Pass input out
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e697b8ed21
commit
9efd9d78d1
@ -1,21 +1,19 @@
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use crate::Parser;
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pub fn choice<'a, I, O, E>(parsers: &'a [&'a dyn Parser<I, O, E>]) -> impl Parser<I, O, E> + 'a
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where
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I: Clone,
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{
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move |input: I| {
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pub fn choice<'a, I, O, E>(parsers: &'a [&'a dyn Parser<I, O, E>]) -> impl Parser<I, O, E> + 'a {
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move |mut input: I| {
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//TODO need a more principled way to return an error when no choices work
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let mut err = None;
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for parser in parsers.iter() {
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match parser.parse(input.clone()) {
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match parser.parse(input) {
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Ok(res) => return Ok(res),
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Err(e) => {
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Err((e, rest)) => {
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err = Some(e);
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input = rest;
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}
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}
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}
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Err(err.unwrap())
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Err((err.unwrap(), input))
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}
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}
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@ -3,15 +3,22 @@ use crate::Parser;
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pub fn repeated<P, I, O, E>(parser: P) -> impl Parser<I, Vec<O>, E>
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where
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P: Parser<I, O, E>,
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I: Copy,
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{
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move |input: I| {
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let mut acc = input;
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let mut results = vec![];
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while let Ok((item, rest)) = parser.parse(acc) {
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results.push(item);
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acc = rest;
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loop {
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match parser.parse(acc) {
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Ok((item, rest)) => {
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results.push(item);
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acc = rest;
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}
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Err((_err, rest)) => {
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acc = rest;
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break;
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}
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}
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}
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Ok((results, acc))
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}
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@ -11,7 +11,7 @@ pub use map::*;
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pub use primitives::*;
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pub use sequence::*;
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type ParseResult<I, O, E> = Result<(O, I), E>;
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type ParseResult<I, O, E> = Result<(O, I), (E, I)>;
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pub trait Parser<I, O, E> {
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fn parse(&self, input: I) -> ParseResult<I, O, E>;
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@ -51,7 +51,7 @@ mod tests {
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let a = literal("bongo");
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let b = literal("sucy");
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let c = literal("ara");
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let inputs = [&a as &dyn Parser<&str, &str, &str>, &b, &c];
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let inputs = [&a as &dyn Parser<&str, &str, ()>, &b, &c];
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let parser = choice(&inputs);
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let output = parser.parse("ara hajimete").unwrap();
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@ -1,16 +1,16 @@
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use crate::{ParseResult, Parser};
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pub fn literal(expected: &'static str) -> impl Fn(&str) -> ParseResult<&str, &str, &str> {
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pub fn literal(expected: &'static str) -> impl Fn(&str) -> ParseResult<&str, &str, ()> {
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move |input| match input.get(0..expected.len()) {
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Some(next) if next == expected => Ok((next, &input[expected.len()..])),
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_ => Err(input),
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_ => Err(((), input)),
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}
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}
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pub fn literal_char<'a>(expected: char) -> impl Parser<&'a str, char, &'a str> {
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pub fn literal_char<'a>(expected: char) -> impl Parser<&'a str, char, ()> {
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move |input: &'a str| match input.chars().next() {
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Some(ch) if ch == expected => Ok((expected, &input[ch.len_utf8()..])),
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_ => Err(input),
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_ => Err(((), input)),
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}
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}
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