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

pest/iterators/
flat_pairs.rs
