1// pest. The Elegant Parser
2// Copyright (c) 2018 Dragoș Tiselice
3//
4// Licensed under the Apache License, Version 2.0
5// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT
6// license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
7// option. All files in the project carrying such notice may not be copied,
8// modified, or distributed except according to those terms.
9
10use alloc::borrow::Cow;
11
12// This structure serves to improve performance over Token objects in two ways:
13//
14// * it is smaller than a Token, leading to both less memory use when stored in the queue but also
15// increased speed when pushing to the queue
16// * it finds its pair in O(1) time instead of O(N), since pair positions are known at parse time
17// and can easily be stored instead of recomputed
18#[derive(Debug)]
19pub enum QueueableToken<'i, R> {
20 Start {
21 end_token_index: usize,
22 input_pos: usize,
23 },
24 End {
25 start_token_index: usize,
26 rule: R,
27 tag: Option<Cow<'i, str>>,
28 input_pos: usize,
29 },
30}
31