feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
swaitsandClaude Opus 4.6 committed 2026-03-29 20:42:54 -06:00
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use crate::combinator::trace;
use crate::error::ParserError;
use crate::stream::Stream;
use crate::*;
#[doc(inline)]
pub use crate::dispatch;
/// Helper trait for the [`alt()`] combinator.
///
/// This trait is implemented for tuples of up to 21 elements
pub trait Alt<I, O, E> {
/// Tests each parser in the tuple and returns the result of the first one that succeeds
fn choice(&mut self, input: &mut I) -> Result<O, E>;
}
/// Pick the first successful parser
///
/// To stop on an error, rather than trying further cases, see
/// [`cut_err`][crate::combinator::cut_err] ([example][crate::_tutorial::chapter_7]).
///
/// For tight control over the error when no match is found, add a final case using [`fail`][crate::combinator::fail].
/// Alternatively, with a [custom error type][crate::_topic::error], it is possible to track all
/// errors or return the error of the parser that went the farthest in the input data.
///
/// When the alternative cases have unique prefixes, [`dispatch`] can offer better performance.
///
/// # Example
///
/// ```rust
/// # use winnow::{error::ErrMode, error::Needed};
/// # use winnow::prelude::*;
/// use winnow::ascii::{alpha1, digit1};
/// use winnow::combinator::alt;
/// # fn main() {
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<&'i str> {
/// alt((alpha1, digit1)).parse_next(input)
/// };
///
/// // the first parser, alpha1, takes the input
/// assert_eq!(parser.parse_peek("abc"), Ok(("", "abc")));
///
/// // the first parser returns an error, so alt tries the second one
/// assert_eq!(parser.parse_peek("123456"), Ok(("", "123456")));
///
/// // both parsers failed, and with the default error type, alt will return the last error
/// assert!(parser.parse_peek(" ").is_err());
/// # }
/// ```
#[doc(alias = "choice")]
#[inline(always)]
pub fn alt<Input: Stream, Output, Error, Alternatives>(
mut alternatives: Alternatives,
) -> impl Parser<Input, Output, Error>
where
Alternatives: Alt<Input, Output, Error>,
Error: ParserError<Input>,
{
trace("alt", move |i: &mut Input| alternatives.choice(i))
}
/// Helper trait for the [`permutation()`] combinator.
///
/// This trait is implemented for tuples of up to 21 elements
pub trait Permutation<I, O, E> {
/// Tries to apply all parsers in the tuple in various orders until all of them succeed
fn permutation(&mut self, input: &mut I) -> Result<O, E>;
}
/// Deprecated, replaced with [`unordered_seq!`][crate::combinator::unordered_seq].
#[deprecated(since = "0.7.14", note = "replaced with `unordered_seq!`")]
#[inline(always)]
pub fn permutation<I: Stream, O, E: ParserError<I>, List: Permutation<I, O, E>>(
mut l: List,
) -> impl Parser<I, O, E> {
trace("permutation", move |i: &mut I| l.permutation(i))
}
impl<const N: usize, I: Stream, O, E: ParserError<I>, P: Parser<I, O, E>> Alt<I, O, E> for [P; N] {
fn choice(&mut self, input: &mut I) -> Result<O, E> {
let mut error: Option<E> = None;
let start = input.checkpoint();
for branch in self {
input.reset(&start);
match branch.parse_next(input) {
Err(e) if e.is_backtrack() => {
error = match error {
Some(error) => Some(error.or(e)),
None => Some(e),
};
}
res => return res,
}
}
match error {
Some(e) => Err(e.append(input, &start)),
None => Err(ParserError::assert(
input,
"`alt` needs at least one parser",
)),
}
}
}
impl<I: Stream, O, E: ParserError<I>, P: Parser<I, O, E>> Alt<I, O, E> for &mut [P] {
fn choice(&mut self, input: &mut I) -> Result<O, E> {
let mut error: Option<E> = None;
let start = input.checkpoint();
for branch in self.iter_mut() {
input.reset(&start);
match branch.parse_next(input) {
Err(e) if e.is_backtrack() => {
error = match error {
Some(error) => Some(error.or(e)),
None => Some(e),
};
}
res => return res,
}
}
match error {
Some(e) => Err(e.append(input, &start)),
None => Err(ParserError::assert(
input,
"`alt` needs at least one parser",
)),
}
}
}
macro_rules! alt_trait(
($first:ident $second:ident $($id: ident)+) => (
alt_trait!(__impl $first $second; $($id)+);
);
(__impl $($current:ident)*; $head:ident $($id: ident)+) => (
alt_trait_impl!($($current)*);
alt_trait!(__impl $($current)* $head; $($id)+);
);
(__impl $($current:ident)*; $head:ident) => (
alt_trait_impl!($($current)*);
alt_trait_impl!($($current)* $head);
);
);
macro_rules! alt_trait_impl(
($($id:ident)+) => (
impl<
I: Stream, Output, Error: ParserError<I>,
$($id: Parser<I, Output, Error>),+
> Alt<I, Output, Error> for ( $($id),+ ) {
fn choice(&mut self, input: &mut I) -> Result<Output, Error> {
let start = input.checkpoint();
match self.0.parse_next(input) {
Err(e) if e.is_backtrack() => alt_trait_inner!(1, self, input, start, e, $($id)+),
res => res,
}
}
}
);
);
macro_rules! succ (
(0, $submac:ident ! ($($rest:tt)*)) => ($submac!(1, $($rest)*));
(1, $submac:ident ! ($($rest:tt)*)) => ($submac!(2, $($rest)*));
(2, $submac:ident ! ($($rest:tt)*)) => ($submac!(3, $($rest)*));
(3, $submac:ident ! ($($rest:tt)*)) => ($submac!(4, $($rest)*));
(4, $submac:ident ! ($($rest:tt)*)) => ($submac!(5, $($rest)*));
(5, $submac:ident ! ($($rest:tt)*)) => ($submac!(6, $($rest)*));
(6, $submac:ident ! ($($rest:tt)*)) => ($submac!(7, $($rest)*));
(7, $submac:ident ! ($($rest:tt)*)) => ($submac!(8, $($rest)*));
(8, $submac:ident ! ($($rest:tt)*)) => ($submac!(9, $($rest)*));
(9, $submac:ident ! ($($rest:tt)*)) => ($submac!(10, $($rest)*));
(10, $submac:ident ! ($($rest:tt)*)) => ($submac!(11, $($rest)*));
(11, $submac:ident ! ($($rest:tt)*)) => ($submac!(12, $($rest)*));
(12, $submac:ident ! ($($rest:tt)*)) => ($submac!(13, $($rest)*));
(13, $submac:ident ! ($($rest:tt)*)) => ($submac!(14, $($rest)*));
(14, $submac:ident ! ($($rest:tt)*)) => ($submac!(15, $($rest)*));
(15, $submac:ident ! ($($rest:tt)*)) => ($submac!(16, $($rest)*));
(16, $submac:ident ! ($($rest:tt)*)) => ($submac!(17, $($rest)*));
(17, $submac:ident ! ($($rest:tt)*)) => ($submac!(18, $($rest)*));
(18, $submac:ident ! ($($rest:tt)*)) => ($submac!(19, $($rest)*));
(19, $submac:ident ! ($($rest:tt)*)) => ($submac!(20, $($rest)*));
(20, $submac:ident ! ($($rest:tt)*)) => ($submac!(21, $($rest)*));
);
macro_rules! alt_trait_inner(
($it:tt, $self:expr, $input:expr, $start:ident, $err:expr, $head:ident $($id:ident)+) => ({
$input.reset(&$start);
match $self.$it.parse_next($input) {
Err(e) if e.is_backtrack() => {
let err = $err.or(e);
succ!($it, alt_trait_inner!($self, $input, $start, err, $($id)+))
}
res => res,
}
});
($it:tt, $self:expr, $input:expr, $start:ident, $err:expr, $head:ident) => ({
Err($err.append($input, &$start))
});
);
alt_trait!(Alt2 Alt3 Alt4 Alt5 Alt6 Alt7 Alt8 Alt9 Alt10 Alt11 Alt12 Alt13 Alt14 Alt15 Alt16 Alt17 Alt18 Alt19 Alt20 Alt21 Alt22);
// Manually implement Alt for (A,), the 1-tuple type
impl<I: Stream, O, E: ParserError<I>, A: Parser<I, O, E>> Alt<I, O, E> for (A,) {
fn choice(&mut self, input: &mut I) -> Result<O, E> {
self.0.parse_next(input)
}
}
macro_rules! permutation_trait(
(
$name1:ident $ty1:ident $item1:ident
$name2:ident $ty2:ident $item2:ident
$($name3:ident $ty3:ident $item3:ident)*
) => (
permutation_trait!(__impl $name1 $ty1 $item1, $name2 $ty2 $item2; $($name3 $ty3 $item3)*);
);
(
__impl $($name:ident $ty:ident $item:ident),+;
$name1:ident $ty1:ident $item1:ident $($name2:ident $ty2:ident $item2:ident)*
) => (
permutation_trait_impl!($($name $ty $item),+);
permutation_trait!(__impl $($name $ty $item),+ , $name1 $ty1 $item1; $($name2 $ty2 $item2)*);
);
(__impl $($name:ident $ty:ident $item:ident),+;) => (
permutation_trait_impl!($($name $ty $item),+);
);
);
macro_rules! permutation_trait_impl(
($($name:ident $ty:ident $item:ident),+) => (
impl<
I: Stream, $($ty),+ , Error: ParserError<I>,
$($name: Parser<I, $ty, Error>),+
> Permutation<I, ( $($ty),+ ), Error> for ( $($name),+ ) {
fn permutation(&mut self, input: &mut I) -> Result<( $($ty),+ ), Error> {
let mut res = ($(Option::<$ty>::None),+);
loop {
let mut err: Option<Error> = None;
let start = input.checkpoint();
permutation_trait_inner!(0, self, input, start, res, err, $($name)+);
// If we reach here, every iterator has either been applied before,
// or errored on the remaining input
if let Some(err) = err {
// There are remaining parsers, and all errored on the remaining input
input.reset(&start);
return Err(err.append(input, &start));
}
// All parsers were applied
match res {
($(Some($item)),+) => return Ok(($($item),+)),
_ => unreachable!(),
}
}
}
}
);
);
macro_rules! permutation_trait_inner(
($it:tt, $self:expr, $input:ident, $start:ident, $res:expr, $err:expr, $head:ident $($id:ident)*) => (
if $res.$it.is_none() {
$input.reset(&$start);
match $self.$it.parse_next($input) {
Ok(o) => {
$res.$it = Some(o);
continue;
}
Err(e) if e.is_backtrack() => {
$err = Some(match $err {
Some(err) => err.or(e),
None => e,
});
}
Err(e) => return Err(e),
};
}
succ!($it, permutation_trait_inner!($self, $input, $start, $res, $err, $($id)*));
);
($it:tt, $self:expr, $input:ident, $start:ident, $res:expr, $err:expr,) => ();
);
permutation_trait!(
P1 O1 o1
P2 O2 o2
P3 O3 o3
P4 O4 o4
P5 O5 o5
P6 O6 o6
P7 O7 o7
P8 O8 o8
P9 O9 o9
P10 O10 o10
P11 O11 o11
P12 O12 o12
P13 O13 o13
P14 O14 o14
P15 O15 o15
P16 O16 o16
P17 O17 o17
P18 O18 o18
P19 O19 o19
P20 O20 o20
P21 O21 o21
);
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use crate::combinator::trace;
use crate::error::{ModalError, ParserError};
use crate::stream::Stream;
use crate::*;
/// Apply a [`Parser`], producing `None` on [`ErrMode::Backtrack`][crate::error::ErrMode::Backtrack].
///
/// To chain an error up, see [`cut_err`].
///
/// # Example
///
/// ```rust
/// # use winnow::prelude::*;
/// use winnow::combinator::opt;
/// use winnow::ascii::alpha1;
/// # fn main() {
///
/// fn parser<'i>(i: &mut &'i str) -> ModalResult<Option<&'i str>> {
/// opt(alpha1).parse_next(i)
/// }
///
/// assert_eq!(parser.parse_peek("abcd;"), Ok((";", Some("abcd"))));
/// assert_eq!(parser.parse_peek("123;"), Ok(("123;", None)));
/// # }
/// ```
pub fn opt<Input: Stream, Output, Error, ParseNext>(
mut parser: ParseNext,
) -> impl Parser<Input, Option<Output>, Error>
where
ParseNext: Parser<Input, Output, Error>,
Error: ParserError<Input>,
{
trace("opt", move |input: &mut Input| {
let start = input.checkpoint();
match parser.parse_next(input) {
Ok(o) => Ok(Some(o)),
Err(e) if e.is_backtrack() => {
input.reset(&start);
Ok(None)
}
Err(e) => Err(e),
}
})
}
/// Calls the parser if the condition is met.
///
/// # Example
///
/// ```rust
/// # use winnow::prelude::*;
/// # use winnow::combinator::opt;
/// use winnow::combinator::cond;
/// use winnow::ascii::alpha1;
/// # fn main() {
///
/// fn parser<'i>(i: &mut &'i str) -> ModalResult<Option<&'i str>> {
/// let prefix = opt("-").parse_next(i)?;
/// let condition = prefix.is_some();
/// cond(condition, alpha1).parse_next(i)
/// }
///
/// assert_eq!(parser.parse_peek("-abcd;"), Ok((";", Some("abcd"))));
/// assert_eq!(parser.parse_peek("abcd;"), Ok(("abcd;", None)));
/// assert!(parser.parse_peek("-123;").is_err());
/// assert_eq!(parser.parse_peek("123;"), Ok(("123;", None)));
/// # }
/// ```
pub fn cond<Input, Output, Error, ParseNext>(
cond: bool,
mut parser: ParseNext,
) -> impl Parser<Input, Option<Output>, Error>
where
Input: Stream,
ParseNext: Parser<Input, Output, Error>,
Error: ParserError<Input>,
{
trace("cond", move |input: &mut Input| {
if cond {
parser.parse_next(input).map(Some)
} else {
Ok(None)
}
})
}
/// Apply the parser without advancing the input.
///
/// To lookahead and only advance on success, see [`opt`].
///
/// # Example
///
/// ```rust
/// # use winnow::prelude::*;
/// use winnow::combinator::peek;
/// use winnow::ascii::alpha1;
/// # fn main() {
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<&'i str> {
/// peek(alpha1).parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("abcd;"), Ok(("abcd;", "abcd")));
/// assert!(parser.parse_peek("123;").is_err());
/// # }
/// ```
#[doc(alias = "look_ahead")]
#[doc(alias = "rewind")]
pub fn peek<Input, Output, Error, ParseNext>(
mut parser: ParseNext,
) -> impl Parser<Input, Output, Error>
where
Input: Stream,
Error: ParserError<Input>,
ParseNext: Parser<Input, Output, Error>,
{
trace("peek", move |input: &mut Input| {
let start = input.checkpoint();
let res = parser.parse_next(input);
input.reset(&start);
res
})
}
/// Match the end of the [`Stream`]
///
/// Otherwise, it will error.
///
/// # Effective Signature
///
/// Assuming you are parsing a `&str` [Stream]:
/// ```rust
/// # use winnow::prelude::*;;
/// pub fn eof<'i>(input: &mut &'i str) -> ModalResult<&'i str>
/// # {
/// # winnow::combinator::eof.parse_next(input)
/// # }
/// ```
///
/// # Example
///
/// ```rust
/// # use std::str;
/// # use winnow::combinator::eof;
/// # use winnow::prelude::*;
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<&'i str> {
/// eof.parse_next(input)
/// }
/// assert!(parser.parse_peek("abc").is_err());
/// assert_eq!(parser.parse_peek(""), Ok(("", "")));
/// ```
#[doc(alias = "end")]
#[doc(alias = "eoi")]
pub fn eof<Input, Error>(input: &mut Input) -> Result<<Input as Stream>::Slice, Error>
where
Input: Stream,
Error: ParserError<Input>,
{
trace("eof", move |input: &mut Input| {
if input.eof_offset() == 0 {
Ok(input.next_slice(0))
} else {
Err(ParserError::from_input(input))
}
})
.parse_next(input)
}
/// Succeeds if the child parser returns an error.
///
/// <div class="warning">
///
/// **Note:** This does not advance the [`Stream`]
///
/// </div>
///
/// # Example
///
/// ```rust
/// # use winnow::prelude::*;
/// use winnow::combinator::not;
/// use winnow::ascii::alpha1;
/// # fn main() {
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<()> {
/// not(alpha1).parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("123"), Ok(("123", ())));
/// assert!(parser.parse_peek("abcd").is_err());
/// # }
/// ```
pub fn not<Input, Output, Error, ParseNext>(mut parser: ParseNext) -> impl Parser<Input, (), Error>
where
Input: Stream,
Error: ParserError<Input>,
ParseNext: Parser<Input, Output, Error>,
{
trace("not", move |input: &mut Input| {
let start = input.checkpoint();
let res = parser.parse_next(input);
input.reset(&start);
match res {
Ok(_) => Err(ParserError::from_input(input)),
Err(e) if e.is_backtrack() => Ok(()),
Err(e) => Err(e),
}
})
}
/// Transforms an [`ErrMode::Backtrack`][crate::error::ErrMode::Backtrack] (recoverable) to [`ErrMode::Cut`][crate::error::ErrMode::Cut] (unrecoverable)
///
/// This commits the parse result, preventing alternative branch paths like with
/// [`winnow::combinator::alt`][crate::combinator::alt].
///
/// See the [tutorial][crate::_tutorial::chapter_7] for more details.
///
/// # Example
///
/// Without `cut_err`:
/// ```rust
/// # use winnow::token::one_of;
/// # use winnow::token::rest;
/// # use winnow::ascii::digit1;
/// # use winnow::combinator::alt;
/// # use winnow::combinator::preceded;
/// # use winnow::prelude::*;
/// # fn main() {
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<&'i str> {
/// alt((
/// preceded(one_of(['+', '-']), digit1),
/// rest
/// )).parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("+10 ab"), Ok((" ab", "10")));
/// assert_eq!(parser.parse_peek("ab"), Ok(("", "ab")));
/// assert_eq!(parser.parse_peek("+"), Ok(("", "+")));
/// # }
/// ```
///
/// With `cut_err`:
/// ```rust
/// # use winnow::{error::ErrMode, error::ContextError};
/// # use winnow::prelude::*;
/// # use winnow::token::one_of;
/// # use winnow::token::rest;
/// # use winnow::ascii::digit1;
/// # use winnow::combinator::alt;
/// # use winnow::combinator::preceded;
/// use winnow::combinator::cut_err;
/// # fn main() {
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<&'i str> {
/// alt((
/// preceded(one_of(['+', '-']), cut_err(digit1)),
/// rest
/// )).parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("+10 ab"), Ok((" ab", "10")));
/// assert_eq!(parser.parse_peek("ab"), Ok(("", "ab")));
/// assert_eq!(parser.parse_peek("+"), Err(ErrMode::Cut(ContextError::new())));
/// # }
/// ```
pub fn cut_err<Input, Output, Error, ParseNext>(
mut parser: ParseNext,
) -> impl Parser<Input, Output, Error>
where
Input: Stream,
Error: ParserError<Input> + ModalError,
ParseNext: Parser<Input, Output, Error>,
{
trace("cut_err", move |input: &mut Input| {
parser.parse_next(input).map_err(|e| e.cut())
})
}
/// Transforms an [`ErrMode::Cut`][crate::error::ErrMode::Cut] (unrecoverable) to [`ErrMode::Backtrack`][crate::error::ErrMode::Backtrack] (recoverable)
///
/// This attempts the parse, allowing other parsers to be tried on failure, like with
/// [`winnow::combinator::alt`][crate::combinator::alt].
pub fn backtrack_err<Input, Output, Error, ParseNext>(
mut parser: ParseNext,
) -> impl Parser<Input, Output, Error>
where
Input: Stream,
Error: ParserError<Input> + ModalError,
ParseNext: Parser<Input, Output, Error>,
{
trace("backtrack_err", move |input: &mut Input| {
parser.parse_next(input).map_err(|e| e.backtrack())
})
}
/// A placeholder for a not-yet-implemented [`Parser`]
///
/// This is analogous to the [`todo!`] macro and helps with prototyping.
///
/// # Panic
///
/// This will panic when parsing
///
/// # Example
///
/// ```rust
/// # use winnow::prelude::*;
/// # use winnow::combinator::todo;
///
/// fn parser(input: &mut &str) -> ModalResult<u64> {
/// todo(input)
/// }
/// ```
#[track_caller]
pub fn todo<Input, Output, Error>(input: &mut Input) -> Result<Output, Error>
where
Input: Stream,
Error: ParserError<Input>,
{
#![allow(clippy::todo)]
trace("todo", move |_input: &mut Input| {
todo!("unimplemented parse")
})
.parse_next(input)
}
/// Repeats the embedded parser, lazily returning the results
///
/// Call the iterator's [`ParserIterator::finish`] method to get the remaining input if successful,
/// or the error value if we encountered an error.
///
/// On [`ErrMode::Backtrack`][crate::error::ErrMode::Backtrack], iteration will stop. To instead chain an error up, see [`cut_err`].
///
/// # Example
///
/// ```rust
/// # use winnow::prelude::*;
/// use winnow::{combinator::iterator, ascii::alpha1, combinator::terminated};
/// use std::collections::HashMap;
///
/// let data = "abc|defg|hijkl|mnopqr|123";
/// let mut it = iterator(data, terminated(alpha1, "|"));
///
/// let parsed = it.map(|v| (v, v.len())).collect::<HashMap<_,_>>();
/// let res: ModalResult<_> = it.finish();
///
/// assert_eq!(parsed, [("abc", 3usize), ("defg", 4), ("hijkl", 5), ("mnopqr", 6)].iter().cloned().collect());
/// assert_eq!(res, Ok(("123", ())));
/// ```
pub fn iterator<Input, Output, Error, ParseNext>(
input: Input,
parser: ParseNext,
) -> ParserIterator<ParseNext, Input, Output, Error>
where
ParseNext: Parser<Input, Output, Error>,
Input: Stream,
Error: ParserError<Input>,
{
ParserIterator {
parser,
input,
state: State::Running,
o: Default::default(),
}
}
/// Main structure associated to [`iterator`].
pub struct ParserIterator<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream,
{
parser: F,
input: I,
state: State<E>,
o: core::marker::PhantomData<O>,
}
impl<F, I, O, E> ParserIterator<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream,
E: ParserError<I>,
{
/// Returns the remaining input if parsing was successful, or the error if we encountered an error.
pub fn finish(self) -> Result<(I, ()), E> {
match self.state {
State::Running | State::Done => Ok((self.input, ())),
State::Cut(e) => Err(e),
}
}
}
impl<F, I, O, E> core::iter::Iterator for &mut ParserIterator<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream,
E: ParserError<I>,
{
type Item = O;
fn next(&mut self) -> Option<Self::Item> {
if matches!(self.state, State::Running) {
let start = self.input.checkpoint();
match self.parser.parse_next(&mut self.input) {
Ok(o) => {
self.state = State::Running;
Some(o)
}
Err(e) if e.is_backtrack() => {
self.input.reset(&start);
self.state = State::Done;
None
}
Err(e) => {
self.state = State::Cut(e);
None
}
}
} else {
None
}
}
}
enum State<E> {
Running,
Done,
Cut(E),
}
/// Succeed, consuming no input
///
/// For example, it can be used as the last alternative in `alt` to
/// specify the default case.
///
/// Useful with:
/// - [`Parser::value`]
/// - [`Parser::default_value`]
/// - [`Parser::map`]
///
/// <div class="warning">
///
/// **Note:** This never advances the [`Stream`]
///
/// </div>
///
/// # Example
///
/// ```rust
/// # use winnow::prelude::*;
/// use winnow::combinator::alt;
/// use winnow::combinator::empty;
///
/// fn sign(input: &mut &str) -> ModalResult<isize> {
/// alt((
/// '-'.value(-1),
/// '+'.value(1),
/// empty.value(1)
/// )).parse_next(input)
/// }
/// assert_eq!(sign.parse_peek("+10"), Ok(("10", 1)));
/// assert_eq!(sign.parse_peek("-10"), Ok(("10", -1)));
/// assert_eq!(sign.parse_peek("10"), Ok(("10", 1)));
/// ```
#[doc(alias = "value")]
#[doc(alias = "success")]
#[inline]
pub fn empty<Input, Error>(_input: &mut Input) -> Result<(), Error>
where
Input: Stream,
Error: ParserError<Input>,
{
Ok(())
}
/// A parser which always fails.
///
/// For example, it can be used as the last alternative in `alt` to
/// control the error message given.
///
/// # Example
///
/// ```rust
/// # use winnow::{error::ErrMode, error::InputError};
/// # use winnow::prelude::*;
/// use winnow::combinator::fail;
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<(), InputError<&'i str>> {
/// fail.parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("string"), Err(ErrMode::Backtrack(InputError::at("string"))));
/// ```
#[doc(alias = "unexpected")]
#[inline]
pub fn fail<Input, Output, Error>(i: &mut Input) -> Result<Output, Error>
where
Input: Stream,
Error: ParserError<Input>,
{
trace("fail", |i: &mut Input| Err(ParserError::from_input(i))).parse_next(i)
}
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#![cfg(feature = "std")]
use std::io::Write;
use crate::error::ParserError;
use crate::stream::Stream;
use crate::*;
pub(crate) struct Trace<P, D, I, O, E>
where
P: Parser<I, O, E>,
I: Stream,
D: std::fmt::Display,
E: ParserError<I>,
{
parser: P,
name: D,
call_count: usize,
i: core::marker::PhantomData<I>,
o: core::marker::PhantomData<O>,
e: core::marker::PhantomData<E>,
}
impl<P, D, I, O, E> Trace<P, D, I, O, E>
where
P: Parser<I, O, E>,
I: Stream,
D: std::fmt::Display,
E: ParserError<I>,
{
#[inline(always)]
pub(crate) fn new(parser: P, name: D) -> Self {
Self {
parser,
name,
call_count: 0,
i: Default::default(),
o: Default::default(),
e: Default::default(),
}
}
}
impl<P, D, I, O, E> Parser<I, O, E> for Trace<P, D, I, O, E>
where
P: Parser<I, O, E>,
I: Stream,
D: std::fmt::Display,
E: ParserError<I>,
{
#[inline]
fn parse_next(&mut self, i: &mut I) -> Result<O, E> {
let depth = Depth::new();
let original = i.checkpoint();
start(*depth, &self.name, self.call_count, i);
let res = self.parser.parse_next(i);
let consumed = i.offset_from(&original);
let severity = Severity::with_result(&res);
end(*depth, &self.name, self.call_count, consumed, severity);
self.call_count += 1;
res
}
}
pub(crate) struct Depth {
depth: usize,
inc: bool,
}
impl Depth {
pub(crate) fn new() -> Self {
let depth = DEPTH.fetch_add(1, std::sync::atomic::Ordering::SeqCst);
let inc = true;
Self { depth, inc }
}
pub(crate) fn existing() -> Self {
let depth = DEPTH.load(std::sync::atomic::Ordering::SeqCst);
let inc = false;
Self { depth, inc }
}
}
impl Drop for Depth {
fn drop(&mut self) {
if self.inc {
let _ = DEPTH.fetch_sub(1, std::sync::atomic::Ordering::SeqCst);
}
}
}
impl AsRef<usize> for Depth {
#[inline(always)]
fn as_ref(&self) -> &usize {
&self.depth
}
}
impl core::ops::Deref for Depth {
type Target = usize;
#[inline(always)]
fn deref(&self) -> &Self::Target {
&self.depth
}
}
static DEPTH: std::sync::atomic::AtomicUsize = std::sync::atomic::AtomicUsize::new(0);
pub(crate) enum Severity {
Success,
Backtrack,
Cut,
Incomplete,
}
impl Severity {
pub(crate) fn with_result<T, I: Stream, E: ParserError<I>>(result: &Result<T, E>) -> Self {
match result {
Ok(_) => Self::Success,
Err(e) if e.is_backtrack() => Self::Backtrack,
Err(e) if e.is_incomplete() => Self::Incomplete,
_ => Self::Cut,
}
}
}
pub(crate) fn start<I: Stream>(
depth: usize,
name: &dyn core::fmt::Display,
count: usize,
input: &I,
) {
let gutter_style = anstyle::Style::new().bold();
let input_style = anstyle::Style::new().underline();
let eof_style = anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Cyan.into()));
let (call_width, input_width) = column_widths();
let count = if 0 < count {
format!(":{count}")
} else {
"".to_owned()
};
let call_column = format!("{:depth$}> {name}{count}", "");
// The debug version of `slice` might be wider, either due to rendering one byte as two nibbles or
// escaping in strings.
let mut debug_slice = format!("{:?}", crate::util::from_fn(|f| input.trace(f)));
let (debug_slice, eof) = if let Some(debug_offset) = debug_slice
.char_indices()
.enumerate()
.find_map(|(pos, (offset, _))| (input_width <= pos).then_some(offset))
{
debug_slice.truncate(debug_offset);
let eof = "";
(debug_slice, eof)
} else {
let eof = if debug_slice.chars().count() < input_width {
"∅"
} else {
""
};
(debug_slice, eof)
};
let writer = anstream::stderr();
let mut writer = writer.lock();
let _ = writeln!(
writer,
"{call_column:call_width$} {gutter_style}|{gutter_reset} {input_style}{debug_slice}{input_reset}{eof_style}{eof}{eof_reset}",
gutter_style=gutter_style.render(),
gutter_reset=gutter_style.render_reset(),
input_style=input_style.render(),
input_reset=input_style.render_reset(),
eof_style=eof_style.render(),
eof_reset=eof_style.render_reset(),
);
}
pub(crate) fn end(
depth: usize,
name: &dyn core::fmt::Display,
count: usize,
consumed: usize,
severity: Severity,
) {
let gutter_style = anstyle::Style::new().bold();
let (call_width, _) = column_widths();
let count = if 0 < count {
format!(":{count}")
} else {
"".to_owned()
};
let call_column = format!("{:depth$}< {name}{count}", "");
let (status_style, status) = match severity {
Severity::Success => {
let style = anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Green.into()));
let status = format!("+{consumed}");
(style, status)
}
Severity::Backtrack => (
anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Yellow.into())),
"backtrack".to_owned(),
),
Severity::Cut => (
anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Red.into())),
"cut".to_owned(),
),
Severity::Incomplete => (
anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Red.into())),
"incomplete".to_owned(),
),
};
let writer = anstream::stderr();
let mut writer = writer.lock();
let _ = writeln!(
writer,
"{status_style}{call_column:call_width$}{status_reset} {gutter_style}|{gutter_reset} {status_style}{status}{status_reset}",
gutter_style=gutter_style.render(),
gutter_reset=gutter_style.render_reset(),
status_style=status_style.render(),
status_reset=status_style.render_reset(),
);
}
pub(crate) fn result(depth: usize, name: &dyn core::fmt::Display, severity: Severity) {
let gutter_style = anstyle::Style::new().bold();
let (call_width, _) = column_widths();
let call_column = format!("{:depth$}| {name}", "");
let (status_style, status) = match severity {
Severity::Success => (
anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Green.into())),
"",
),
Severity::Backtrack => (
anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Yellow.into())),
"backtrack",
),
Severity::Cut => (
anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Red.into())),
"cut",
),
Severity::Incomplete => (
anstyle::Style::new().fg_color(Some(anstyle::AnsiColor::Red.into())),
"incomplete",
),
};
let writer = anstream::stderr();
let mut writer = writer.lock();
let _ = writeln!(
writer,
"{status_style}{call_column:call_width$}{status_reset} {gutter_style}|{gutter_reset} {status_style}{status}{status_reset}",
gutter_style=gutter_style.render(),
gutter_reset=gutter_style.render_reset(),
status_style=status_style.render(),
status_reset=status_style.render_reset(),
);
}
fn column_widths() -> (usize, usize) {
let term_width = term_width();
let min_call_width = 40;
let min_input_width = 20;
let decor_width = 3;
let extra_width = term_width
.checked_sub(min_call_width + min_input_width + decor_width)
.unwrap_or_default();
let call_width = min_call_width + 2 * extra_width / 3;
let input_width = min_input_width + extra_width / 3;
(call_width, input_width)
}
fn term_width() -> usize {
columns_env().or_else(query_width).unwrap_or(80)
}
fn query_width() -> Option<usize> {
use is_terminal_polyfill::IsTerminal;
if std::io::stderr().is_terminal() {
terminal_size::terminal_size().map(|(w, _h)| w.0.into())
} else {
None
}
}
fn columns_env() -> Option<usize> {
std::env::var("COLUMNS")
.ok()
.and_then(|c| c.parse::<usize>().ok())
}
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#![cfg_attr(feature = "debug", allow(clippy::std_instead_of_core))]
#[cfg(feature = "debug")]
mod internals;
use crate::error::ParserError;
use crate::stream::Stream;
use crate::Parser;
/// Trace the execution of the parser
///
/// Note that [`Parser::context`] also provides high level trace information.
///
/// See [tutorial][crate::_tutorial::chapter_8] for more details.
///
/// # Example
///
/// ```rust
/// # use winnow::{error::ErrMode, error::Needed};
/// # use winnow::token::take_while;
/// # use winnow::stream::AsChar;
/// # use winnow::prelude::*;
/// use winnow::combinator::trace;
///
/// fn short_alpha<'s>(s: &mut &'s [u8]) -> ModalResult<&'s [u8]> {
/// trace("short_alpha",
/// take_while(3..=6, AsChar::is_alpha)
/// ).parse_next(s)
/// }
///
/// assert_eq!(short_alpha.parse_peek(b"latin123"), Ok((&b"123"[..], &b"latin"[..])));
/// assert_eq!(short_alpha.parse_peek(b"lengthy"), Ok((&b"y"[..], &b"length"[..])));
/// assert_eq!(short_alpha.parse_peek(b"latin"), Ok((&b""[..], &b"latin"[..])));
/// assert!(short_alpha.parse_peek(b"ed").is_err());
/// assert!(short_alpha.parse_peek(b"12345").is_err());
/// ```
#[cfg_attr(not(feature = "debug"), allow(unused_variables))]
#[cfg_attr(not(feature = "debug"), allow(unused_mut))]
#[cfg_attr(not(feature = "debug"), inline(always))]
pub fn trace<I: Stream, O, E: ParserError<I>>(
name: impl core::fmt::Display,
parser: impl Parser<I, O, E>,
) -> impl Parser<I, O, E> {
#[cfg(feature = "debug")]
{
internals::Trace::new(parser, name)
}
#[cfg(not(feature = "debug"))]
{
parser
}
}
#[cfg_attr(not(feature = "debug"), allow(unused_variables))]
pub(crate) fn trace_result<T, I: Stream, E: ParserError<I>>(
name: impl core::fmt::Display,
res: &Result<T, E>,
) {
#[cfg(feature = "debug")]
{
let depth = internals::Depth::existing();
let severity = internals::Severity::with_result(res);
internals::result(*depth, &name, severity);
}
}
pub(crate) struct DisplayDebug<D>(pub(crate) D);
impl<D: core::fmt::Debug> core::fmt::Display for DisplayDebug<D> {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
write!(f, "{:?}", self.0)
}
}
#[test]
#[cfg(feature = "std")]
#[cfg_attr(miri, ignore)]
#[cfg(unix)]
#[cfg(feature = "debug")]
fn example() {
use term_transcript::{test::TestConfig, ShellOptions};
let path = snapbox::cmd::compile_example("string", ["--features=debug"]).unwrap();
let current_dir = path.parent().unwrap();
let cmd = path.file_name().unwrap();
// HACK: term_transcript doesn't allow non-UTF8 paths
let cmd = format!("./{}", cmd.to_string_lossy());
TestConfig::new(
ShellOptions::default()
.with_current_dir(current_dir)
.with_env("CLICOLOR_FORCE", "1"),
)
.test("assets/trace.svg", [format!(r#"{cmd} '"abc"'"#).as_str()]);
}
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use crate::combinator::empty;
use crate::combinator::fail;
use crate::combinator::opt;
use crate::combinator::trace;
use crate::error::ParserError;
use crate::stream::Stream;
use crate::stream::StreamIsPartial;
use crate::Parser;
use crate::Result;
/// Parses an expression based on operator precedence.
///
/// It uses a Pratt parsing algorithm, where operators are
/// associated with a binding power. The higher the power,
/// the more tightly an operator will bind to its operands.
///
/// This method returns an [`Expression`], which configures
/// the Pratt parser.
///
/// Each operator type is configured with [`Prefix`], [`Postfix`],
/// and [`Infix`]. These describe the operator's binding power,
/// a function that applies the operator to its operand, and the
/// operator's associativity (infix only).
///
/// For a more full-featured example, look at the [C-style Expression][crate::_topic::arithmetic#c-style-expression]
/// topic.
///
/// # Example
///
/// Parsing a simple arithmetic expression without parenthesis.
///
/// ```rust
/// # use winnow::prelude::*;
/// # use winnow::error::ContextError;
/// # use winnow::ascii::digit1;
/// # use winnow::combinator::{dispatch, fail};
/// # use winnow::token::any;
/// use winnow::combinator::expression;
/// use winnow::combinator::{Prefix, Postfix, Infix};
///
/// fn parser<'i>() -> impl Parser<&'i str, i32, ContextError> {
/// move |i: &mut &str| {
/// use Infix::*;
/// expression(digit1.parse_to::<i32>()) // operands are 32-bit integers
/// .prefix(dispatch! {any;
/// '-' => Prefix(12, |_, a: i32| Ok(-a)),
/// _ => fail,
/// })
/// .infix(dispatch! {any;
/// '+' => Left(5, |_, a, b| Ok(a + b)),
/// '-' => Left(5, |_, a, b| Ok(a - b)),
/// '*' => Left(7, |_, a, b| Ok(a * b)),
/// '/' => Left(7, |_, a: i32, b| Ok(a.checked_div(b).unwrap_or_default())),
/// _ => fail,
/// })
/// .postfix(dispatch! {any;
/// '!' => Postfix(15, |_, a| if a < 1 { Ok(1) } else { Ok((1..=a).fold(1, |acc, a| acc*a)) }),
/// _ => fail,
/// })
/// .parse_next(i)
/// }
/// }
///
/// assert_eq!(parser().parse("1+1"), Ok(2));
/// assert_eq!(parser().parse("0!"), Ok(1));
/// assert_eq!(parser().parse("-1*5*2*10+30/3!"), Ok(-95));
/// ```
#[doc(alias = "pratt")]
#[doc(alias = "separated")]
#[doc(alias = "shunting_yard")]
#[doc(alias = "precedence_climbing")]
#[inline(always)]
#[allow(clippy::type_complexity)]
pub fn expression<I, ParseOperand, O, E>(
parse_operand: ParseOperand,
) -> Expression<
I,
O,
ParseOperand,
impl Parser<I, Prefix<I, O, E>, E>,
impl Parser<I, Postfix<I, O, E>, E>,
impl Parser<I, Infix<I, O, E>, E>,
E,
>
where
I: Stream + StreamIsPartial,
ParseOperand: Parser<I, O, E>,
E: ParserError<I>,
{
Expression {
precedence_level: 0,
parse_operand,
parse_prefix: fail,
parse_postfix: fail,
parse_infix: fail,
i: Default::default(),
o: Default::default(),
e: Default::default(),
}
}
/// A helper struct for [`expression()`].
///
/// Holds the configuration for the Pratt parser, including
/// the operator and operand parsers. A precedence level can
/// also be set, which is useful to disambiguate parse trees
/// based on the parent operator's precedence.
///
/// Implements [`Parser`]. When parsing an input, it applies
/// the Pratt parser.
pub struct Expression<I, O, ParseOperand, Pre, Post, Pix, E>
where
I: Stream + StreamIsPartial,
ParseOperand: Parser<I, O, E>,
E: ParserError<I>,
{
precedence_level: i64,
parse_operand: ParseOperand,
parse_prefix: Pre,
parse_postfix: Post,
parse_infix: Pix,
i: core::marker::PhantomData<I>,
o: core::marker::PhantomData<O>,
e: core::marker::PhantomData<E>,
}
impl<I, O, ParseOperand, Pre, Post, Pix, E> Expression<I, O, ParseOperand, Pre, Post, Pix, E>
where
ParseOperand: Parser<I, O, E>,
I: Stream + StreamIsPartial,
E: ParserError<I>,
{
/// Sets the prefix operator parser.
///
/// The parser should parse the input to a [`Prefix`],
/// which contains the operator's binding power and
/// a fold function which applies the operator to its
/// operands.
#[inline(always)]
pub fn prefix<NewParsePrefix>(
self,
parser: NewParsePrefix,
) -> Expression<I, O, ParseOperand, NewParsePrefix, Post, Pix, E>
where
NewParsePrefix: Parser<I, Prefix<I, O, E>, E>,
{
Expression {
precedence_level: self.precedence_level,
parse_operand: self.parse_operand,
parse_prefix: parser,
parse_postfix: self.parse_postfix,
parse_infix: self.parse_infix,
i: Default::default(),
o: Default::default(),
e: Default::default(),
}
}
/// Sets the postfix operator parser.
///
/// The parser should parse the input to a [`Postfix`],
/// which contains the operator's binding power and
/// a fold function which applies the operator to its
/// operands.
#[inline(always)]
pub fn postfix<NewParsePostfix>(
self,
parser: NewParsePostfix,
) -> Expression<I, O, ParseOperand, Pre, NewParsePostfix, Pix, E>
where
NewParsePostfix: Parser<I, Postfix<I, O, E>, E>,
{
Expression {
precedence_level: self.precedence_level,
parse_operand: self.parse_operand,
parse_prefix: self.parse_prefix,
parse_postfix: parser,
parse_infix: self.parse_infix,
i: Default::default(),
o: Default::default(),
e: Default::default(),
}
}
/// Sets the infix operator parser.
///
/// The parser should parse the input to a [`Infix`],
/// which contains the operator's binding power and
/// a fold function which applies the operator to its
/// operands.
#[inline(always)]
pub fn infix<NewParseInfix>(
self,
parser: NewParseInfix,
) -> Expression<I, O, ParseOperand, Pre, Post, NewParseInfix, E>
where
NewParseInfix: Parser<I, Infix<I, O, E>, E>,
{
Expression {
precedence_level: self.precedence_level,
parse_operand: self.parse_operand,
parse_prefix: self.parse_prefix,
parse_postfix: self.parse_postfix,
parse_infix: parser,
i: Default::default(),
o: Default::default(),
e: Default::default(),
}
}
/// Sets the precedence level for the current instance of the parser.
///
/// It defaults to 0, which is traditionally treated as the "lowest"
/// possible precedence when parsing an expression.
///
/// This is useful to disambiguate grammars based on the parent operator's
/// precedence. This comes up primarily when parsing recursive expressions.
///
/// The parsing machinery underpinning [`Expression`] assumes that a "more
/// tightly binding" operator is numerically large, while a "more loosely
/// binding" operator is numerically small. For example, `13` is a higher
/// precedence level than `1` because `13 > 1`.
///
/// Other ways of describing this relationship:
/// - `13` has a higher precedence compared to `1`
/// - `13` has a higher binding power compared to `1`
///
/// Note: Binding power and precedence both refer to the same concept and
/// may be used interchangeably.
///
/// # Motivation
///
/// If you don't understand why this is useful to have, this section tries
/// to explain in more detail.
///
/// The [C-style Expressions][crate::_topic::arithmetic#c-style-expression]
/// example has source code for parsing the expression described below, and
/// can provide a clearer usage example.
///
/// Consider the following expression in the C language:
///
/// ```c
/// int x = (1 == 1 ? 0 : 1, -123); // <-- let's parse this
/// printf("%d\n", x); // -123
/// ```
///
/// Let's look at the right-hand side of the expression on the first line,
/// and replace some of the sub-expressions with symbols:
///
/// ```text
/// (1 == 1 ? 0 : 1, -123) // rhs
/// (a ? b : c, d ) // symbolic
/// (a ? b : c, d) // remove whitespace
/// (, (? a b c) d) // prefix notation
/// ```
///
/// Written symbolically:
/// - `a` is the condition, like `1 == 1`
/// - `b` is the value when the condition is true
/// - `c` is the value when the condition is false
/// - `d` is a secondary expression unrelated to the ternary
///
/// In prefix notation, it's easier to see the specific operators and what
/// they bind to:
/// - COMMA (`,`) binds to `(? a b c)` and `d`
/// - TERNARY (`?`) binds to `a`, `b`, and `c`
///
/// ## Parsing `c` and `d`
///
/// Let's focus on parsing the sub-expressions `c` and `d`, as that
/// motivates why a parser precedence level is necessary.
///
/// To parse `c`, we would really like to re-use the parser produced by
/// [`expression()`], because `c` is really *any* valid expression that
/// can be parsed by `expression()` already.
///
/// However, we can't re-use the parser naively. When parsing `c`, we need
/// to "escape" from the inner parser when encountering the comma separating
/// `c` from `d`.
///
/// The reason we have to "escape" is because of how operator precedence is
/// defined in the C language: the comma operator has the lowest precedence
/// among all the operators. When we're parsing `c`, we're in the context of
/// the ternary operator. We don't want to parse any valid expression! Just
/// what the ternary operator captures.
///
/// That's where the precedence level comes in: you specify the minimum
/// precedence this parser is willing to accept. If you come across an
/// expression in the top-level with a lower binding power than the starting
/// precedence, you know to stop parsing.
///
/// The parsing machinery inside of [`Expression`] handles most of this for
/// you, but it can't determine what the precedence level should be for a
/// given expression. That's a language-specific detail, and it depends on
/// what you want to parse.
#[inline(always)]
pub fn current_precedence_level(
mut self,
level: i64,
) -> Expression<I, O, ParseOperand, Pre, Post, Pix, E> {
self.precedence_level = level;
self
}
}
impl<I, O, Pop, Pre, Post, Pix, E> Parser<I, O, E> for Expression<I, O, Pop, Pre, Post, Pix, E>
where
I: Stream + StreamIsPartial,
Pop: Parser<I, O, E>,
Pix: Parser<I, Infix<I, O, E>, E>,
Pre: Parser<I, Prefix<I, O, E>, E>,
Post: Parser<I, Postfix<I, O, E>, E>,
E: ParserError<I>,
{
#[inline(always)]
fn parse_next(&mut self, input: &mut I) -> Result<O, E> {
trace("expression", move |i: &mut I| {
expression_impl(
i,
&mut self.parse_operand,
&mut self.parse_prefix,
&mut self.parse_postfix,
&mut self.parse_infix,
self.precedence_level,
)
})
.parse_next(input)
}
}
/// Opaque implementation of the Pratt parser.
fn expression_impl<I, O, Pop, Pre, Post, Pix, E>(
i: &mut I,
parse_operand: &mut Pop,
prefix: &mut Pre,
postfix: &mut Post,
infix: &mut Pix,
min_power: i64,
) -> Result<O, E>
where
I: Stream + StreamIsPartial,
Pop: Parser<I, O, E>,
Pix: Parser<I, Infix<I, O, E>, E>,
Pre: Parser<I, Prefix<I, O, E>, E>,
Post: Parser<I, Postfix<I, O, E>, E>,
E: ParserError<I>,
{
let operand = opt(trace("operand", parse_operand.by_ref())).parse_next(i)?;
let mut operand = if let Some(operand) = operand {
operand
} else {
// Prefix unary operators
let len = i.eof_offset();
let Prefix(power, fold_prefix) = trace("prefix", prefix.by_ref()).parse_next(i)?;
// infinite loop check: the parser must always consume
if i.eof_offset() == len {
return Err(E::assert(i, "`prefix` parsers must always consume"));
}
let operand = expression_impl(i, parse_operand, prefix, postfix, infix, power)?;
fold_prefix(i, operand)?
};
// A variable to stop the `'parse` loop when `Assoc::Neither` with the same
// precedence is encountered e.g. `a == b == c`. `Assoc::Neither` has similar
// associativity rules as `Assoc::Left`, but we stop parsing when the next operator
// is the same as the current one.
let mut prev_op_is_neither = None;
'parse: while i.eof_offset() > 0 {
// Postfix unary operators
let start = i.checkpoint();
if let Some(Postfix(power, fold_postfix)) =
opt(trace("postfix", postfix.by_ref())).parse_next(i)?
{
// control precedence over the prefix e.g.:
// `--(i++)` or `(--i)++`
if power < min_power {
i.reset(&start);
break 'parse;
}
operand = fold_postfix(i, operand)?;
continue 'parse;
}
// Infix binary operators
let start = i.checkpoint();
let parse_result = opt(trace("infix", infix.by_ref())).parse_next(i)?;
if let Some(infix_op) = parse_result {
let mut is_neither = None;
let (lpower, rpower, fold_infix) = match infix_op {
Infix::Right(p, f) => (p, p - 1, f),
Infix::Left(p, f) => (p, p + 1, f),
Infix::Neither(p, f) => {
is_neither = Some(p);
(p, p + 1, f)
}
};
if lpower < min_power
// MSRV: `is_some_and`
|| match prev_op_is_neither {
None => false,
Some(p) => lpower == p,
}
{
i.reset(&start);
break 'parse;
}
prev_op_is_neither = is_neither;
let rhs = expression_impl(i, parse_operand, prefix, postfix, infix, rpower)?;
operand = fold_infix(i, operand, rhs)?;
continue 'parse;
}
break 'parse;
}
Ok(operand)
}
/// Define an [`expression()`]'s prefix operator
///
/// It requires an operator binding power, as well as a
/// fold function which applies the operator.
pub struct Prefix<I, O, E>(
/// Binding power
pub i64,
/// Unary operator
pub fn(&mut I, O) -> Result<O, E>,
);
impl<I, O, E> Clone for Prefix<I, O, E> {
#[inline(always)]
fn clone(&self) -> Self {
Prefix(self.0, self.1)
}
}
impl<I: Stream, O, E: ParserError<I>> Parser<I, Prefix<I, O, E>, E> for Prefix<I, O, E> {
#[inline(always)]
fn parse_next(&mut self, input: &mut I) -> Result<Prefix<I, O, E>, E> {
empty.value(self.clone()).parse_next(input)
}
}
/// Define an [`expression()`]'s postfix operator
///
/// It requires an operator binding power, as well as a
/// fold function which applies the operator.
pub struct Postfix<I, O, E>(
/// Binding power
pub i64,
/// Unary operator
pub fn(&mut I, O) -> Result<O, E>,
);
impl<I, O, E> Clone for Postfix<I, O, E> {
#[inline(always)]
fn clone(&self) -> Self {
Postfix(self.0, self.1)
}
}
impl<I: Stream, O, E: ParserError<I>> Parser<I, Postfix<I, O, E>, E> for Postfix<I, O, E> {
#[inline(always)]
fn parse_next(&mut self, input: &mut I) -> Result<Postfix<I, O, E>, E> {
empty.value(self.clone()).parse_next(input)
}
}
/// Define an [`expression()`]'s infix operator
///
/// It requires an operator binding power, as well as a
/// fold function which applies the operator.
pub enum Infix<I, O, E> {
/// Left-associative operator
///
/// The operators will bind more tightly to their rightmost operands.
///
/// e.g `A op B op C` -> `(A op B) op C`
Left(
/// Binding power
i64,
/// Binary operator
fn(&mut I, O, O) -> Result<O, E>,
),
/// Right-associative operator
///
/// The operators will bind more tightly to their leftmost operands.
///
/// e.g `A op B op C` -> `A op (B op C)`
Right(
/// Binding power
i64,
/// Binary operator
fn(&mut I, O, O) -> Result<O, E>,
),
/// Neither left or right associative
///
/// `Infix::Neither` has similar associativity rules as `Assoc::Left`, but we stop
/// parsing when the next operator is the same as the current one.
///
/// e.g. `a == b == c` -> `(a == b)`, fail: `(== c)`
Neither(
/// Binding power
i64,
/// Binary operator
fn(&mut I, O, O) -> Result<O, E>,
),
}
impl<I, O, E> Clone for Infix<I, O, E> {
#[inline(always)]
fn clone(&self) -> Self {
match self {
Infix::Left(p, f) => Infix::Left(*p, *f),
Infix::Right(p, f) => Infix::Right(*p, *f),
Infix::Neither(p, f) => Infix::Neither(*p, *f),
}
}
}
impl<I: Stream, O, E: ParserError<I>> Parser<I, Infix<I, O, E>, E> for Infix<I, O, E> {
#[inline(always)]
fn parse_next(&mut self, input: &mut I) -> Result<Infix<I, O, E>, E> {
empty.value(self.clone()).parse_next(input)
}
}
#[cfg(test)]
mod tests {
use crate::ascii::digit1;
use crate::combinator::fail;
use crate::dispatch;
use crate::error::ContextError;
use crate::token::any;
use super::*;
fn parser<'i>() -> impl Parser<&'i str, i32, ContextError> {
move |i: &mut &str| {
use Infix::*;
expression(digit1.parse_to::<i32>())
.current_precedence_level(0)
.prefix(dispatch! {any;
'+' => Prefix(12, |_, a| Ok(a)),
'-' => Prefix(12, |_, a: i32| Ok(-a)),
_ => fail
})
.infix(dispatch! {any;
'+' => Left(5, |_, a, b| Ok(a + b)),
'-' => Left(5, |_, a, b| Ok(a - b)),
'*' => Left(7, |_, a, b| Ok(a * b)),
'/' => Left(7, |_, a, b| Ok(a / b)),
'%' => Left(7, |_, a, b| Ok(a % b)),
'^' => Left(9, |_, a, b| Ok(a ^ b)),
_ => fail
})
.parse_next(i)
}
}
#[test]
fn test_expression() {
assert_eq!(parser().parse("-3+-3*4"), Ok(-15));
assert_eq!(parser().parse("+2+3*4"), Ok(14));
assert_eq!(parser().parse("2*3+4"), Ok(10));
}
}
+800
View File
@@ -0,0 +1,800 @@
//! Opaque implementations of [`Parser`]
use crate::combinator::trace;
use crate::combinator::trace_result;
use crate::combinator::DisplayDebug;
#[cfg(feature = "unstable-recover")]
#[cfg(feature = "std")]
use crate::error::FromRecoverableError;
use crate::error::{AddContext, FromExternalError, ParserError};
#[cfg(feature = "unstable-recover")]
#[cfg(feature = "std")]
use crate::stream::Recover;
use crate::stream::StreamIsPartial;
use crate::stream::{Location, Stream};
use crate::*;
use core::borrow::Borrow;
use core::ops::Range;
/// [`Parser`] implementation for [`Parser::by_ref`]
pub struct ByRef<'p, P, I, O, E> {
pub(crate) p: &'p mut P,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<I, O, E, P> Parser<I, O, E> for ByRef<'_, P, I, O, E>
where
P: Parser<I, O, E>,
{
#[inline(always)]
fn parse_next(&mut self, i: &mut I) -> Result<O, E> {
self.p.parse_next(i)
}
}
/// [`Parser`] implementation for [`Parser::map`]
pub struct Map<F, G, I, O, O2, E>
where
F: Parser<I, O, E>,
G: FnMut(O) -> O2,
{
pub(crate) parser: F,
pub(crate) map: G,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, G, I, O, O2, E> Parser<I, O2, E> for Map<F, G, I, O, O2, E>
where
F: Parser<I, O, E>,
G: FnMut(O) -> O2,
{
#[inline]
fn parse_next(&mut self, i: &mut I) -> Result<O2, E> {
match self.parser.parse_next(i) {
Err(e) => Err(e),
Ok(o) => Ok((self.map)(o)),
}
}
}
/// [`Parser`] implementation for [`Parser::try_map`]
pub struct TryMap<F, G, I, O, O2, E, E2>
where
F: Parser<I, O, E>,
G: FnMut(O) -> Result<O2, E2>,
I: Stream,
E: FromExternalError<I, E2>,
E: ParserError<I>,
{
pub(crate) parser: F,
pub(crate) map: G,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) e: core::marker::PhantomData<E>,
pub(crate) e2: core::marker::PhantomData<E2>,
}
impl<F, G, I, O, O2, E, E2> Parser<I, O2, E> for TryMap<F, G, I, O, O2, E, E2>
where
F: Parser<I, O, E>,
G: FnMut(O) -> Result<O2, E2>,
I: Stream,
E: FromExternalError<I, E2>,
E: ParserError<I>,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<O2, E> {
let start = input.checkpoint();
let o = self.parser.parse_next(input)?;
let res = (self.map)(o).map_err(|err| {
input.reset(&start);
E::from_external_error(input, err)
});
trace_result("verify", &res);
res
}
}
/// [`Parser`] implementation for [`Parser::verify_map`]
pub struct VerifyMap<F, G, I, O, O2, E>
where
F: Parser<I, O, E>,
G: FnMut(O) -> Option<O2>,
I: Stream,
E: ParserError<I>,
{
pub(crate) parser: F,
pub(crate) map: G,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, G, I, O, O2, E> Parser<I, O2, E> for VerifyMap<F, G, I, O, O2, E>
where
F: Parser<I, O, E>,
G: FnMut(O) -> Option<O2>,
I: Stream,
E: ParserError<I>,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<O2, E> {
let start = input.checkpoint();
let o = self.parser.parse_next(input)?;
let res = (self.map)(o).ok_or_else(|| {
input.reset(&start);
ParserError::from_input(input)
});
trace_result("verify", &res);
res
}
}
/// [`Parser`] implementation for [`Parser::and_then`]
pub struct AndThen<F, G, I, O, O2, E>
where
F: Parser<I, O, E>,
G: Parser<O, O2, E>,
O: StreamIsPartial,
I: Stream,
{
pub(crate) outer: F,
pub(crate) inner: G,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, G, I, O, O2, E> Parser<I, O2, E> for AndThen<F, G, I, O, O2, E>
where
F: Parser<I, O, E>,
G: Parser<O, O2, E>,
O: StreamIsPartial,
I: Stream,
{
#[inline(always)]
fn parse_next(&mut self, i: &mut I) -> Result<O2, E> {
let start = i.checkpoint();
let mut o = self.outer.parse_next(i)?;
let _ = o.complete();
let o2 = self.inner.parse_next(&mut o).map_err(|err| {
i.reset(&start);
err
})?;
Ok(o2)
}
}
/// [`Parser`] implementation for [`Parser::parse_to`]
pub struct ParseTo<P, I, O, O2, E>
where
P: Parser<I, O, E>,
I: Stream,
O: crate::stream::ParseSlice<O2>,
E: ParserError<I>,
{
pub(crate) p: P,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<P, I, O, O2, E> Parser<I, O2, E> for ParseTo<P, I, O, O2, E>
where
P: Parser<I, O, E>,
I: Stream,
O: crate::stream::ParseSlice<O2>,
E: ParserError<I>,
{
#[inline]
fn parse_next(&mut self, i: &mut I) -> Result<O2, E> {
let start = i.checkpoint();
let o = self.p.parse_next(i)?;
let res = o.parse_slice().ok_or_else(|| {
i.reset(&start);
ParserError::from_input(i)
});
trace_result("verify", &res);
res
}
}
/// [`Parser`] implementation for [`Parser::flat_map`]
pub struct FlatMap<F, G, H, I, O, O2, E>
where
F: Parser<I, O, E>,
G: FnMut(O) -> H,
H: Parser<I, O2, E>,
{
pub(crate) f: F,
pub(crate) g: G,
pub(crate) h: core::marker::PhantomData<H>,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, G, H, I, O, O2, E> Parser<I, O2, E> for FlatMap<F, G, H, I, O, O2, E>
where
F: Parser<I, O, E>,
G: FnMut(O) -> H,
H: Parser<I, O2, E>,
{
#[inline(always)]
fn parse_next(&mut self, i: &mut I) -> Result<O2, E> {
let o = self.f.parse_next(i)?;
(self.g)(o).parse_next(i)
}
}
/// [`Parser`] implementation for [`Parser::complete_err`]
pub struct CompleteErr<P, I, O, E> {
pub(crate) p: P,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<P, I, O, E> Parser<I, O, E> for CompleteErr<P, I, O, E>
where
P: Parser<I, O, E>,
I: Stream,
E: ParserError<I>,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<O, E> {
trace("complete_err", |input: &mut I| {
match (self.p).parse_next(input) {
Err(err) => match err.needed() {
Some(_) => Err(ParserError::from_input(input)),
None => Err(err),
},
rest => rest,
}
})
.parse_next(input)
}
}
/// [`Parser`] implementation for [`Parser::verify`]
pub struct Verify<F, G, I, O, O2, E>
where
F: Parser<I, O, E>,
G: FnMut(&O2) -> bool,
I: Stream,
O: Borrow<O2>,
O2: ?Sized,
E: ParserError<I>,
{
pub(crate) parser: F,
pub(crate) filter: G,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, G, I, O, O2, E> Parser<I, O, E> for Verify<F, G, I, O, O2, E>
where
F: Parser<I, O, E>,
G: FnMut(&O2) -> bool,
I: Stream,
O: Borrow<O2>,
O2: ?Sized,
E: ParserError<I>,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<O, E> {
let start = input.checkpoint();
let o = self.parser.parse_next(input)?;
let res = (self.filter)(o.borrow()).then_some(o).ok_or_else(|| {
input.reset(&start);
ParserError::from_input(input)
});
trace_result("verify", &res);
res
}
}
/// [`Parser`] implementation for [`Parser::value`]
pub struct Value<F, I, O, O2, E>
where
F: Parser<I, O, E>,
O2: Clone,
{
pub(crate) parser: F,
pub(crate) val: O2,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, I, O, O2, E> Parser<I, O2, E> for Value<F, I, O, O2, E>
where
F: Parser<I, O, E>,
O2: Clone,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<O2, E> {
(self.parser).parse_next(input).map(|_| self.val.clone())
}
}
/// [`Parser`] implementation for [`Parser::default_value`]
pub struct DefaultValue<F, I, O, O2, E>
where
F: Parser<I, O, E>,
O2: core::default::Default,
{
pub(crate) parser: F,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, I, O, O2, E> Parser<I, O2, E> for DefaultValue<F, I, O, O2, E>
where
F: Parser<I, O, E>,
O2: core::default::Default,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<O2, E> {
(self.parser).parse_next(input).map(|_| O2::default())
}
}
/// [`Parser`] implementation for [`Parser::void`]
pub struct Void<F, I, O, E>
where
F: Parser<I, O, E>,
{
pub(crate) parser: F,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, I, O, E> Parser<I, (), E> for Void<F, I, O, E>
where
F: Parser<I, O, E>,
{
#[inline(always)]
fn parse_next(&mut self, input: &mut I) -> Result<(), E> {
(self.parser).parse_next(input).map(|_| ())
}
}
/// [`Parser`] implementation for [`Parser::take`]
pub struct Take<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream,
{
pub(crate) parser: F,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<I, O, E, F> Parser<I, <I as Stream>::Slice, E> for Take<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<<I as Stream>::Slice, E> {
let checkpoint = input.checkpoint();
match (self.parser).parse_next(input) {
Ok(_) => {
let offset = input.offset_from(&checkpoint);
input.reset(&checkpoint);
let taken = input.next_slice(offset);
Ok(taken)
}
Err(e) => Err(e),
}
}
}
/// [`Parser`] implementation for [`Parser::with_taken`]
pub struct WithTaken<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream,
{
pub(crate) parser: F,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, I, O, E> Parser<I, (O, <I as Stream>::Slice), E> for WithTaken<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<(O, <I as Stream>::Slice), E> {
let checkpoint = input.checkpoint();
match (self.parser).parse_next(input) {
Ok(result) => {
let offset = input.offset_from(&checkpoint);
input.reset(&checkpoint);
let taken = input.next_slice(offset);
Ok((result, taken))
}
Err(e) => Err(e),
}
}
}
/// [`Parser`] implementation for [`Parser::span`]
pub struct Span<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream + Location,
{
pub(crate) parser: F,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<I, O, E, F> Parser<I, Range<usize>, E> for Span<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream + Location,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<Range<usize>, E> {
let start = input.current_token_start();
self.parser.parse_next(input).map(move |_| {
let end = input.previous_token_end();
start..end
})
}
}
/// [`Parser`] implementation for [`Parser::with_span`]
pub struct WithSpan<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream + Location,
{
pub(crate) parser: F,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, I, O, E> Parser<I, (O, Range<usize>), E> for WithSpan<F, I, O, E>
where
F: Parser<I, O, E>,
I: Stream + Location,
{
#[inline]
fn parse_next(&mut self, input: &mut I) -> Result<(O, Range<usize>), E> {
let start = input.current_token_start();
self.parser.parse_next(input).map(move |output| {
let end = input.previous_token_end();
(output, (start..end))
})
}
}
/// [`Parser`] implementation for [`Parser::output_into`]
pub struct OutputInto<F, I, O, O2, E>
where
F: Parser<I, O, E>,
O: Into<O2>,
{
pub(crate) parser: F,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) o2: core::marker::PhantomData<O2>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, I, O, O2, E> Parser<I, O2, E> for OutputInto<F, I, O, O2, E>
where
F: Parser<I, O, E>,
O: Into<O2>,
{
#[inline]
fn parse_next(&mut self, i: &mut I) -> Result<O2, E> {
self.parser.parse_next(i).map(|o| o.into())
}
}
/// [`Parser`] implementation for [`Parser::err_into`]
pub struct ErrInto<F, I, O, E, E2>
where
F: Parser<I, O, E>,
E: Into<E2>,
{
pub(crate) parser: F,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
pub(crate) e2: core::marker::PhantomData<E2>,
}
impl<F, I, O, E, E2> Parser<I, O, E2> for ErrInto<F, I, O, E, E2>
where
F: Parser<I, O, E>,
E: Into<E2>,
{
#[inline]
fn parse_next(&mut self, i: &mut I) -> Result<O, E2> {
self.parser.parse_next(i).map_err(|err| err.into())
}
}
/// [`Parser`] implementation for [`Parser::context`]
pub struct Context<F, I, O, E, C>
where
F: Parser<I, O, E>,
I: Stream,
E: AddContext<I, C>,
E: ParserError<I>,
C: Clone + core::fmt::Debug,
{
pub(crate) parser: F,
pub(crate) context: C,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
impl<F, I, O, E, C> Parser<I, O, E> for Context<F, I, O, E, C>
where
F: Parser<I, O, E>,
I: Stream,
E: AddContext<I, C>,
E: ParserError<I>,
C: Clone + core::fmt::Debug,
{
#[inline]
fn parse_next(&mut self, i: &mut I) -> Result<O, E> {
let context = self.context.clone();
trace(DisplayDebug(self.context.clone()), move |i: &mut I| {
let start = i.checkpoint();
(self.parser)
.parse_next(i)
.map_err(|err| err.add_context(i, &start, context.clone()))
})
.parse_next(i)
}
}
/// [`Parser`] implementation for [`Parser::context`]
pub struct ContextWith<P, I, O, E, F, C, FI>
where
P: Parser<I, O, E>,
I: Stream,
E: AddContext<I, C>,
E: ParserError<I>,
F: Fn() -> FI + Clone,
C: core::fmt::Debug,
FI: Iterator<Item = C>,
{
pub(crate) parser: P,
pub(crate) context: F,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
pub(crate) c: core::marker::PhantomData<C>,
pub(crate) fi: core::marker::PhantomData<FI>,
}
impl<P, I, O, E, F, C, FI> Parser<I, O, E> for ContextWith<P, I, O, E, F, C, FI>
where
P: Parser<I, O, E>,
I: Stream,
E: AddContext<I, C>,
E: ParserError<I>,
F: Fn() -> FI + Clone,
C: core::fmt::Debug,
FI: Iterator<Item = C>,
{
#[inline]
fn parse_next(&mut self, i: &mut I) -> Result<O, E> {
let context = self.context.clone();
let start = i.checkpoint();
(self.parser).parse_next(i).map_err(|mut err| {
for context in context() {
err = err.add_context(i, &start, context);
}
err
})
}
}
/// [`Parser`] implementation for [`Parser::map_err`]
pub struct MapErr<F, G, I, O, E, E2>
where
F: Parser<I, O, E>,
G: FnMut(E) -> E2,
{
pub(crate) parser: F,
pub(crate) map: G,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
pub(crate) e2: core::marker::PhantomData<E2>,
}
impl<F, G, I, O, E, E2> Parser<I, O, E2> for MapErr<F, G, I, O, E, E2>
where
F: Parser<I, O, E>,
G: FnMut(E) -> E2,
{
#[inline]
fn parse_next(&mut self, i: &mut I) -> Result<O, E2> {
match self.parser.parse_next(i) {
Err(e) => Err((self.map)(e)),
Ok(o) => Ok(o),
}
}
}
/// [`Parser`] implementation for [`Parser::retry_after`]
#[cfg(feature = "unstable-recover")]
#[cfg(feature = "std")]
pub struct RetryAfter<P, R, I, O, E>
where
P: Parser<I, O, E>,
R: Parser<I, (), E>,
I: Stream,
I: Recover<E>,
E: ParserError<I> + FromRecoverableError<I, E>,
{
pub(crate) parser: P,
pub(crate) recover: R,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
#[cfg(feature = "unstable-recover")]
#[cfg(feature = "std")]
impl<P, R, I, O, E> Parser<I, O, E> for RetryAfter<P, R, I, O, E>
where
P: Parser<I, O, E>,
R: Parser<I, (), E>,
I: Stream,
I: Recover<E>,
E: ParserError<I> + FromRecoverableError<I, E>,
{
#[inline(always)]
fn parse_next(&mut self, i: &mut I) -> Result<O, E> {
if I::is_recovery_supported() {
retry_after_inner(&mut self.parser, &mut self.recover, i)
} else {
self.parser.parse_next(i)
}
}
}
#[cfg(feature = "unstable-recover")]
#[cfg(feature = "std")]
fn retry_after_inner<P, R, I, O, E>(parser: &mut P, recover: &mut R, i: &mut I) -> Result<O, E>
where
P: Parser<I, O, E>,
R: Parser<I, (), E>,
I: Stream,
I: Recover<E>,
E: ParserError<I> + FromRecoverableError<I, E>,
{
loop {
let token_start = i.checkpoint();
let mut err = match parser.parse_next(i) {
Ok(o) => {
return Ok(o);
}
Err(e) if e.is_incomplete() => return Err(e),
Err(err) => err,
};
let err_start = i.checkpoint();
let err_start_eof_offset = i.eof_offset();
if recover.parse_next(i).is_ok() {
let i_eof_offset = i.eof_offset();
if err_start_eof_offset == i_eof_offset {
// Didn't advance so bubble the error up
} else if let Err(err_) = i.record_err(&token_start, &err_start, err) {
err = err_;
} else {
continue;
}
}
i.reset(&err_start);
err = E::from_recoverable_error(&token_start, &err_start, i, err);
return Err(err);
}
}
/// [`Parser`] implementation for [`Parser::resume_after`]
#[cfg(feature = "unstable-recover")]
#[cfg(feature = "std")]
pub struct ResumeAfter<P, R, I, O, E>
where
P: Parser<I, O, E>,
R: Parser<I, (), E>,
I: Stream,
I: Recover<E>,
E: ParserError<I> + FromRecoverableError<I, E>,
{
pub(crate) parser: P,
pub(crate) recover: R,
pub(crate) i: core::marker::PhantomData<I>,
pub(crate) o: core::marker::PhantomData<O>,
pub(crate) e: core::marker::PhantomData<E>,
}
#[cfg(feature = "unstable-recover")]
#[cfg(feature = "std")]
impl<P, R, I, O, E> Parser<I, Option<O>, E> for ResumeAfter<P, R, I, O, E>
where
P: Parser<I, O, E>,
R: Parser<I, (), E>,
I: Stream,
I: Recover<E>,
E: ParserError<I> + FromRecoverableError<I, E>,
{
#[inline(always)]
fn parse_next(&mut self, i: &mut I) -> Result<Option<O>, E> {
if I::is_recovery_supported() {
resume_after_inner(&mut self.parser, &mut self.recover, i)
} else {
self.parser.parse_next(i).map(Some)
}
}
}
#[cfg(feature = "unstable-recover")]
#[cfg(feature = "std")]
fn resume_after_inner<P, R, I, O, E>(
parser: &mut P,
recover: &mut R,
i: &mut I,
) -> Result<Option<O>, E>
where
P: Parser<I, O, E>,
R: Parser<I, (), E>,
I: Stream,
I: Recover<E>,
E: ParserError<I> + FromRecoverableError<I, E>,
{
let token_start = i.checkpoint();
let mut err = match parser.parse_next(i) {
Ok(o) => {
return Ok(Some(o));
}
Err(e) if e.is_incomplete() => return Err(e),
Err(err) => err,
};
let err_start = i.checkpoint();
if recover.parse_next(i).is_ok() {
if let Err(err_) = i.record_err(&token_start, &err_start, err) {
err = err_;
} else {
return Ok(None);
}
}
i.reset(&err_start);
err = FromRecoverableError::from_recoverable_error(&token_start, &err_start, i, err);
Err(err)
}
+184
View File
@@ -0,0 +1,184 @@
//! # List of parsers and combinators
//!
//! <div class="warning">
//!
//! **Note**: this list is meant to provide a nicer way to find a parser than reading through the documentation on docs.rs. Function combinators are organized in module so they are a bit easier to find.
//!
//! </div>
//!
//! ## Basic elements
//!
//! Those are used to take a series of tokens for the lowest level elements of your grammar, like, "here is a dot", or "here is an big endian integer".
//!
//! | combinator | usage | input | new input | output | comment |
//! |---|---|---|---|---|---|
//! | [`one_of`][crate::token::one_of] | `one_of(['a', 'b', 'c'])` | `"abc"` | `"bc"` | `Ok('a')` |Matches one of the provided [set of tokens][crate::stream::ContainsToken] (works with non ASCII characters too)|
//! | [`none_of`][crate::token::none_of] | `none_of(['a', 'b', 'c'])` | `"xyab"` | `"yab"` | `Ok('x')` |Matches anything but one of the provided [set of tokens][crate::stream::ContainsToken]|
//! | [`literal`][crate::token::literal] | `"hello"` | `"hello world"` | `" world"` | `Ok("hello")` |Recognizes a specific suite of characters or bytes (see also [`Caseless`][crate::ascii::Caseless])|
//! | [`take`][crate::token::take] | `take(4)` | `"hello"` | `"o"` | `Ok("hell")` |Takes a specific number of bytes or characters|
//! | [`take_while`][crate::token::take_while] | `take_while(0.., is_alphabetic)` | `"abc123"` | `"123"` | `Ok("abc")` |Returns the longest slice of bytes or characters for which the provided [set of tokens][crate::stream::ContainsToken] matches.|
//! | [`take_till`][crate::token::take_till] | `take_till(0.., is_alphabetic)` | `"123abc"` | `"abc"` | `Ok("123")` |Returns a slice of bytes or characters until the provided [set of tokens][crate::stream::ContainsToken] matches. This is the reverse behaviour from `take_while`: `take_till(f)` is equivalent to `take_while(0.., \|c\| !f(c))`|
//! | [`take_until`][crate::token::take_until] | `take_until(0.., "world")` | `"Hello world"` | `"world"` | `Ok("Hello ")` |Returns a slice of bytes or characters until the provided [literal][crate::token::literal] is found.|
//!
//! ## Choice combinators
//!
//! | combinator | usage | input | new input | output | comment |
//! |---|---|---|---|---|---|
//! | [`alt`] | `alt(("ab", "cd"))` | `"cdef"` | `"ef"` | `Ok("cd")` |Try a list of parsers and return the result of the first successful one|
//! | [`dispatch`] | \- | \- | \- | \- | `match` for parsers |
//! | [`permutation`] | `permutation(("ab", "cd", "12"))` | `"cd12abc"` | `"c"` | `Ok(("ab", "cd", "12"))` |Succeeds when all its child parser have succeeded, whatever the order|
//!
//! ## Sequence combinators
//!
//! | combinator | usage | input | new input | output | comment |
//! |---|---|---|---|---|---|
//! | [`(...)` (tuples)][crate::Parser] | `("ab", "XY", take(1))` | `"abXYZ!"` | `"!"` | `Ok(("ab", "XY", "Z"))` |Parse a series of values|
//! | [`seq!`] | `seq!(_: '(', take(2), _: ')')` | `"(ab)cd"` | `"cd"` | `Ok("ab")` |Parse a series of values, discarding those you specify|
//! | [`delimited`] | `delimited('(', take(2), ')')` | `"(ab)cd"` | `"cd"` | `Ok("ab")` |Parse three values, discarding the first and third value|
//! | [`preceded`] | `preceded("ab", "XY")` | `"abXYZ"` | `"Z"` | `Ok("XY")` |Parse two values, discarding the first value|
//! | [`terminated`] | `terminated("ab", "XY")` | `"abXYZ"` | `"Z"` | `Ok("ab")` |Parse two values, discarding the second value|
//! | [`separated_pair`] | `separated_pair("hello", ',', "world")` | `"hello,world!"` | `"!"` | `Ok(("hello", "world"))` | Parse three values, discarding the middle value|
//!
//! ## Applying a parser multiple times
//!
//! | combinator | usage | input | new input | output | comment |
//! |---|---|---|---|---|---|
//! | [`repeat`] | `repeat(1..=3, "ab")` | `"ababc"` | `"c"` | `Ok(vec!["ab", "ab"])` |Applies the parser between m and n times (n included) and returns the list of results in a Vec|
//! | [`repeat_till`] | `repeat_till(0.., "ab", "ef")` | `"ababefg"` | `"g"` | `Ok((vec!["ab", "ab"], "ef"))` |Applies the first parser until the second applies. Returns a tuple containing the list of results from the first in a Vec and the result of the second|
//! | [`separated`] | `separated(1..=3, "ab", ",")` | `"ab,ab,ab."` | `"."` | `Ok(vec!["ab", "ab", "ab"])` |Applies the parser and separator between m and n times (n included) and returns the list of results in a Vec|
//! | [`Repeat::fold`] | <code>repeat(1..=2, `be_u8`).fold(\|\| 0, \|acc, item\| acc + item)</code> | `[1, 2, 3]` | `[3]` | `Ok(3)` |Applies the parser between m and n times (n included) and folds the list of return value|
//!
//! ## Partial related
//!
//! - [`eof`]: Returns its input if it is at the end of input data
//! - [`Parser::complete_err`]: Replaces an `Incomplete` returned by the child parser with an `Backtrack`
//!
//! ## Modifiers
//!
//! - [`cond`]: Conditional combinator. Wraps another parser and calls it if the condition is met
//! - [`Parser::flat_map`]: method to map a new parser from the output of the first parser, then apply that parser over the rest of the input
//! - [`Parser::value`]: method to replace the result of a parser
//! - [`Parser::default_value`]: method to replace the result of a parser
//! - [`Parser::void`]: method to discard the result of a parser
//! - [`Parser::map`]: method to map a function on the result of a parser
//! - [`Parser::and_then`]: Applies a second parser over the output of the first one
//! - [`Parser::verify_map`]: Maps a function returning an `Option` on the output of a parser
//! - [`Parser::try_map`]: Maps a function returning a `Result` on the output of a parser
//! - [`Parser::parse_to`]: Apply [`std::str::FromStr`] to the output of the parser
//! - [`not`]: Returns a result only if the embedded parser returns `Backtrack` or `Incomplete`. Does not consume the input
//! - [`opt`]: Make the underlying parser optional
//! - [`peek`]: Returns a result without consuming the input
//! - [`Parser::take`]: If the child parser was successful, return the consumed input as the produced value
//! - [`Parser::with_taken`]: If the child parser was successful, return a tuple of the consumed input and the produced output.
//! - [`Parser::span`]: If the child parser was successful, return the location of the consumed input as the produced value
//! - [`Parser::with_span`]: If the child parser was successful, return a tuple of the location of the consumed input and the produced output.
//! - [`Parser::verify`]: Returns the result of the child parser if it satisfies a verification function
//!
//! ## Error management and debugging
//!
//! - [`cut_err`]: Commit the parse result, disallowing alternative parsers from being attempted
//! - [`backtrack_err`]: Attempts a parse, allowing alternative parsers to be attempted despite
//! use of `cut_err`
//! - [`Parser::context`]: Add context to the error if the parser fails
//! - [`trace`]: Print the parse state with the `debug` feature flag
//! - [`todo()`]: Placeholder parser
//!
//! ## Remaining combinators
//!
//! - [`empty`]: Succeed, consuming no input
//! - [`fail`]: Inversion of [`empty`]. Always fails.
//! - [`Parser::by_ref`]: Allow moving `&mut impl Parser` into other parsers
//!
//! ## Text parsing
//!
//! - [`any`][crate::token::any]: Matches one token
//! - [`tab`][crate::ascii::tab]: Matches a tab character `\t`
//! - [`crlf`][crate::ascii::crlf]: Recognizes the string `\r\n`
//! - [`line_ending`][crate::ascii::line_ending]: Recognizes an end of line (both `\n` and `\r\n`)
//! - [`newline`][crate::ascii::newline]: Matches a newline character `\n`
//! - [`till_line_ending`][crate::ascii::till_line_ending]: Recognizes a string of any char except `\r` or `\n`
//! - [`rest`][crate::token::rest]: Return the remaining input
//!
//! - [`alpha0`][crate::ascii::alpha0]: Recognizes zero or more lowercase and uppercase alphabetic characters: `[a-zA-Z]`. [`alpha1`][crate::ascii::alpha1] does the same but returns at least one character
//! - [`alphanumeric0`][crate::ascii::alphanumeric0]: Recognizes zero or more numerical and alphabetic characters: `[0-9a-zA-Z]`. [`alphanumeric1`][crate::ascii::alphanumeric1] does the same but returns at least one character
//! - [`space0`][crate::ascii::space0]: Recognizes zero or more spaces and tabs. [`space1`][crate::ascii::space1] does the same but returns at least one character
//! - [`multispace0`][crate::ascii::multispace0]: Recognizes zero or more spaces, tabs, carriage returns and line feeds. [`multispace1`][crate::ascii::multispace1] does the same but returns at least one character
//! - [`digit0`][crate::ascii::digit0]: Recognizes zero or more numerical characters: `[0-9]`. [`digit1`][crate::ascii::digit1] does the same but returns at least one character
//! - [`hex_digit0`][crate::ascii::hex_digit0]: Recognizes zero or more hexadecimal numerical characters: `[0-9A-Fa-f]`. [`hex_digit1`][crate::ascii::hex_digit1] does the same but returns at least one character
//! - [`oct_digit0`][crate::ascii::oct_digit0]: Recognizes zero or more octal characters: `[0-7]`. [`oct_digit1`][crate::ascii::oct_digit1] does the same but returns at least one character
//!
//! - [`float`][crate::ascii::float]: Parse a floating point number in a byte string
//! - [`dec_int`][crate::ascii::dec_int]: Decode a variable-width, decimal signed integer
//! - [`dec_uint`][crate::ascii::dec_uint]: Decode a variable-width, decimal unsigned integer
//! - [`hex_uint`][crate::ascii::hex_uint]: Decode a variable-width, hexadecimal integer
//!
//! - [`take_escaped`][crate::ascii::take_escaped]: Recognize the input slice with escaped characters
//! - [`escaped`][crate::ascii::escaped]: Parse escaped characters, unescaping them
//!
//! - [`expression()`]: Parse an operator precedence expression with Pratt parsing
//!
//! ### Character test functions
//!
//! Use these functions with a combinator like `take_while`:
//!
//! - [`AsChar::is_alpha`][crate::stream::AsChar::is_alpha]: Tests if byte is ASCII alphabetic: `[A-Za-z]`
//! - [`AsChar::is_alphanum`][crate::stream::AsChar::is_alphanum]: Tests if byte is ASCII alphanumeric: `[A-Za-z0-9]`
//! - [`AsChar::is_dec_digit`][crate::stream::AsChar::is_dec_digit]: Tests if byte is ASCII digit: `[0-9]`
//! - [`AsChar::is_hex_digit`][crate::stream::AsChar::is_hex_digit]: Tests if byte is ASCII hex digit: `[0-9A-Fa-f]`
//! - [`AsChar::is_oct_digit`][crate::stream::AsChar::is_oct_digit]: Tests if byte is ASCII octal digit: `[0-7]`
//! - [`AsChar::is_space`][crate::stream::AsChar::is_space]: Tests if byte is ASCII space or tab: `[ \t]`
//! - [`AsChar::is_newline`][crate::stream::AsChar::is_newline]: Tests if byte is ASCII newline: `[\n]`
//!
//! ## Binary format parsing
//!
//! - [`length_repeat`][crate::binary::length_repeat] Gets a number from the first parser, then applies the second parser that many times
//! - [`length_take`][crate::binary::length_take]: Gets a number from the first parser, then takes a subslice of the input of that size, and returns that subslice
//! - [`length_and_then`][crate::binary::length_and_then]: Gets a number from the first parser, takes a subslice of the input of that size, then applies the second parser on that subslice. If the second parser returns `Incomplete`, `length_value` will return an error
//!
//! ### Integers
//!
//! Parsing integers from binary formats can be done in two ways: With parser functions, or combinators with configurable endianness.
//!
//! - **configurable endianness:** [`i16`][crate::binary::i16], [`i32`][crate::binary::i32],
//! [`i64`][crate::binary::i64], [`u16`][crate::binary::u16], [`u32`][crate::binary::u32],
//! [`u64`][crate::binary::u64] are combinators that take as argument a
//! [`winnow::binary::Endianness`][crate::binary::Endianness], like this: `i16(endianness)`. If the
//! parameter is `winnow::binary::Endianness::Big`, parse a big endian `i16` integer, otherwise a
//! little endian `i16` integer.
//! - **fixed endianness**: The functions are prefixed by `be_` for big endian numbers, and by `le_` for little endian numbers, and the suffix is the type they parse to. As an example, `be_u32` parses a big endian unsigned integer stored in 32 bits.
//! - [`be_f32`][crate::binary::be_f32], [`be_f64`][crate::binary::be_f64]: Big endian floating point numbers
//! - [`le_f32`][crate::binary::le_f32], [`le_f64`][crate::binary::le_f64]: Little endian floating point numbers
//! - [`be_i8`][crate::binary::be_i8], [`be_i16`][crate::binary::be_i16], [`be_i24`][crate::binary::be_i24], [`be_i32`][crate::binary::be_i32], [`be_i64`][crate::binary::be_i64], [`be_i128`][crate::binary::be_i128]: Big endian signed integers
//! - [`be_u8`][crate::binary::be_u8], [`be_u16`][crate::binary::be_u16], [`be_u24`][crate::binary::be_u24], [`be_u32`][crate::binary::be_u32], [`be_u64`][crate::binary::be_u64], [`be_u128`][crate::binary::be_u128]: Big endian unsigned integers
//! - [`le_i8`][crate::binary::le_i8], [`le_i16`][crate::binary::le_i16], [`le_i24`][crate::binary::le_i24], [`le_i32`][crate::binary::le_i32], [`le_i64`][crate::binary::le_i64], [`le_i128`][crate::binary::le_i128]: Little endian signed integers
//! - [`le_u8`][crate::binary::le_u8], [`le_u16`][crate::binary::le_u16], [`le_u24`][crate::binary::le_u24], [`le_u32`][crate::binary::le_u32], [`le_u64`][crate::binary::le_u64], [`le_u128`][crate::binary::le_u128]: Little endian unsigned integers
//!
//! ### Bit stream parsing
//!
//! - [`bits`][crate::binary::bits::bits]: Transforms the current input type (byte slice `&[u8]`) to a bit stream on which bit specific parsers and more general combinators can be applied
//! - [`bytes`][crate::binary::bits::bytes]: Transforms its bits stream input back into a byte slice for the underlying parser
//! - [`take`][crate::binary::bits::take]: Take a set number of bits
//! - [`pattern`][crate::binary::bits::pattern]: Check if a set number of bits matches a pattern
//! - [`bool`][crate::binary::bits::bool]: Match any one bit
mod branch;
mod core;
mod debug;
mod expression;
mod multi;
mod sequence;
#[cfg(test)]
mod tests;
pub mod impls;
pub use self::branch::*;
pub use self::core::*;
pub use self::debug::*;
pub use self::expression::*;
pub use self::multi::*;
pub use self::sequence::*;
#[allow(unused_imports)]
use crate::Parser;
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use crate::combinator::trace;
use crate::error::ParserError;
use crate::stream::Stream;
use crate::*;
#[doc(inline)]
pub use crate::seq;
#[doc(inline)]
pub use crate::unordered_seq;
/// Sequence two parsers, only returning the output from the second.
///
/// See also [`seq`] to generalize this across any number of fields.
///
/// # Example
///
/// ```rust
/// # use winnow::{error::ErrMode, error::Needed};
/// # use winnow::prelude::*;
/// # use winnow::error::Needed::Size;
/// use winnow::combinator::preceded;
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<&'i str> {
/// preceded("abc", "efg").parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("abcefg"), Ok(("", "efg")));
/// assert_eq!(parser.parse_peek("abcefghij"), Ok(("hij", "efg")));
/// assert!(parser.parse_peek("").is_err());
/// assert!(parser.parse_peek("123").is_err());
/// ```
#[doc(alias = "ignore_then")]
pub fn preceded<Input, Ignored, Output, Error, IgnoredParser, ParseNext>(
mut ignored: IgnoredParser,
mut parser: ParseNext,
) -> impl Parser<Input, Output, Error>
where
Input: Stream,
Error: ParserError<Input>,
IgnoredParser: Parser<Input, Ignored, Error>,
ParseNext: Parser<Input, Output, Error>,
{
trace("preceded", move |input: &mut Input| {
let _ = ignored.parse_next(input)?;
parser.parse_next(input)
})
}
/// Sequence two parsers, only returning the output of the first.
///
/// See also [`seq`] to generalize this across any number of fields.
///
/// # Example
///
/// ```rust
/// # use winnow::{error::ErrMode, error::Needed};
/// # use winnow::prelude::*;
/// # use winnow::error::Needed::Size;
/// use winnow::combinator::terminated;
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<&'i str> {
/// terminated("abc", "efg").parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("abcefg"), Ok(("", "abc")));
/// assert_eq!(parser.parse_peek("abcefghij"), Ok(("hij", "abc")));
/// assert!(parser.parse_peek("").is_err());
/// assert!(parser.parse_peek("123").is_err());
/// ```
#[doc(alias = "then_ignore")]
pub fn terminated<Input, Output, Ignored, Error, ParseNext, IgnoredParser>(
mut parser: ParseNext,
mut ignored: IgnoredParser,
) -> impl Parser<Input, Output, Error>
where
Input: Stream,
Error: ParserError<Input>,
ParseNext: Parser<Input, Output, Error>,
IgnoredParser: Parser<Input, Ignored, Error>,
{
trace("terminated", move |input: &mut Input| {
let o = parser.parse_next(input)?;
ignored.parse_next(input).map(|_| o)
})
}
/// Sequence three parsers, only returning the values of the first and third.
///
/// See also [`seq`] to generalize this across any number of fields.
///
/// # Example
///
/// ```rust
/// # use winnow::{error::ErrMode, error::Needed};
/// # use winnow::error::Needed::Size;
/// # use winnow::prelude::*;
/// use winnow::combinator::separated_pair;
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<(&'i str, &'i str)> {
/// separated_pair("abc", "|", "efg").parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("abc|efg"), Ok(("", ("abc", "efg"))));
/// assert_eq!(parser.parse_peek("abc|efghij"), Ok(("hij", ("abc", "efg"))));
/// assert!(parser.parse_peek("").is_err());
/// assert!(parser.parse_peek("123").is_err());
/// ```
pub fn separated_pair<Input, O1, Sep, O2, Error, P1, SepParser, P2>(
mut first: P1,
mut sep: SepParser,
mut second: P2,
) -> impl Parser<Input, (O1, O2), Error>
where
Input: Stream,
Error: ParserError<Input>,
P1: Parser<Input, O1, Error>,
SepParser: Parser<Input, Sep, Error>,
P2: Parser<Input, O2, Error>,
{
trace("separated_pair", move |input: &mut Input| {
let o1 = first.parse_next(input)?;
let _ = sep.parse_next(input)?;
second.parse_next(input).map(|o2| (o1, o2))
})
}
/// Sequence three parsers, only returning the output of the second.
///
/// See also [`seq`] to generalize this across any number of fields.
///
/// # Example
///
/// ```rust
/// # use winnow::{error::ErrMode, error::Needed};
/// # use winnow::error::Needed::Size;
/// # use winnow::prelude::*;
/// use winnow::combinator::delimited;
///
/// fn parser<'i>(input: &mut &'i str) -> ModalResult<&'i str> {
/// delimited("(", "abc", ")").parse_next(input)
/// }
///
/// assert_eq!(parser.parse_peek("(abc)"), Ok(("", "abc")));
/// assert_eq!(parser.parse_peek("(abc)def"), Ok(("def", "abc")));
/// assert!(parser.parse_peek("").is_err());
/// assert!(parser.parse_peek("123").is_err());
/// ```
#[doc(alias = "between")]
#[doc(alias = "padded")]
pub fn delimited<
Input,
Ignored1,
Output,
Ignored2,
Error,
IgnoredParser1,
ParseNext,
IgnoredParser2,
>(
mut ignored1: IgnoredParser1,
mut parser: ParseNext,
mut ignored2: IgnoredParser2,
) -> impl Parser<Input, Output, Error>
where
Input: Stream,
Error: ParserError<Input>,
IgnoredParser1: Parser<Input, Ignored1, Error>,
ParseNext: Parser<Input, Output, Error>,
IgnoredParser2: Parser<Input, Ignored2, Error>,
{
trace("delimited", move |input: &mut Input| {
let _ = ignored1.parse_next(input)?;
let o2 = parser.parse_next(input)?;
ignored2.parse_next(input).map(|_| o2)
})
}
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