179 lines
4.1 KiB
Rust
179 lines
4.1 KiB
Rust
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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P: Parser<I, O, E>,
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I: Clone,
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{
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move |input: I| match parser.parse(input.clone()) {
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Ok((output, rest)) => Ok((Some(output), rest)),
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Err(_e) => Ok((None, input)),
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}
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}
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pub fn map<P, F, I, O1, O2, E>(parser: P, map_fn: F) -> impl Parser<I, O2, E>
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where
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P: Parser<I, O1, E>,
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F: Fn(O1) -> O2,
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{
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move |input| {
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parser
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.parse(input)
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.map(|(result, rest)| (map_fn(result), rest))
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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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pub fn delimited_by<D, O2>(self, delimiter: D) -> DelimitedBy<'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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DelimitedBy {
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inner_repeated: self,
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delimiter: BoxedParser::new(delimiter.to(())),
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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 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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}
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pub struct DelimitedBy<'a, I, O>
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where
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I: Clone,
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{
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inner_repeated: Repeated<'a, I, O>,
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delimiter: BoxedParser<'a, I, (), I>,
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}
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impl<'a, I, O> Parser<I, Vec<O>, I> for DelimitedBy<'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 at_least = self.inner_repeated.at_least.unwrap_or(0);
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let at_most = self.inner_repeated.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
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.inner_repeated
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.inner_parser
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.parse(further_input.clone())
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{
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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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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::primitives::literal;
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#[test]
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fn test_map() {
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let lit_a = literal("a");
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let output = lit_a.map(|s| s.to_uppercase()).parse("a yolo");
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assert_eq!(output.unwrap(), ("A".to_string(), " yolo"));
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}
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#[test]
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fn test_one_or_more() {
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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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assert_eq!(rest, "");
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assert_eq!(output.len(), 5);
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let (output, rest) = p.parse("bongo ecks").unwrap();
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assert_eq!(output.len(), 1);
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assert_eq!(rest, "ecks");
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}
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}
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