pest/iterators/
flat_pairs.rs

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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::rc::Rc;
11use alloc::vec::Vec;
12use core::fmt;
13
14use super::line_index::LineIndex;
15use super::pair::{self, Pair};
16use super::queueable_token::QueueableToken;
17use super::tokens::{self, Tokens};
18use crate::RuleType;
19
20/// An iterator over [`Pair`]s. It is created by [`Pairs::flatten`].
21///
22/// [`Pair`]: struct.Pair.html
23/// [`Pairs::flatten`]: struct.Pairs.html#method.flatten
24pub struct FlatPairs<'i, R> {
25    queue: Rc<Vec<QueueableToken<'i, R>>>,
26    input: &'i str,
27    start: usize,
28    end: usize,
29    line_index: Rc<LineIndex>,
30}
31
32pub fn new<'i, R: RuleType>(
33    queue: Rc<Vec<QueueableToken<'i, R>>>,
34    input: &'i str,
35    line_index: Rc<LineIndex>,
36    start: usize,
37    end: usize,
38) -> FlatPairs<'i, R> {
39    FlatPairs {
40        queue,
41        input,
42        line_index,
43        start,
44        end,
45    }
46}
47
48impl<'i, R: RuleType> FlatPairs<'i, R> {
49    /// Returns the `Tokens` for these pairs.
50    ///
51    /// # Examples
52    ///
53    /// ```
54    /// # use std::rc::Rc;
55    /// # use pest;
56    /// # #[allow(non_camel_case_types)]
57    /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
58    /// enum Rule {
59    ///     a
60    /// }
61    ///
62    /// let input = "";
63    /// let pairs = pest::state(input, |state| {
64    ///     // generating Token pair with Rule::a ...
65    /// #     state.rule(Rule::a, |s| Ok(s))
66    /// }).unwrap();
67    /// let tokens: Vec<_> = pairs.flatten().tokens().collect();
68    ///
69    /// assert_eq!(tokens.len(), 2);
70    /// ```
71    #[inline]
72    pub fn tokens(self) -> Tokens<'i, R> {
73        tokens::new(self.queue, self.input, self.start, self.end)
74    }
75
76    fn next_start(&mut self) {
77        self.start += 1;
78
79        while self.start < self.end && !self.is_start(self.start) {
80            self.start += 1;
81        }
82    }
83
84    fn next_start_from_end(&mut self) {
85        self.end -= 1;
86
87        while self.end >= self.start && !self.is_start(self.end) {
88            self.end -= 1;
89        }
90    }
91
92    fn is_start(&self, index: usize) -> bool {
93        match self.queue[index] {
94            QueueableToken::Start { .. } => true,
95            QueueableToken::End { .. } => false,
96        }
97    }
98}
99
100impl<'i, R: RuleType> ExactSizeIterator for FlatPairs<'i, R> {
101    fn len(&self) -> usize {
102        // Tokens len is exactly twice as flatten pairs len
103        (self.end - self.start) >> 1
104    }
105}
106
107impl<'i, R: RuleType> Iterator for FlatPairs<'i, R> {
108    type Item = Pair<'i, R>;
109
110    fn next(&mut self) -> Option<Self::Item> {
111        if self.start >= self.end {
112            return None;
113        }
114
115        let pair = pair::new(
116            Rc::clone(&self.queue),
117            self.input,
118            Rc::clone(&self.line_index),
119            self.start,
120        );
121        self.next_start();
122
123        Some(pair)
124    }
125
126    fn size_hint(&self) -> (usize, Option<usize>) {
127        let len = <Self as ExactSizeIterator>::len(self);
128        (len, Some(len))
129    }
130}
131
132impl<'i, R: RuleType> DoubleEndedIterator for FlatPairs<'i, R> {
133    fn next_back(&mut self) -> Option<Self::Item> {
134        if self.end <= self.start {
135            return None;
136        }
137
138        self.next_start_from_end();
139
140        let pair = pair::new(
141            Rc::clone(&self.queue),
142            self.input,
143            Rc::clone(&self.line_index),
144            self.end,
145        );
146
147        Some(pair)
148    }
149}
150
151impl<'i, R: RuleType> fmt::Debug for FlatPairs<'i, R> {
152    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
153        f.debug_struct("FlatPairs")
154            .field("pairs", &self.clone().collect::<Vec<_>>())
155            .finish()
156    }
157}
158
159impl<'i, R: Clone> Clone for FlatPairs<'i, R> {
160    fn clone(&self) -> FlatPairs<'i, R> {
161        FlatPairs {
162            queue: Rc::clone(&self.queue),
163            input: self.input,
164            line_index: Rc::clone(&self.line_index),
165            start: self.start,
166            end: self.end,
167        }
168    }
169}
170
171#[cfg(test)]
172mod tests {
173    use super::super::super::macros::tests::*;
174    use super::super::super::Parser;
175    use alloc::vec;
176    use alloc::vec::Vec;
177
178    #[test]
179    fn iter_for_flat_pairs() {
180        let pairs = AbcParser::parse(Rule::a, "abcde").unwrap();
181
182        assert_eq!(
183            pairs.flatten().map(|p| p.as_rule()).collect::<Vec<Rule>>(),
184            vec![Rule::a, Rule::b, Rule::c]
185        );
186    }
187
188    #[test]
189    fn double_ended_iter_for_flat_pairs() {
190        let pairs = AbcParser::parse(Rule::a, "abcde").unwrap();
191        assert_eq!(
192            pairs
193                .flatten()
194                .rev()
195                .map(|p| p.as_rule())
196                .collect::<Vec<Rule>>(),
197            vec![Rule::c, Rule::b, Rule::a]
198        );
199    }
200
201    #[test]
202    fn test_line_col() {
203        let mut pairs = AbcParser::parse(Rule::a, "abcNe\nabcde").unwrap().flatten();
204
205        let pair = pairs.next().unwrap();
206        assert_eq!(pair.as_str(), "abc");
207        assert_eq!(pair.line_col(), (1, 1));
208        assert_eq!(pair.line_col(), pair.as_span().start_pos().line_col());
209
210        let pair = pairs.next().unwrap();
211        assert_eq!(pair.as_str(), "b");
212        assert_eq!(pair.line_col(), (1, 2));
213        assert_eq!(pair.line_col(), pair.as_span().start_pos().line_col());
214
215        let pair = pairs.next().unwrap();
216        assert_eq!(pair.as_str(), "e");
217        assert_eq!(pair.line_col(), (1, 5));
218        assert_eq!(pair.line_col(), pair.as_span().start_pos().line_col());
219    }
220
221    #[test]
222    fn exact_size_iter_for_pairs() {
223        let pairs = AbcParser::parse(Rule::a, "abc\nefgh").unwrap().flatten();
224        assert_eq!(pairs.len(), pairs.count());
225
226        let pairs = AbcParser::parse(Rule::a, "我很漂亮efgh").unwrap().flatten();
227        assert_eq!(pairs.len(), pairs.count());
228
229        let pairs = AbcParser::parse(Rule::a, "abc\nefgh").unwrap().flatten();
230        let pairs = pairs.rev();
231        assert_eq!(pairs.len(), pairs.count());
232
233        let mut pairs = AbcParser::parse(Rule::a, "abc\nefgh").unwrap().flatten();
234        let pairs_len = pairs.len();
235        let _ = pairs.next().unwrap();
236        assert_eq!(pairs.count() + 1, pairs_len);
237    }
238}
pest/iterators/flat_pairs.rs

pest/iterators/
flat_pairs.rs
