forked from Mirrors/helix
Add a parser-combinator crate
Parser-combinators are one of the simpler tools for building ad-hoc parsers. They're a good fit because they are... * Small: each parser / parser-combinator is around 10 LOC. * Functional: helix_core strives to be a functional set of utilities usable throughout the rest of the editor. * Flexible: use them to build any sort of ad-hoc parser. In the child commit, we'll parse LSP Snippet syntax using these new parser combinators. Why not use an existing parser-combinator crate? Existing popular parser-combinator crates have histories of making breaking changes (for example nom and combine). > Implementation note: I tried to not introduce a new trait since the > types can be expressed in terms of `impl Fn`s. The trait is necessary > to build `seq` implementations without a proc macro though, and also > allows us to use `&'static str`s very conveniently: see the trait > implementation for `&'static str`.pull/5/head
Michael Davis
2 years ago
committed by
Blaž Hrastnik
parent
f976c004e2
commit
c8e6857aff
@ -0,0 +1,14 @@
|
||||
[package]
|
||||
name = "helix-parsec"
|
||||
version = "0.6.0"
|
||||
authors = ["Blaž Hrastnik <blaz@mxxn.io>"]
|
||||
edition = "2021"
|
||||
license = "MPL-2.0"
|
||||
description = "Parser combinators for Helix"
|
||||
categories = ["editor"]
|
||||
repository = "https://github.com/helix-editor/helix"
|
||||
homepage = "https://helix-editor.com"
|
||||
include = ["src/**/*", "README.md"]
|
||||
|
||||
[dependencies]
|
||||
regex = "1"
|
||||
@ -0,0 +1,560 @@
|
||||
//! Parser-combinator functions
|
||||
//!
|
||||
//! This module provides parsers and parser combinators which can be used
|
||||
//! together to build parsers by functional composition.
|
||||
|
||||
use regex::Regex;
|
||||
|
||||
// This module implements parser combinators following https://bodil.lol/parser-combinators/.
|
||||
// `sym` (trait implementation for `&'static str`), `map`, `pred` (filter), `one_or_more`,
|
||||
// `zero_or_more`, as well as the `Parser` trait originate mostly from that post.
|
||||
// The remaining parsers and parser combinators are either based on
|
||||
// https://github.com/archseer/snippets.nvim/blob/a583da6ef130d2a4888510afd8c4e5ffd62d0dce/lua/snippet/parser.lua#L5-L138
|
||||
// or are novel.
|
||||
|
||||
// When a parser matches the input successfully, it returns `Ok((next_input, some_value))`
|
||||
// where the type of the returned value depends on the parser. If the parser fails to match,
|
||||
// it returns `Err(input)`.
|
||||
type ParseResult<'a, Output> = Result<(&'a str, Output), &'a str>;
|
||||
|
||||
/// A parser or parser-combinator.
|
||||
///
|
||||
/// Parser-combinators compose multiple parsers together to parse input.
|
||||
/// For example, two basic parsers (`&'static str`s) may be combined with
|
||||
/// a parser-combinator like [or] to produce a new parser.
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{or, Parser};
|
||||
/// let foo = "foo"; // matches "foo" literally
|
||||
/// let bar = "bar"; // matches "bar" literally
|
||||
/// let foo_or_bar = or(foo, bar); // matches either "foo" or "bar"
|
||||
/// assert_eq!(Ok(("", "foo")), foo_or_bar.parse("foo"));
|
||||
/// assert_eq!(Ok(("", "bar")), foo_or_bar.parse("bar"));
|
||||
/// assert_eq!(Err("baz"), foo_or_bar.parse("baz"));
|
||||
/// ```
|
||||
pub trait Parser<'a> {
|
||||
type Output;
|
||||
|
||||
fn parse(&self, input: &'a str) -> ParseResult<'a, Self::Output>;
|
||||
}
|
||||
|
||||
// Most parser-combinators are written as higher-order functions which take some
|
||||
// parser(s) as input and return a new parser: a function that takes input and returns
|
||||
// a parse result. The underlying implementation of [Parser::parse] for these functions
|
||||
// is simply application.
|
||||
#[doc(hidden)]
|
||||
impl<'a, F, T> Parser<'a> for F
|
||||
where
|
||||
F: Fn(&'a str) -> ParseResult<T>,
|
||||
{
|
||||
type Output = T;
|
||||
|
||||
fn parse(&self, input: &'a str) -> ParseResult<'a, Self::Output> {
|
||||
self(input)
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser which matches the string literal exactly.
|
||||
///
|
||||
/// This parser succeeds if the next characters in the input are equal to the given
|
||||
/// string literal.
|
||||
///
|
||||
/// Note that [str::parse] interferes with calling [Parser::parse] on string literals
|
||||
/// directly; this trait implementation works when used within any parser combinator
|
||||
/// but does not work on its own. To call [Parser::parse] on a parser for a string
|
||||
/// literal, use the [token] parser.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{or, Parser};
|
||||
/// let parser = or("foo", "bar");
|
||||
/// assert_eq!(Ok(("", "foo")), parser.parse("foo"));
|
||||
/// assert_eq!(Ok(("", "bar")), parser.parse("bar"));
|
||||
/// assert_eq!(Err("baz"), parser.parse("baz"));
|
||||
/// ```
|
||||
impl<'a> Parser<'a> for &'static str {
|
||||
type Output = &'a str;
|
||||
|
||||
fn parse(&self, input: &'a str) -> ParseResult<'a, Self::Output> {
|
||||
match input.get(0..self.len()) {
|
||||
Some(actual) if actual == *self => Ok((&input[self.len()..], &input[0..self.len()])),
|
||||
_ => Err(input),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Parsers
|
||||
|
||||
/// A parser which matches the given string literally.
|
||||
///
|
||||
/// This function is a convenience for interpreting string literals as parsers
|
||||
/// and is only necessary to avoid conflict with [str::parse]. See the documentation
|
||||
/// for the `&'static str` implementation of [Parser].
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{token, Parser};
|
||||
/// let parser = token("foo");
|
||||
/// assert_eq!(Ok(("", "foo")), parser.parse("foo"));
|
||||
/// assert_eq!(Err("bar"), parser.parse("bar"));
|
||||
/// ```
|
||||
pub fn token<'a>(literal: &'static str) -> impl Parser<'a, Output = &'a str> {
|
||||
literal
|
||||
}
|
||||
|
||||
/// A parser which matches the pattern described by the given regular expression.
|
||||
///
|
||||
/// The pattern must match from the beginning of the input as if the regular expression
|
||||
/// included the `^` anchor. Using a `^` anchor in the regular expression is
|
||||
/// recommended in order to reduce any work done by the regex on non-matching input.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{pattern, Parser};
|
||||
/// use regex::Regex;
|
||||
/// let regex = Regex::new(r"Hello, \w+!").unwrap();
|
||||
/// let parser = pattern(®ex);
|
||||
/// assert_eq!(Ok(("", "Hello, world!")), parser.parse("Hello, world!"));
|
||||
/// assert_eq!(Err("Hey, you!"), parser.parse("Hey, you!"));
|
||||
/// assert_eq!(Err("Oh Hello, world!"), parser.parse("Oh Hello, world!"));
|
||||
/// ```
|
||||
pub fn pattern<'a>(regex: &'a Regex) -> impl Parser<'a, Output = &'a str> {
|
||||
move |input: &'a str| match regex.find(input) {
|
||||
Some(match_) if match_.start() == 0 => {
|
||||
Ok((&input[match_.end()..], &input[0..match_.end()]))
|
||||
}
|
||||
_ => Err(input),
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser which matches all values until the specified pattern is found.
|
||||
///
|
||||
/// If the pattern is not found, this parser does not match. The input up to the
|
||||
/// character which returns `true` is returned but not that character itself.
|
||||
///
|
||||
/// If the pattern function returns true on the first input character, this
|
||||
/// parser fails.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{take_until, Parser};
|
||||
/// let parser = take_until(|c| c == '.');
|
||||
/// assert_eq!(Ok((".bar", "foo")), parser.parse("foo.bar"));
|
||||
/// assert_eq!(Err(".foo"), parser.parse(".foo"));
|
||||
/// assert_eq!(Err("foo"), parser.parse("foo"));
|
||||
/// ```
|
||||
pub fn take_until<'a, F>(pattern: F) -> impl Parser<'a, Output = &'a str>
|
||||
where
|
||||
F: Fn(char) -> bool,
|
||||
{
|
||||
move |input: &'a str| match input.find(&pattern) {
|
||||
Some(index) if index != 0 => Ok((&input[index..], &input[0..index])),
|
||||
_ => Err(input),
|
||||
}
|
||||
}
|
||||
|
||||
// Variadic parser combinators
|
||||
|
||||
/// A parser combinator which matches a sequence of parsers in an all-or-nothing fashion.
|
||||
///
|
||||
/// The returned value is a tuple containing the outputs of all parsers in order. Each
|
||||
/// parser in the sequence may be typed differently.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{seq, Parser};
|
||||
/// let parser = seq!("<", "a", ">");
|
||||
/// assert_eq!(Ok(("", ("<", "a", ">"))), parser.parse("<a>"));
|
||||
/// assert_eq!(Err("<b>"), parser.parse("<b>"));
|
||||
/// ```
|
||||
#[macro_export]
|
||||
macro_rules! seq {
|
||||
($($parsers: expr),+ $(,)?) => {
|
||||
($($parsers),+)
|
||||
}
|
||||
}
|
||||
|
||||
// Seq is implemented using trait-implementations of Parser for various size tuples.
|
||||
// This allows sequences to be typed heterogeneously.
|
||||
macro_rules! seq_impl {
|
||||
($($parser:ident),+) => {
|
||||
#[allow(non_snake_case)]
|
||||
impl<'a, $($parser),+> Parser<'a> for ($($parser),+)
|
||||
where
|
||||
$($parser: Parser<'a>),+
|
||||
{
|
||||
type Output = ($($parser::Output),+);
|
||||
|
||||
fn parse(&self, input: &'a str) -> ParseResult<'a, Self::Output> {
|
||||
let ($($parser),+) = self;
|
||||
seq_body_impl!(input, input, $($parser),+ ; )
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
macro_rules! seq_body_impl {
|
||||
($input:expr, $next_input:expr, $head:ident, $($tail:ident),+ ; $(,)? $($acc:ident),*) => {
|
||||
match $head.parse($next_input) {
|
||||
Ok((next_input, $head)) => seq_body_impl!($input, next_input, $($tail),+ ; $($acc),*, $head),
|
||||
Err(_) => Err($input),
|
||||
}
|
||||
};
|
||||
($input:expr, $next_input:expr, $last:ident ; $(,)? $($acc:ident),*) => {
|
||||
match $last.parse($next_input) {
|
||||
Ok((next_input, last)) => Ok((next_input, ($($acc),+, last))),
|
||||
Err(_) => Err($input),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
seq_impl!(A, B);
|
||||
seq_impl!(A, B, C);
|
||||
seq_impl!(A, B, C, D);
|
||||
seq_impl!(A, B, C, D, E);
|
||||
seq_impl!(A, B, C, D, E, F);
|
||||
seq_impl!(A, B, C, D, E, F, G);
|
||||
seq_impl!(A, B, C, D, E, F, G, H);
|
||||
seq_impl!(A, B, C, D, E, F, G, H, I);
|
||||
seq_impl!(A, B, C, D, E, F, G, H, I, J);
|
||||
|
||||
/// A parser combinator which chooses the first of the input parsers which matches
|
||||
/// successfully.
|
||||
///
|
||||
/// All input parsers must have the same output type. This is a variadic form for [or].
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{choice, or, Parser};
|
||||
/// let parser = choice!("foo", "bar", "baz");
|
||||
/// assert_eq!(Ok(("", "foo")), parser.parse("foo"));
|
||||
/// assert_eq!(Ok(("", "bar")), parser.parse("bar"));
|
||||
/// assert_eq!(Err("quiz"), parser.parse("quiz"));
|
||||
/// ```
|
||||
#[macro_export]
|
||||
macro_rules! choice {
|
||||
($parser: expr $(,)?) => {
|
||||
$parser
|
||||
};
|
||||
($parser: expr, $($rest: expr),+ $(,)?) => {
|
||||
or($parser, choice!($($rest),+))
|
||||
}
|
||||
}
|
||||
|
||||
// Ordinary parser combinators
|
||||
|
||||
/// A parser combinator which takes a parser as input and maps the output using the
|
||||
/// given transformation function.
|
||||
///
|
||||
/// This corresponds to [Result::map]. The value is only mapped if the input parser
|
||||
/// matches against input.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{map, Parser};
|
||||
/// let parser = map("123", |s| s.parse::<i32>().unwrap());
|
||||
/// assert_eq!(Ok(("", 123)), parser.parse("123"));
|
||||
/// assert_eq!(Err("abc"), parser.parse("abc"));
|
||||
/// ```
|
||||
pub fn map<'a, P, F, T>(parser: P, map_fn: F) -> impl Parser<'a, Output = T>
|
||||
where
|
||||
P: Parser<'a>,
|
||||
F: Fn(P::Output) -> T,
|
||||
{
|
||||
move |input| {
|
||||
parser
|
||||
.parse(input)
|
||||
.map(|(next_input, result)| (next_input, map_fn(result)))
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser combinator which succeeds if the given parser matches the input and
|
||||
/// the given `filter_map_fn` returns `Some`.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{filter_map, take_until, Parser};
|
||||
/// let parser = filter_map(take_until(|c| c == '.'), |s| s.parse::<i32>().ok());
|
||||
/// assert_eq!(Ok((".456", 123)), parser.parse("123.456"));
|
||||
/// assert_eq!(Err("abc.def"), parser.parse("abc.def"));
|
||||
/// ```
|
||||
pub fn filter_map<'a, P, F, T>(parser: P, filter_map_fn: F) -> impl Parser<'a, Output = T>
|
||||
where
|
||||
P: Parser<'a>,
|
||||
F: Fn(P::Output) -> Option<T>,
|
||||
{
|
||||
move |input| match parser.parse(input) {
|
||||
Ok((next_input, value)) => match filter_map_fn(value) {
|
||||
Some(value) => Ok((next_input, value)),
|
||||
None => Err(input),
|
||||
},
|
||||
Err(_) => Err(input),
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser combinator which succeeds if the first given parser matches the input and
|
||||
/// the second given parse also matches.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{reparse_as, take_until, one_or_more, Parser};
|
||||
/// let parser = reparse_as(take_until(|c| c == '/'), one_or_more("a"));
|
||||
/// assert_eq!(Ok(("/bb", vec!["a", "a"])), parser.parse("aa/bb"));
|
||||
/// ```
|
||||
pub fn reparse_as<'a, P1, P2, T>(parser1: P1, parser2: P2) -> impl Parser<'a, Output = T>
|
||||
where
|
||||
P1: Parser<'a, Output = &'a str>,
|
||||
P2: Parser<'a, Output = T>,
|
||||
{
|
||||
filter_map(parser1, move |str| {
|
||||
parser2.parse(str).map(|(_, value)| value).ok()
|
||||
})
|
||||
}
|
||||
|
||||
/// A parser combinator which only matches the input when the predicate function
|
||||
/// returns true.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{filter, take_until, Parser};
|
||||
/// let parser = filter(take_until(|c| c == '.'), |s| s == &"123");
|
||||
/// assert_eq!(Ok((".456", "123")), parser.parse("123.456"));
|
||||
/// assert_eq!(Err("456.123"), parser.parse("456.123"));
|
||||
/// ```
|
||||
pub fn filter<'a, P, F, T>(parser: P, pred_fn: F) -> impl Parser<'a, Output = T>
|
||||
where
|
||||
P: Parser<'a, Output = T>,
|
||||
F: Fn(&P::Output) -> bool,
|
||||
{
|
||||
move |input| {
|
||||
if let Ok((next_input, value)) = parser.parse(input) {
|
||||
if pred_fn(&value) {
|
||||
return Ok((next_input, value));
|
||||
}
|
||||
}
|
||||
Err(input)
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser combinator which matches either of the input parsers.
|
||||
///
|
||||
/// Both parsers must have the same output type. For a variadic form which
|
||||
/// can take any number of parsers, use `choice!`.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{or, Parser};
|
||||
/// let parser = or("foo", "bar");
|
||||
/// assert_eq!(Ok(("", "foo")), parser.parse("foo"));
|
||||
/// assert_eq!(Ok(("", "bar")), parser.parse("bar"));
|
||||
/// assert_eq!(Err("baz"), parser.parse("baz"));
|
||||
/// ```
|
||||
pub fn or<'a, P1, P2, T>(parser1: P1, parser2: P2) -> impl Parser<'a, Output = T>
|
||||
where
|
||||
P1: Parser<'a, Output = T>,
|
||||
P2: Parser<'a, Output = T>,
|
||||
{
|
||||
move |input| match parser1.parse(input) {
|
||||
ok @ Ok(_) => ok,
|
||||
Err(_) => parser2.parse(input),
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser combinator which attempts to match the given parser, returning a
|
||||
/// `None` output value if the parser does not match.
|
||||
///
|
||||
/// The parser produced with this combinator always succeeds. If the given parser
|
||||
/// succeeds, `Some(value)` is returned where `value` is the output of the given
|
||||
/// parser. Otherwise, `None`.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{optional, Parser};
|
||||
/// let parser = optional("foo");
|
||||
/// assert_eq!(Ok(("bar", Some("foo"))), parser.parse("foobar"));
|
||||
/// assert_eq!(Ok(("bar", None)), parser.parse("bar"));
|
||||
/// ```
|
||||
pub fn optional<'a, P, T>(parser: P) -> impl Parser<'a, Output = Option<T>>
|
||||
where
|
||||
P: Parser<'a, Output = T>,
|
||||
{
|
||||
move |input| match parser.parse(input) {
|
||||
Ok((next_input, value)) => Ok((next_input, Some(value))),
|
||||
Err(_) => Ok((input, None)),
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser combinator which runs the given parsers in sequence and returns the
|
||||
/// value of `left` if both are matched.
|
||||
///
|
||||
/// This is useful for two-element sequences in which you only want the output
|
||||
/// value of the `left` parser.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{left, Parser};
|
||||
/// let parser = left("foo", "bar");
|
||||
/// assert_eq!(Ok(("", "foo")), parser.parse("foobar"));
|
||||
/// ```
|
||||
pub fn left<'a, L, R, T>(left: L, right: R) -> impl Parser<'a, Output = T>
|
||||
where
|
||||
L: Parser<'a, Output = T>,
|
||||
R: Parser<'a>,
|
||||
{
|
||||
map(seq!(left, right), |(left_value, _)| left_value)
|
||||
}
|
||||
|
||||
/// A parser combinator which runs the given parsers in sequence and returns the
|
||||
/// value of `right` if both are matched.
|
||||
///
|
||||
/// This is useful for two-element sequences in which you only want the output
|
||||
/// value of the `right` parser.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{right, Parser};
|
||||
/// let parser = right("foo", "bar");
|
||||
/// assert_eq!(Ok(("", "bar")), parser.parse("foobar"));
|
||||
/// ```
|
||||
pub fn right<'a, L, R, T>(left: L, right: R) -> impl Parser<'a, Output = T>
|
||||
where
|
||||
L: Parser<'a>,
|
||||
R: Parser<'a, Output = T>,
|
||||
{
|
||||
map(seq!(left, right), |(_, right_value)| right_value)
|
||||
}
|
||||
|
||||
/// A parser combinator which matches the given parser against the input zero or
|
||||
/// more times.
|
||||
///
|
||||
/// This parser always succeeds and returns the empty Vec when it matched zero
|
||||
/// times.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{zero_or_more, Parser};
|
||||
/// let parser = zero_or_more("a");
|
||||
/// assert_eq!(Ok(("", vec![])), parser.parse(""));
|
||||
/// assert_eq!(Ok(("", vec!["a"])), parser.parse("a"));
|
||||
/// assert_eq!(Ok(("", vec!["a", "a"])), parser.parse("aa"));
|
||||
/// assert_eq!(Ok(("bb", vec![])), parser.parse("bb"));
|
||||
/// ```
|
||||
pub fn zero_or_more<'a, P, T>(parser: P) -> impl Parser<'a, Output = Vec<T>>
|
||||
where
|
||||
P: Parser<'a, Output = T>,
|
||||
{
|
||||
move |mut input| {
|
||||
let mut values = Vec::new();
|
||||
|
||||
while let Ok((next_input, value)) = parser.parse(input) {
|
||||
input = next_input;
|
||||
values.push(value);
|
||||
}
|
||||
|
||||
Ok((input, values))
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser combinator which matches the given parser against the input one or
|
||||
/// more times.
|
||||
///
|
||||
/// This parser combinator acts the same as [zero_or_more] but must match at
|
||||
/// least once.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use helix_parsec::{one_or_more, Parser};
|
||||
/// let parser = one_or_more("a");
|
||||
/// assert_eq!(Err(""), parser.parse(""));
|
||||
/// assert_eq!(Ok(("", vec!["a"])), parser.parse("a"));
|
||||
/// assert_eq!(Ok(("", vec!["a", "a"])), parser.parse("aa"));
|
||||
/// assert_eq!(Err("bb"), parser.parse("bb"));
|
||||
/// ```
|
||||
pub fn one_or_more<'a, P, T>(parser: P) -> impl Parser<'a, Output = Vec<T>>
|
||||
where
|
||||
P: Parser<'a, Output = T>,
|
||||
{
|
||||
move |mut input| {
|
||||
let mut values = Vec::new();
|
||||
|
||||
match parser.parse(input) {
|
||||
Ok((next_input, value)) => {
|
||||
input = next_input;
|
||||
values.push(value);
|
||||
}
|
||||
Err(err) => return Err(err),
|
||||
}
|
||||
|
||||
while let Ok((next_input, value)) = parser.parse(input) {
|
||||
input = next_input;
|
||||
values.push(value);
|
||||
}
|
||||
|
||||
Ok((input, values))
|
||||
}
|
||||
}
|
||||
|
||||
/// A parser combinator which matches one or more instances of the given parser
|
||||
/// interspersed with the separator parser.
|
||||
///
|
||||
/// Output values of the separator parser are discarded.
|
||||
///
|
||||
/// This is typically used to parse function arguments or list items.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```rust
|
||||
/// use helix_parsec::{sep, Parser};
|
||||
/// let parser = sep("a", ",");
|
||||
/// assert_eq!(Ok(("", vec!["a", "a", "a"])), parser.parse("a,a,a"));
|
||||
/// ```
|
||||
pub fn sep<'a, P, S, T>(parser: P, separator: S) -> impl Parser<'a, Output = Vec<T>>
|
||||
where
|
||||
P: Parser<'a, Output = T>,
|
||||
S: Parser<'a>,
|
||||
{
|
||||
move |mut input| {
|
||||
let mut values = Vec::new();
|
||||
|
||||
match parser.parse(input) {
|
||||
Ok((next_input, value)) => {
|
||||
input = next_input;
|
||||
values.push(value);
|
||||
}
|
||||
Err(err) => return Err(err),
|
||||
}
|
||||
|
||||
loop {
|
||||
match separator.parse(input) {
|
||||
Ok((next_input, _)) => input = next_input,
|
||||
Err(_) => break,
|
||||
}
|
||||
|
||||
match parser.parse(input) {
|
||||
Ok((next_input, value)) => {
|
||||
input = next_input;
|
||||
values.push(value);
|
||||
}
|
||||
Err(_) => break,
|
||||
}
|
||||
}
|
||||
|
||||
Ok((input, values))
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue