diff options
Diffstat (limited to 'vendor/pest/src/parser_state.rs')
| -rw-r--r-- | vendor/pest/src/parser_state.rs | 1160 |
1 files changed, 1160 insertions, 0 deletions
diff --git a/vendor/pest/src/parser_state.rs b/vendor/pest/src/parser_state.rs new file mode 100644 index 000000000..09bc92710 --- /dev/null +++ b/vendor/pest/src/parser_state.rs @@ -0,0 +1,1160 @@ +// 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::ops::Range; +use std::rc::Rc; + +use error::{Error, ErrorVariant}; +use iterators::{pairs, QueueableToken}; +use position::{self, Position}; +use span::Span; +use stack::Stack; +use RuleType; + +/// The current lookahead status of a [`ParserState`]. +/// +/// [`ParserState`]: struct.ParserState.html +#[derive(Clone, Copy, Debug, Eq, PartialEq)] +pub enum Lookahead { + Positive, + Negative, + None, +} + +/// The current atomicity of a [`ParserState`]. +/// +/// [`ParserState`]: struct.ParserState.html +#[derive(Clone, Copy, Debug, Eq, PartialEq)] +pub enum Atomicity { + Atomic, + CompoundAtomic, + NonAtomic, +} + +/// Type alias to simplify specifying the return value of chained closures. +pub type ParseResult<S> = Result<S, S>; + +/// Match direction for the stack. Used in `PEEK[a..b]`/`stack_match_peek_slice`. +#[derive(Clone, Copy, Debug, Eq, PartialEq)] +pub enum MatchDir { + BottomToTop, + TopToBottom, +} + +/// The complete state of a [`Parser`]. +/// +/// [`Parser`]: trait.Parser.html +#[derive(Debug)] +pub struct ParserState<'i, R: RuleType> { + position: Position<'i>, + queue: Vec<QueueableToken<R>>, + lookahead: Lookahead, + pos_attempts: Vec<R>, + neg_attempts: Vec<R>, + attempt_pos: usize, + atomicity: Atomicity, + stack: Stack<Span<'i>>, +} + +/// Creates a `ParserState` from a `&str`, supplying it to a closure `f`. +/// +/// # Examples +/// +/// ``` +/// # use pest; +/// let input = ""; +/// pest::state::<(), _>(input, |s| Ok(s)).unwrap(); +/// ``` +pub fn state<'i, R: RuleType, F>(input: &'i str, f: F) -> Result<pairs::Pairs<'i, R>, Error<R>> +where + F: FnOnce(Box<ParserState<'i, R>>) -> ParseResult<Box<ParserState<'i, R>>>, +{ + let state = ParserState::new(input); + + match f(state) { + Ok(state) => { + let len = state.queue.len(); + Ok(pairs::new(Rc::new(state.queue), input, 0, len)) + } + Err(mut state) => { + state.pos_attempts.sort(); + state.pos_attempts.dedup(); + state.neg_attempts.sort(); + state.neg_attempts.dedup(); + + Err(Error::new_from_pos( + ErrorVariant::ParsingError { + positives: state.pos_attempts.clone(), + negatives: state.neg_attempts.clone(), + }, + // TODO(performance): Guarantee state.attempt_pos is a valid position + position::Position::new(input, state.attempt_pos).unwrap(), + )) + } + } +} + +impl<'i, R: RuleType> ParserState<'i, R> { + /// Allocates a fresh `ParserState` object to the heap and returns the owned `Box`. This `Box` + /// will be passed from closure to closure based on the needs of the specified `Parser`. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// let input = ""; + /// let state: Box<pest::ParserState<&str>> = pest::ParserState::new(input); + /// ``` + #[allow(clippy::new_ret_no_self)] + pub fn new(input: &'i str) -> Box<Self> { + Box::new(ParserState { + position: Position::from_start(input), + queue: vec![], + lookahead: Lookahead::None, + pos_attempts: vec![], + neg_attempts: vec![], + attempt_pos: 0, + atomicity: Atomicity::NonAtomic, + stack: Stack::new(), + }) + } + + /// Returns a reference to the current `Position` of the `ParserState`. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule { + /// ab + /// } + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let position = state.position(); + /// assert_eq!(position.pos(), 0); + /// ``` + pub fn position(&self) -> &Position<'i> { + &self.position + } + + /// Returns the current atomicity of the `ParserState`. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # use pest::Atomicity; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule { + /// ab + /// } + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let atomicity = state.atomicity(); + /// assert_eq!(atomicity, Atomicity::NonAtomic); + /// ``` + pub fn atomicity(&self) -> Atomicity { + self.atomicity + } + + /// Wrapper needed to generate tokens. This will associate the `R` type rule to the closure + /// meant to match the rule. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule { + /// a + /// } + /// + /// let input = "a"; + /// let pairs: Vec<_> = pest::state(input, |state| { + /// state.rule(Rule::a, |s| Ok(s)) + /// }).unwrap().collect(); + /// + /// assert_eq!(pairs.len(), 1); + /// ``` + #[inline] + pub fn rule<F>(mut self: Box<Self>, rule: R, f: F) -> ParseResult<Box<Self>> + where + F: FnOnce(Box<Self>) -> ParseResult<Box<Self>>, + { + let actual_pos = self.position.pos(); + let index = self.queue.len(); + + let (pos_attempts_index, neg_attempts_index) = if actual_pos == self.attempt_pos { + (self.pos_attempts.len(), self.neg_attempts.len()) + } else { + // Attempts have not been cleared yet since the attempt_pos is older. + (0, 0) + }; + + if self.lookahead == Lookahead::None && self.atomicity != Atomicity::Atomic { + // Pair's position will only be known after running the closure. + self.queue.push(QueueableToken::Start { + end_token_index: 0, + input_pos: actual_pos, + }); + } + + let attempts = self.attempts_at(actual_pos); + + let result = f(self); + + match result { + Ok(mut new_state) => { + if new_state.lookahead == Lookahead::Negative { + new_state.track( + rule, + actual_pos, + pos_attempts_index, + neg_attempts_index, + attempts, + ); + } + + if new_state.lookahead == Lookahead::None + && new_state.atomicity != Atomicity::Atomic + { + // Storing the pair's index in the first token that was added before the closure was + // run. + let new_index = new_state.queue.len(); + match new_state.queue[index] { + QueueableToken::Start { + ref mut end_token_index, + .. + } => *end_token_index = new_index, + _ => unreachable!(), + }; + + let new_pos = new_state.position.pos(); + + new_state.queue.push(QueueableToken::End { + start_token_index: index, + rule, + input_pos: new_pos, + }); + } + + Ok(new_state) + } + Err(mut new_state) => { + if new_state.lookahead != Lookahead::Negative { + new_state.track( + rule, + actual_pos, + pos_attempts_index, + neg_attempts_index, + attempts, + ); + } + + if new_state.lookahead == Lookahead::None + && new_state.atomicity != Atomicity::Atomic + { + new_state.queue.truncate(index); + } + + Err(new_state) + } + } + } + + fn attempts_at(&self, pos: usize) -> usize { + if self.attempt_pos == pos { + self.pos_attempts.len() + self.neg_attempts.len() + } else { + 0 + } + } + + fn track( + &mut self, + rule: R, + pos: usize, + pos_attempts_index: usize, + neg_attempts_index: usize, + prev_attempts: usize, + ) { + if self.atomicity == Atomicity::Atomic { + return; + } + + // If nested rules made no progress, there is no use to report them; it's only useful to + // track the current rule, the exception being when only one attempt has been made during + // the children rules. + let curr_attempts = self.attempts_at(pos); + if curr_attempts > prev_attempts && curr_attempts - prev_attempts == 1 { + return; + } + + if pos == self.attempt_pos { + self.pos_attempts.truncate(pos_attempts_index); + self.neg_attempts.truncate(neg_attempts_index); + } + + if pos > self.attempt_pos { + self.pos_attempts.clear(); + self.neg_attempts.clear(); + self.attempt_pos = pos; + } + + let attempts = if self.lookahead != Lookahead::Negative { + &mut self.pos_attempts + } else { + &mut self.neg_attempts + }; + + if pos == self.attempt_pos { + attempts.push(rule); + } + } + + /// Starts a sequence of transformations provided by `f` from the `Box<ParserState>`. Returns + /// the same `Result` returned by `f` in the case of an `Ok`, or `Err` with the current + /// `Box<ParserState>` otherwise. + /// + /// This method is useful to parse sequences that only match together which usually come in the + /// form of chained `Result`s with + /// [`Result::and_then`](https://doc.rust-lang.org/std/result/enum.Result.html#method.and_then). + /// + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule { + /// a + /// } + /// + /// let input = "a"; + /// let pairs: Vec<_> = pest::state(input, |state| { + /// state.sequence(|s| { + /// s.rule(Rule::a, |s| Ok(s)).and_then(|s| { + /// s.match_string("b") + /// }) + /// }).or_else(|s| { + /// Ok(s) + /// }) + /// }).unwrap().collect(); + /// + /// assert_eq!(pairs.len(), 0); + /// ``` + #[inline] + pub fn sequence<F>(self: Box<Self>, f: F) -> ParseResult<Box<Self>> + where + F: FnOnce(Box<Self>) -> ParseResult<Box<Self>>, + { + let token_index = self.queue.len(); + let initial_pos = self.position.clone(); + + let result = f(self); + + match result { + Ok(new_state) => Ok(new_state), + Err(mut new_state) => { + // Restore the initial position and truncate the token queue. + new_state.position = initial_pos; + new_state.queue.truncate(token_index); + Err(new_state) + } + } + } + + /// Repeatedly applies the transformation provided by `f` from the `Box<ParserState>`. Returns + /// `Ok` with the updated `Box<ParserState>` returned by `f` wrapped up in an `Err`. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule { + /// ab + /// } + /// + /// let input = "aab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.repeat(|s| { + /// s.match_string("a") + /// }); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 2); + /// + /// state = pest::ParserState::new(input); + /// result = state.repeat(|s| { + /// s.match_string("b") + /// }); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 0); + /// ``` + #[inline] + pub fn repeat<F>(self: Box<Self>, mut f: F) -> ParseResult<Box<Self>> + where + F: FnMut(Box<Self>) -> ParseResult<Box<Self>>, + { + let mut result = f(self); + + loop { + match result { + Ok(state) => result = f(state), + Err(state) => return Ok(state), + }; + } + } + + /// Optionally applies the transformation provided by `f` from the `Box<ParserState>`. Returns + /// `Ok` with the updated `Box<ParserState>` returned by `f` regardless of the `Result`. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule { + /// ab + /// } + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let result = state.optional(|s| { + /// s.match_string("ab") + /// }); + /// assert!(result.is_ok()); + /// + /// state = pest::ParserState::new(input); + /// let result = state.optional(|s| { + /// s.match_string("ac") + /// }); + /// assert!(result.is_ok()); + /// ``` + #[inline] + pub fn optional<F>(self: Box<Self>, f: F) -> ParseResult<Box<Self>> + where + F: FnOnce(Box<Self>) -> ParseResult<Box<Self>>, + { + match f(self) { + Ok(state) | Err(state) => Ok(state), + } + } + + /// Attempts to match a single character based on a filter function. Returns `Ok` with the + /// updated `Box<ParserState>` if successful, or `Err` with the updated `Box<ParserState>` + /// otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let result = state.match_char_by(|c| c.is_ascii()); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 1); + /// + /// let input = "❤"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let result = state.match_char_by(|c| c.is_ascii()); + /// assert!(result.is_err()); + /// assert_eq!(result.unwrap_err().position().pos(), 0); + /// ``` + #[inline] + pub fn match_char_by<F>(mut self: Box<Self>, f: F) -> ParseResult<Box<Self>> + where + F: FnOnce(char) -> bool, + { + if self.position.match_char_by(f) { + Ok(self) + } else { + Err(self) + } + } + + /// Attempts to match the given string. Returns `Ok` with the updated `Box<ParserState>` if + /// successful, or `Err` with the updated `Box<ParserState>` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.match_string("ab"); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 2); + /// + /// state = pest::ParserState::new(input); + /// result = state.match_string("ac"); + /// assert!(result.is_err()); + /// assert_eq!(result.unwrap_err().position().pos(), 0); + /// ``` + #[inline] + pub fn match_string(mut self: Box<Self>, string: &str) -> ParseResult<Box<Self>> { + if self.position.match_string(string) { + Ok(self) + } else { + Err(self) + } + } + + /// Attempts to case-insensitively match the given string. Returns `Ok` with the updated + /// `Box<ParserState>` if successful, or `Err` with the updated `Box<ParserState>` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.match_insensitive("AB"); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 2); + /// + /// state = pest::ParserState::new(input); + /// result = state.match_insensitive("AC"); + /// assert!(result.is_err()); + /// assert_eq!(result.unwrap_err().position().pos(), 0); + /// ``` + #[inline] + pub fn match_insensitive(mut self: Box<Self>, string: &str) -> ParseResult<Box<Self>> { + if self.position.match_insensitive(string) { + Ok(self) + } else { + Err(self) + } + } + + /// Attempts to match a single character from the given range. Returns `Ok` with the updated + /// `Box<ParserState>` if successful, or `Err` with the updated `Box<ParserState>` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.match_range('a'..'z'); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 1); + /// + /// state = pest::ParserState::new(input); + /// result = state.match_range('A'..'Z'); + /// assert!(result.is_err()); + /// assert_eq!(result.unwrap_err().position().pos(), 0); + /// ``` + #[inline] + pub fn match_range(mut self: Box<Self>, range: Range<char>) -> ParseResult<Box<Self>> { + if self.position.match_range(range) { + Ok(self) + } else { + Err(self) + } + } + + /// Attempts to skip `n` characters forward. Returns `Ok` with the updated `Box<ParserState>` + /// if successful, or `Err` with the updated `Box<ParserState>` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.skip(1); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 1); + /// + /// state = pest::ParserState::new(input); + /// result = state.skip(3); + /// assert!(result.is_err()); + /// assert_eq!(result.unwrap_err().position().pos(), 0); + /// ``` + #[inline] + pub fn skip(mut self: Box<Self>, n: usize) -> ParseResult<Box<Self>> { + if self.position.skip(n) { + Ok(self) + } else { + Err(self) + } + } + + /// Attempts to skip forward until one of the given strings is found. Returns `Ok` with the + /// updated `Box<ParserState>` whether or not one of the strings is found. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "abcd"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.skip_until(&["c", "d"]); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 2); + /// ``` + #[inline] + pub fn skip_until(mut self: Box<Self>, strings: &[&str]) -> ParseResult<Box<Self>> { + self.position.skip_until(strings); + Ok(self) + } + + /// Attempts to match the start of the input. Returns `Ok` with the current `Box<ParserState>` + /// if the parser has not yet advanced, or `Err` with the current `Box<ParserState>` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.start_of_input(); + /// assert!(result.is_ok()); + /// + /// state = pest::ParserState::new(input); + /// state = state.match_string("ab").unwrap(); + /// result = state.start_of_input(); + /// assert!(result.is_err()); + /// ``` + #[inline] + pub fn start_of_input(self: Box<Self>) -> ParseResult<Box<Self>> { + if self.position.at_start() { + Ok(self) + } else { + Err(self) + } + } + + /// Attempts to match the end of the input. Returns `Ok` with the current `Box<ParserState>` if + /// there is no input remaining, or `Err` with the current `Box<ParserState>` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.end_of_input(); + /// assert!(result.is_err()); + /// + /// state = pest::ParserState::new(input); + /// state = state.match_string("ab").unwrap(); + /// result = state.end_of_input(); + /// assert!(result.is_ok()); + /// ``` + #[inline] + pub fn end_of_input(self: Box<Self>) -> ParseResult<Box<Self>> { + if self.position.at_end() { + Ok(self) + } else { + Err(self) + } + } + + /// Starts a lookahead transformation provided by `f` from the `Box<ParserState>`. It returns + /// `Ok` with the current `Box<ParserState>` if `f` also returns an `Ok`, or `Err` with the current + /// `Box<ParserState>` otherwise. If `is_positive` is `false`, it swaps the `Ok` and `Err` + /// together, negating the `Result`. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule { + /// a + /// } + /// + /// let input = "a"; + /// let pairs: Vec<_> = pest::state(input, |state| { + /// state.lookahead(true, |state| { + /// state.rule(Rule::a, |s| Ok(s)) + /// }) + /// }).unwrap().collect(); + /// + /// assert_eq!(pairs.len(), 0); + /// ``` + #[inline] + pub fn lookahead<F>(mut self: Box<Self>, is_positive: bool, f: F) -> ParseResult<Box<Self>> + where + F: FnOnce(Box<Self>) -> ParseResult<Box<Self>>, + { + let initial_lookahead = self.lookahead; + + self.lookahead = if is_positive { + match initial_lookahead { + Lookahead::None | Lookahead::Positive => Lookahead::Positive, + Lookahead::Negative => Lookahead::Negative, + } + } else { + match initial_lookahead { + Lookahead::None | Lookahead::Positive => Lookahead::Negative, + Lookahead::Negative => Lookahead::Positive, + } + }; + + let initial_pos = self.position.clone(); + + let result = f(self.checkpoint()); + + let result_state = match result { + Ok(mut new_state) => { + new_state.position = initial_pos; + new_state.lookahead = initial_lookahead; + Ok(new_state.restore()) + } + Err(mut new_state) => { + new_state.position = initial_pos; + new_state.lookahead = initial_lookahead; + Err(new_state.restore()) + } + }; + + if is_positive { + result_state + } else { + match result_state { + Ok(state) => Err(state), + Err(state) => Ok(state), + } + } + } + + /// Transformation which stops `Token`s from being generated according to `is_atomic`. + /// + /// # Examples + /// + /// ``` + /// # use pest::{self, Atomicity}; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule { + /// a + /// } + /// + /// let input = "a"; + /// let pairs: Vec<_> = pest::state(input, |state| { + /// state.atomic(Atomicity::Atomic, |s| { + /// s.rule(Rule::a, |s| Ok(s)) + /// }) + /// }).unwrap().collect(); + /// + /// assert_eq!(pairs.len(), 0); + /// ``` + #[inline] + pub fn atomic<F>(mut self: Box<Self>, atomicity: Atomicity, f: F) -> ParseResult<Box<Self>> + where + F: FnOnce(Box<Self>) -> ParseResult<Box<Self>>, + { + let initial_atomicity = self.atomicity; + let should_toggle = self.atomicity != atomicity; + + if should_toggle { + self.atomicity = atomicity; + } + + let result = f(self); + + match result { + Ok(mut new_state) => { + if should_toggle { + new_state.atomicity = initial_atomicity; + } + Ok(new_state) + } + Err(mut new_state) => { + if should_toggle { + new_state.atomicity = initial_atomicity; + } + Err(new_state) + } + } + } + + /// Evaluates the result of closure `f` and pushes the span of the input consumed from before + /// `f` is called to after `f` is called to the stack. Returns `Ok(Box<ParserState>)` if `f` is + /// called successfully, or `Err(Box<ParserState>)` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.stack_push(|state| state.match_string("a")); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 1); + /// ``` + #[inline] + pub fn stack_push<F>(self: Box<Self>, f: F) -> ParseResult<Box<Self>> + where + F: FnOnce(Box<Self>) -> ParseResult<Box<Self>>, + { + let start = self.position.clone(); + + let result = f(self); + + match result { + Ok(mut state) => { + let end = state.position.clone(); + state.stack.push(start.span(&end)); + Ok(state) + } + Err(state) => Err(state), + } + } + + /// Peeks the top of the stack and attempts to match the string. Returns `Ok(Box<ParserState>)` + /// if the string is matched successfully, or `Err(Box<ParserState>)` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "aa"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.stack_push(|state| state.match_string("a")).and_then( + /// |state| state.stack_peek() + /// ); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 2); + /// ``` + #[inline] + pub fn stack_peek(self: Box<Self>) -> ParseResult<Box<Self>> { + let string = self + .stack + .peek() + .expect("peek was called on empty stack") + .as_str(); + self.match_string(string) + } + + /// Pops the top of the stack and attempts to match the string. Returns `Ok(Box<ParserState>)` + /// if the string is matched successfully, or `Err(Box<ParserState>)` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "aa"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.stack_push(|state| state.match_string("a")).and_then( + /// |state| state.stack_pop() + /// ); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 2); + /// ``` + #[inline] + pub fn stack_pop(mut self: Box<Self>) -> ParseResult<Box<Self>> { + let string = self + .stack + .pop() + .expect("pop was called on empty stack") + .as_str(); + self.match_string(string) + } + + /// Matches part of the state of the stack. + /// + /// # Examples + /// + /// ``` + /// # use pest::{self, MatchDir}; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "abcd cd cb"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state + /// .stack_push(|state| state.match_string("a")) + /// .and_then(|state| state.stack_push(|state| state.match_string("b"))) + /// .and_then(|state| state.stack_push(|state| state.match_string("c"))) + /// .and_then(|state| state.stack_push(|state| state.match_string("d"))) + /// .and_then(|state| state.match_string(" ")) + /// .and_then(|state| state.stack_match_peek_slice(2, None, MatchDir::BottomToTop)) + /// .and_then(|state| state.match_string(" ")) + /// .and_then(|state| state.stack_match_peek_slice(1, Some(-1), MatchDir::TopToBottom)); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 10); + /// ``` + #[inline] + pub fn stack_match_peek_slice( + mut self: Box<Self>, + start: i32, + end: Option<i32>, + match_dir: MatchDir, + ) -> ParseResult<Box<Self>> { + let range = match constrain_idxs(start, end, self.stack.len()) { + Some(r) => r, + None => return Err(self), + }; + // return true if an empty sequence is requested + if range.end <= range.start { + return Ok(self); + } + + let mut position = self.position.clone(); + let result = { + let mut iter_b2t = self.stack[range].iter(); + let matcher = |span: &Span| position.match_string(span.as_str()); + match match_dir { + MatchDir::BottomToTop => iter_b2t.all(matcher), + MatchDir::TopToBottom => iter_b2t.rev().all(matcher), + } + }; + if result { + self.position = position; + Ok(self) + } else { + Err(self) + } + } + + /// Matches the full state of the stack. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "abba"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state + /// .stack_push(|state| state.match_string("a")) + /// .and_then(|state| { state.stack_push(|state| state.match_string("b")) }) + /// .and_then(|state| state.stack_match_peek()); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 4); + /// ``` + #[inline] + pub fn stack_match_peek(self: Box<Self>) -> ParseResult<Box<Self>> { + self.stack_match_peek_slice(0, None, MatchDir::TopToBottom) + } + + /// Matches the full state of the stack. This method will clear the stack as it evaluates. + /// + /// # Examples + /// + /// ``` + /// /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "aaaa"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.stack_push(|state| state.match_string("a")).and_then(|state| { + /// state.stack_push(|state| state.match_string("a")) + /// }).and_then(|state| state.stack_match_peek()); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 4); + /// ``` + #[inline] + pub fn stack_match_pop(mut self: Box<Self>) -> ParseResult<Box<Self>> { + let mut position = self.position.clone(); + let mut result = true; + while let Some(span) = self.stack.pop() { + result = position.match_string(span.as_str()); + if !result { + break; + } + } + + if result { + self.position = position; + Ok(self) + } else { + Err(self) + } + } + + /// Drops the top of the stack. Returns `Ok(Box<ParserState>)` if there was a value to drop, or + /// `Err(Box<ParserState>)` otherwise. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "aa"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.stack_push(|state| state.match_string("a")).and_then( + /// |state| state.stack_drop() + /// ); + /// assert!(result.is_ok()); + /// assert_eq!(result.unwrap().position().pos(), 1); + /// ``` + #[inline] + pub fn stack_drop(mut self: Box<Self>) -> ParseResult<Box<Self>> { + match self.stack.pop() { + Some(_) => Ok(self), + None => Err(self), + } + } + + /// Restores the original state of the `ParserState` when `f` returns an `Err`. Currently, + /// this method only restores the stack. + /// + /// # Examples + /// + /// ``` + /// # use pest; + /// # #[allow(non_camel_case_types)] + /// # #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] + /// enum Rule {} + /// + /// let input = "ab"; + /// let mut state: Box<pest::ParserState<Rule>> = pest::ParserState::new(input); + /// let mut result = state.restore_on_err(|state| state.stack_push(|state| + /// state.match_string("a")).and_then(|state| state.match_string("a")) + /// ); + /// + /// assert!(result.is_err()); + /// + /// // Since the the rule doesn't match, the "a" pushed to the stack will be removed. + /// let catch_panic = std::panic::catch_unwind(|| result.unwrap_err().stack_pop()); + /// assert!(catch_panic.is_err()); + /// ``` + #[inline] + pub fn restore_on_err<F>(self: Box<Self>, f: F) -> ParseResult<Box<Self>> + where + F: FnOnce(Box<Self>) -> ParseResult<Box<Self>>, + { + match f(self.checkpoint()) { + Ok(state) => Ok(state.checkpoint_ok()), + Err(state) => Err(state.restore()), + } + } + + // Mark the current state as a checkpoint and return the `Box`. + #[inline] + pub(crate) fn checkpoint(mut self: Box<Self>) -> Box<Self> { + self.stack.snapshot(); + self + } + + // The checkpoint was cleared successfully + // so remove it without touching other stack state. + #[inline] + pub(crate) fn checkpoint_ok(mut self: Box<Self>) -> Box<Self> { + self.stack.clear_snapshot(); + self + } + + // Restore the current state to the most recent checkpoint. + #[inline] + pub(crate) fn restore(mut self: Box<Self>) -> Box<Self> { + self.stack.restore(); + self + } +} + +fn constrain_idxs(start: i32, end: Option<i32>, len: usize) -> Option<Range<usize>> { + let start_norm = normalize_index(start, len)?; + let end_norm = end.map_or(Some(len), |e| normalize_index(e, len))?; + Some(start_norm..end_norm) +} + +/// Normalizes the index using its sequence’s length. +/// Returns `None` if the normalized index is OOB. +fn normalize_index(i: i32, len: usize) -> Option<usize> { + if i > len as i32 { + None + } else if i >= 0 { + Some(i as usize) + } else { + let real_i = len as i32 + i; + if real_i >= 0 { + Some(real_i as usize) + } else { + None + } + } +} + +#[cfg(test)] +mod test { + use super::*; + + #[test] + fn normalize_index_pos() { + assert_eq!(normalize_index(4, 6), Some(4)); + assert_eq!(normalize_index(5, 5), Some(5)); + assert_eq!(normalize_index(6, 3), None); + } + + #[test] + fn normalize_index_neg() { + assert_eq!(normalize_index(-4, 6), Some(2)); + assert_eq!(normalize_index(-5, 5), Some(0)); + assert_eq!(normalize_index(-6, 3), None); + } +} |