repeated combinator

This commit is contained in:
Greg Shuflin 2022-10-19 19:42:29 -07:00
parent 26f813ee16
commit 567ea60642
3 changed files with 80 additions and 6 deletions

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@ -147,12 +147,15 @@ where
#[cfg(test)] #[cfg(test)]
mod tests { mod tests {
use super::*; use super::*;
use crate::combinators::one_or_more; use crate::combinators::repeated;
use crate::primitives::literal; use crate::primitives::literal;
#[test] #[test]
fn test_choice() { fn test_choice() {
let p = choice2(literal("gnostika").to(1), one_or_more(literal(" ")).to(2)); let p = choice2(
literal("gnostika").to(1),
repeated(literal(" ")).at_least(1).to(2),
);
assert_eq!(p.parse("gnostika twentynine"), Ok((1, " twentynine"))); assert_eq!(p.parse("gnostika twentynine"), Ok((1, " twentynine")));
} }
} }

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@ -1,4 +1,4 @@
use crate::parser::Parser; use crate::parser::{BoxedParser, ParseResult, Parser};
pub fn optional<P, I, O, E>(parser: P) -> impl Parser<I, Option<O>, E> pub fn optional<P, I, O, E>(parser: P) -> impl Parser<I, Option<O>, E>
where where
@ -23,6 +23,78 @@ where
} }
} }
pub struct Repeated<'a, I, O>
where
I: Clone,
{
inner_parser: BoxedParser<'a, I, O, I>,
at_least: Option<u16>,
at_most: Option<u16>,
}
impl<'a, I, O> Repeated<'a, I, O>
where
I: Clone,
{
pub fn at_least(self, n: u16) -> Self {
Self {
at_least: Some(n),
..self
}
}
pub fn at_most(self, n: u16) -> Self {
Self {
at_most: Some(n),
..self
}
}
}
impl<'a, I, O> Parser<I, Vec<O>, I> for Repeated<'a, I, O>
where
I: Clone + 'a,
{
fn parse(&self, input: I) -> ParseResult<I, Vec<O>, I> {
let mut results = Vec::new();
let mut count: u16 = 0;
let at_least = self.at_least.unwrap_or(0);
let at_most = self.at_most.unwrap_or(u16::MAX);
if at_most == 0 {
return Ok((results, input));
}
let mut further_input = input.clone();
while let Ok((item, rest)) = self.inner_parser.parse(further_input.clone()) {
results.push(item);
further_input = rest;
count += 1;
if count >= at_most {
break;
}
}
if count < at_least {
return Err(input);
}
Ok((results, further_input))
}
}
pub fn repeated<'a, P, I, O>(parser: P) -> Repeated<'a, I, O>
where
P: Parser<I, O, I> + 'static,
I: Clone + 'static,
{
Repeated {
inner_parser: BoxedParser::new(parser),
at_least: None,
at_most: None,
}
}
pub fn zero_or_more<P, I, O>(parser: P) -> impl Parser<I, Vec<O>, I> pub fn zero_or_more<P, I, O>(parser: P) -> impl Parser<I, Vec<O>, I>
where where
P: Parser<I, O, I>, P: Parser<I, O, I>,
@ -60,7 +132,6 @@ where
#[cfg(test)] #[cfg(test)]
mod tests { mod tests {
use super::*; use super::*;
use crate::combinators::one_or_more;
use crate::primitives::literal; use crate::primitives::literal;
#[test] #[test]
@ -72,7 +143,7 @@ mod tests {
#[test] #[test]
fn test_one_or_more() { fn test_one_or_more() {
let p = one_or_more(literal("bongo ")); let p = repeated(literal("bongo ")).at_least(1);
let input = "bongo bongo bongo bongo bongo "; let input = "bongo bongo bongo bongo bongo ";
let (output, rest) = p.parse(input).unwrap(); let (output, rest) = p.parse(input).unwrap();

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@ -60,7 +60,7 @@ pub struct BoxedParser<'a, I, O, E> {
} }
impl<'a, I, O, E> BoxedParser<'a, I, O, E> { impl<'a, I, O, E> BoxedParser<'a, I, O, E> {
fn new<P>(inner: P) -> Self pub(crate) fn new<P>(inner: P) -> Self
where where
P: Parser<I, O, E> + 'a, P: Parser<I, O, E> + 'a,
{ {