pest/iterators/
tokens.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
// pest. The Elegant Parser
// Copyright (c) 2018 Dragoș Tiselice
//
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. All files in the project carrying such notice may not be copied,
// modified, or distributed except according to those terms.

use alloc::rc::Rc;
use alloc::vec::Vec;
use core::fmt;
use core::str;

use super::queueable_token::QueueableToken;
use crate::position;
use crate::token::Token;
use crate::RuleType;

/// An iterator over [`Token`]s. It is created by [`Pair::tokens`] and [`Pairs::tokens`].
///
/// [`Token`]: ../enum.Token.html
/// [`Pair::tokens`]: struct.Pair.html#method.tokens
/// [`Pairs::tokens`]: struct.Pairs.html#method.tokens
#[derive(Clone)]
pub struct Tokens<'i, R> {
    /// # Safety:
    ///
    /// All `QueueableToken`s' `input_pos` must be valid character boundary indices into `input`.
    queue: Rc<Vec<QueueableToken<'i, R>>>,
    input: &'i str,
    start: usize,
    end: usize,
}

// TODO(safety): QueueableTokens must be valid indices into input.
pub fn new<'i, R: RuleType>(
    queue: Rc<Vec<QueueableToken<'i, R>>>,
    input: &'i str,
    start: usize,
    end: usize,
) -> Tokens<'i, R> {
    if cfg!(debug_assertions) {
        for tok in queue.iter() {
            match *tok {
                QueueableToken::Start { input_pos, .. } | QueueableToken::End { input_pos, .. } => {
                    assert!(
                        input.get(input_pos..).is_some(),
                        "💥 UNSAFE `Tokens` CREATED 💥"
                    )
                }
            }
        }
    }

    Tokens {
        queue,
        input,
        start,
        end,
    }
}

impl<'i, R: RuleType> Tokens<'i, R> {
    fn create_token(&self, index: usize) -> Token<'i, R> {
        match self.queue[index] {
            QueueableToken::Start {
                end_token_index,
                input_pos,
            } => {
                let rule = match self.queue[end_token_index] {
                    QueueableToken::End { rule, .. } => rule,
                    _ => unreachable!(),
                };

                Token::Start {
                    rule,
                    // QueueableTokens are safely created.
                    pos: unsafe { position::Position::new_unchecked(self.input, input_pos) },
                }
            }
            QueueableToken::End {
                rule, input_pos, ..
            } => {
                Token::End {
                    rule,
                    // QueueableTokens are safely created.
                    pos: unsafe { position::Position::new_unchecked(self.input, input_pos) },
                }
            }
        }
    }
}

impl<'i, R: RuleType> ExactSizeIterator for Tokens<'i, R> {
    fn len(&self) -> usize {
        self.end - self.start
    }
}

impl<'i, R: RuleType> Iterator for Tokens<'i, R> {
    type Item = Token<'i, R>;

    fn next(&mut self) -> Option<Self::Item> {
        if self.start >= self.end {
            return None;
        }

        let token = self.create_token(self.start);

        self.start += 1;

        Some(token)
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        let len = <Self as ExactSizeIterator>::len(self);
        (len, Some(len))
    }
}

impl<'i, R: RuleType> DoubleEndedIterator for Tokens<'i, R> {
    fn next_back(&mut self) -> Option<Self::Item> {
        if self.end <= self.start {
            return None;
        }

        let token = self.create_token(self.end - 1);

        self.end -= 1;

        Some(token)
    }
}

impl<'i, R: RuleType> fmt::Debug for Tokens<'i, R> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_list().entries(self.clone()).finish()
    }
}

#[cfg(test)]
mod tests {
    use super::super::super::macros::tests::*;
    use super::super::super::Parser;
    use super::Token;
    use alloc::vec::Vec;

    #[test]
    fn double_ended_iter_for_tokens() {
        let pairs = AbcParser::parse(Rule::a, "abcde").unwrap();
        let mut tokens = pairs.clone().tokens().collect::<Vec<Token<'_, Rule>>>();
        tokens.reverse();
        let reverse_tokens = pairs.tokens().rev().collect::<Vec<Token<'_, Rule>>>();
        assert_eq!(tokens, reverse_tokens);
    }

    #[test]
    fn exact_size_iter_for_tokens() {
        let tokens = AbcParser::parse(Rule::a, "abcde").unwrap().tokens();
        assert_eq!(tokens.len(), tokens.count());

        let tokens = AbcParser::parse(Rule::a, "我很漂亮e").unwrap().tokens();
        assert_eq!(tokens.len(), tokens.count());

        let tokens = AbcParser::parse(Rule::a, "abcde").unwrap().tokens().rev();
        assert_eq!(tokens.len(), tokens.count());

        let mut tokens = AbcParser::parse(Rule::a, "abcde").unwrap().tokens();
        let tokens_len = tokens.len();
        let _ = tokens.next().unwrap();
        assert_eq!(tokens.count() + 1, tokens_len);
    }
}