| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/combine-4.6.6/src/parser/choice.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>choice.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../combine/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../combine/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| <span id="848">848</span> |
| <span id="849">849</span> |
| </pre><pre class="rust"><code><span class="doccomment">//! Combinators which take one or more parsers and attempts to parse successfully with at least one |
| //! of them. |
| |
| </span><span class="kw">use crate</span>::{ |
| error::{ |
| ParseError, |
| ParseResult::{<span class="self">self</span>, <span class="kw-2">*</span>}, |
| ResultExt, StreamError, Tracked, |
| }, |
| parser::ParseMode, |
| ErrorOffset, Parser, Stream, StreamOnce, |
| }; |
| |
| <span class="doccomment">/// Takes a number of parsers and tries to apply them each in order. |
| /// Fails if all the parsers fails or if an applied parser fails after it has committed to its |
| /// parse. |
| /// |
| /// ``` |
| /// # #[macro_use] |
| /// # extern crate combine; |
| /// # use combine::*; |
| /// # use combine::parser::char::{digit, letter, string}; |
| /// # use combine::stream::easy::Error; |
| /// # fn main() { |
| /// let mut parser = choice!( |
| /// many1(digit()), |
| /// string("let").map(|s| s.to_string()), |
| /// many1(letter())); |
| /// assert_eq!(parser.parse("let"), Ok(("let".to_string(), ""))); |
| /// assert_eq!(parser.parse("123abc"), Ok(("123".to_string(), "abc"))); |
| /// assert!(parser.parse(":123").is_err()); |
| /// # } |
| /// ``` |
| </span><span class="attribute">#[macro_export] |
| </span><span class="macro">macro_rules! </span>choice { |
| (<span class="macro-nonterminal">$first </span>: expr) => { |
| <span class="macro-nonterminal">$first |
| </span>}; |
| (<span class="macro-nonterminal">$first </span>: expr, $(<span class="macro-nonterminal">$rest </span>: expr),+) => { |
| <span class="macro-nonterminal">$first</span>.or(<span class="macro">choice!</span>($(<span class="macro-nonterminal">$rest</span>),+)) |
| } |
| } |
| |
| <span class="attribute">#[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>parse_mode_choice { |
| (Input) => { |
| <span class="kw">fn </span>parse_partial( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> { |
| <span class="self">self</span>.parse_mode_choice(<span class="macro-nonterminal">$crate::parser::PartialMode::default</span>(), input, state) |
| } |
| |
| <span class="kw">fn </span>parse_first( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, Input::Error> { |
| <span class="self">self</span>.parse_mode_choice(<span class="macro-nonterminal">$crate::parser::FirstMode</span>, input, state) |
| } |
| }; |
| } |
| |
| <span class="doccomment">/// `ChoiceParser` represents a parser which may parse one of several different choices depending |
| /// on the input. |
| /// |
| /// This is an internal trait used to overload the `choice` function. |
| </span><span class="kw">pub trait </span>ChoiceParser<Input: Stream> { |
| <span class="kw">type </span>Output; |
| <span class="kw">type </span>PartialState: Default; |
| |
| <span class="kw">fn </span>parse_first( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error>; |
| |
| <span class="kw">fn </span>parse_partial( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error>; |
| |
| <span class="kw">fn </span>parse_mode_choice<M>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| mode: M, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>M: ParseMode, |
| <span class="self">Self</span>: Sized; |
| |
| <span class="kw">fn </span>add_error_choice(<span class="kw-2">&mut </span><span class="self">self</span>, error: <span class="kw-2">&mut </span>Tracked<<Input <span class="kw">as </span>StreamOnce>::Error>); |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, Input, P> ChoiceParser<Input> <span class="kw">for </span><span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>P |
| <span class="kw">where |
| </span>Input: Stream, |
| P: <span class="question-mark">?</span>Sized + ChoiceParser<Input>, |
| { |
| <span class="kw">type </span>Output = P::Output; |
| <span class="kw">type </span>PartialState = P::PartialState; |
| |
| <span class="macro">parse_mode_choice!</span>(Input); |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_mode_choice<M>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| mode: M, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>M: ParseMode, |
| { |
| <span class="kw">if </span>mode.is_first() { |
| (<span class="kw-2">**</span><span class="self">self</span>).parse_first(input, state) |
| } <span class="kw">else </span>{ |
| (<span class="kw-2">**</span><span class="self">self</span>).parse_partial(input, state) |
| } |
| } |
| |
| <span class="kw">fn </span>add_error_choice(<span class="kw-2">&mut </span><span class="self">self</span>, error: <span class="kw-2">&mut </span>Tracked<<Input <span class="kw">as </span>StreamOnce>::Error>) { |
| (<span class="kw-2">**</span><span class="self">self</span>).add_error_choice(error) |
| } |
| } |
| |
| <span class="macro">macro_rules! </span>merge { |
| (<span class="macro-nonterminal">$head</span>: ident) => { |
| <span class="macro-nonterminal">$head</span>.error |
| }; |
| (<span class="macro-nonterminal">$head</span>: ident $(<span class="macro-nonterminal">$tail</span>: ident)+) => { |
| <span class="macro-nonterminal">$head</span>.error.merge(<span class="macro">merge!</span>($(<span class="macro-nonterminal">$tail</span>)+)) |
| }; |
| } |
| |
| <span class="macro">macro_rules! </span>do_choice { |
| ( |
| <span class="macro-nonterminal">$input</span>: ident |
| <span class="macro-nonterminal">$before_position</span>: ident |
| <span class="macro-nonterminal">$before</span>: ident |
| <span class="macro-nonterminal">$partial_state</span>: ident |
| <span class="macro-nonterminal">$state</span>: ident |
| ( ) |
| $(<span class="macro-nonterminal">$parser</span>: ident <span class="macro-nonterminal">$error</span>: ident)+ |
| ) => { { |
| <span class="kw">let </span><span class="kw-2">mut </span>error = Tracked::from(<span class="macro">merge!</span>($(<span class="macro-nonterminal">$error</span>)+)); |
| <span class="comment">// If offset != 1 then the nested parser is a sequence of parsers where 1 or |
| // more parsers returned `PeekOk` before the parser finally failed with |
| // `PeekErr`. Since we lose the offsets of the nested parsers when we merge |
| // the errors we must first extract the errors before we do the merge. |
| // If the offset == 0 on the other hand (which should be the common case) then |
| // we can delay the addition of the error since we know for certain that only |
| // the first parser in the sequence were tried |
| </span>$( |
| <span class="kw">if </span><span class="macro-nonterminal">$error</span>.offset != ErrorOffset(<span class="number">1</span>) { |
| error.offset = <span class="macro-nonterminal">$error</span>.offset; |
| <span class="macro-nonterminal">$parser</span>.add_error(<span class="kw-2">&mut </span>error); |
| error.offset = ErrorOffset(<span class="number">0</span>); |
| } |
| )+ |
| PeekErr(error) |
| } }; |
| ( |
| <span class="macro-nonterminal">$input</span>: ident |
| <span class="macro-nonterminal">$before_position</span>: ident |
| <span class="macro-nonterminal">$before</span>: ident |
| <span class="macro-nonterminal">$partial_state</span>: ident |
| <span class="macro-nonterminal">$state</span>: ident |
| ( <span class="macro-nonterminal">$head</span>: ident $(<span class="macro-nonterminal">$tail</span>: ident)* ) |
| $(<span class="macro-nonterminal">$all</span>: ident)* |
| ) => { { |
| <span class="kw">let </span>parser = <span class="macro-nonterminal">$head</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>state = <span class="macro-nonterminal">$head::PartialState::default</span>(); |
| <span class="kw">match </span>parser.parse_mode(<span class="kw">crate</span>::parser::FirstMode, <span class="macro-nonterminal">$input</span>, <span class="kw-2">&mut </span>state) { |
| CommitOk(x) => CommitOk(x), |
| PeekOk(x) => PeekOk(x), |
| CommitErr(err) => { |
| <span class="comment">// If we get `CommitErr` but the input is the same this is a partial parse we |
| // cannot commit to so leave the state as `Peek` to retry all the parsers |
| // on the next call to `parse_partial` |
| </span><span class="kw">if </span><span class="macro-nonterminal">$input</span>.position() != <span class="macro-nonterminal">$before_position </span>{ |
| <span class="kw-2">*</span><span class="macro-nonterminal">$state </span>= <span class="self">self</span>::<span class="macro-nonterminal">$partial_state</span>::<span class="macro-nonterminal">$head</span>(state); |
| } |
| CommitErr(err) |
| } |
| PeekErr(<span class="macro-nonterminal">$head</span>) => { |
| <span class="macro">ctry!</span>(<span class="macro-nonterminal">$input</span>.reset(<span class="macro-nonterminal">$before</span>.clone()).committed()); |
| <span class="macro">do_choice!</span>( |
| <span class="macro-nonterminal">$input |
| $before_position |
| $before |
| $partial_state |
| $state |
| </span>( $(<span class="macro-nonterminal">$tail</span>)* ) |
| $(<span class="macro-nonterminal">$all</span>)* |
| parser |
| <span class="macro-nonterminal">$head |
| </span>) |
| } |
| } |
| } } |
| } |
| |
| <span class="macro">macro_rules! </span>tuple_choice_parser { |
| (<span class="macro-nonterminal">$head</span>: ident) => { |
| <span class="macro">tuple_choice_parser_inner!</span>(<span class="macro-nonterminal">$head</span>; <span class="macro-nonterminal">$head</span>); |
| }; |
| (<span class="macro-nonterminal">$head</span>: ident $(<span class="macro-nonterminal">$id</span>: ident)+) => { |
| <span class="macro">tuple_choice_parser_inner!</span>(<span class="macro-nonterminal">$head</span>; <span class="macro-nonterminal">$head </span>$(<span class="macro-nonterminal">$id</span>)+); |
| <span class="macro">tuple_choice_parser!</span>($(<span class="macro-nonterminal">$id</span>)+); |
| }; |
| } |
| |
| <span class="macro">macro_rules! </span>tuple_choice_parser_inner { |
| (<span class="macro-nonterminal">$partial_state</span>: ident; $(<span class="macro-nonterminal">$id</span>: ident)+) => { |
| <span class="attribute">#[doc(hidden)] |
| </span><span class="kw">pub enum </span><span class="macro-nonterminal">$partial_state</span><$(<span class="macro-nonterminal">$id</span>),+> { |
| Peek, |
| $( |
| <span class="macro-nonterminal">$id</span>(<span class="macro-nonterminal">$id</span>), |
| )+ |
| } |
| |
| <span class="kw">impl</span><$(<span class="macro-nonterminal">$id</span>),+> Default <span class="kw">for </span><span class="self">self</span>::<span class="macro-nonterminal">$partial_state</span><$(<span class="macro-nonterminal">$id</span>),+> { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| <span class="self">self</span>::<span class="macro-nonterminal">$partial_state::Peek |
| </span>} |
| } |
| |
| <span class="attribute">#[allow(non_snake_case)] |
| </span><span class="kw">impl</span><Input, Output $(,<span class="macro-nonterminal">$id</span>)+> ChoiceParser<Input> <span class="kw">for </span>($(<span class="macro-nonterminal">$id</span>,)+) |
| <span class="kw">where |
| </span>Input: Stream, |
| $(<span class="macro-nonterminal">$id</span>: Parser< Input, Output = Output>),+ |
| { |
| |
| <span class="kw">type </span>Output = Output; |
| <span class="kw">type </span>PartialState = <span class="self">self</span>::<span class="macro-nonterminal">$partial_state</span><$(<span class="macro-nonterminal">$id::PartialState</span>),+>; |
| |
| <span class="macro">parse_mode_choice!</span>(Input); |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_mode_choice<Mode>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| mode: Mode, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>Mode: ParseMode, |
| { |
| <span class="kw">let </span>($(<span class="kw-2">ref mut </span><span class="macro-nonterminal">$id</span>,)+) = <span class="kw-2">*</span><span class="self">self</span>; |
| <span class="kw">let </span>empty = <span class="kw">match </span><span class="kw-2">*</span>state { |
| <span class="self">self</span>::<span class="macro-nonterminal">$partial_state::Peek </span>=> <span class="bool-val">true</span>, |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| }; |
| <span class="kw">if </span>mode.is_first() || empty { |
| <span class="kw">let </span>before_position = input.position(); |
| <span class="kw">let </span>before = input.checkpoint(); |
| <span class="macro">do_choice!</span>(input before_position before <span class="macro-nonterminal">$partial_state </span>state ( $(<span class="macro-nonterminal">$id</span>)+ ) ) |
| } <span class="kw">else </span>{ |
| <span class="kw">match </span><span class="kw-2">*</span>state { |
| <span class="self">self</span>::<span class="macro-nonterminal">$partial_state::Peek </span>=> <span class="macro">unreachable!</span>(), |
| $( |
| <span class="self">self</span>::<span class="macro-nonterminal">$partial_state</span>::<span class="macro-nonterminal">$id</span>(<span class="kw">_</span>) => { |
| <span class="kw">let </span>result = <span class="kw">match </span><span class="kw-2">*</span>state { |
| <span class="self">self</span>::<span class="macro-nonterminal">$partial_state</span>::<span class="macro-nonterminal">$id</span>(<span class="kw-2">ref mut </span>state) => { |
| <span class="macro-nonterminal">$id</span>.parse_mode(mode, input, state) |
| } |
| <span class="kw">_ </span>=> <span class="macro">unreachable!</span>() |
| }; |
| <span class="kw">if </span>result.is_ok() { |
| <span class="kw-2">*</span>state = <span class="self">self</span>::<span class="macro-nonterminal">$partial_state::Peek</span>; |
| } |
| result |
| } |
| )+ |
| } |
| } |
| } |
| |
| <span class="kw">fn </span>add_error_choice( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| error: <span class="kw-2">&mut </span>Tracked<<Input <span class="kw">as </span>StreamOnce>::Error> |
| ) { |
| <span class="kw">if </span>error.offset != ErrorOffset(<span class="number">0</span>) { |
| <span class="kw">let </span>($(<span class="kw-2">ref mut </span><span class="macro-nonterminal">$id</span>,)+) = <span class="kw-2">*</span><span class="self">self</span>; |
| <span class="comment">// Reset the offset to 1 on every add so that we always (and only) takes the |
| // error of the first parser. If we don't do this the first parser will consume |
| // the offset to the detriment for all the other parsers. |
| </span>$( |
| error.offset = ErrorOffset(<span class="number">1</span>); |
| <span class="macro-nonterminal">$id</span>.add_error(error); |
| )+ |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="macro">tuple_choice_parser!</span>(A B C D E F G H I J K L M N O P Q R S T U V X Y Z); |
| |
| <span class="macro">macro_rules! </span>array_choice_parser { |
| ($(<span class="macro-nonterminal">$t</span>: tt)+) => { |
| $( |
| <span class="kw">impl</span><Input, P> ChoiceParser<Input> <span class="kw">for </span>[P; <span class="macro-nonterminal">$t</span>] |
| <span class="kw">where |
| </span>Input: Stream, |
| P: Parser<Input>, |
| { |
| |
| <span class="kw">type </span>Output = P::Output; |
| <span class="kw">type </span>PartialState = <[P] <span class="kw">as </span>ChoiceParser<Input>>::PartialState; |
| |
| <span class="macro">parse_mode_choice!</span>(Input); |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_mode_choice<M>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| mode: M, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>M: ParseMode, |
| { |
| <span class="kw">if </span>mode.is_first() { |
| <span class="self">self</span>[..].parse_first(input, state) |
| } <span class="kw">else </span>{ |
| <span class="self">self</span>[..].parse_partial(input, state) |
| } |
| } |
| <span class="kw">fn </span>add_error_choice( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| error: <span class="kw-2">&mut </span>Tracked<<Input <span class="kw">as </span>StreamOnce>::Error> |
| ) { |
| <span class="self">self</span>[..].add_error_choice(error) |
| } |
| } |
| )+ |
| }; |
| } |
| |
| <span class="attribute">#[rustfmt::skip] |
| </span><span class="macro">array_choice_parser!</span>( |
| <span class="number">0 1 2 3 4 5 6 7 8 9 |
| 10 11 12 13 14 15 16 17 18 19 |
| 20 21 22 23 24 25 26 27 28 29 |
| 30 31 32 |
| </span>); |
| |
| <span class="attribute">#[derive(Copy, Clone)] |
| </span><span class="kw">pub struct </span>Choice<P>(P); |
| |
| <span class="kw">impl</span><Input, P> Parser<Input> <span class="kw">for </span>Choice<P> |
| <span class="kw">where |
| </span>Input: Stream, |
| P: ChoiceParser<Input>, |
| { |
| <span class="kw">type </span>Output = P::Output; |
| <span class="kw">type </span>PartialState = P::PartialState; |
| |
| <span class="macro">parse_mode!</span>(Input); |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_mode_impl<M>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| mode: M, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>M: ParseMode, |
| { |
| <span class="self">self</span>.<span class="number">0</span>.parse_mode_choice(mode, input, state) |
| } |
| |
| <span class="kw">fn </span>add_error(<span class="kw-2">&mut </span><span class="self">self</span>, error: <span class="kw-2">&mut </span>Tracked<<Input <span class="kw">as </span>StreamOnce>::Error>) { |
| <span class="kw">let </span>before = error.offset.<span class="number">0</span>; |
| <span class="self">self</span>.<span class="number">0</span>.add_error_choice(error); |
| error.offset.<span class="number">0 </span>= before.saturating_sub(<span class="number">1</span>); |
| } |
| } |
| |
| <span class="kw">fn </span>slice_parse_mode<Input, P, M>( |
| self_: <span class="kw-2">&mut </span>[P], |
| mode: M, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span>(usize, P::PartialState), |
| ) -> ParseResult<P::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>P: Parser<Input>, |
| Input: Stream, |
| M: ParseMode, |
| { |
| <span class="kw">let </span><span class="kw-2">mut </span>prev_err = <span class="prelude-val">None</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>last_parser_having_non_1_offset = <span class="number">0</span>; |
| <span class="kw">let </span>before = input.checkpoint(); |
| |
| <span class="kw">let </span>(<span class="kw-2">ref mut </span>index_state, <span class="kw-2">ref mut </span>child_state) = <span class="kw-2">*</span>state; |
| <span class="kw">if </span>!mode.is_first() && <span class="kw-2">*</span>index_state != <span class="number">0 </span>{ |
| <span class="kw">return </span>self_[<span class="kw-2">*</span>index_state - <span class="number">1</span>] |
| .parse_partial(input, child_state) |
| .map(|x| { |
| <span class="kw-2">*</span>index_state = <span class="number">0</span>; |
| x |
| }); |
| } |
| |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..self_.len() { |
| <span class="macro">ctry!</span>(input.reset(before.clone()).committed()); |
| |
| <span class="kw">match </span>self_[i].parse_mode(mode, input, child_state) { |
| committed_err @ CommitErr(<span class="kw">_</span>) => { |
| <span class="kw-2">*</span>index_state = i + <span class="number">1</span>; |
| <span class="kw">return </span>committed_err; |
| } |
| PeekErr(err) => { |
| prev_err = <span class="kw">match </span>prev_err { |
| <span class="prelude-val">None </span>=> <span class="prelude-val">Some</span>(err), |
| <span class="prelude-val">Some</span>(<span class="kw-2">mut </span>prev_err) => { |
| <span class="kw">if </span>prev_err.offset != ErrorOffset(<span class="number">1</span>) { |
| <span class="comment">// First add the errors of all the preceding parsers which did not |
| // have a sequence of parsers returning `PeekOk` before failing |
| // with `PeekErr`. |
| </span><span class="kw">let </span>offset = prev_err.offset; |
| <span class="kw">for </span>p <span class="kw">in </span><span class="kw-2">&mut </span>self_[last_parser_having_non_1_offset..(i - <span class="number">1</span>)] { |
| prev_err.offset = ErrorOffset(<span class="number">1</span>); |
| p.add_error(<span class="kw-2">&mut </span>prev_err); |
| } |
| <span class="comment">// Then add the errors if the current parser |
| </span>prev_err.offset = offset; |
| self_[i - <span class="number">1</span>].add_error(<span class="kw-2">&mut </span>prev_err); |
| last_parser_having_non_1_offset = i; |
| } |
| <span class="prelude-val">Some</span>(Tracked { |
| error: prev_err.error.merge(err.error), |
| offset: err.offset, |
| }) |
| } |
| }; |
| } |
| ok @ CommitOk(<span class="kw">_</span>) | ok @ PeekOk(<span class="kw">_</span>) => { |
| <span class="kw-2">*</span>index_state = <span class="number">0</span>; |
| <span class="kw">return </span>ok; |
| } |
| } |
| } |
| PeekErr(<span class="kw">match </span>prev_err { |
| <span class="prelude-val">None </span>=> Input::Error::from_error( |
| input.position(), |
| StreamError::message_static_message(<span class="string">"parser choice is empty"</span>), |
| ) |
| .into(), |
| <span class="prelude-val">Some</span>(<span class="kw-2">mut </span>prev_err) => { |
| <span class="kw">if </span>prev_err.offset != ErrorOffset(<span class="number">1</span>) { |
| <span class="kw">let </span>offset = prev_err.offset; |
| <span class="kw">let </span>len = self_.len(); |
| <span class="kw">for </span>p <span class="kw">in </span><span class="kw-2">&mut </span>self_[last_parser_having_non_1_offset..(len - <span class="number">1</span>)] { |
| prev_err.offset = ErrorOffset(<span class="number">1</span>); |
| p.add_error(<span class="kw-2">&mut </span>prev_err); |
| } |
| prev_err.offset = offset; |
| self_.last_mut().unwrap().add_error(<span class="kw-2">&mut </span>prev_err); |
| prev_err.offset = ErrorOffset(<span class="number">0</span>); |
| } |
| prev_err |
| } |
| }) |
| } |
| |
| <span class="kw">impl</span><Input, O, P> ChoiceParser<Input> <span class="kw">for </span>[P] |
| <span class="kw">where |
| </span>Input: Stream, |
| P: Parser<Input, Output = O>, |
| { |
| <span class="kw">type </span>Output = O; |
| <span class="kw">type </span>PartialState = (usize, P::PartialState); |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_partial( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> { |
| slice_parse_mode(<span class="self">self</span>, <span class="kw">crate</span>::parser::PartialMode::default(), input, state) |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_first( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> { |
| slice_parse_mode(<span class="self">self</span>, <span class="kw">crate</span>::parser::FirstMode, input, state) |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_mode_choice<M>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| _mode: M, |
| _input: <span class="kw-2">&mut </span>Input, |
| _state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>M: ParseMode, |
| { |
| <span class="macro">unreachable!</span>() |
| } |
| |
| <span class="kw">fn </span>add_error_choice(<span class="kw-2">&mut </span><span class="self">self</span>, error: <span class="kw-2">&mut </span>Tracked<<Input <span class="kw">as </span>StreamOnce>::Error>) { |
| <span class="kw">if </span>error.offset != ErrorOffset(<span class="number">0</span>) { |
| <span class="kw">for </span>p <span class="kw">in </span><span class="self">self </span>{ |
| error.offset = ErrorOffset(<span class="number">1</span>); |
| p.add_error(error); |
| } |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Takes a tuple, a slice or an array of parsers and tries to apply them each in order. |
| /// Fails if all the parsers fails or if an applied parser consumes input before failing. |
| /// |
| /// ``` |
| /// # extern crate combine; |
| /// # use combine::*; |
| /// # use combine::parser::char::{digit, string}; |
| /// # fn main() { |
| /// // `choice` is overloaded on tuples so that different types of parsers can be used |
| /// // (each parser must still have the same input and output types) |
| /// let mut parser = choice(( |
| /// string("Apple").map(|s| s.to_string()), |
| /// many1(digit()), |
| /// string("Orange").map(|s| s.to_string()), |
| /// )); |
| /// assert_eq!(parser.parse("1234"), Ok(("1234".to_string(), ""))); |
| /// assert_eq!(parser.parse("Orangexx"), Ok(("Orange".to_string(), "xx"))); |
| /// assert!(parser.parse("Appl").is_err()); |
| /// assert!(parser.parse("Pear").is_err()); |
| /// |
| /// // If arrays or slices are used then all parsers must have the same type |
| /// // (`string` in this case) |
| /// let mut parser2 = choice([string("one"), string("two"), string("three")]); |
| /// // Fails as the parser for "two" consumes the first 't' before failing |
| /// assert!(parser2.parse("three").is_err()); |
| /// |
| /// // Use 'attempt' to make failing parsers always act as if they have not committed any input |
| /// let mut parser3 = choice([attempt(string("one")), attempt(string("two")), attempt(string("three"))]); |
| /// assert_eq!(parser3.parse("three"), Ok(("three", ""))); |
| /// # } |
| /// ``` |
| </span><span class="kw">pub fn </span>choice<Input, P>(ps: P) -> Choice<P> |
| <span class="kw">where |
| </span>Input: Stream, |
| P: ChoiceParser<Input>, |
| { |
| Choice(ps) |
| } |
| |
| <span class="attribute">#[derive(Copy, Clone)] |
| </span><span class="kw">pub struct </span>Or<P1, P2>(Choice<(P1, P2)>); |
| <span class="kw">impl</span><Input, O, P1, P2> Parser<Input> <span class="kw">for </span>Or<P1, P2> |
| <span class="kw">where |
| </span>Input: Stream, |
| P1: Parser<Input, Output = O>, |
| P2: Parser<Input, Output = O>, |
| { |
| <span class="kw">type </span>Output = O; |
| <span class="kw">type </span>PartialState = <Choice<(P1, P2)> <span class="kw">as </span>Parser<Input>>::PartialState; |
| |
| <span class="macro">parse_mode!</span>(Input); |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_mode_impl<M>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| mode: M, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>M: ParseMode, |
| { |
| <span class="self">self</span>.<span class="number">0</span>.parse_mode(mode, input, state) |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>add_error(<span class="kw-2">&mut </span><span class="self">self</span>, errors: <span class="kw-2">&mut </span>Tracked<<Input <span class="kw">as </span>StreamOnce>::Error>) { |
| <span class="kw">if </span>errors.offset != ErrorOffset(<span class="number">0</span>) { |
| <span class="self">self</span>.<span class="number">0</span>.add_error(errors); |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Equivalent to [`p1.or(p2)`]. |
| /// |
| /// If you are looking to chain 3 or more parsers using `or` you may consider using the |
| /// [`choice!`] macro instead, which can be clearer and may result in a faster parser. |
| /// |
| /// ``` |
| /// # extern crate combine; |
| /// # use combine::*; |
| /// # use combine::parser::choice::or; |
| /// # use combine::parser::char::{digit, string}; |
| /// # fn main() { |
| /// let mut parser = or( |
| /// string("let"), |
| /// or(digit().map(|_| "digit"), string("led")), |
| /// ); |
| /// assert_eq!(parser.parse("let"), Ok(("let", ""))); |
| /// assert_eq!(parser.parse("1"), Ok(("digit", ""))); |
| /// assert!(parser.parse("led").is_err()); |
| /// |
| /// let mut parser2 = or(string("two"), string("three")); |
| /// // Fails as the parser for "two" consumes the first 't' before failing |
| /// assert!(parser2.parse("three").is_err()); |
| /// |
| /// // Use 'attempt' to make failing parsers always act as if they have not committed any input |
| /// let mut parser3 = or(attempt(string("two")), attempt(string("three"))); |
| /// assert_eq!(parser3.parse("three"), Ok(("three", ""))); |
| /// # } |
| /// ``` |
| /// |
| /// [`choice!`]: ../../macro.choice.html |
| /// [`p1.or(p2)`]: ../trait.Parser.html#method.or |
| </span><span class="kw">pub fn </span>or<Input, P1, P2>(p1: P1, p2: P2) -> Or<P1, P2> |
| <span class="kw">where |
| </span>Input: Stream, |
| P1: Parser<Input>, |
| P2: Parser<Input, Output = P1::Output>, |
| { |
| Or(choice((p1, p2))) |
| } |
| |
| <span class="attribute">#[derive(Copy, Clone)] |
| </span><span class="kw">pub struct </span>Optional<P>(P); |
| <span class="kw">impl</span><Input, P> Parser<Input> <span class="kw">for </span>Optional<P> |
| <span class="kw">where |
| </span>Input: Stream, |
| P: Parser<Input>, |
| { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Option</span><P::Output>; |
| <span class="kw">type </span>PartialState = P::PartialState; |
| |
| <span class="macro">parse_mode!</span>(Input); |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>parse_mode_impl<M>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| mode: M, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> |
| <span class="kw">where |
| </span>M: ParseMode, |
| { |
| <span class="kw">let </span>before = input.checkpoint(); |
| <span class="kw">match </span><span class="self">self</span>.<span class="number">0</span>.parse_mode(mode, input, state) { |
| PeekOk(x) => PeekOk(<span class="prelude-val">Some</span>(x)), |
| CommitOk(x) => CommitOk(<span class="prelude-val">Some</span>(x)), |
| CommitErr(err) => CommitErr(err), |
| PeekErr(<span class="kw">_</span>) => { |
| <span class="macro">ctry!</span>(input.reset(before).committed()); |
| PeekOk(<span class="prelude-val">None</span>) |
| } |
| } |
| } |
| |
| <span class="macro">forward_parser!</span>(Input, add_error parser_count, <span class="number">0</span>); |
| } |
| |
| <span class="doccomment">/// Parses `parser` and outputs `Some(value)` if it succeeds, `None` if it fails without |
| /// consuming any input. Fails if `parser` fails after having committed some input. |
| /// |
| /// ``` |
| /// # extern crate combine; |
| /// # use combine::*; |
| /// # use combine::parser::char::string; |
| /// # fn main() { |
| /// let mut parser = optional(string("hello")); |
| /// assert_eq!(parser.parse("hello"), Ok((Some("hello"), ""))); |
| /// assert_eq!(parser.parse("world"), Ok((None, "world"))); |
| /// assert!(parser.parse("heya").is_err()); |
| /// # } |
| /// ``` |
| </span><span class="kw">pub fn </span>optional<Input, P>(parser: P) -> Optional<P> |
| <span class="kw">where |
| </span>Input: Stream, |
| P: Parser<Input>, |
| { |
| Optional(parser) |
| } |
| |
| <span class="attribute">#[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>parse_mode_dispatch { |
| () => { |
| <span class="kw">fn </span>parse_partial( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> { |
| <span class="self">self</span>.parse_mode_dispatch(<span class="macro-nonterminal">$crate::parser::PartialMode::default</span>(), input, state) |
| } |
| |
| <span class="kw">fn </span>parse_first( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> ParseResult<<span class="self">Self</span>::Output, <Input <span class="kw">as </span>StreamOnce>::Error> { |
| <span class="self">self</span>.parse_mode_dispatch(<span class="macro-nonterminal">$crate::parser::FirstMode</span>, input, state) |
| } |
| }; |
| } |
| |
| <span class="attribute">#[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>dispatch_parser_impl { |
| (<span class="macro-nonterminal">$parser_name</span>: ident [<span class="macro-nonterminal">$first_ident</span>: ident $(<span class="macro-nonterminal">$id</span>: ident)<span class="kw-2">*</span>] [$(<span class="macro-nonterminal">$collected_idents</span>: ident)<span class="kw-2">*</span>] <span class="macro-nonterminal">$expr</span>: expr, $(<span class="macro-nonterminal">$rest</span>: expr,)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::dispatch_parser_impl!</span>{ <span class="macro-nonterminal">$parser_name </span>[ $(<span class="macro-nonterminal">$id</span>)* ] [$(<span class="macro-nonterminal">$collected_idents</span>)* <span class="macro-nonterminal">$first_ident</span>] $(<span class="macro-nonterminal">$rest</span>,)<span class="kw-2">*</span>} |
| }; |
| (<span class="macro-nonterminal">$parser_name</span>: ident [$(<span class="macro-nonterminal">$id</span>: ident)<span class="kw-2">*</span>] [$(<span class="macro-nonterminal">$collected_idents</span>: ident)<span class="kw-2">*</span>]) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::dispatch_parser_impl!</span>{ <span class="macro-nonterminal">$parser_name</span>; $(<span class="macro-nonterminal">$collected_idents</span>)* } |
| }; |
| |
| (<span class="macro-nonterminal">$parser_name</span>: ident; $(<span class="macro-nonterminal">$id</span>: ident)<span class="kw-2">*</span>) => { |
| <span class="kw">pub enum </span><span class="macro-nonterminal">$parser_name</span><$(<span class="macro-nonterminal">$id</span>),<span class="kw-2">*</span>> { |
| $( |
| <span class="macro-nonterminal">$id</span>(<span class="macro-nonterminal">$id</span>), |
| )* |
| } |
| |
| <span class="attribute">#[allow(non_snake_case)] |
| </span><span class="kw">impl</span><Input, Output, $(<span class="macro-nonterminal">$id</span>),<span class="kw-2">*</span>> <span class="macro-nonterminal">$crate::Parser</span><Input> <span class="kw">for </span><span class="macro-nonterminal">$parser_name</span><$(<span class="macro-nonterminal">$id</span>),<span class="kw-2">*</span>> |
| <span class="kw">where |
| </span>$( <span class="macro-nonterminal">$id</span>: <span class="macro-nonterminal">$crate::Parser</span><Input, Output = Output>, )* |
| Input: <span class="macro-nonterminal">$crate::Stream</span>, |
| { |
| <span class="kw">type </span>Output = Output; |
| <span class="kw">type </span>PartialState = <span class="prelude-ty">Option</span><<span class="macro-nonterminal">$parser_name</span><$(<span class="macro-nonterminal">$id::PartialState</span>),<span class="kw-2">*</span>>>; |
| |
| <span class="macro-nonterminal">$</span><span class="macro">crate::parse_mode!</span>(<span class="macro-nonterminal">Input</span>); |
| <span class="kw">fn </span>parse_mode<Mode>( |
| <span class="kw-2">&mut </span><span class="self">self</span>, |
| mode: Mode, |
| input: <span class="kw-2">&mut </span>Input, |
| state: <span class="kw-2">&mut </span><span class="self">Self</span>::PartialState, |
| ) -> <span class="macro-nonterminal">$crate::error::ParseResult</span><<span class="self">Self</span>::Output, <Input <span class="kw">as </span><span class="macro-nonterminal">$crate::StreamOnce</span>>::Error> |
| <span class="kw">where |
| </span>Mode: <span class="macro-nonterminal">$crate::parser::ParseMode</span>, |
| { |
| <span class="kw">match </span><span class="self">self </span>{ |
| $( |
| <span class="macro-nonterminal">$parser_name</span>::<span class="macro-nonterminal">$id</span>(<span class="macro-nonterminal">$id</span>) => { |
| <span class="kw">let </span>state = <span class="kw">match </span>state { |
| <span class="prelude-val">Some</span>(<span class="macro-nonterminal">$parser_name</span>::<span class="macro-nonterminal">$id</span>(s)) => s, |
| <span class="kw">_ </span>=> { |
| <span class="kw-2">*</span>state = <span class="prelude-val">Some</span>(<span class="macro-nonterminal">$parser_name</span>::<span class="macro-nonterminal">$id</span>(Default::default())); |
| <span class="kw">match </span>state { |
| <span class="prelude-val">Some</span>(<span class="macro-nonterminal">$parser_name</span>::<span class="macro-nonterminal">$id</span>(s)) => s, |
| <span class="kw">_ </span>=> <span class="macro">unreachable!</span>(), |
| } |
| } |
| }; |
| <span class="macro-nonterminal">$id</span>.parse_mode(mode, input, state) |
| } |
| )* |
| } |
| } |
| |
| <span class="kw">fn </span>add_error(<span class="kw-2">&mut </span><span class="self">self</span>, error: <span class="kw-2">&mut </span><span class="macro-nonterminal">$crate::error::Tracked</span><<Input <span class="kw">as </span><span class="macro-nonterminal">$crate::StreamOnce</span>>::Error>) { |
| <span class="kw">match </span><span class="self">self </span>{ |
| $( |
| <span class="macro-nonterminal">$parser_name</span>::<span class="macro-nonterminal">$id</span>(<span class="macro-nonterminal">$id</span>) => <span class="macro-nonterminal">$id</span>.add_error(error), |
| )* |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>dispatch_inner { |
| (<span class="macro-nonterminal">$expr_ident</span>: ident [<span class="macro-nonterminal">$first_ident</span>: ident $(<span class="macro-nonterminal">$id</span>: ident)<span class="kw-2">*</span>] [$(<span class="macro-nonterminal">$collected</span>: tt)<span class="kw-2">*</span>] $(<span class="macro-nonterminal">$pat</span>: pat)|+ $(<span class="kw">if </span><span class="macro-nonterminal">$pred</span>:expr)<span class="question-mark">? </span>=> <span class="macro-nonterminal">$expr</span>: expr, $(<span class="macro-nonterminal">$rest_alt</span>: tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::dispatch_inner!</span>{ <span class="macro-nonterminal">$expr_ident </span>[ $(<span class="macro-nonterminal">$id</span>)* ] [$(<span class="macro-nonterminal">$collected</span>)* <span class="macro-nonterminal">$first_ident </span>$(<span class="macro-nonterminal">$pat</span>)|+ $(<span class="kw">if </span><span class="macro-nonterminal">$pred</span>)<span class="question-mark">? </span>=> <span class="macro-nonterminal">$expr</span>,] $(<span class="macro-nonterminal">$rest_alt</span>)<span class="kw-2">*</span>} |
| }; |
| (<span class="macro-nonterminal">$expr_ident</span>: ident [$(<span class="macro-nonterminal">$id</span>: ident)<span class="kw-2">*</span>] [$(<span class="macro-nonterminal">$collected</span>: tt)<span class="kw-2">*</span>]) => { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::dispatch_inner!</span>{ <span class="macro-nonterminal">$expr_ident </span>$(<span class="macro-nonterminal">$collected</span>)* } |
| }; |
| (<span class="macro-nonterminal">$expr_ident</span>: ident [$(<span class="macro-nonterminal">$ident_tt</span>: tt)<span class="kw-2">*</span>]) => { |
| <span class="macro">unreachable!</span>() |
| }; |
| (<span class="macro-nonterminal">$expr_ident</span>: ident $( <span class="macro-nonterminal">$ident</span>: ident $(<span class="macro-nonterminal">$pat</span>: pat)|+ $(<span class="kw">if </span><span class="macro-nonterminal">$pred</span>:expr)<span class="question-mark">? </span>=> <span class="macro-nonterminal">$expr</span>: expr,)+ ) => { |
| <span class="kw">match </span><span class="macro-nonterminal">$expr_ident </span>{ |
| $( |
| $(<span class="macro-nonterminal">$pat</span>)|+ $(<span class="kw">if </span><span class="macro-nonterminal">$pred</span>)<span class="question-mark">? </span>=> Dispatch::<span class="macro-nonterminal">$ident</span>(check_parser(<span class="macro-nonterminal">$expr</span>)), |
| )+ |
| } |
| } |
| } |
| |
| <span class="doccomment">/// `dispatch!` allows a parser to be constructed depending on earlier input, without forcing each |
| /// branch to have the same type of parser |
| /// |
| /// ``` |
| /// use combine::{dispatch, any, token, satisfy, EasyParser, Parser}; |
| /// |
| /// let mut parser = any().then(|e| { |
| /// dispatch!(e; |
| /// 'a' => token('a'), |
| /// 'b' => satisfy(|b| b == 'b'), |
| /// t if t == 'c' => any(), |
| /// _ => token('d') |
| /// ) |
| /// }); |
| /// assert_eq!(parser.easy_parse("aa"), Ok(('a', ""))); |
| /// assert_eq!(parser.easy_parse("cc"), Ok(('c', ""))); |
| /// assert_eq!(parser.easy_parse("cd"), Ok(('d', ""))); |
| /// assert!(parser.easy_parse("ab").is_err()); |
| /// ``` |
| </span><span class="attribute">#[macro_export] |
| </span><span class="macro">macro_rules! </span>dispatch { |
| (<span class="macro-nonterminal">$match_expr</span>: expr; $( $(<span class="macro-nonterminal">$pat</span>: pat)|+ $(<span class="kw">if </span><span class="macro-nonterminal">$pred</span>:expr)<span class="question-mark">? </span>=> <span class="macro-nonterminal">$expr</span>: expr ),+ $(,)<span class="question-mark">? </span>) => { |
| { |
| <span class="macro-nonterminal">$</span><span class="macro">crate::dispatch_parser_impl!</span>{ <span class="macro-nonterminal">Dispatch </span>[A B C D E F G H I J K L M N O P Q R S T U V X Y Z] [] $(<span class="macro-nonterminal">$expr</span>,)+ } |
| |
| <span class="kw">fn </span>check_parser<Input, P>(p: P) -> P <span class="kw">where </span>P: <span class="macro-nonterminal">$crate::Parser</span><Input>, Input: <span class="macro-nonterminal">$crate::Stream </span>{ p } |
| |
| <span class="kw">let </span>e = <span class="macro-nonterminal">$match_expr</span>; |
| <span class="kw">let </span>parser = <span class="macro-nonterminal">$</span><span class="macro">crate::dispatch_inner!</span>(<span class="macro-nonterminal">e </span>[A B C D E F G H I J K L M N O P Q R S T U V X Y Z] [] |
| $( |
| $(<span class="macro-nonterminal">$pat</span>)|+ $(<span class="kw">if </span><span class="macro-nonterminal">$pred</span>)<span class="question-mark">? </span>=> <span class="macro-nonterminal">$expr</span>, |
| )* |
| ); |
| parser |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(all(feature = <span class="string">"std"</span>, test))] |
| </span><span class="kw">mod </span>tests { |
| |
| <span class="kw">use </span><span class="kw">crate</span>::parser::{token::any, EasyParser}; |
| |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>choice_single_parser() { |
| <span class="macro">assert!</span>(choice((any(),),).easy_parse(<span class="string">"a"</span>).is_ok()); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="combine" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
