self, reader: &SegmentReader, doc: DocId) -> crate::Result<Explanation> {
         let mut scorer = self.scorer(reader)?;
         if scorer.skip_next(doc) != SkipResult::Reached {
             return Err(does_not_match(doc));

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) -> 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/fuzzy_query.rs

@@ -1,8 +1,7 @@
-use crate::error::TantivyError::InvalidArgument;
 use crate::query::{AutomatonWeight, Query, Weight};
 use crate::schema::Term;
-use crate::Result;
 use crate::Searcher;
+use crate::TantivyError::InvalidArgument;
 use levenshtein_automata::{LevenshteinAutomatonBuilder, DFA};
 use once_cell::sync::Lazy;
 use std::collections::HashMap;
@@ -31,9 +30,9 @@ 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();
@@ -102,7 +101,7 @@ impl FuzzyTermQuery {
         }
     }
 
-    fn specialized_weight(&self) -> Result<AutomatonWeight<DFA>> {
+    fn specialized_weight(&self) -> crate::Result<AutomatonWeight<DFA>> {
         // 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)
@@ -119,7 +118,11 @@ 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()?))
     }
 }

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/query.rs

@@ -2,7 +2,6 @@ use super::Weight;
 use crate::core::searcher::Searcher;
 use crate::query::Explanation;
 use crate::DocAddress;
-use crate::Result;
 use crate::Term;
 use downcast_rs::impl_downcast;
 use std::collections::BTreeSet;
@@ -48,17 +47,17 @@ 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())
     }
 
     /// 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 +85,11 @@ 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/query_parser.rs

@@ -8,7 +8,7 @@ use crate::query::PhraseQuery;
 use crate::query::Query;
 use crate::query::RangeQuery;
 use crate::query::TermQuery;
-use crate::schema::IndexRecordOption;
+use crate::schema::{Facet, IndexRecordOption};
 use crate::schema::{Field, Schema};
 use crate::schema::{FieldType, Term};
 use crate::tokenizer::TokenizerManager;
@@ -319,7 +319,10 @@ impl QueryParser {
                     ))
                 }
             }
-            FieldType::HierarchicalFacet => Ok(vec![(0, Term::from_field_text(field, phrase))]),
+            FieldType::HierarchicalFacet => {
+                let facet = Facet::from_text(phrase);
+                Ok(vec![(0, Term::from_field_text(field, facet.encoded_str()))])
+            }
             FieldType::Bytes => {
                 let field_name = self.schema.get_field_name(field).to_string();
                 Err(QueryParserError::FieldNotIndexed(field_name))
@@ -530,7 +533,7 @@ mod test {
     use crate::schema::{IndexRecordOption, TextFieldIndexing, TextOptions};
     use crate::schema::{Schema, Term, INDEXED, STORED, STRING, TEXT};
     use crate::tokenizer::{
-        LowerCaser, SimpleTokenizer, StopWordFilter, Tokenizer, TokenizerManager,
+        LowerCaser, SimpleTokenizer, StopWordFilter, TextAnalyzer, TokenizerManager,
     };
     use crate::Index;
     use matches::assert_matches;
@@ -554,12 +557,13 @@ mod test {
         schema_builder.add_text_field("with_stop_words", text_options);
         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];
         let tokenizer_manager = TokenizerManager::default();
         tokenizer_manager.register(
             "en_with_stop_words",
-            SimpleTokenizer
+            TextAnalyzer::from(SimpleTokenizer)
                 .filter(LowerCaser)
                 .filter(StopWordFilter::remove(vec!["the".to_string()])),
         );
@@ -588,9 +592,13 @@ mod test {
     }
 
     #[test]
-    pub fn test_parse_query_simple() {
+    pub fn test_parse_query_facet() {
         let query_parser = make_query_parser();
-        assert!(query_parser.parse_query("toto").is_ok());
+        let query = query_parser.parse_query("facet:/root/branch/leaf").unwrap();
+        assert_eq!(
+            format!("{:?}", query),
+            "TermQuery(Term(field=11,bytes=[114, 111, 111, 116, 0, 98, 114, 97, 110, 99, 104, 0, 108, 101, 97, 102]))"
+        );
     }
 
     #[test]

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/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/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/schema/facet.rs

@@ -122,6 +122,11 @@ impl Facet {
     pub fn to_path(&self) -> Vec<&str> {
         self.encoded_str().split(|c| c == FACET_SEP_CHAR).collect()
     }
+
+    /// This function is the inverse of Facet::from(&str).
+    pub fn to_path_string(&self) -> String {
+        format!("{}", self.to_string())
+    }
 }
 
 impl Borrow<str> for Facet {
@@ -265,4 +270,21 @@ mod tests {
         let facet = Facet::from_path(v.iter());
         assert_eq!(facet.to_path(), v);
     }
+
+    #[test]
+    fn test_to_path_string() {
+        let v = ["first", "second", "third/not_fourth"];
+        let facet = Facet::from_path(v.iter());
+        assert_eq!(
+            facet.to_path_string(),
+            String::from("/first/second/third\\/not_fourth")
+        );
+    }
+
+    #[test]
+    fn test_to_path_string_empty() {
+        let v: Vec<&str> = vec![];
+        let facet = Facet::from_path(v.iter());
+        assert_eq!(facet.to_path_string(), "/");
+    }
 }

src/schema/schema.rs

@@ -166,7 +166,7 @@ impl SchemaBuilder {
     }
 
     /// Adds a field entry to the schema in build.
-    fn add_field(&mut self, field_entry: FieldEntry) -> Field {
+    pub fn add_field(&mut self, field_entry: FieldEntry) -> Field {
         let field = Field::from_field_id(self.fields.len() as u32);
         let field_name = field_entry.name().to_string();
         self.fields.push(field_entry);
@@ -401,6 +401,7 @@ pub enum DocParsingError {
 mod tests {
 
     use crate::schema::field_type::ValueParsingError;
+    use crate::schema::int_options::Cardinality::SingleValue;
     use crate::schema::schema::DocParsingError::NotJSON;
     use crate::schema::*;
     use matches::{assert_matches, matches};
@@ -715,4 +716,94 @@ mod tests {
             assert_matches!(json_err, Err(NotJSON(_)));
         }
     }
+
+    #[test]
+    pub fn test_schema_add_field() {
+        let mut schema_builder = SchemaBuilder::default();
+        let id_options = TextOptions::default().set_stored().set_indexing_options(
+            TextFieldIndexing::default()
+                .set_tokenizer("raw")
+                .set_index_option(IndexRecordOption::Basic),
+        );
+        let timestamp_options = IntOptions::default()
+            .set_stored()
+            .set_indexed()
+            .set_fast(SingleValue);
+        schema_builder.add_text_field("_id", id_options);
+        schema_builder.add_date_field("_timestamp", timestamp_options);
+
+        let schema_content = r#"[
+  {
+    "name": "text",
+    "type": "text",
+    "options": {
+      "indexing": {
+        "record": "position",
+        "tokenizer": "default"
+      },
+      "stored": false
+    }
+  },
+  {
+    "name": "popularity",
+    "type": "i64",
+    "options": {
+      "indexed": false,
+      "fast": "single",
+      "stored": true
+    }
+  }
+]"#;
+        let tmp_schema: Schema =
+            serde_json::from_str(&schema_content).expect("error while reading json");
+        for (_field, field_entry) in tmp_schema.fields() {
+            schema_builder.add_field(field_entry.clone());
+        }
+
+        let schema = schema_builder.build();
+        let schema_json = serde_json::to_string_pretty(&schema).unwrap();
+        let expected = r#"[
+  {
+    "name": "_id",
+    "type": "text",
+    "options": {
+      "indexing": {
+        "record": "basic",
+        "tokenizer": "raw"
+      },
+      "stored": true
+    }
+  },
+  {
+    "name": "_timestamp",
+    "type": "date",
+    "options": {
+      "indexed": true,
+      "fast": "single",
+      "stored": true
+    }
+  },
+  {
+    "name": "text",
+    "type": "text",
+    "options": {
+      "indexing": {
+        "record": "position",
+        "tokenizer": "default"
+      },
+      "stored": false
+    }
+  },
+  {
+    "name": "popularity",
+    "type": "i64",
+    "options": {
+      "indexed": false,
+      "fast": "single",
+      "stored": true
+    }
+  }
+]"#;
+        assert_eq!(schema_json, expected);
+    }
 }

src/schema/value.rs

@@ -209,8 +209,8 @@ impl From<f64> for Value {
     }
 }
 
-impl From<DateTime> for Value {
-    fn from(date_time: DateTime) -> Value {
+impl From<crate::DateTime> for Value {
+    fn from(date_time: crate::DateTime) -> Value {
         Value::Date(date_time)
     }
 }

src/snippet/mod.rs

@@ -1,10 +1,8 @@
 use crate::query::Query;
 use crate::schema::Field;
 use crate::schema::Value;
-use crate::tokenizer::BoxedTokenizer;
-use crate::tokenizer::{Token, TokenStream};
+use crate::tokenizer::{TextAnalyzer, Token};
 use crate::Document;
-use crate::Result;
 use crate::Searcher;
 use htmlescape::encode_minimal;
 use std::cmp::Ordering;
@@ -142,7 +140,7 @@ impl Snippet {
 /// Fragments must be valid in the sense that `&text[fragment.start..fragment.stop]`\
 /// has to be a valid string.
 fn search_fragments<'a>(
-    tokenizer: &BoxedTokenizer,
+    tokenizer: &TextAnalyzer,
     text: &'a str,
     terms: &BTreeMap<String, f32>,
     max_num_chars: usize,
@@ -251,7 +249,7 @@ fn select_best_fragment_combination(fragments: &[FragmentCandidate], text: &str)
 /// ```
 pub struct SnippetGenerator {
     terms_text: BTreeMap<String, f32>,
-    tokenizer: BoxedTokenizer,
+    tokenizer: TextAnalyzer,
     field: Field,
     max_num_chars: usize,
 }
@@ -262,7 +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
@@ -347,12 +345,11 @@ Survey in 2016, 2017, and 2018."#;
 
     #[test]
     fn test_snippet() {
-        let boxed_tokenizer = SimpleTokenizer.into();
         let terms = btreemap! {
             String::from("rust") => 1.0,
             String::from("language") => 0.9
         };
-        let fragments = search_fragments(&boxed_tokenizer, TEST_TEXT, &terms, 100);
+        let fragments = search_fragments(&From::from(SimpleTokenizer), TEST_TEXT, &terms, 100);
         assert_eq!(fragments.len(), 7);
         {
             let first = &fragments[0];
@@ -374,13 +371,12 @@ Survey in 2016, 2017, and 2018."#;
 
     #[test]
     fn test_snippet_scored_fragment() {
-        let boxed_tokenizer = SimpleTokenizer.into();
         {
             let terms = btreemap! {
                 String::from("rust") =>1.0f32,
                 String::from("language") => 0.9f32
             };
-            let fragments = search_fragments(&boxed_tokenizer, TEST_TEXT, &terms, 20);
+            let fragments = search_fragments(&From::from(SimpleTokenizer), TEST_TEXT, &terms, 20);
             {
                 let first = &fragments[0];
                 assert_eq!(first.score, 1.0);
@@ -389,13 +385,12 @@ Survey in 2016, 2017, and 2018."#;
             let snippet = select_best_fragment_combination(&fragments[..], &TEST_TEXT);
             assert_eq!(snippet.to_html(), "<b>Rust</b> is a systems")
         }
-        let boxed_tokenizer = SimpleTokenizer.into();
         {
             let terms = btreemap! {
                 String::from("rust") =>0.9f32,
                 String::from("language") => 1.0f32
             };
-            let fragments = search_fragments(&boxed_tokenizer, TEST_TEXT, &terms, 20);
+            let fragments = search_fragments(&From::from(SimpleTokenizer), TEST_TEXT, &terms, 20);
             //assert_eq!(fragments.len(), 7);
             {
                 let first = &fragments[0];
@@ -409,14 +404,12 @@ Survey in 2016, 2017, and 2018."#;
 
     #[test]
     fn test_snippet_in_second_fragment() {
-        let boxed_tokenizer = SimpleTokenizer.into();
-
         let text = "a b c d e f g";
 
         let mut terms = BTreeMap::new();
         terms.insert(String::from("c"), 1.0);
 
-        let fragments = search_fragments(&boxed_tokenizer, &text, &terms, 3);
+        let fragments = search_fragments(&From::from(SimpleTokenizer), &text, &terms, 3);
 
         assert_eq!(fragments.len(), 1);
         {
@@ -433,14 +426,12 @@ Survey in 2016, 2017, and 2018."#;
 
     #[test]
     fn test_snippet_with_term_at_the_end_of_fragment() {
-        let boxed_tokenizer = SimpleTokenizer.into();
-
         let text = "a b c d e f f g";
 
         let mut terms = BTreeMap::new();
         terms.insert(String::from("f"), 1.0);
 
-        let fragments = search_fragments(&boxed_tokenizer, &text, &terms, 3);
+        let fragments = search_fragments(&From::from(SimpleTokenizer), &text, &terms, 3);
 
         assert_eq!(fragments.len(), 2);
         {
@@ -457,15 +448,13 @@ Survey in 2016, 2017, and 2018."#;
 
     #[test]
     fn test_snippet_with_second_fragment_has_the_highest_score() {
-        let boxed_tokenizer = SimpleTokenizer.into();
-
         let text = "a b c d e f g";
 
         let mut terms = BTreeMap::new();
         terms.insert(String::from("f"), 1.0);
         terms.insert(String::from("a"), 0.9);
 
-        let fragments = search_fragments(&boxed_tokenizer, &text, &terms, 7);
+        let fragments = search_fragments(&From::from(SimpleTokenizer), &text, &terms, 7);
 
         assert_eq!(fragments.len(), 2);
         {
@@ -482,14 +471,12 @@ Survey in 2016, 2017, and 2018."#;
 
     #[test]
     fn test_snippet_with_term_not_in_text() {
-        let boxed_tokenizer = SimpleTokenizer.into();
-
         let text = "a b c d";
 
         let mut terms = BTreeMap::new();
         terms.insert(String::from("z"), 1.0);
 
-        let fragments = search_fragments(&boxed_tokenizer, &text, &terms, 3);
+        let fragments = search_fragments(&From::from(SimpleTokenizer), &text, &terms, 3);
 
         assert_eq!(fragments.len(), 0);
 
@@ -500,12 +487,10 @@ Survey in 2016, 2017, and 2018."#;
 
     #[test]
     fn test_snippet_with_no_terms() {
-        let boxed_tokenizer = SimpleTokenizer.into();
-
         let text = "a b c d";
 
         let terms = BTreeMap::new();
-        let fragments = search_fragments(&boxed_tokenizer, &text, &terms, 3);
+        let fragments = search_fragments(&From::from(SimpleTokenizer), &text, &terms, 3);
         assert_eq!(fragments.len(), 0);
 
         let snippet = select_best_fragment_combination(&fragments[..], &text);

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

@@ -38,7 +38,7 @@ mod tests {
     use crate::core::Index;
     use crate::directory::{Directory, RAMDirectory, ReadOnlySource};
     use crate::postings::TermInfo;
-    use crate::schema::{Document, FieldType, Schema, TEXT};
+    use crate::schema::{Document, Schema, TEXT};
     use std::path::PathBuf;
     use std::str;
 
@@ -52,6 +52,12 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_empty_term_dictionary() {
+        let empty = TermDictionary::empty();
+        assert!(empty.stream().next().is_none());
+    }
+
     #[test]
     fn test_term_ordinals() {
         const COUNTRIES: [&'static str; 7] = [
@@ -67,9 +73,7 @@ mod tests {
         let path = PathBuf::from("TermDictionary");
         {
             let write = directory.open_write(&path).unwrap();
-            let field_type = FieldType::Str(TEXT);
-            let mut term_dictionary_builder =
-                TermDictionaryBuilder::create(write, &field_type).unwrap();
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(write).unwrap();
             for term in COUNTRIES.iter() {
                 term_dictionary_builder
                     .insert(term.as_bytes(), &make_term_info(0u64))
@@ -93,9 +97,7 @@ mod tests {
         let path = PathBuf::from("TermDictionary");
         {
             let write = directory.open_write(&path).unwrap();
-            let field_type = FieldType::Str(TEXT);
-            let mut term_dictionary_builder =
-                TermDictionaryBuilder::create(write, &field_type).unwrap();
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(write).unwrap();
             term_dictionary_builder
                 .insert("abc".as_bytes(), &make_term_info(34u64))
                 .unwrap();
@@ -179,10 +181,8 @@ mod tests {
         let ids: Vec<_> = (0u32..10_000u32)
             .map(|i| (format!("doc{:0>6}", i), i))
             .collect();
-        let field_type = FieldType::Str(TEXT);
         let buffer: Vec<u8> = {
-            let mut term_dictionary_builder =
-                TermDictionaryBuilder::create(vec![], &field_type).unwrap();
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
             for &(ref id, ref i) in &ids {
                 term_dictionary_builder
                     .insert(id.as_bytes(), &make_term_info(*i as u64))
@@ -209,10 +209,8 @@ mod tests {
 
     #[test]
     fn test_stream_high_range_prefix_suffix() {
-        let field_type = FieldType::Str(TEXT);
         let buffer: Vec<u8> = {
-            let mut term_dictionary_builder =
-                TermDictionaryBuilder::create(vec![], &field_type).unwrap();
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
             // term requires more than 16bits
             term_dictionary_builder
                 .insert("abcdefghijklmnopqrstuvwxy", &make_term_info(1))
@@ -244,10 +242,8 @@ mod tests {
         let ids: Vec<_> = (0u32..10_000u32)
             .map(|i| (format!("doc{:0>6}", i), i))
             .collect();
-        let field_type = FieldType::Str(TEXT);
         let buffer: Vec<u8> = {
-            let mut term_dictionary_builder =
-                TermDictionaryBuilder::create(vec![], &field_type).unwrap();
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
             for &(ref id, ref i) in &ids {
                 term_dictionary_builder
                     .insert(id.as_bytes(), &make_term_info(*i as u64))
@@ -313,10 +309,8 @@ mod tests {
 
     #[test]
     fn test_empty_string() {
-        let field_type = FieldType::Str(TEXT);
         let buffer: Vec<u8> = {
-            let mut term_dictionary_builder =
-                TermDictionaryBuilder::create(vec![], &field_type).unwrap();
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
             term_dictionary_builder
                 .insert(&[], &make_term_info(1 as u64))
                 .unwrap();
@@ -337,10 +331,8 @@ mod tests {
 
     #[test]
     fn test_stream_range_boundaries() {
-        let field_type = FieldType::Str(TEXT);
         let buffer: Vec<u8> = {
-            let mut term_dictionary_builder =
-                TermDictionaryBuilder::create(vec![], &field_type).unwrap();
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
             for i in 0u8..10u8 {
                 let number_arr = [i; 1];
                 term_dictionary_builder
@@ -352,41 +344,91 @@ mod tests {
         let source = ReadOnlySource::from(buffer);
         let term_dictionary: TermDictionary = TermDictionary::from_source(&source);
 
-        let value_list = |mut streamer: TermStreamer<'_>| {
+        let value_list = |mut streamer: TermStreamer<'_>, backwards: bool| {
             let mut res: Vec<u32> = vec![];
             while let Some((_, ref v)) = streamer.next() {
                 res.push(v.doc_freq);
             }
+            if backwards {
+                res.reverse();
+            }
             res
         };
+        {
+            let range = term_dictionary.range().backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
+            );
+        }
         {
             let range = term_dictionary.range().ge([2u8]).into_stream();
             assert_eq!(
-                value_list(range),
+                value_list(range, false),
+                vec![2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().ge([2u8]).backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
                 vec![2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
             );
         }
         {
             let range = term_dictionary.range().gt([2u8]).into_stream();
             assert_eq!(
-                value_list(range),
+                value_list(range, false),
+                vec![3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().gt([2u8]).backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
                 vec![3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
             );
         }
         {
             let range = term_dictionary.range().lt([6u8]).into_stream();
-            assert_eq!(value_list(range), vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32]);
+            assert_eq!(
+                value_list(range, false),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().lt([6u8]).backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32]
+            );
         }
         {
             let range = term_dictionary.range().le([6u8]).into_stream();
             assert_eq!(
-                value_list(range),
+                value_list(range, false),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().le([6u8]).backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
                 vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32]
             );
         }
         {
             let range = term_dictionary.range().ge([0u8]).lt([5u8]).into_stream();
-            assert_eq!(value_list(range), vec![0u32, 1u32, 2u32, 3u32, 4u32]);
+            assert_eq!(value_list(range, false), vec![0u32, 1u32, 2u32, 3u32, 4u32]);
+        }
+        {
+            let range = term_dictionary
+                .range()
+                .ge([0u8])
+                .lt([5u8])
+                .backward()
+                .into_stream();
+            assert_eq!(value_list(range, true), vec![0u32, 1u32, 2u32, 3u32, 4u32]);
         }
     }
 
@@ -408,9 +450,7 @@ mod tests {
         let path = PathBuf::from("TermDictionary");
         {
             let write = directory.open_write(&path).unwrap();
-            let field_type = FieldType::Str(TEXT);
-            let mut term_dictionary_builder =
-                TermDictionaryBuilder::create(write, &field_type).unwrap();
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(write).unwrap();
             for term in COUNTRIES.iter() {
                 term_dictionary_builder
                     .insert(term.as_bytes(), &make_term_info(0u64))

src/termdict/streamer.rs

@@ -51,6 +51,12 @@ where
         self
     }
 
+    /// Iterate over the range backwards.
+    pub fn backward(mut self) -> Self {
+        self.stream_builder = self.stream_builder.backward();
+        self
+    }
+
     /// Creates the stream corresponding to the range
     /// of terms defined using the `TermStreamerBuilder`.
     pub fn into_stream(self) -> TermStreamer<'a, A> {

src/termdict/termdict.rs

@@ -4,8 +4,8 @@ use crate::common::BinarySerializable;
 use crate::common::CountingWriter;
 use crate::directory::ReadOnlySource;
 use crate::postings::TermInfo;
-use crate::schema::FieldType;
 use crate::termdict::TermOrdinal;
+use once_cell::sync::Lazy;
 use std::io::{self, Write};
 use tantivy_fst;
 use tantivy_fst::raw::Fst;
@@ -29,7 +29,7 @@ where
     W: Write,
 {
     /// Creates a new `TermDictionaryBuilder`
-    pub fn create(w: W, _field_type: &FieldType) -> io::Result<Self> {
+    pub fn create(w: W) -> io::Result<Self> {
         let fst_builder = tantivy_fst::MapBuilder::new(w).map_err(convert_fst_error)?;
         Ok(TermDictionaryBuilder {
             fst_builder,
@@ -92,6 +92,14 @@ fn open_fst_index(source: ReadOnlySource) -> tantivy_fst::Map<ReadOnlySource> {
     tantivy_fst::Map::from(fst)
 }
 
+static EMPTY_DATA_SOURCE: Lazy<ReadOnlySource> = Lazy::new(|| {
+    let term_dictionary_data: Vec<u8> = TermDictionaryBuilder::create(Vec::<u8>::new())
+        .expect("Creating a TermDictionaryBuilder in a Vec<u8> should never fail")
+        .finish()
+        .expect("Writing in a Vec<u8> should never fail");
+    ReadOnlySource::from(term_dictionary_data)
+});
+
 /// The term dictionary contains all of the terms in
 /// `tantivy index` in a sorted manner.
 ///
@@ -122,14 +130,8 @@ impl TermDictionary {
     }
 
     /// Creates an empty term dictionary which contains no terms.
-    pub fn empty(field_type: &FieldType) -> Self {
-        let term_dictionary_data: Vec<u8> =
-            TermDictionaryBuilder::create(Vec::<u8>::new(), &field_type)
-                .expect("Creating a TermDictionaryBuilder in a Vec<u8> should never fail")
-                .finish()
-                .expect("Writing in a Vec<u8> should never fail");
-        let source = ReadOnlySource::from(term_dictionary_data);
-        Self::from_source(&source)
+    pub fn empty() -> Self {
+        TermDictionary::from_source(&*EMPTY_DATA_SOURCE)
     }
 
     /// Returns the number of terms in the dictionary.

src/tokenizer/alphanum_only.rs

@@ -2,7 +2,7 @@
 //! ```rust
 //! use tantivy::tokenizer::*;
 //!
-//! let tokenizer = RawTokenizer
+//! let tokenizer = TextAnalyzer::from(RawTokenizer)
 //!   .filter(AlphaNumOnlyFilter);
 //!
 //! let mut stream = tokenizer.token_stream("hello there");
@@ -10,7 +10,7 @@
 //! // contains a space
 //! assert!(stream.next().is_none());
 //!
-//! let tokenizer = SimpleTokenizer
+//! let tokenizer = TextAnalyzer::from(SimpleTokenizer)
 //!   .filter(AlphaNumOnlyFilter);
 //!
 //! let mut stream = tokenizer.token_stream("hello there 💣");
@@ -19,56 +19,30 @@
 //! // the "emoji" is dropped because its not an alphanum
 //! assert!(stream.next().is_none());
 //! ```
-use super::{Token, TokenFilter, TokenStream};
+use super::{BoxTokenStream, Token, TokenFilter, TokenStream};
 
 /// `TokenFilter` that removes all tokens that contain non
 /// ascii alphanumeric characters.
 #[derive(Clone)]
 pub struct AlphaNumOnlyFilter;
 
-pub struct AlphaNumOnlyFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    tail: TailTokenStream,
+pub struct AlphaNumOnlyFilterStream<'a> {
+    tail: BoxTokenStream<'a>,
 }
 
-impl<TailTokenStream> AlphaNumOnlyFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
+impl<'a> AlphaNumOnlyFilterStream<'a> {
     fn predicate(&self, token: &Token) -> bool {
         token.text.chars().all(|c| c.is_ascii_alphanumeric())
     }
+}
 
-    fn wrap(tail: TailTokenStream) -> AlphaNumOnlyFilterStream<TailTokenStream> {
-        AlphaNumOnlyFilterStream { tail }
+impl TokenFilter for AlphaNumOnlyFilter {
+    fn transform<'a>(&self, token_stream: BoxTokenStream<'a>) -> BoxTokenStream<'a> {
+        BoxTokenStream::from(AlphaNumOnlyFilterStream { tail: token_stream })
     }
 }
 
-impl<TailTokenStream> TokenFilter<TailTokenStream> for AlphaNumOnlyFilter
-where
-    TailTokenStream: TokenStream,
-{
-    type ResultTokenStream = AlphaNumOnlyFilterStream<TailTokenStream>;
-
-    fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream {
-        AlphaNumOnlyFilterStream::wrap(token_stream)
-    }
-}
-
-impl<TailTokenStream> TokenStream for AlphaNumOnlyFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    fn token(&self) -> &Token {
-        self.tail.token()
-    }
-
-    fn token_mut(&mut self) -> &mut Token {
-        self.tail.token_mut()
-    }
-
+impl<'a> TokenStream for AlphaNumOnlyFilterStream<'a> {
     fn advance(&mut self) -> bool {
         while self.tail.advance() {
             if self.predicate(self.tail.token()) {
@@ -78,4 +52,12 @@ where
 
         false
     }
+
+    fn token(&self) -> &Token {
+        self.tail.token()
+    }
+
+    fn token_mut(&mut self) -> &mut Token {
+        self.tail.token_mut()
+    }
 }

src/tokenizer/ascii_folding_filter.rs

@@ -1,4 +1,4 @@
-use super::{Token, TokenFilter, TokenStream};
+use super::{BoxTokenStream, Token, TokenFilter, TokenStream};
 use std::mem;
 
 /// This class converts alphabetic, numeric, and symbolic Unicode characters
@@ -7,26 +7,21 @@ use std::mem;
 #[derive(Clone)]
 pub struct AsciiFoldingFilter;
 
-impl<TailTokenStream> TokenFilter<TailTokenStream> for AsciiFoldingFilter
-where
-    TailTokenStream: TokenStream,
-{
-    type ResultTokenStream = AsciiFoldingFilterTokenStream<TailTokenStream>;
-
-    fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream {
-        AsciiFoldingFilterTokenStream::wrap(token_stream)
+impl TokenFilter for AsciiFoldingFilter {
+    fn transform<'a>(&self, token_stream: BoxTokenStream<'a>) -> BoxTokenStream<'a> {
+        From::from(AsciiFoldingFilterTokenStream {
+            tail: token_stream,
+            buffer: String::with_capacity(100),
+        })
     }
 }
 
-pub struct AsciiFoldingFilterTokenStream<TailTokenStream> {
+pub struct AsciiFoldingFilterTokenStream<'a> {
     buffer: String,
-    tail: TailTokenStream,
+    tail: BoxTokenStream<'a>,
 }
 
-impl<TailTokenStream> TokenStream for AsciiFoldingFilterTokenStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
+impl<'a> TokenStream for AsciiFoldingFilterTokenStream<'a> {
     fn advance(&mut self) -> bool {
         if !self.tail.advance() {
             return false;
@@ -48,18 +43,6 @@ where
     }
 }
 
-impl<TailTokenStream> AsciiFoldingFilterTokenStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    fn wrap(tail: TailTokenStream) -> AsciiFoldingFilterTokenStream<TailTokenStream> {
-        AsciiFoldingFilterTokenStream {
-            tail,
-            buffer: String::with_capacity(100),
-        }
-    }
-}
-
 // Returns a string that represents the ascii folded version of
 // the character. If the `char` does not require ascii folding
 // (e.g. simple ASCII chars like `A`) or if the `char`
@@ -1561,8 +1544,7 @@ mod tests {
     use crate::tokenizer::AsciiFoldingFilter;
     use crate::tokenizer::RawTokenizer;
     use crate::tokenizer::SimpleTokenizer;
-    use crate::tokenizer::TokenStream;
-    use crate::tokenizer::Tokenizer;
+    use crate::tokenizer::TextAnalyzer;
     use std::iter;
 
     #[test]
@@ -1579,7 +1561,7 @@ mod tests {
 
     fn folding_helper(text: &str) -> Vec<String> {
         let mut tokens = Vec::new();
-        SimpleTokenizer
+        TextAnalyzer::from(SimpleTokenizer)
             .filter(AsciiFoldingFilter)
             .token_stream(text)
             .process(&mut |token| {
@@ -1589,7 +1571,9 @@ mod tests {
     }
 
     fn folding_using_raw_tokenizer_helper(text: &str) -> String {
-        let mut token_stream = RawTokenizer.filter(AsciiFoldingFilter).token_stream(text);
+        let mut token_stream = TextAnalyzer::from(RawTokenizer)
+            .filter(AsciiFoldingFilter)
+            .token_stream(text);
         token_stream.advance();
         token_stream.token().text.clone()
     }

src/tokenizer/facet_tokenizer.rs

@@ -1,4 +1,4 @@
-use super::{Token, TokenStream, Tokenizer};
+use super::{BoxTokenStream, Token, TokenStream, Tokenizer};
 use crate::schema::FACET_SEP_BYTE;
 
 /// The `FacetTokenizer` process a `Facet` binary representation
@@ -25,15 +25,14 @@ pub struct FacetTokenStream<'a> {
     token: Token,
 }
 
-impl<'a> Tokenizer<'a> for FacetTokenizer {
-    type TokenStreamImpl = FacetTokenStream<'a>;
-
-    fn token_stream(&self, text: &'a str) -> Self::TokenStreamImpl {
+impl Tokenizer for FacetTokenizer {
+    fn token_stream<'a>(&self, text: &'a str) -> BoxTokenStream<'a> {
         FacetTokenStream {
             text,
             state: State::RootFacetNotEmitted, //< pos is the first char that has not been processed yet.
             token: Token::default(),
         }
+        .into()
     }
 }
 
@@ -84,7 +83,7 @@ mod tests {
 
     use super::FacetTokenizer;
     use crate::schema::Facet;
-    use crate::tokenizer::{Token, TokenStream, Tokenizer};
+    use crate::tokenizer::{Token, Tokenizer};
 
     #[test]
     fn test_facet_tokenizer() {

src/tokenizer/lower_caser.rs

@@ -1,24 +1,23 @@
 use super::{Token, TokenFilter, TokenStream};
+use crate::tokenizer::BoxTokenStream;
 use std::mem;
 
+impl TokenFilter for LowerCaser {
+    fn transform<'a>(&self, token_stream: BoxTokenStream<'a>) -> BoxTokenStream<'a> {
+        BoxTokenStream::from(LowerCaserTokenStream {
+            tail: token_stream,
+            buffer: String::with_capacity(100),
+        })
+    }
+}
+
 /// Token filter that lowercase terms.
 #[derive(Clone)]
 pub struct LowerCaser;
 
-impl<TailTokenStream> TokenFilter<TailTokenStream> for LowerCaser
-where
-    TailTokenStream: TokenStream,
-{
-    type ResultTokenStream = LowerCaserTokenStream<TailTokenStream>;
-
-    fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream {
-        LowerCaserTokenStream::wrap(token_stream)
-    }
-}
-
-pub struct LowerCaserTokenStream<TailTokenStream> {
+pub struct LowerCaserTokenStream<'a> {
     buffer: String,
-    tail: TailTokenStream,
+    tail: BoxTokenStream<'a>,
 }
 
 // writes a lowercased version of text into output.
@@ -31,18 +30,7 @@ fn to_lowercase_unicode(text: &mut String, output: &mut String) {
     }
 }
 
-impl<TailTokenStream> TokenStream for LowerCaserTokenStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    fn token(&self) -> &Token {
-        self.tail.token()
-    }
-
-    fn token_mut(&mut self) -> &mut Token {
-        self.tail.token_mut()
-    }
-
+impl<'a> TokenStream for LowerCaserTokenStream<'a> {
     fn advance(&mut self) -> bool {
         if !self.tail.advance() {
             return false;
@@ -56,26 +44,19 @@ where
         }
         true
     }
-}
 
-impl<TailTokenStream> LowerCaserTokenStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    fn wrap(tail: TailTokenStream) -> LowerCaserTokenStream<TailTokenStream> {
-        LowerCaserTokenStream {
-            tail,
-            buffer: String::with_capacity(100),
-        }
+    fn token(&self) -> &Token {
+        self.tail.token()
+    }
+
+    fn token_mut(&mut self) -> &mut Token {
+        self.tail.token_mut()
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use crate::tokenizer::LowerCaser;
-    use crate::tokenizer::SimpleTokenizer;
-    use crate::tokenizer::TokenStream;
-    use crate::tokenizer::Tokenizer;
+    use crate::tokenizer::{LowerCaser, SimpleTokenizer, TextAnalyzer};
 
     #[test]
     fn test_to_lower_case() {
@@ -87,7 +68,9 @@ mod tests {
 
     fn lowercase_helper(text: &str) -> Vec<String> {
         let mut tokens = vec![];
-        let mut token_stream = SimpleTokenizer.filter(LowerCaser).token_stream(text);
+        let mut token_stream = TextAnalyzer::from(SimpleTokenizer)
+            .filter(LowerCaser)
+            .token_stream(text);
         while token_stream.advance() {
             let token_text = token_stream.token().text.clone();
             tokens.push(token_text);

src/tokenizer/mod.rs

@@ -64,7 +64,7 @@
 //! ```rust
 //! use tantivy::tokenizer::*;
 //!
-//! let en_stem = SimpleTokenizer
+//! let en_stem = TextAnalyzer::from(SimpleTokenizer)
 //!     .filter(RemoveLongFilter::limit(40))
 //!     .filter(LowerCaser)
 //!     .filter(Stemmer::new(Language::English));
@@ -109,7 +109,7 @@
 //! let index = Index::create_in_ram(schema);
 //!
 //! // We need to register our tokenizer :
-//! let custom_en_tokenizer = SimpleTokenizer
+//! let custom_en_tokenizer = TextAnalyzer::from(SimpleTokenizer)
 //!     .filter(RemoveLongFilter::limit(40))
 //!     .filter(LowerCaser);
 //! index
@@ -143,10 +143,11 @@ pub use self::simple_tokenizer::SimpleTokenizer;
 pub use self::stemmer::{Language, Stemmer};
 pub use self::stop_word_filter::StopWordFilter;
 pub(crate) use self::token_stream_chain::TokenStreamChain;
-pub use self::tokenizer::BoxedTokenizer;
 
 pub use self::tokenized_string::{PreTokenizedStream, PreTokenizedString};
-pub use self::tokenizer::{Token, TokenFilter, TokenStream, Tokenizer};
+pub use self::tokenizer::{
+    BoxTokenFilter, BoxTokenStream, TextAnalyzer, Token, TokenFilter, TokenStream, Tokenizer,
+};
 
 pub use self::tokenizer_manager::TokenizerManager;
 
@@ -160,9 +161,9 @@ pub const MAX_TOKEN_LEN: usize = u16::max_value() as usize - 4;
 #[cfg(test)]
 pub mod tests {
     use super::{
-        Language, LowerCaser, RemoveLongFilter, SimpleTokenizer, Stemmer, Token, Tokenizer,
-        TokenizerManager,
+        Language, LowerCaser, RemoveLongFilter, SimpleTokenizer, Stemmer, Token, TokenizerManager,
     };
+    use crate::tokenizer::TextAnalyzer;
 
     /// This is a function that can be used in tests and doc tests
     /// to assert a token's correctness.
@@ -229,7 +230,7 @@ pub mod tests {
         let tokenizer_manager = TokenizerManager::default();
         tokenizer_manager.register(
             "el_stem",
-            SimpleTokenizer
+            TextAnalyzer::from(SimpleTokenizer)
                 .filter(RemoveLongFilter::limit(40))
                 .filter(LowerCaser)
                 .filter(Stemmer::new(Language::Greek)),

src/tokenizer/ngram_tokenizer.rs

@@ -1,4 +1,5 @@
 use super::{Token, TokenStream, Tokenizer};
+use crate::tokenizer::BoxTokenStream;
 
 /// Tokenize the text by splitting words into n-grams of the given size(s)
 ///
@@ -129,11 +130,9 @@ pub struct NgramTokenStream<'a> {
     token: Token,
 }
 
-impl<'a> Tokenizer<'a> for NgramTokenizer {
-    type TokenStreamImpl = NgramTokenStream<'a>;
-
-    fn token_stream(&self, text: &'a str) -> Self::TokenStreamImpl {
-        NgramTokenStream {
+impl Tokenizer for NgramTokenizer {
+    fn token_stream<'a>(&self, text: &'a str) -> BoxTokenStream<'a> {
+        From::from(NgramTokenStream {
             ngram_charidx_iterator: StutteringIterator::new(
                 CodepointFrontiers::for_str(text),
                 self.min_gram,
@@ -142,7 +141,7 @@ impl<'a> Tokenizer<'a> for NgramTokenizer {
             prefix_only: self.prefix_only,
             text,
             token: Token::default(),
-        }
+        })
     }
 }
 
@@ -308,10 +307,10 @@ mod tests {
     use super::NgramTokenizer;
     use super::StutteringIterator;
     use crate::tokenizer::tests::assert_token;
-    use crate::tokenizer::tokenizer::{TokenStream, Tokenizer};
-    use crate::tokenizer::Token;
+    use crate::tokenizer::tokenizer::Tokenizer;
+    use crate::tokenizer::{BoxTokenStream, Token};
 
-    fn test_helper<T: TokenStream>(mut tokenizer: T) -> Vec<Token> {
+    fn test_helper(mut tokenizer: BoxTokenStream) -> Vec<Token> {
         let mut tokens: Vec<Token> = vec![];
         tokenizer.process(&mut |token: &Token| tokens.push(token.clone()));
         tokens

src/tokenizer/raw_tokenizer.rs

@@ -1,4 +1,5 @@
 use super::{Token, TokenStream, Tokenizer};
+use crate::tokenizer::BoxTokenStream;
 
 /// For each value of the field, emit a single unprocessed token.
 #[derive(Clone)]
@@ -9,10 +10,8 @@ pub struct RawTokenStream {
     has_token: bool,
 }
 
-impl<'a> Tokenizer<'a> for RawTokenizer {
-    type TokenStreamImpl = RawTokenStream;
-
-    fn token_stream(&self, text: &'a str) -> Self::TokenStreamImpl {
+impl Tokenizer for RawTokenizer {
+    fn token_stream<'a>(&self, text: &'a str) -> BoxTokenStream<'a> {
         let token = Token {
             offset_from: 0,
             offset_to: text.len(),
@@ -24,6 +23,7 @@ impl<'a> Tokenizer<'a> for RawTokenizer {
             token,
             has_token: true,
         }
+        .into()
     }
 }
 

src/tokenizer/remove_long.rs

@@ -2,7 +2,7 @@
 //! ```rust
 //! use tantivy::tokenizer::*;
 //!
-//! let tokenizer = SimpleTokenizer
+//! let tokenizer = TextAnalyzer::from(SimpleTokenizer)
 //!   .filter(RemoveLongFilter::limit(5));
 //!
 //! let mut stream = tokenizer.token_stream("toolong nice");
@@ -13,6 +13,7 @@
 //! ```
 //!
 use super::{Token, TokenFilter, TokenStream};
+use crate::tokenizer::BoxTokenStream;
 
 /// `RemoveLongFilter` removes tokens that are longer
 /// than a given number of bytes (in UTF-8 representation).
@@ -31,56 +32,27 @@ impl RemoveLongFilter {
     }
 }
 
-impl<TailTokenStream> RemoveLongFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
+impl<'a> RemoveLongFilterStream<'a> {
     fn predicate(&self, token: &Token) -> bool {
         token.text.len() < self.token_length_limit
     }
+}
 
-    fn wrap(
-        token_length_limit: usize,
-        tail: TailTokenStream,
-    ) -> RemoveLongFilterStream<TailTokenStream> {
-        RemoveLongFilterStream {
-            token_length_limit,
-            tail,
-        }
+impl TokenFilter for RemoveLongFilter {
+    fn transform<'a>(&self, token_stream: BoxTokenStream<'a>) -> BoxTokenStream<'a> {
+        BoxTokenStream::from(RemoveLongFilterStream {
+            token_length_limit: self.length_limit,
+            tail: token_stream,
+        })
     }
 }
 
-impl<TailTokenStream> TokenFilter<TailTokenStream> for RemoveLongFilter
-where
-    TailTokenStream: TokenStream,
-{
-    type ResultTokenStream = RemoveLongFilterStream<TailTokenStream>;
-
-    fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream {
-        RemoveLongFilterStream::wrap(self.length_limit, token_stream)
-    }
-}
-
-pub struct RemoveLongFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
+pub struct RemoveLongFilterStream<'a> {
     token_length_limit: usize,
-    tail: TailTokenStream,
+    tail: BoxTokenStream<'a>,
 }
 
-impl<TailTokenStream> TokenStream for RemoveLongFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    fn token(&self) -> &Token {
-        self.tail.token()
-    }
-
-    fn token_mut(&mut self) -> &mut Token {
-        self.tail.token_mut()
-    }
-
+impl<'a> TokenStream for RemoveLongFilterStream<'a> {
     fn advance(&mut self) -> bool {
         while self.tail.advance() {
             if self.predicate(self.tail.token()) {
@@ -89,4 +61,12 @@ where
         }
         false
     }
+
+    fn token(&self) -> &Token {
+        self.tail.token()
+    }
+
+    fn token_mut(&mut self) -> &mut Token {
+        self.tail.token_mut()
+    }
 }

src/tokenizer/simple_tokenizer.rs

@@ -1,3 +1,4 @@
+use super::BoxTokenStream;
 use super::{Token, TokenStream, Tokenizer};
 use std::str::CharIndices;
 
@@ -11,15 +12,13 @@ pub struct SimpleTokenStream<'a> {
     token: Token,
 }
 
-impl<'a> Tokenizer<'a> for SimpleTokenizer {
-    type TokenStreamImpl = SimpleTokenStream<'a>;
-
-    fn token_stream(&self, text: &'a str) -> Self::TokenStreamImpl {
-        SimpleTokenStream {
+impl Tokenizer for SimpleTokenizer {
+    fn token_stream<'a>(&self, text: &'a str) -> BoxTokenStream<'a> {
+        BoxTokenStream::from(SimpleTokenStream {
             text,
             chars: text.char_indices(),
             token: Token::default(),
-        }
+        })
     }
 }
 

src/tokenizer/stemmer.rs

@@ -1,4 +1,5 @@
 use super::{Token, TokenFilter, TokenStream};
+use crate::tokenizer::BoxTokenStream;
 use rust_stemmers::{self, Algorithm};
 
 /// Available stemmer languages.
@@ -75,38 +76,22 @@ impl Default for Stemmer {
     }
 }
 
-impl<TailTokenStream> TokenFilter<TailTokenStream> for Stemmer
-where
-    TailTokenStream: TokenStream,
-{
-    type ResultTokenStream = StemmerTokenStream<TailTokenStream>;
-
-    fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream {
+impl TokenFilter for Stemmer {
+    fn transform<'a>(&self, token_stream: BoxTokenStream<'a>) -> BoxTokenStream<'a> {
         let inner_stemmer = rust_stemmers::Stemmer::create(self.stemmer_algorithm);
-        StemmerTokenStream::wrap(inner_stemmer, token_stream)
+        BoxTokenStream::from(StemmerTokenStream {
+            tail: token_stream,
+            stemmer: inner_stemmer,
+        })
     }
 }
 
-pub struct StemmerTokenStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    tail: TailTokenStream,
+pub struct StemmerTokenStream<'a> {
+    tail: BoxTokenStream<'a>,
     stemmer: rust_stemmers::Stemmer,
 }
 
-impl<TailTokenStream> TokenStream for StemmerTokenStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    fn token(&self) -> &Token {
-        self.tail.token()
-    }
-
-    fn token_mut(&mut self) -> &mut Token {
-        self.tail.token_mut()
-    }
-
+impl<'a> TokenStream for StemmerTokenStream<'a> {
     fn advance(&mut self) -> bool {
         if !self.tail.advance() {
             return false;
@@ -117,16 +102,12 @@ where
         self.token_mut().text.push_str(&stemmed_str);
         true
     }
-}
 
-impl<TailTokenStream> StemmerTokenStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    fn wrap(
-        stemmer: rust_stemmers::Stemmer,
-        tail: TailTokenStream,
-    ) -> StemmerTokenStream<TailTokenStream> {
-        StemmerTokenStream { tail, stemmer }
+    fn token(&self) -> &Token {
+        self.tail.token()
+    }
+
+    fn token_mut(&mut self) -> &mut Token {
+        self.tail.token_mut()
     }
 }

src/tokenizer/stop_word_filter.rs

@@ -2,7 +2,7 @@
 //! ```rust
 //! use tantivy::tokenizer::*;
 //!
-//! let tokenizer = SimpleTokenizer
+//! let tokenizer = TextAnalyzer::from(SimpleTokenizer)
 //!   .filter(StopWordFilter::remove(vec!["the".to_string(), "is".to_string()]));
 //!
 //! let mut stream = tokenizer.token_stream("the fox is crafty");
@@ -11,6 +11,7 @@
 //! assert!(stream.next().is_none());
 //! ```
 use super::{Token, TokenFilter, TokenStream};
+use crate::tokenizer::BoxTokenStream;
 use fnv::FnvHasher;
 use std::collections::HashSet;
 use std::hash::BuildHasherDefault;
@@ -48,53 +49,27 @@ impl StopWordFilter {
     }
 }
 
-pub struct StopWordFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
+pub struct StopWordFilterStream<'a> {
     words: StopWordHashSet,
-    tail: TailTokenStream,
+    tail: BoxTokenStream<'a>,
 }
 
-impl<TailTokenStream> TokenFilter<TailTokenStream> for StopWordFilter
-where
-    TailTokenStream: TokenStream,
-{
-    type ResultTokenStream = StopWordFilterStream<TailTokenStream>;
-
-    fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream {
-        StopWordFilterStream::wrap(self.words.clone(), token_stream)
+impl TokenFilter for StopWordFilter {
+    fn transform<'a>(&self, token_stream: BoxTokenStream<'a>) -> BoxTokenStream<'a> {
+        BoxTokenStream::from(StopWordFilterStream {
+            words: self.words.clone(),
+            tail: token_stream,
+        })
     }
 }
 
-impl<TailTokenStream> StopWordFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
+impl<'a> StopWordFilterStream<'a> {
     fn predicate(&self, token: &Token) -> bool {
         !self.words.contains(&token.text)
     }
-
-    fn wrap(
-        words: StopWordHashSet,
-        tail: TailTokenStream,
-    ) -> StopWordFilterStream<TailTokenStream> {
-        StopWordFilterStream { words, tail }
-    }
 }
 
-impl<TailTokenStream> TokenStream for StopWordFilterStream<TailTokenStream>
-where
-    TailTokenStream: TokenStream,
-{
-    fn token(&self) -> &Token {
-        self.tail.token()
-    }
-
-    fn token_mut(&mut self) -> &mut Token {
-        self.tail.token_mut()
-    }
-
+impl<'a> TokenStream for StopWordFilterStream<'a> {
     fn advance(&mut self) -> bool {
         while self.tail.advance() {
             if self.predicate(self.tail.token()) {
@@ -103,6 +78,14 @@ where
         }
         false
     }
+
+    fn token(&self) -> &Token {
+        self.tail.token()
+    }
+
+    fn token_mut(&mut self) -> &mut Token {
+        self.tail.token_mut()
+    }
 }
 
 impl Default for StopWordFilter {

src/tokenizer/token_stream_chain.rs

@@ -1,23 +1,21 @@
-use crate::tokenizer::{Token, TokenStream};
+use crate::tokenizer::{BoxTokenStream, Token, TokenStream};
+use std::ops::DerefMut;
 
 const POSITION_GAP: usize = 2;
 
-pub(crate) struct TokenStreamChain<TTokenStream: TokenStream> {
+pub(crate) struct TokenStreamChain<'a> {
     offsets: Vec<usize>,
-    token_streams: Vec<TTokenStream>,
+    token_streams: Vec<BoxTokenStream<'a>>,
     position_shift: usize,
     stream_idx: usize,
     token: Token,
 }
 
-impl<'a, TTokenStream> TokenStreamChain<TTokenStream>
-where
-    TTokenStream: TokenStream,
-{
+impl<'a> TokenStreamChain<'a> {
     pub fn new(
         offsets: Vec<usize>,
-        token_streams: Vec<TTokenStream>,
-    ) -> TokenStreamChain<TTokenStream> {
+        token_streams: Vec<BoxTokenStream<'a>>,
+    ) -> TokenStreamChain<'a> {
         TokenStreamChain {
             offsets,
             stream_idx: 0,
@@ -28,13 +26,10 @@ where
     }
 }
 
-impl<'a, TTokenStream> TokenStream for TokenStreamChain<TTokenStream>
-where
-    TTokenStream: TokenStream,
-{
+impl<'a> TokenStream for TokenStreamChain<'a> {
     fn advance(&mut self) -> bool {
         while self.stream_idx < self.token_streams.len() {
-            let token_stream = &mut self.token_streams[self.stream_idx];
+            let token_stream = self.token_streams[self.stream_idx].deref_mut();
             if token_stream.advance() {
                 let token = token_stream.token();
                 let offset_offset = self.offsets[self.stream_idx];

src/tokenizer/tokenized_string.rs

@@ -1,4 +1,4 @@
-use crate::tokenizer::{Token, TokenStream, TokenStreamChain};
+use crate::tokenizer::{BoxTokenStream, Token, TokenStream, TokenStreamChain};
 use std::cmp::Ordering;
 
 /// Struct representing pre-tokenized text
@@ -41,9 +41,9 @@ impl PreTokenizedStream {
     /// Creates a TokenStream from PreTokenizedString array
     pub fn chain_tokenized_strings<'a>(
         tok_strings: &'a [&'a PreTokenizedString],
-    ) -> Box<dyn TokenStream + 'a> {
+    ) -> BoxTokenStream {
         if tok_strings.len() == 1 {
-            Box::new(PreTokenizedStream::from((*tok_strings[0]).clone()))
+            PreTokenizedStream::from((*tok_strings[0]).clone()).into()
         } else {
             let mut offsets = vec![];
             let mut total_offset = 0;
@@ -53,11 +53,12 @@ impl PreTokenizedStream {
                     total_offset += last_token.offset_to;
                 }
             }
-            let token_streams: Vec<_> = tok_strings
+            // TODO remove the string cloning.
+            let token_streams: Vec<BoxTokenStream<'static>> = tok_strings
                 .iter()
-                .map(|tok_string| PreTokenizedStream::from((*tok_string).clone()))
+                .map(|&tok_string| PreTokenizedStream::from((*tok_string).clone()).into())
                 .collect();
-            Box::new(TokenStreamChain::new(offsets, token_streams))
+            TokenStreamChain::new(offsets, token_streams).into()
         }
     }
 }

src/tokenizer/tokenizer.rs

@@ -2,6 +2,7 @@ use crate::tokenizer::TokenStreamChain;
 /// The tokenizer module contains all of the tools used to process
 /// text in `tantivy`.
 use std::borrow::{Borrow, BorrowMut};
+use std::ops::{Deref, DerefMut};
 
 /// Token
 #[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq)]
@@ -33,20 +34,31 @@ impl Default for Token {
     }
 }
 
-/// `Tokenizer` are in charge of splitting text into a stream of token
-/// before indexing.
+/// `TextAnalyzer` tokenizes an input text into tokens and modifies the resulting `TokenStream`.
 ///
-/// See the [module documentation](./index.html) for more detail.
-///
-/// # Warning
-///
-/// This API may change to use associated types.
-pub trait Tokenizer<'a>: Sized + Clone {
-    /// Type associated to the resulting tokenstream tokenstream.
-    type TokenStreamImpl: TokenStream;
+/// It simply wraps a `Tokenizer` and a list of `TokenFilter` that are applied sequentially.
+pub struct TextAnalyzer {
+    tokenizer: Box<dyn Tokenizer>,
+    token_filters: Vec<BoxTokenFilter>,
+}
 
-    /// Creates a token stream for a given `str`.
-    fn token_stream(&self, text: &'a str) -> Self::TokenStreamImpl;
+impl<T: Tokenizer> From<T> for TextAnalyzer {
+    fn from(tokenizer: T) -> Self {
+        TextAnalyzer::new(tokenizer, Vec::new())
+    }
+}
+
+impl TextAnalyzer {
+    /// Creates a new `TextAnalyzer` given a tokenizer and a vector of `BoxTokenFilter`.
+    ///
+    /// When creating a `TextAnalyzer` from a `Tokenizer` alone, prefer using
+    /// `TextAnalyzer::from(tokenizer)`.
+    pub fn new<T: Tokenizer>(tokenizer: T, token_filters: Vec<BoxTokenFilter>) -> TextAnalyzer {
+        TextAnalyzer {
+            tokenizer: Box::new(tokenizer),
+            token_filters,
+        }
+    }
 
     /// Appends a token filter to the current tokenizer.
     ///
@@ -58,90 +70,26 @@ pub trait Tokenizer<'a>: Sized + Clone {
     /// ```rust
     /// use tantivy::tokenizer::*;
     ///
-    /// let en_stem = SimpleTokenizer
+    /// let en_stem = TextAnalyzer::from(SimpleTokenizer)
     ///     .filter(RemoveLongFilter::limit(40))
     ///     .filter(LowerCaser)
     ///     .filter(Stemmer::default());
     /// ```
     ///
-    fn filter<NewFilter>(self, new_filter: NewFilter) -> ChainTokenizer<NewFilter, Self>
-    where
-        NewFilter: TokenFilter<<Self as Tokenizer<'a>>::TokenStreamImpl>,
-    {
-        ChainTokenizer {
-            head: new_filter,
-            tail: self,
-        }
-    }
-}
-
-/// A boxed tokenizer
-trait BoxedTokenizerTrait: Send + Sync {
-    /// Tokenize a `&str`
-    fn token_stream<'a>(&self, text: &'a str) -> Box<dyn TokenStream + 'a>;
-
-    /// Tokenize an array`&str`
-    ///
-    /// The resulting `TokenStream` is equivalent to what would be obtained if the &str were
-    /// one concatenated `&str`, with an artificial position gap of `2` between the different fields
-    /// to prevent accidental `PhraseQuery` to match accross two terms.
-    fn token_stream_texts<'b>(&self, texts: &'b [&'b str]) -> Box<dyn TokenStream + 'b>;
-
-    /// Return a boxed clone of the tokenizer
-    fn boxed_clone(&self) -> BoxedTokenizer;
-}
-
-/// A boxed tokenizer
-pub struct BoxedTokenizer(Box<dyn BoxedTokenizerTrait>);
-
-impl<T> From<T> for BoxedTokenizer
-where
-    T: 'static + Send + Sync + for<'a> Tokenizer<'a>,
-{
-    fn from(tokenizer: T) -> BoxedTokenizer {
-        BoxedTokenizer(Box::new(BoxableTokenizer(tokenizer)))
-    }
-}
-
-impl BoxedTokenizer {
-    /// Tokenize a `&str`
-    pub fn token_stream<'a>(&self, text: &'a str) -> Box<dyn TokenStream + 'a> {
-        self.0.token_stream(text)
+    pub fn filter<F: Into<BoxTokenFilter>>(mut self, token_filter: F) -> Self {
+        self.token_filters.push(token_filter.into());
+        self
     }
 
     /// Tokenize an array`&str`
     ///
-    /// The resulting `TokenStream` is equivalent to what would be obtained if the &str were
+    /// The resulting `BoxTokenStream` is equivalent to what would be obtained if the &str were
     /// one concatenated `&str`, with an artificial position gap of `2` between the different fields
     /// to prevent accidental `PhraseQuery` to match accross two terms.
-    pub fn token_stream_texts<'b>(&self, texts: &'b [&'b str]) -> Box<dyn TokenStream + 'b> {
-        self.0.token_stream_texts(texts)
-    }
-}
-
-impl Clone for BoxedTokenizer {
-    fn clone(&self) -> BoxedTokenizer {
-        self.0.boxed_clone()
-    }
-}
-
-#[derive(Clone)]
-struct BoxableTokenizer<A>(A)
-where
-    A: for<'a> Tokenizer<'a> + Send + Sync;
-
-impl<A> BoxedTokenizerTrait for BoxableTokenizer<A>
-where
-    A: 'static + Send + Sync + for<'a> Tokenizer<'a>,
-{
-    fn token_stream<'a>(&self, text: &'a str) -> Box<dyn TokenStream + 'a> {
-        Box::new(self.0.token_stream(text))
-    }
-
-    fn token_stream_texts<'b>(&self, texts: &'b [&'b str]) -> Box<dyn TokenStream + 'b> {
+    pub fn token_stream_texts<'a>(&self, texts: &'a [&'a str]) -> BoxTokenStream<'a> {
         assert!(!texts.is_empty());
         if texts.len() == 1 {
-            Box::new(self.0.token_stream(texts[0]))
+            self.token_stream(texts[0])
         } else {
             let mut offsets = vec![];
             let mut total_offset = 0;
@@ -149,34 +97,124 @@ where
                 offsets.push(total_offset);
                 total_offset += text.len();
             }
-            let token_streams: Vec<_> =
-                texts.iter().map(|text| self.0.token_stream(text)).collect();
-            Box::new(TokenStreamChain::new(offsets, token_streams))
+            let token_streams: Vec<BoxTokenStream<'a>> = texts
+                .iter()
+                .cloned()
+                .map(|text| self.token_stream(text))
+                .collect();
+            From::from(TokenStreamChain::new(offsets, token_streams))
         }
     }
 
-    fn boxed_clone(&self) -> BoxedTokenizer {
-        self.0.clone().into()
+    /// Creates a token stream for a given `str`.
+    pub fn token_stream<'a>(&self, text: &'a str) -> BoxTokenStream<'a> {
+        let mut token_stream = self.tokenizer.token_stream(text);
+        for token_filter in &self.token_filters {
+            token_stream = token_filter.transform(token_stream);
+        }
+        token_stream
     }
 }
 
-impl<'b> TokenStream for Box<dyn TokenStream + 'b> {
+impl Clone for TextAnalyzer {
+    fn clone(&self) -> Self {
+        TextAnalyzer {
+            tokenizer: self.tokenizer.box_clone(),
+            token_filters: self
+                .token_filters
+                .iter()
+                .map(|token_filter| token_filter.box_clone())
+                .collect(),
+        }
+    }
+}
+
+/// `Tokenizer` are in charge of splitting text into a stream of token
+/// before indexing.
+///
+/// See the [module documentation](./index.html) for more detail.
+///
+/// # Warning
+///
+/// This API may change to use associated types.
+pub trait Tokenizer: 'static + Send + Sync + TokenizerClone {
+    /// Creates a token stream for a given `str`.
+    fn token_stream<'a>(&self, text: &'a str) -> BoxTokenStream<'a>;
+}
+
+pub trait TokenizerClone {
+    fn box_clone(&self) -> Box<dyn Tokenizer>;
+}
+
+impl<T: Tokenizer + Clone> TokenizerClone for T {
+    fn box_clone(&self) -> Box<dyn Tokenizer> {
+        Box::new(self.clone())
+    }
+}
+
+impl<'a> TokenStream for Box<dyn TokenStream + 'a> {
     fn advance(&mut self) -> bool {
         let token_stream: &mut dyn TokenStream = self.borrow_mut();
         token_stream.advance()
     }
 
-    fn token(&self) -> &Token {
-        let token_stream: &dyn TokenStream = self.borrow();
+    fn token<'b>(&'b self) -> &'b Token {
+        let token_stream: &'b (dyn TokenStream + 'a) = self.borrow();
         token_stream.token()
     }
 
-    fn token_mut(&mut self) -> &mut Token {
-        let token_stream: &mut dyn TokenStream = self.borrow_mut();
+    fn token_mut<'b>(&'b mut self) -> &'b mut Token {
+        let token_stream: &'b mut (dyn TokenStream + 'a) = self.borrow_mut();
         token_stream.token_mut()
     }
 }
 
+/// Simple wrapper of `Box<dyn TokenStream + 'a>`.
+///
+/// See `TokenStream` for more information.
+pub struct BoxTokenStream<'a>(Box<dyn TokenStream + 'a>);
+
+impl<'a, T> From<T> for BoxTokenStream<'a>
+where
+    T: TokenStream + 'a,
+{
+    fn from(token_stream: T) -> BoxTokenStream<'a> {
+        BoxTokenStream(Box::new(token_stream))
+    }
+}
+
+impl<'a> Deref for BoxTokenStream<'a> {
+    type Target = dyn TokenStream + 'a;
+
+    fn deref(&self) -> &Self::Target {
+        &*self.0
+    }
+}
+impl<'a> DerefMut for BoxTokenStream<'a> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut *self.0
+    }
+}
+
+/// Simple wrapper of `Box<dyn TokenFilter + 'a>`.
+///
+/// See `TokenStream` for more information.
+pub struct BoxTokenFilter(Box<dyn TokenFilter>);
+
+impl Deref for BoxTokenFilter {
+    type Target = dyn TokenFilter;
+
+    fn deref(&self) -> &dyn TokenFilter {
+        &*self.0
+    }
+}
+
+impl<T: TokenFilter> From<T> for BoxTokenFilter {
+    fn from(tokenizer: T) -> BoxTokenFilter {
+        BoxTokenFilter(Box::new(tokenizer))
+    }
+}
+
 /// `TokenStream` is the result of the tokenization.
 ///
 /// It consists consumable stream of `Token`s.
@@ -186,7 +224,7 @@ impl<'b> TokenStream for Box<dyn TokenStream + 'b> {
 /// ```
 /// use tantivy::tokenizer::*;
 ///
-/// let tokenizer = SimpleTokenizer
+/// let tokenizer = TextAnalyzer::from(SimpleTokenizer)
 ///        .filter(RemoveLongFilter::limit(40))
 ///        .filter(LowerCaser);
 /// let mut token_stream = tokenizer.token_stream("Hello, happy tax payer");
@@ -225,7 +263,7 @@ pub trait TokenStream {
     /// ```
     /// use tantivy::tokenizer::*;
     ///
-    /// let tokenizer = SimpleTokenizer
+    /// let tokenizer = TextAnalyzer::from(SimpleTokenizer)
     ///       .filter(RemoveLongFilter::limit(40))
     ///       .filter(LowerCaser);
     /// let mut token_stream = tokenizer.token_stream("Hello, happy tax payer");
@@ -243,6 +281,8 @@ pub trait TokenStream {
 
     /// Helper function to consume the entire `TokenStream`
     /// and push the tokens to a sink function.
+    ///
+    /// Remove this.
     fn process(&mut self, sink: &mut dyn FnMut(&Token)) -> u32 {
         let mut num_tokens_pushed = 0u32;
         while self.advance() {
@@ -253,33 +293,20 @@ pub trait TokenStream {
     }
 }
 
-#[derive(Clone)]
-pub struct ChainTokenizer<HeadTokenFilterFactory, TailTokenizer> {
-    head: HeadTokenFilterFactory,
-    tail: TailTokenizer,
-}
-
-impl<'a, HeadTokenFilterFactory, TailTokenizer> Tokenizer<'a>
-    for ChainTokenizer<HeadTokenFilterFactory, TailTokenizer>
-where
-    HeadTokenFilterFactory: TokenFilter<TailTokenizer::TokenStreamImpl>,
-    TailTokenizer: Tokenizer<'a>,
-{
-    type TokenStreamImpl = HeadTokenFilterFactory::ResultTokenStream;
-
-    fn token_stream(&self, text: &'a str) -> Self::TokenStreamImpl {
-        let tail_token_stream = self.tail.token_stream(text);
-        self.head.transform(tail_token_stream)
-    }
+pub trait TokenFilterClone {
+    fn box_clone(&self) -> BoxTokenFilter;
 }
 
 /// Trait for the pluggable components of `Tokenizer`s.
-pub trait TokenFilter<TailTokenStream: TokenStream>: Clone {
-    /// The resulting `TokenStream` type.
-    type ResultTokenStream: TokenStream;
-
+pub trait TokenFilter: 'static + Send + Sync + TokenFilterClone {
     /// Wraps a token stream and returns the modified one.
-    fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream;
+    fn transform<'a>(&self, token_stream: BoxTokenStream<'a>) -> BoxTokenStream<'a>;
+}
+
+impl<T: TokenFilter + Clone> TokenFilterClone for T {
+    fn box_clone(&self) -> BoxTokenFilter {
+        BoxTokenFilter::from(self.clone())
+    }
 }
 
 #[cfg(test)]

src/tokenizer/tokenizer_manager.rs

@@ -1,11 +1,10 @@
 use crate::tokenizer::stemmer::Language;
-use crate::tokenizer::BoxedTokenizer;
+use crate::tokenizer::tokenizer::TextAnalyzer;
 use crate::tokenizer::LowerCaser;
 use crate::tokenizer::RawTokenizer;
 use crate::tokenizer::RemoveLongFilter;
 use crate::tokenizer::SimpleTokenizer;
 use crate::tokenizer::Stemmer;
-use crate::tokenizer::Tokenizer;
 use std::collections::HashMap;
 use std::sync::{Arc, RwLock};
 
@@ -23,16 +22,16 @@ use std::sync::{Arc, RwLock};
 ///  search engine.
 #[derive(Clone)]
 pub struct TokenizerManager {
-    tokenizers: Arc<RwLock<HashMap<String, BoxedTokenizer>>>,
+    tokenizers: Arc<RwLock<HashMap<String, TextAnalyzer>>>,
 }
 
 impl TokenizerManager {
     /// Registers a new tokenizer associated with a given name.
-    pub fn register<A>(&self, tokenizer_name: &str, tokenizer: A)
+    pub fn register<T>(&self, tokenizer_name: &str, tokenizer: T)
     where
-        A: Into<BoxedTokenizer>,
+        TextAnalyzer: From<T>,
     {
-        let boxed_tokenizer = tokenizer.into();
+        let boxed_tokenizer: TextAnalyzer = TextAnalyzer::from(tokenizer);
         self.tokenizers
             .write()
             .expect("Acquiring the lock should never fail")
@@ -40,7 +39,7 @@ impl TokenizerManager {
     }
 
     /// Accessing a tokenizer given its name.
-    pub fn get(&self, tokenizer_name: &str) -> Option<BoxedTokenizer> {
+    pub fn get(&self, tokenizer_name: &str) -> Option<TextAnalyzer> {
         self.tokenizers
             .read()
             .expect("Acquiring the lock should never fail")
@@ -62,13 +61,13 @@ impl Default for TokenizerManager {
         manager.register("raw", RawTokenizer);
         manager.register(
             "default",
-            SimpleTokenizer
+            TextAnalyzer::from(SimpleTokenizer)
                 .filter(RemoveLongFilter::limit(40))
                 .filter(LowerCaser),
         );
         manager.register(
             "en_stem",
-            SimpleTokenizer
+            TextAnalyzer::from(SimpleTokenizer)
                 .filter(RemoveLongFilter::limit(40))
                 .filter(LowerCaser)
                 .filter(Stemmer::new(Language::English)),