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
175
176
177
// 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 std::fmt;
use std::rc::Rc;

use super::pair::{self, Pair};
use super::queueable_token::QueueableToken;
use super::tokens::{self, Tokens};
use RuleType;

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

/// # Safety
///
/// All `QueueableToken`s' `input_pos` must be valid character boundary indices into `input`.
pub unsafe fn new<R: RuleType>(
    queue: Rc<Vec<QueueableToken<R>>>,
    input: &str,
    start: usize,
    end: usize,
) -> FlatPairs<R> {
    FlatPairs {
        queue,
        input,
        start,
        end,
    }
}

impl<'i, R: RuleType> FlatPairs<'i, R> {
    /// Returns the `Tokens` for these pairs.
    ///
    /// # Examples
    ///
    /// ```
    /// # use std::rc::Rc;
    /// # use pest;
    /// # #[allow(non_camel_case_types)]
    /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
    /// enum Rule {
    ///     a
    /// }
    ///
    /// let input = "";
    /// let pairs = pest::state(input, |state| {
    ///     // generating Token pair with Rule::a ...
    /// #     state.rule(Rule::a, |s| Ok(s))
    /// }).unwrap();
    /// let tokens: Vec<_> = pairs.flatten().tokens().collect();
    ///
    /// assert_eq!(tokens.len(), 2);
    /// ```
    #[inline]
    pub fn tokens(self) -> Tokens<'i, R> {
        tokens::new(self.queue, self.input, self.start, self.end)
    }

    fn next_start(&mut self) {
        self.start += 1;

        while self.start < self.end && !self.is_start(self.start) {
            self.start += 1;
        }
    }

    fn next_start_from_end(&mut self) {
        self.end -= 1;

        while self.end >= self.start && !self.is_start(self.end) {
            self.end -= 1;
        }
    }

    fn is_start(&self, index: usize) -> bool {
        match self.queue[index] {
            QueueableToken::Start { .. } => true,
            QueueableToken::End { .. } => false,
        }
    }
}

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

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

        let pair = unsafe { pair::new(Rc::clone(&self.queue), self.input, self.start) };

        self.next_start();

        Some(pair)
    }
}

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

        self.next_start_from_end();

        let pair = unsafe { pair::new(Rc::clone(&self.queue), self.input, self.end) };

        Some(pair)
    }
}

impl<'i, R: RuleType> fmt::Debug for FlatPairs<'i, R> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_struct("FlatPairs")
            .field("pairs", &self.clone().collect::<Vec<_>>())
            .finish()
    }
}

impl<'i, R: Clone> Clone for FlatPairs<'i, R> {
    fn clone(&self) -> FlatPairs<'i, R> {
        FlatPairs {
            queue: Rc::clone(&self.queue),
            input: self.input,
            start: self.start,
            end: self.end,
        }
    }
}

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

    #[test]
    fn iter_for_flat_pairs() {
        let pairs = AbcParser::parse(Rule::a, "abcde").unwrap();

        assert_eq!(
            pairs.flatten().map(|p| p.as_rule()).collect::<Vec<Rule>>(),
            vec![Rule::a, Rule::b, Rule::c]
        );
    }

    #[test]
    fn double_ended_iter_for_flat_pairs() {
        let pairs = AbcParser::parse(Rule::a, "abcde").unwrap();
        assert_eq!(
            pairs
                .flatten()
                .rev()
                .map(|p| p.as_rule())
                .collect::<Vec<Rule>>(),
            vec![Rule::c, Rule::b, Rule::a]
        );
    }
}