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use crate::tokenizer::TokenStreamChain;
use std::borrow::{Borrow, BorrowMut};
#[derive(Debug, Clone)]
pub struct Token {
pub offset_from: usize,
pub offset_to: usize,
pub position: usize,
pub text: String,
pub position_length: usize,
}
impl Default for Token {
fn default() -> Token {
Token {
offset_from: 0,
offset_to: 0,
position: usize::max_value(),
text: String::with_capacity(200),
position_length: 1,
}
}
}
pub trait Tokenizer<'a>: Sized + Clone {
type TokenStreamImpl: TokenStream;
fn token_stream(&self, text: &'a str) -> Self::TokenStreamImpl;
fn filter<NewFilter>(self, new_filter: NewFilter) -> ChainTokenizer<NewFilter, Self>
where
NewFilter: TokenFilter<<Self as Tokenizer<'a>>::TokenStreamImpl>,
{
ChainTokenizer {
head: new_filter,
tail: self,
}
}
}
pub trait BoxedTokenizer: Send + Sync {
fn token_stream<'a>(&self, text: &'a str) -> Box<dyn TokenStream + 'a>;
fn token_stream_texts<'b>(&self, texts: &'b [&'b str]) -> Box<dyn TokenStream + 'b>;
fn boxed_clone(&self) -> Box<dyn BoxedTokenizer>;
}
#[derive(Clone)]
struct BoxableTokenizer<A>(A)
where
A: for<'a> Tokenizer<'a> + Send + Sync;
impl<A> BoxedTokenizer 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> {
assert!(!texts.is_empty());
if texts.len() == 1 {
Box::new(self.0.token_stream(texts[0]))
} else {
let mut offsets = vec![];
let mut total_offset = 0;
for &text in texts {
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))
}
}
fn boxed_clone(&self) -> Box<dyn BoxedTokenizer> {
Box::new(self.clone())
}
}
pub(crate) fn box_tokenizer<A>(a: A) -> Box<dyn BoxedTokenizer>
where
A: 'static + Send + Sync + for<'a> Tokenizer<'a>,
{
Box::new(BoxableTokenizer(a))
}
impl<'b> TokenStream for Box<dyn TokenStream + 'b> {
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();
token_stream.token()
}
fn token_mut(&mut self) -> &mut Token {
let token_stream: &mut dyn TokenStream = self.borrow_mut();
token_stream.token_mut()
}
}
pub trait TokenStream {
fn advance(&mut self) -> bool;
fn token(&self) -> &Token;
fn token_mut(&mut self) -> &mut Token;
fn next(&mut self) -> Option<&Token> {
if self.advance() {
Some(self.token())
} else {
None
}
}
fn process(&mut self, sink: &mut dyn FnMut(&Token)) -> u32 {
let mut num_tokens_pushed = 0u32;
while self.advance() {
sink(self.token());
num_tokens_pushed += 1u32;
}
num_tokens_pushed
}
}
#[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 TokenFilter<TailTokenStream: TokenStream>: Clone {
type ResultTokenStream: TokenStream;
fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream;
}
#[cfg(test)]
mod test {
use super::Token;
#[test]
fn clone() {
let t1 = Token {
position: 1,
offset_from: 2,
offset_to: 3,
text: "abc".to_string(),
position_length: 1,
};
let t2 = t1.clone();
assert_eq!(t1.position, t2.position);
assert_eq!(t1.offset_from, t2.offset_from);
assert_eq!(t1.offset_to, t2.offset_to);
assert_eq!(t1.text, t2.text);
}
}