Update import statements in examples, doctests (#633)

Update import statements to edition 2018, including removing
`extern crate` and  `#[macro_use]`. Alphabetize the statements.

examples/basic_search.rs

@@ -12,13 +12,10 @@
 
 // ---
 // Importing tantivy...
-#[macro_use]
-extern crate tantivy;
 use tantivy::collector::TopDocs;
 use tantivy::query::QueryParser;
 use tantivy::schema::*;
-use tantivy::Index;
-use tantivy::ReloadPolicy;
+use tantivy::{doc, Index, ReloadPolicy};
 use tempfile::TempDir;
 
 fn main() -> tantivy::Result<()> {

examples/custom_collector.rs

@@ -9,15 +9,12 @@
 
 // ---
 // Importing tantivy...
-#[macro_use]
-extern crate tantivy;
 use tantivy::collector::{Collector, SegmentCollector};
 use tantivy::fastfield::FastFieldReader;
 use tantivy::query::QueryParser;
 use tantivy::schema::Field;
 use tantivy::schema::{Schema, FAST, INDEXED, TEXT};
-use tantivy::SegmentReader;
-use tantivy::{Index, TantivyError};
+use tantivy::{doc, Index, SegmentReader, TantivyError};
 
 #[derive(Default)]
 struct Stats {

examples/custom_tokenizer.rs

@@ -2,14 +2,11 @@
 //
 // In this example, we'll see how to define a tokenizer pipeline
 // by aligning a bunch of `TokenFilter`.
-
-#[macro_use]
-extern crate tantivy;
 use tantivy::collector::TopDocs;
 use tantivy::query::QueryParser;
 use tantivy::schema::*;
 use tantivy::tokenizer::NgramTokenizer;
-use tantivy::Index;
+use tantivy::{doc, Index};
 
 fn main() -> tantivy::Result<()> {
     // # Defining the schema

examples/deleting_updating_documents.rs

@@ -8,13 +8,10 @@
 //
 // ---
 // Importing tantivy...
-#[macro_use]
-extern crate tantivy;
 use tantivy::collector::TopDocs;
 use tantivy::query::TermQuery;
 use tantivy::schema::*;
-use tantivy::Index;
-use tantivy::IndexReader;
+use tantivy::{doc, Index, IndexReader};
 
 // A simple helper function to fetch a single document
 // given its id from our index.

examples/faceted_search.rs

@@ -12,12 +12,10 @@
 
 // ---
 // Importing tantivy...
-#[macro_use]
-extern crate tantivy;
 use tantivy::collector::FacetCollector;
 use tantivy::query::AllQuery;
 use tantivy::schema::*;
-use tantivy::Index;
+use tantivy::{doc, Index};
 use tempfile::TempDir;
 
 fn main() -> tantivy::Result<()> {

examples/integer_range_search.rs

@@ -2,14 +2,10 @@
 //
 // Below is an example of creating an indexed integer field in your schema
 // You can use RangeQuery to get a Count of all occurrences in a given range.
-
-#[macro_use]
-extern crate tantivy;
 use tantivy::collector::Count;
 use tantivy::query::RangeQuery;
 use tantivy::schema::{Schema, INDEXED};
-use tantivy::Index;
-use tantivy::Result;
+use tantivy::{doc, Index, Result};
 
 fn run() -> Result<()> {
     // For the sake of simplicity, this schema will only have 1 field

examples/iterating_docs_and_positions.rs

@@ -9,11 +9,8 @@
 
 // ---
 // Importing tantivy...
-#[macro_use]
-extern crate tantivy;
 use tantivy::schema::*;
-use tantivy::Index;
-use tantivy::{DocId, DocSet, Postings};
+use tantivy::{doc, DocId, DocSet, Index, Postings};
 
 fn main() -> tantivy::Result<()> {
     // We first create a schema for the sake of the

examples/multiple_producer.rs

@@ -25,14 +25,11 @@
 
 // ---
 // Importing tantivy...
-#[macro_use]
-extern crate tantivy;
 use std::sync::{Arc, RwLock};
 use std::thread;
 use std::time::Duration;
 use tantivy::schema::{Schema, STORED, TEXT};
-use tantivy::Opstamp;
-use tantivy::{Index, IndexWriter};
+use tantivy::{doc, Index, IndexWriter, Opstamp};
 
 fn main() -> tantivy::Result<()> {
     // # Defining the schema

examples/snippet.rs

@@ -7,13 +7,10 @@
 
 // ---
 // Importing tantivy...
-#[macro_use]
-extern crate tantivy;
 use tantivy::collector::TopDocs;
 use tantivy::query::QueryParser;
 use tantivy::schema::*;
-use tantivy::Index;
-use tantivy::{Snippet, SnippetGenerator};
+use tantivy::{doc, Index, Snippet, SnippetGenerator};
 use tempfile::TempDir;
 
 fn main() -> tantivy::Result<()> {

examples/stop_words.rs

@@ -11,13 +11,11 @@
 
 // ---
 // Importing tantivy...
-#[macro_use]
-extern crate tantivy;
 use tantivy::collector::TopDocs;
 use tantivy::query::QueryParser;
 use tantivy::schema::*;
 use tantivy::tokenizer::*;
-use tantivy::Index;
+use tantivy::{doc, Index};
 
 fn main() -> tantivy::Result<()> {
     // this example assumes you understand the content in `basic_search`

src/collector/count_collector.rs

@@ -10,12 +10,10 @@ use crate::SegmentReader;
 /// documents match the query.
 ///
 /// ```rust
-/// #[macro_use]
-/// extern crate tantivy;
-/// use tantivy::schema::{Schema, TEXT};
-/// use tantivy::{Index, Result};
 /// use tantivy::collector::Count;
 /// use tantivy::query::QueryParser;
+/// use tantivy::schema::{Schema, TEXT};
+/// use tantivy::{doc, Index, Result};
 ///
 /// # fn main() { example().unwrap(); }
 /// fn example() -> Result<()> {

src/collector/facet_collector.rs

@@ -81,12 +81,10 @@ fn facet_depth(facet_bytes: &[u8]) -> usize {
 ///
 ///
 /// ```rust
-/// #[macro_use]
-/// extern crate tantivy;
-/// use tantivy::schema::{Facet, Schema, TEXT};
-/// use tantivy::{Index, Result};
 /// use tantivy::collector::FacetCollector;
 /// use tantivy::query::AllQuery;
+/// use tantivy::schema::{Facet, Schema, TEXT};
+/// use tantivy::{doc, Index, Result};
 ///
 /// # fn main() { example().unwrap(); }
 /// fn example() -> Result<()> {

src/collector/mod.rs

@@ -35,7 +35,6 @@ The resulting `Fruit` will then be a typed tuple with each collector's original
 in their respective position.
 
 ```rust
-# extern crate tantivy;
 # use tantivy::schema::*;
 # use tantivy::*;
 # use tantivy::query::*;

src/collector/multi_collector.rs

@@ -105,12 +105,10 @@ impl<TFruit: Fruit> FruitHandle<TFruit> {
 /// [Combining several collectors section of the collector documentation](./index.html#combining-several-collectors).
 ///
 /// ```rust
-/// #[macro_use]
-/// extern crate tantivy;
-/// use tantivy::schema::{Schema, TEXT};
-/// use tantivy::{Index, Result};
 /// use tantivy::collector::{Count, TopDocs, MultiCollector};
 /// use tantivy::query::QueryParser;
+/// use tantivy::schema::{Schema, TEXT};
+/// use tantivy::{doc, Index, Result};
 ///
 /// # fn main() { example().unwrap(); }
 /// fn example() -> Result<()> {

src/collector/top_score_collector.rs

@@ -23,13 +23,10 @@ use std::fmt;
 /// is `O(n log K)`.
 ///
 /// ```rust
-/// #[macro_use]
-/// extern crate tantivy;
-/// use tantivy::DocAddress;
-/// use tantivy::schema::{Schema, TEXT};
-/// use tantivy::{Index, Result};
 /// use tantivy::collector::TopDocs;
 /// use tantivy::query::QueryParser;
+/// use tantivy::schema::{Schema, TEXT};
+/// use tantivy::{doc, DocAddress, Index, Result};
 ///
 /// # fn main() { example().unwrap(); }
 /// fn example() -> Result<()> {
@@ -87,10 +84,8 @@ impl TopDocs {
     /// Set top-K to rank documents by a given fast field.
     ///
     /// ```rust
-    /// #[macro_use]
-    /// extern crate tantivy;
     /// # use tantivy::schema::{Schema, FAST, TEXT};
-    /// # use tantivy::{Index, Result, DocAddress};
+    /// # use tantivy::{doc, Index, Result, DocAddress};
     /// # use tantivy::query::{Query, QueryParser};
     /// use tantivy::Searcher;
     /// use tantivy::collector::TopDocs;
@@ -197,10 +192,8 @@ impl TopDocs {
     /// learning-to-rank model over various features
     ///
     /// ```rust
-    /// #[macro_use]
-    /// extern crate tantivy;
     /// # use tantivy::schema::{Schema, FAST, TEXT};
-    /// # use tantivy::{Index, DocAddress, DocId, Score};
+    /// # use tantivy::{doc, Index, DocAddress, DocId, Score};
     /// # use tantivy::query::QueryParser;
     /// use tantivy::SegmentReader;
     /// use tantivy::collector::TopDocs;
@@ -302,10 +295,8 @@ impl TopDocs {
     /// # Example
     ///
     /// ```rust
-    /// # #[macro_use]
-    /// # extern crate tantivy;
     /// # use tantivy::schema::{Schema, FAST, TEXT};
-    /// # use tantivy::{Index, DocAddress, DocId};
+    /// # use tantivy::{doc, Index, DocAddress, DocId};
     /// # use tantivy::query::QueryParser;
     /// use tantivy::SegmentReader;
     /// use tantivy::collector::TopDocs;

src/indexer/index_writer.rs

@@ -450,12 +450,10 @@ impl IndexWriter {
     /// by clearing and resubmitting necessary documents
     ///
     /// ```rust
-    /// #[macro_use]
-    /// extern crate tantivy;
-    /// use tantivy::query::QueryParser;
     /// use tantivy::collector::TopDocs;
+    /// use tantivy::query::QueryParser;
     /// use tantivy::schema::*;
-    /// use tantivy::Index;
+    /// use tantivy::{doc, Index};
     ///
     /// fn main() -> tantivy::Result<()> {
     ///     let mut schema_builder = Schema::builder();

src/lib.rs

@@ -11,21 +11,12 @@
 //! Think `Lucene`, but in Rust.
 //!
 //! ```rust
-
-//! # extern crate tempfile;
-//! #
-//! #[macro_use]
-//! extern crate tantivy;
-//!
-//! // ...
-//!
 //! # use std::path::Path;
 //! # use tempfile::TempDir;
-//! # use tantivy::Index;
-//! # use tantivy::schema::*;
-//! # use tantivy::{Score, DocAddress};
 //! # use tantivy::collector::TopDocs;
 //! # use tantivy::query::QueryParser;
+//! # use tantivy::schema::*;
+//! # use tantivy::{doc, DocAddress, Index, Score};
 //! #
 //! # fn main() {
 //! #     // Let's create a temporary directory for the

src/macros.rs

@@ -22,11 +22,9 @@
 ///
 /// # Example
 ///
-/// ```
-/// #[macro_use]
-/// extern crate tantivy;
-///
+/// ```rust
 /// use tantivy::schema::{Schema, TEXT, FAST};
+/// use tantivy::doc;
 ///
 /// //...
 ///

src/query/fuzzy_query.rs

@@ -28,12 +28,10 @@ static LEV_BUILDER: Lazy<HashMap<(u8, bool), LevenshteinAutomatonBuilder>> = Laz
 /// containing a specific term that is within
 /// Levenshtein distance
 /// ```rust
-/// #[macro_use]
-/// extern crate tantivy;
-/// use tantivy::schema::{Schema, TEXT};
-/// use tantivy::{Index, Result, Term};
 /// use tantivy::collector::{Count, TopDocs};
 /// use tantivy::query::FuzzyTermQuery;
+/// use tantivy::schema::{Schema, TEXT};
+/// use tantivy::{doc, Index, Result, Term};
 ///
 /// # fn main() { example().unwrap(); }
 /// fn example() -> Result<()> {

src/query/range_query.rs

@@ -38,14 +38,10 @@ fn map_bound<TFrom, TTo, Transform: Fn(&TFrom) -> TTo>(
 /// # Example
 ///
 /// ```rust
-///
-/// # #[macro_use]
-/// # extern crate tantivy;
-/// # use tantivy::Index;
-/// # use tantivy::schema::{Schema, INDEXED};
 /// # use tantivy::collector::Count;
-/// # use tantivy::Result;
 /// # use tantivy::query::RangeQuery;
+/// # use tantivy::schema::{Schema, INDEXED};
+/// # use tantivy::{doc, Index, Result};
 /// #
 /// # fn run() -> Result<()> {
 /// #     let mut schema_builder = Schema::builder();

src/query/regex_query.rs

@@ -14,12 +14,10 @@ use tantivy_fst::Regex;
 /// Levenshtein distance
 ///
 /// ```rust
-/// #[macro_use]
-/// extern crate tantivy;
-/// use tantivy::schema::{Schema, TEXT};
-/// use tantivy::{Index, Result, Term};
 /// use tantivy::collector::Count;
 /// use tantivy::query::RegexQuery;
+/// use tantivy::schema::{Schema, TEXT};
+/// use tantivy::{doc, Index, Result, Term};
 ///
 /// # fn main() { example().unwrap(); }
 /// fn example() -> Result<()> {

src/query/term_query/term_query.rs

@@ -20,12 +20,10 @@ use std::fmt;
 /// * `field norm` - number of tokens in the field.
 ///
 /// ```rust
-/// #[macro_use]
-/// extern crate tantivy;
-/// use tantivy::schema::{Schema, TEXT, IndexRecordOption};
-/// use tantivy::{Index, Result, Term};
 /// use tantivy::collector::{Count, TopDocs};
 /// use tantivy::query::TermQuery;
+/// use tantivy::schema::{Schema, TEXT, IndexRecordOption};
+/// use tantivy::{doc, Index, Result, Term};
 ///
 /// # fn main() { example().unwrap(); }
 /// fn example() -> Result<()> {

src/snippet/mod.rs

@@ -213,11 +213,9 @@ fn select_best_fragment_combination(fragments: &[FragmentCandidate], text: &str)
 /// # Example
 ///
 /// ```rust
-/// # #[macro_use]
-/// # extern crate tantivy;
-/// # use tantivy::Index;
-/// # use tantivy::schema::{Schema, TEXT};
 /// # use tantivy::query::QueryParser;
+/// # use tantivy::schema::{Schema, TEXT};
+/// # use tantivy::{doc, Index};
 /// use tantivy::SnippetGenerator;
 ///
 /// # fn main() -> tantivy::Result<()> {

src/tokenizer/alphanum_only.rs

@@ -1,6 +1,5 @@
 //! # Example
-//! ```
-//! extern crate tantivy;
+//! ```rust
 //! use tantivy::tokenizer::*;
 //!
 //! # fn main() {

src/tokenizer/mod.rs

@@ -4,8 +4,7 @@
 //! You must define in your schema which tokenizer should be used for
 //! each of your fields :
 //!
-//! ```
-//! extern crate tantivy;
+//! ```rust
 //! use tantivy::schema::*;
 //!
 //! # fn main() {
@@ -65,8 +64,6 @@
 //! For instance, the `en_stem` is defined as follows.
 //!
 //! ```rust
-//! # extern crate tantivy;
-//!
 //! use tantivy::tokenizer::*;
 //!
 //! # fn main() {
@@ -80,8 +77,7 @@
 //! Once your tokenizer is defined, you need to
 //! register it with a name in your index's [`TokenizerManager`](./struct.TokenizerManager.html).
 //!
-//! ```
-//! # extern crate tantivy;
+//! ```rust
 //! # use tantivy::schema::Schema;
 //! # use tantivy::tokenizer::*;
 //! # use tantivy::Index;
@@ -101,8 +97,7 @@
 //!
 //! # Example
 //!
-//! ```
-//! extern crate tantivy;
+//! ```rust
 //! use tantivy::schema::{Schema, IndexRecordOption, TextOptions, TextFieldIndexing};
 //! use tantivy::tokenizer::*;
 //! use tantivy::Index;

src/tokenizer/ngram_tokenizer.rs

@@ -29,8 +29,7 @@ use super::{Token, TokenStream, Tokenizer};
 ///
 /// # Example
 ///
-/// ```
-/// # extern crate tantivy;
+/// ```rust
 /// use tantivy::tokenizer::*;
 /// # fn main() {
 /// let tokenizer = NgramTokenizer::new(2, 3, false);

src/tokenizer/remove_long.rs

@@ -1,6 +1,5 @@
 //! # Example
-//! ```
-//! extern crate tantivy;
+//! ```rust
 //! use tantivy::tokenizer::*;
 //!
 //! # fn main() {

src/tokenizer/stop_word_filter.rs

@@ -1,6 +1,5 @@
 //! # Example
-//! ```
-//! extern crate tantivy;
+//! ```rust
 //! use tantivy::tokenizer::*;
 //!
 //! # fn main() {