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// 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);
}
}
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