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//! Tokenizer are in charge of chopping text into a stream of tokens
//! ready for indexing.
//!
//! You must define in your schema which tokenizer should be used for
//! each of your fields :
//!
//! ```rust
//! use tantivy::schema::*;
//!
//! let mut schema_builder = Schema::builder();
//!
//! let text_options = TextOptions::default()
//! .set_indexing_options(
//! TextFieldIndexing::default()
//! .set_tokenizer("en_stem")
//! .set_index_option(IndexRecordOption::Basic)
//! )
//! .set_stored();
//!
//! let id_options = TextOptions::default()
//! .set_indexing_options(
//! TextFieldIndexing::default()
//! .set_tokenizer("raw_ids")
//! .set_index_option(IndexRecordOption::WithFreqsAndPositions)
//! )
//! .set_stored();
//!
//! schema_builder.add_text_field("title", text_options.clone());
//! schema_builder.add_text_field("text", text_options);
//! schema_builder.add_text_field("uuid", id_options);
//!
//! let schema = schema_builder.build();
//! ```
//!
//! By default, `tantivy` offers the following tokenizers:
//!
//! ## `default`
//!
//! `default` is the tokenizer that will be used if you do not
//! assign a specific tokenizer to your text field.
//! It will chop your text on punctuation and whitespaces,
//! removes tokens that are longer than 40 chars, and lowercase your text.
//!
//! ## `raw`
//! Does not actual tokenizer your text. It keeps it entirely unprocessed.
//! It can be useful to index uuids, or urls for instance.
//!
//! ## `en_stem`
//!
//! In addition to what `default` does, the `en_stem` tokenizer also
//! apply stemming to your tokens. Stemming consists in trimming words to
//! remove their inflection. This tokenizer is slower than the default one,
//! but is recommended to improve recall.
//!
//! # Custom tokenizer Library
//! Avoid using tantivy as dependency and prefer `tantivy-tokenizer-api` instead.
//!
//! # Custom tokenizers
//!
//! You can write your own tokenizer by implementing the [`Tokenizer`] trait
//! or you can extend an existing [`Tokenizer`] by chaining it with several
//! [`TokenFilter`]s.
//!
//! For instance, the `en_stem` is defined as follows.
//!
//! ```rust
//! use tantivy::tokenizer::*;
//!
//! let en_stem = TextAnalyzer::builder(SimpleTokenizer::default())
//! .filter(RemoveLongFilter::limit(40))
//! .filter(LowerCaser)
//! .filter(Stemmer::new(Language::English))
//! .build();
//! ```
//!
//! Once your tokenizer is defined, you need to
//! register it with a name in your index's [`TokenizerManager`].
//!
//! ```rust
//! # use tantivy::schema::Schema;
//! # use tantivy::tokenizer::*;
//! # use tantivy::Index;
//! #
//! let custom_en_tokenizer = SimpleTokenizer::default();
//! # let schema = Schema::builder().build();
//! let index = Index::create_in_ram(schema);
//! index.tokenizers()
//! .register("custom_en", custom_en_tokenizer);
//! ```
//!
//! If you built your schema programmatically, a complete example
//! could like this for instance.
//!
//! Note that tokens with a len greater or equal to
//! [`MAX_TOKEN_LEN`].
//!
//! # Example
//!
//! ```rust
//! use tantivy::schema::{Schema, IndexRecordOption, TextOptions, TextFieldIndexing};
//! use tantivy::tokenizer::*;
//! use tantivy::Index;
//!
//! let mut schema_builder = Schema::builder();
//! let text_field_indexing = TextFieldIndexing::default()
//! .set_tokenizer("custom_en")
//! .set_index_option(IndexRecordOption::WithFreqsAndPositions);
//! let text_options = TextOptions::default()
//! .set_indexing_options(text_field_indexing)
//! .set_stored();
//! schema_builder.add_text_field("title", text_options);
//! let schema = schema_builder.build();
//! let index = Index::create_in_ram(schema);
//!
//! // We need to register our tokenizer :
//! let custom_en_tokenizer = TextAnalyzer::builder(SimpleTokenizer::default())
//! .filter(RemoveLongFilter::limit(40))
//! .filter(LowerCaser)
//! .build();
//! index
//! .tokenizers()
//! .register("custom_en", custom_en_tokenizer);
//! ```
mod alphanum_only;
mod ascii_folding_filter;
mod empty_tokenizer;
mod facet_tokenizer;
mod lower_caser;
mod ngram_tokenizer;
mod raw_tokenizer;
mod regex_tokenizer;
mod remove_long;
mod simple_tokenizer;
mod split_compound_words;
mod stemmer;
mod stop_word_filter;
mod tokenized_string;
mod tokenizer;
mod tokenizer_manager;
mod whitespace_tokenizer;
pub use tokenizer_api::{BoxTokenStream, Token, TokenFilter, TokenStream, Tokenizer};
pub use self::alphanum_only::AlphaNumOnlyFilter;
pub use self::ascii_folding_filter::AsciiFoldingFilter;
pub use self::facet_tokenizer::FacetTokenizer;
pub use self::lower_caser::LowerCaser;
pub use self::ngram_tokenizer::NgramTokenizer;
pub use self::raw_tokenizer::RawTokenizer;
pub use self::regex_tokenizer::RegexTokenizer;
pub use self::remove_long::RemoveLongFilter;
pub use self::simple_tokenizer::{SimpleTokenStream, SimpleTokenizer};
pub use self::split_compound_words::SplitCompoundWords;
pub use self::stemmer::{Language, Stemmer};
pub use self::stop_word_filter::StopWordFilter;
pub use self::tokenized_string::{PreTokenizedStream, PreTokenizedString};
pub use self::tokenizer::{TextAnalyzer, TextAnalyzerBuilder};
pub use self::tokenizer_manager::TokenizerManager;
pub use self::whitespace_tokenizer::WhitespaceTokenizer;
/// Maximum authorized len (in bytes) for a token.
///
/// Tokenizers are in charge of not emitting tokens larger than this value.
/// Currently, if a faulty tokenizer implementation emits tokens with a length larger than
/// `2^16 - 1 - 5`, the token will simply be ignored downstream.
pub const MAX_TOKEN_LEN: usize = u16::MAX as usize - 5;
#[cfg(test)]
pub mod tests {
use super::{
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.
pub fn assert_token(token: &Token, position: usize, text: &str, from: usize, to: usize) {
assert_eq!(
token.position, position,
"expected position {position} but {token:?}"
);
assert_eq!(token.text, text, "expected text {text} but {token:?}");
assert_eq!(
token.offset_from, from,
"expected offset_from {from} but {token:?}"
);
assert_eq!(token.offset_to, to, "expected offset_to {to} but {token:?}");
}
#[test]
fn test_raw_tokenizer2() {
let tokenizer_manager = TokenizerManager::default();
let mut en_tokenizer = tokenizer_manager.get("raw").unwrap();
let mut tokens: Vec<Token> = vec![];
{
let mut add_token = |token: &Token| {
tokens.push(token.clone());
};
en_tokenizer
.token_stream("Hello, happy tax payer!")
.process(&mut add_token);
}
assert_eq!(tokens.len(), 1);
assert_token(&tokens[0], 0, "Hello, happy tax payer!", 0, 23);
}
#[test]
fn test_en_tokenizer() {
let tokenizer_manager = TokenizerManager::default();
assert!(tokenizer_manager.get("en_doesnotexist").is_none());
let mut en_tokenizer = tokenizer_manager.get("en_stem").unwrap();
let mut tokens: Vec<Token> = vec![];
{
let mut add_token = |token: &Token| {
tokens.push(token.clone());
};
en_tokenizer
.token_stream("Hello, happy tax payer!")
.process(&mut add_token);
}
assert_eq!(tokens.len(), 4);
assert_token(&tokens[0], 0, "hello", 0, 5);
assert_token(&tokens[1], 1, "happi", 7, 12);
assert_token(&tokens[2], 2, "tax", 13, 16);
assert_token(&tokens[3], 3, "payer", 17, 22);
}
#[test]
fn test_non_en_tokenizer() {
let tokenizer_manager = TokenizerManager::default();
tokenizer_manager.register(
"el_stem",
TextAnalyzer::builder(SimpleTokenizer::default())
.filter(RemoveLongFilter::limit(40))
.filter(LowerCaser)
.filter(Stemmer::new(Language::Greek))
.build(),
);
let mut en_tokenizer = tokenizer_manager.get("el_stem").unwrap();
let mut tokens: Vec<Token> = vec![];
{
let mut add_token = |token: &Token| {
tokens.push(token.clone());
};
en_tokenizer
.token_stream("Καλημέρα, χαρούμενε φορολογούμενε!")
.process(&mut add_token);
}
assert_eq!(tokens.len(), 3);
assert_token(&tokens[0], 0, "καλημερ", 0, 16);
assert_token(&tokens[1], 1, "χαρουμεν", 18, 36);
assert_token(&tokens[2], 2, "φορολογουμεν", 37, 63);
}
#[test]
fn test_tokenizer_empty() {
let tokenizer_manager = TokenizerManager::default();
let mut en_tokenizer = tokenizer_manager.get("en_stem").unwrap();
{
let mut tokens: Vec<Token> = vec![];
{
let mut add_token = |token: &Token| {
tokens.push(token.clone());
};
en_tokenizer.token_stream(" ").process(&mut add_token);
}
assert!(tokens.is_empty());
}
{
let mut tokens: Vec<Token> = vec![];
{
let mut add_token = |token: &Token| {
tokens.push(token.clone());
};
en_tokenizer.token_stream(" ").process(&mut add_token);
}
assert!(tokens.is_empty());
}
}
#[test]
fn test_whitespace_tokenizer() {
let tokenizer_manager = TokenizerManager::default();
let mut ws_tokenizer = tokenizer_manager.get("whitespace").unwrap();
let mut tokens: Vec<Token> = vec![];
{
let mut add_token = |token: &Token| {
tokens.push(token.clone());
};
ws_tokenizer
.token_stream("Hello, happy tax payer!")
.process(&mut add_token);
}
assert_eq!(tokens.len(), 4);
assert_token(&tokens[0], 0, "Hello,", 0, 6);
assert_token(&tokens[1], 1, "happy", 7, 12);
assert_token(&tokens[2], 2, "tax", 13, 16);
assert_token(&tokens[3], 3, "payer!", 17, 23);
}
}