repeated combinator
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26f813ee16
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567ea60642
@ -147,12 +147,15 @@ where
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::combinators::one_or_more;
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use crate::combinators::repeated;
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use crate::primitives::literal;
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#[test]
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fn test_choice() {
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let p = choice2(literal("gnostika").to(1), one_or_more(literal(" ")).to(2));
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let p = choice2(
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literal("gnostika").to(1),
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repeated(literal(" ")).at_least(1).to(2),
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);
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assert_eq!(p.parse("gnostika twentynine"), Ok((1, " twentynine")));
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}
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}
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@ -1,4 +1,4 @@
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use crate::parser::Parser;
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use crate::parser::{BoxedParser, ParseResult, Parser};
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pub fn optional<P, I, O, E>(parser: P) -> impl Parser<I, Option<O>, E>
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where
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@ -23,6 +23,78 @@ where
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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: Clone,
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{
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inner_parser: BoxedParser<'a, I, O, I>,
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at_least: Option<u16>,
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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: 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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}
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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: 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 mut results = Vec::new();
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let mut count: u16 = 0;
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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((results, input));
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}
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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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}
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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> + 'static,
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I: Clone + 'static,
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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 fn zero_or_more<P, I, O>(parser: P) -> impl Parser<I, Vec<O>, I>
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where
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P: Parser<I, O, I>,
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@ -60,7 +132,6 @@ where
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::combinators::one_or_more;
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use crate::primitives::literal;
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#[test]
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@ -72,7 +143,7 @@ mod tests {
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#[test]
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fn test_one_or_more() {
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let p = one_or_more(literal("bongo "));
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let p = repeated(literal("bongo ")).at_least(1);
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let input = "bongo bongo bongo bongo bongo ";
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let (output, rest) = p.parse(input).unwrap();
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@ -60,7 +60,7 @@ pub struct BoxedParser<'a, I, O, E> {
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}
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impl<'a, I, O, E> BoxedParser<'a, I, O, E> {
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fn new<P>(inner: P) -> Self
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pub(crate) fn new<P>(inner: P) -> Self
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where
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P: Parser<I, O, E> + 'a,
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{
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