18b4ac0d4b
git-subtree-dir: subtrees/parser-combinator git-subtree-split: 5526ce7bd17beda52047fbc3442e23e0174b79a7
95 lines
2.3 KiB
Rust
95 lines
2.3 KiB
Rust
use crate::combinators::separated_by::SeparatedBy;
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use crate::parser::{BoxedParser, ParseResult, Parser, ParserInput, Representation};
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pub fn repeated<'a, P, I, O>(parser: P) -> Repeated<'a, I, O>
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where
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P: Parser<I, O, I> + 'a,
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I: ParserInput + Clone + 'a,
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{
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Repeated {
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inner_parser: BoxedParser::new(parser),
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at_least: None,
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at_most: None,
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}
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}
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pub struct Repeated<'a, I, O>
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where
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I: ParserInput + Clone,
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{
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pub(super) inner_parser: BoxedParser<'a, I, O, I>,
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pub(super) at_least: Option<u16>,
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pub(super) at_most: Option<u16>,
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}
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impl<'a, I, O> Repeated<'a, I, O>
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where
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I: ParserInput + Clone,
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{
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pub fn at_least(self, n: u16) -> Self {
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Self {
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at_least: Some(n),
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..self
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}
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}
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pub fn at_most(self, n: u16) -> Self {
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Self {
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at_most: Some(n),
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..self
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}
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}
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pub fn separated_by<D, O2>(self, delimiter: D, allow_trailing: bool) -> SeparatedBy<'a, I, O>
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where
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D: Parser<I, O2, I> + 'a,
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O2: 'a,
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I: 'a,
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{
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SeparatedBy {
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inner_repeated: self,
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delimiter: BoxedParser::new(delimiter.to(())),
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allow_trailing,
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}
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}
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}
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impl<'a, I, O> Parser<I, Vec<O>, I> for Repeated<'a, I, O>
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where
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I: ParserInput + Clone + 'a,
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{
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fn parse(&self, input: I) -> ParseResult<I, Vec<O>, I> {
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let at_least = self.at_least.unwrap_or(0);
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let at_most = self.at_most.unwrap_or(u16::MAX);
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if at_most == 0 {
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return Ok((vec![], input));
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}
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let mut results = Vec::new();
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let mut count: u16 = 0;
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let mut further_input = input.clone();
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while let Ok((item, rest)) = self.inner_parser.parse(further_input.clone()) {
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results.push(item);
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further_input = rest;
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count += 1;
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if count >= at_most {
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break;
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}
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}
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if count < at_least {
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return Err(input);
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}
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Ok((results, further_input))
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}
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fn representation(&self) -> Representation {
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Representation::repeated(
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self.inner_parser.representation(),
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self.at_least.unwrap_or(0),
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self.at_most.unwrap_or(u16::MAX),
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)
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}
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}
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