nom/
internal.rs

1//! Basic types to build the parsers
2
3use self::Needed::*;
4use crate::error::{self, ErrorKind, FromExternalError, ParseError};
5use crate::lib::std::fmt;
6use core::marker::PhantomData;
7use core::num::NonZeroUsize;
8
9/// Holds the result of parsing functions
10///
11/// It depends on the input type `I`, the output type `O`, and the error type `E`
12/// (by default `(I, nom::ErrorKind)`)
13///
14/// The `Ok` side is a pair containing the remainder of the input (the part of the data that
15/// was not parsed) and the produced value. The `Err` side contains an instance of `nom::Err`.
16///
17/// Outside of the parsing code, you can use the [Finish::finish] method to convert
18/// it to a more common result type
19pub type IResult<I, O, E = error::Error<I>> = Result<(I, O), Err<E>>;
20
21/// Helper trait to convert a parser's result to a more manageable type
22pub trait Finish<I, O, E> {
23  /// converts the parser's result to a type that is more consumable by error
24  /// management libraries. It keeps the same `Ok` branch, and merges `Err::Error`
25  /// and `Err::Failure` into the `Err` side.
26  ///
27  /// *warning*: if the result is `Err(Err::Incomplete(_))`, this method will panic.
28  /// - "complete" parsers: It will not be an issue, `Incomplete` is never used
29  /// - "streaming" parsers: `Incomplete` will be returned if there's not enough data
30  ///   for the parser to decide, and you should gather more data before parsing again.
31  ///   Once the parser returns either `Ok(_)`, `Err(Err::Error(_))` or `Err(Err::Failure(_))`,
32  ///   you can get out of the parsing loop and call `finish()` on the parser's result
33  fn finish(self) -> Result<(I, O), E>;
34}
35
36impl<I, O, E> Finish<I, O, E> for IResult<I, O, E> {
37  fn finish(self) -> Result<(I, O), E> {
38    match self {
39      Ok(res) => Ok(res),
40      Err(Err::Error(e)) | Err(Err::Failure(e)) => Err(e),
41      Err(Err::Incomplete(_)) => {
42        panic!("Cannot call `finish()` on `Err(Err::Incomplete(_))`: this result means that the parser does not have enough data to decide, you should gather more data and try to reapply the parser instead")
43      }
44    }
45  }
46}
47
48/// Contains information on needed data if a parser returned `Incomplete`
49#[derive(Debug, PartialEq, Eq, Clone, Copy)]
50pub enum Needed {
51  /// Needs more data, but we do not know how much
52  Unknown,
53  /// Contains the required data size in bytes
54  Size(NonZeroUsize),
55}
56
57impl Needed {
58  /// Creates `Needed` instance, returns `Needed::Unknown` if the argument is zero
59  pub fn new(s: usize) -> Self {
60    match NonZeroUsize::new(s) {
61      Some(sz) => Needed::Size(sz),
62      None => Needed::Unknown,
63    }
64  }
65
66  /// Indicates if we know how many bytes we need
67  pub fn is_known(&self) -> bool {
68    *self != Unknown
69  }
70
71  /// Maps a `Needed` to `Needed` by applying a function to a contained `Size` value.
72  #[inline]
73  pub fn map<F: Fn(NonZeroUsize) -> usize>(self, f: F) -> Needed {
74    match self {
75      Unknown => Unknown,
76      Size(n) => Needed::new(f(n)),
77    }
78  }
79}
80
81/// The `Err` enum indicates the parser was not successful
82///
83/// It has three cases:
84///
85/// * `Incomplete` indicates that more data is needed to decide. The `Needed` enum
86///   can contain how many additional bytes are necessary. If you are sure your parser
87///   is working on full data, you can wrap your parser with the `complete` combinator
88///   to transform that case in `Error`
89/// * `Error` means some parser did not succeed, but another one might (as an example,
90///   when testing different branches of an `alt` combinator)
91/// * `Failure` indicates an unrecoverable error. For example, when a prefix has been
92///   recognised and the next parser has been confirmed, if that parser fails, then the
93///   entire process fails; there are no more parsers to try.
94///
95/// Distinguishing `Failure` this from `Error` is only relevant inside the parser's code. For
96/// external consumers, both mean that parsing failed.
97///
98/// See also: [`Finish`].
99///
100#[derive(Debug, Clone, PartialEq)]
101pub enum Err<Failure, Error = Failure> {
102  /// There was not enough data
103  Incomplete(Needed),
104  /// The parser had an error (recoverable)
105  Error(Error),
106  /// The parser had an unrecoverable error: we got to the right
107  /// branch and we know other branches won't work, so backtrack
108  /// as fast as possible
109  Failure(Failure),
110}
111
112impl<E> Err<E> {
113  /// Tests if the result is Incomplete
114  pub fn is_incomplete(&self) -> bool {
115    matches!(self, Err::Incomplete(..))
116  }
117
118  /// Applies the given function to the inner error
119  pub fn map<E2, F>(self, f: F) -> Err<E2>
120  where
121    F: FnOnce(E) -> E2,
122  {
123    match self {
124      Err::Incomplete(n) => Err::Incomplete(n),
125      Err::Failure(t) => Err::Failure(f(t)),
126      Err::Error(t) => Err::Error(f(t)),
127    }
128  }
129
130  /// Automatically converts between errors if the underlying type supports it
131  pub fn convert<F>(e: Err<F>) -> Self
132  where
133    E: From<F>,
134  {
135    e.map(crate::lib::std::convert::Into::into)
136  }
137}
138
139impl<T> Err<(T, ErrorKind)> {
140  /// Maps `Err<(T, ErrorKind)>` to `Err<(U, ErrorKind)>` with the given `F: T -> U`
141  pub fn map_input<U, F>(self, f: F) -> Err<(U, ErrorKind)>
142  where
143    F: FnOnce(T) -> U,
144  {
145    match self {
146      Err::Incomplete(n) => Err::Incomplete(n),
147      Err::Failure((input, k)) => Err::Failure((f(input), k)),
148      Err::Error((input, k)) => Err::Error((f(input), k)),
149    }
150  }
151}
152
153impl<T> Err<error::Error<T>> {
154  /// Maps `Err<error::Error<T>>` to `Err<error::Error<U>>` with the given `F: T -> U`
155  pub fn map_input<U, F>(self, f: F) -> Err<error::Error<U>>
156  where
157    F: FnOnce(T) -> U,
158  {
159    match self {
160      Err::Incomplete(n) => Err::Incomplete(n),
161      Err::Failure(error::Error { input, code }) => Err::Failure(error::Error {
162        input: f(input),
163        code,
164      }),
165      Err::Error(error::Error { input, code }) => Err::Error(error::Error {
166        input: f(input),
167        code,
168      }),
169    }
170  }
171}
172
173#[cfg(feature = "alloc")]
174use crate::lib::std::{borrow::ToOwned, string::String, vec::Vec};
175#[cfg(feature = "alloc")]
176impl Err<(&[u8], ErrorKind)> {
177  /// Obtaining ownership
178  #[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
179  pub fn to_owned(self) -> Err<(Vec<u8>, ErrorKind)> {
180    self.map_input(ToOwned::to_owned)
181  }
182}
183
184#[cfg(feature = "alloc")]
185impl Err<(&str, ErrorKind)> {
186  /// Obtaining ownership
187  #[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
188  pub fn to_owned(self) -> Err<(String, ErrorKind)> {
189    self.map_input(ToOwned::to_owned)
190  }
191}
192
193#[cfg(feature = "alloc")]
194impl Err<error::Error<&[u8]>> {
195  /// Obtaining ownership
196  #[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
197  pub fn to_owned(self) -> Err<error::Error<Vec<u8>>> {
198    self.map_input(ToOwned::to_owned)
199  }
200}
201
202#[cfg(feature = "alloc")]
203impl Err<error::Error<&str>> {
204  /// Obtaining ownership
205  #[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
206  pub fn to_owned(self) -> Err<error::Error<String>> {
207    self.map_input(ToOwned::to_owned)
208  }
209}
210
211impl<E: Eq> Eq for Err<E> {}
212
213impl<E> fmt::Display for Err<E>
214where
215  E: fmt::Debug,
216{
217  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
218    match self {
219      Err::Incomplete(Needed::Size(u)) => write!(f, "Parsing requires {} bytes/chars", u),
220      Err::Incomplete(Needed::Unknown) => write!(f, "Parsing requires more data"),
221      Err::Failure(c) => write!(f, "Parsing Failure: {:?}", c),
222      Err::Error(c) => write!(f, "Parsing Error: {:?}", c),
223    }
224  }
225}
226
227#[cfg(feature = "std")]
228use std::error::Error;
229
230#[cfg(feature = "std")]
231impl<E> Error for Err<E>
232where
233  E: fmt::Debug,
234{
235  fn source(&self) -> Option<&(dyn Error + 'static)> {
236    None // no underlying error
237  }
238}
239
240/// Parser mode: influences how combinators build values
241///
242/// the [Parser] trait is generic over types implementing [Mode]. Its method are
243/// called to produce and manipulate output values or errors.
244///
245/// The main implementations of this trait are:
246/// * [Emit]: produce a value
247/// * [Check]: apply the parser but do not generate a value
248pub trait Mode {
249  /// The output type that may be generated
250  type Output<T>;
251
252  /// Produces a value
253  fn bind<T, F: FnOnce() -> T>(f: F) -> Self::Output<T>;
254
255  /// Applies a function over the produced value
256  fn map<T, U, F: FnOnce(T) -> U>(x: Self::Output<T>, f: F) -> Self::Output<U>;
257
258  /// Combines two values generated by previous parsers
259  fn combine<T, U, V, F: FnOnce(T, U) -> V>(
260    x: Self::Output<T>,
261    y: Self::Output<U>,
262    f: F,
263  ) -> Self::Output<V>;
264}
265
266/// Produces a value. This is the default behaviour for parsers
267pub struct Emit;
268impl Mode for Emit {
269  type Output<T> = T;
270
271  #[inline(always)]
272  fn bind<T, F: FnOnce() -> T>(f: F) -> Self::Output<T> {
273    f()
274  }
275
276  #[inline(always)]
277  fn map<T, U, F: FnOnce(T) -> U>(x: Self::Output<T>, f: F) -> Self::Output<U> {
278    f(x)
279  }
280
281  #[inline(always)]
282  fn combine<T, U, V, F: FnOnce(T, U) -> V>(
283    x: Self::Output<T>,
284    y: Self::Output<U>,
285    f: F,
286  ) -> Self::Output<V> {
287    f(x, y)
288  }
289}
290
291/// Applies the parser, but do not a produce a value
292///
293/// This has the effect of greatly reducing the amount of code generated and the
294/// parser memory usage. Some combinators check for an error in a child parser but
295/// discard the error, and for those, using [Check] makes sure the error is not
296/// even generated, only the fact that an error happened remains
297pub struct Check;
298impl Mode for Check {
299  type Output<T> = ();
300
301  #[inline(always)]
302  fn bind<T, F: FnOnce() -> T>(_: F) -> Self::Output<T> {}
303
304  #[inline(always)]
305  fn map<T, U, F: FnOnce(T) -> U>(_: Self::Output<T>, _: F) -> Self::Output<U> {}
306
307  #[inline(always)]
308  fn combine<T, U, V, F: FnOnce(T, U) -> V>(
309    _: Self::Output<T>,
310    _: Self::Output<U>,
311    _: F,
312  ) -> Self::Output<V> {
313  }
314}
315
316/// Parser result type
317///
318/// * `Ok` branch: a tuple of the remaining input data, and the output value.
319///   The output value is of the `O` type if the output mode was [Emit], and `()`
320///   if the mode was [Check]
321/// * `Err` branch: an error of the `E` type if the erroor mode was [Emit], and `()`
322///   if the mode was [Check]
323pub type PResult<OM, I, O, E> = Result<
324  (I, <<OM as OutputMode>::Output as Mode>::Output<O>),
325  Err<E, <<OM as OutputMode>::Error as Mode>::Output<E>>,
326>;
327
328/// Trait Defining the parser's execution
329///
330/// The same parser implementation can vary in behaviour according to the chosen
331/// output mode
332pub trait OutputMode {
333  /// Defines the [Mode] for the output type. [Emit] will generate the value, [Check] will
334  /// apply the parser but will only generate `()` if successful. This can be used when
335  /// verifying that the input data conforms to the format without having to generate any
336  /// output data
337  type Output: Mode;
338  /// Defines the [Mode] for the output type. [Emit] will generate the value, [Check] will
339  /// apply the parser but will only generate `()` if an error happened. [Emit] should be
340  /// used when we want to handle the error and extract useful information from it. [Check]
341  /// is used when we just want to know if parsing failed and reject the data quickly.
342  type Error: Mode;
343  /// Indicates whether the input data is "complete", ie we already have the entire data in the
344  /// buffer, or if it is "streaming", where more data can be added later in the buffer. In
345  /// streaming mode, the parser will understand that a failure may mean that we are missing
346  /// data, and will return a specific error branch, [Err::Incomplete] to signal it. In complete
347  /// mode, the parser will generate a normal error
348  type Incomplete: IsStreaming;
349}
350
351/// Specifies the behaviour when a parser encounters an error that could be due to partial ata
352pub trait IsStreaming {
353  /// called by parsers on partial data errors
354  /// * `needed` can hold the amount of additional data the parser would need to decide
355  /// * `err_f`: produces the error when in "complete" mode
356  fn incomplete<E, F: FnOnce() -> E>(needed: Needed, err_f: F) -> Err<E>;
357  /// Indicates whether the data is in streaming mode or not
358  fn is_streaming() -> bool;
359}
360
361/// Indicates that the input data is streaming: more data may be available later
362pub struct Streaming;
363
364impl IsStreaming for Streaming {
365  fn incomplete<E, F: FnOnce() -> E>(needed: Needed, _err_f: F) -> Err<E> {
366    Err::Incomplete(needed)
367  }
368
369  #[inline]
370  fn is_streaming() -> bool {
371    true
372  }
373}
374
375/// Indicates that the input data is complete: no more data may be added later
376pub struct Complete;
377
378impl IsStreaming for Complete {
379  fn incomplete<E, F: FnOnce() -> E>(_needed: Needed, err_f: F) -> Err<E> {
380    Err::Error(err_f())
381  }
382
383  #[inline]
384  fn is_streaming() -> bool {
385    false
386  }
387}
388
389/// Holds the parser execution modifiers: output [Mode], error [Mode] and
390/// streaming behaviour for input data
391pub struct OutputM<M: Mode, EM: Mode, S: IsStreaming> {
392  m: PhantomData<M>,
393  em: PhantomData<EM>,
394  s: PhantomData<S>,
395}
396
397impl<M: Mode, EM: Mode, S: IsStreaming> OutputMode for OutputM<M, EM, S> {
398  type Output = M;
399  type Error = EM;
400  type Incomplete = S;
401}
402/// All nom parsers implement this trait
403pub trait Parser<Input> {
404  /// Type of the produced value
405  type Output;
406  /// Error type of this parser
407  type Error: ParseError<Input>;
408
409  /// A parser takes in input type, and returns a `Result` containing
410  /// either the remaining input and the output value, or an error
411  #[inline]
412  fn parse(&mut self, input: Input) -> IResult<Input, Self::Output, Self::Error> {
413    self.process::<OutputM<Emit, Emit, Streaming>>(input)
414  }
415
416  /// A parser takes in input type, and returns a `Result` containing
417  /// either the remaining input and the output value, or an error
418  #[inline]
419  fn parse_complete(&mut self, input: Input) -> IResult<Input, Self::Output, Self::Error> {
420    self.process::<OutputM<Emit, Emit, Complete>>(input)
421  }
422
423  /// A parser takes in input type, and returns a `Result` containing
424  /// either the remaining input and the output value, or an error
425  fn process<OM: OutputMode>(
426    &mut self,
427    input: Input,
428  ) -> PResult<OM, Input, Self::Output, Self::Error>;
429
430  /// Maps a function over the result of a parser
431  fn map<G, O2>(self, g: G) -> Map<Self, G>
432  where
433    G: FnMut(Self::Output) -> O2,
434    Self: core::marker::Sized,
435  {
436    Map { f: self, g }
437  }
438
439  /// Applies a function returning a `Result` over the result of a parser.
440  fn map_res<G, O2, E2>(self, g: G) -> MapRes<Self, G>
441  where
442    G: FnMut(Self::Output) -> Result<O2, E2>,
443    Self::Error: FromExternalError<Input, E2>,
444    Self: core::marker::Sized,
445  {
446    MapRes { f: self, g }
447  }
448
449  /// Applies a function returning an `Option` over the result of a parser.
450  fn map_opt<G, O2>(self, g: G) -> MapOpt<Self, G>
451  where
452    G: FnMut(Self::Output) -> Option<O2>,
453    Self: core::marker::Sized,
454  {
455    MapOpt { f: self, g }
456  }
457
458  /// Creates a second parser from the output of the first one, then apply over the rest of the input
459  fn flat_map<G, H>(self, g: G) -> FlatMap<Self, G>
460  where
461    G: FnMut(Self::Output) -> H,
462    H: Parser<Input, Error = Self::Error>,
463    Self: core::marker::Sized,
464  {
465    FlatMap { f: self, g }
466  }
467
468  /// Applies a second parser over the output of the first one
469  fn and_then<G>(self, g: G) -> AndThen<Self, G>
470  where
471    G: Parser<Self::Output, Error = Self::Error>,
472    Self: core::marker::Sized,
473  {
474    AndThen { f: self, g }
475  }
476
477  /// Applies a second parser after the first one, return their results as a tuple
478  fn and<G, O2>(self, g: G) -> And<Self, G>
479  where
480    G: Parser<Input, Output = O2, Error = Self::Error>,
481    Self: core::marker::Sized,
482  {
483    And { f: self, g }
484  }
485
486  /// Applies a second parser over the input if the first one failed
487  fn or<G>(self, g: G) -> Or<Self, G>
488  where
489    G: Parser<Input, Output = Self::Output, Error = Self::Error>,
490    Self: core::marker::Sized,
491  {
492    Or { f: self, g }
493  }
494
495  /// automatically converts the parser's output and error values to another type, as long as they
496  /// implement the `From` trait
497  fn into<O2: From<Self::Output>, E2: From<Self::Error>>(self) -> Into<Self, O2, E2>
498  where
499    Self: core::marker::Sized,
500  {
501    Into {
502      f: self,
503      phantom_out2: core::marker::PhantomData,
504      phantom_err2: core::marker::PhantomData,
505    }
506  }
507}
508
509impl<I, O, E: ParseError<I>, F> Parser<I> for F
510where
511  F: FnMut(I) -> IResult<I, O, E>,
512{
513  type Output = O;
514  type Error = E;
515
516  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
517    let (i, o) = self(i).map_err(|e| match e {
518      Err::Incomplete(i) => Err::Incomplete(i),
519      Err::Error(e) => Err::Error(OM::Error::bind(|| e)),
520      Err::Failure(e) => Err::Failure(e),
521    })?;
522    Ok((i, OM::Output::bind(|| o)))
523  }
524}
525
526macro_rules! impl_parser_for_tuple {
527  ($($parser:ident $output:ident),+) => (
528    #[allow(non_snake_case)]
529    impl<I, $($output),+, E: ParseError<I>, $($parser),+> Parser<I> for ($($parser),+,)
530    where
531      $($parser: Parser<I, Output = $output, Error = E>),+
532    {
533      type Output = ($($output),+,);
534      type Error = E;
535
536      #[inline(always)]
537      fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
538        let ($(ref mut $parser),+,) = *self;
539
540        // FIXME: is there a way to avoid producing the output values?
541        $(let(i, $output) = $parser.process::<OutputM<Emit, OM::Error, OM::Incomplete>>(i)?;)+
542
543        // ???
544        Ok((i, OM::Output::bind(|| ($($output),+,))))
545      }
546    }
547  )
548}
549
550macro_rules! impl_parser_for_tuples {
551    ($parser1:ident $output1:ident, $($parser:ident $output:ident),+) => {
552        impl_parser_for_tuples!(__impl $parser1 $output1; $($parser $output),+);
553    };
554    (__impl $($parser:ident $output:ident),+; $parser1:ident $output1:ident $(,$parser2:ident $output2:ident)*) => {
555        impl_parser_for_tuple!($($parser $output),+);
556        impl_parser_for_tuples!(__impl $($parser $output),+, $parser1 $output1; $($parser2 $output2),*);
557    };
558    (__impl $($parser:ident $output:ident),+;) => {
559        impl_parser_for_tuple!($($parser $output),+);
560    }
561}
562
563impl_parser_for_tuples!(P1 O1, P2 O2, P3 O3, P4 O4, P5 O5, P6 O6, P7 O7, P8 O8, P9 O9, P10 O10, P11 O11, P12 O12, P13 O13, P14 O14, P15 O15, P16 O16, P17 O17, P18 O18, P19 O19, P20 O20, P21 O21);
564
565/*
566#[cfg(feature = "alloc")]
567use alloc::boxed::Box;
568
569#[cfg(feature = "alloc")]
570impl<I, O, E: ParseError<I>> Parser<I> for Box<dyn Parser<I, Output = O, Error = E>> {
571  type Output = O;
572  type Error = E;
573
574  fn process<OM: OutputMode>(&mut self, input: I) -> PResult<OM, I, Self::Output, Self::Error> {
575    (**self).process(input)
576  }
577}
578*/
579/// Implementation of `Parser::map`
580pub struct Map<F, G> {
581  f: F,
582  g: G,
583}
584
585impl<I, O2, E: ParseError<I>, F: Parser<I, Error = E>, G: FnMut(<F as Parser<I>>::Output) -> O2>
586  Parser<I> for Map<F, G>
587{
588  type Output = O2;
589  type Error = E;
590
591  #[inline(always)]
592  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
593    match self.f.process::<OM>(i) {
594      Err(e) => Err(e),
595      Ok((i, o)) => Ok((i, OM::Output::map(o, |o| (self.g)(o)))),
596    }
597  }
598}
599
600/// Implementation of `Parser::map_res`
601pub struct MapRes<F, G> {
602  f: F,
603  g: G,
604}
605
606impl<I, O2, E2, F, G> Parser<I> for MapRes<F, G>
607where
608  I: Clone,
609  <F as Parser<I>>::Error: FromExternalError<I, E2>,
610  F: Parser<I>,
611  G: FnMut(<F as Parser<I>>::Output) -> Result<O2, E2>,
612{
613  type Output = O2;
614  type Error = <F as Parser<I>>::Error;
615
616  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
617    let (input, o1) = self
618      .f
619      .process::<OutputM<Emit, OM::Error, OM::Incomplete>>(i.clone())?;
620
621    match (self.g)(o1) {
622      Ok(o2) => Ok((input, OM::Output::bind(|| o2))),
623      Err(e) => Err(Err::Error(OM::Error::bind(|| {
624        <F as Parser<I>>::Error::from_external_error(i, ErrorKind::MapRes, e)
625      }))),
626    }
627  }
628}
629
630/// Implementation of `Parser::map_opt`
631pub struct MapOpt<F, G> {
632  f: F,
633  g: G,
634}
635
636impl<I, O2, F, G> Parser<I> for MapOpt<F, G>
637where
638  I: Clone,
639  F: Parser<I>,
640  G: FnMut(<F as Parser<I>>::Output) -> Option<O2>,
641{
642  type Output = O2;
643  type Error = <F as Parser<I>>::Error;
644
645  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
646    let (input, o1) = self
647      .f
648      .process::<OutputM<Emit, OM::Error, OM::Incomplete>>(i.clone())?;
649
650    match (self.g)(o1) {
651      Some(o2) => Ok((input, OM::Output::bind(|| o2))),
652      None => Err(Err::Error(OM::Error::bind(|| {
653        <F as Parser<I>>::Error::from_error_kind(i, ErrorKind::MapOpt)
654      }))),
655    }
656  }
657}
658
659/// Implementation of `Parser::flat_map`
660pub struct FlatMap<F, G> {
661  f: F,
662  g: G,
663}
664
665impl<
666    I,
667    E: ParseError<I>,
668    F: Parser<I, Error = E>,
669    G: FnMut(<F as Parser<I>>::Output) -> H,
670    H: Parser<I, Error = E>,
671  > Parser<I> for FlatMap<F, G>
672{
673  type Output = <H as Parser<I>>::Output;
674  type Error = E;
675
676  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
677    let (input, o1) = self
678      .f
679      .process::<OutputM<Emit, OM::Error, OM::Incomplete>>(i)?;
680
681    (self.g)(o1).process::<OM>(input)
682  }
683}
684
685/// Implementation of `Parser::and_then`
686pub struct AndThen<F, G> {
687  f: F,
688  g: G,
689}
690
691impl<I, F: Parser<I>, G: Parser<<F as Parser<I>>::Output, Error = <F as Parser<I>>::Error>>
692  Parser<I> for AndThen<F, G>
693{
694  type Output = <G as Parser<<F as Parser<I>>::Output>>::Output;
695  type Error = <F as Parser<I>>::Error;
696
697  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
698    let (input, o1) = self
699      .f
700      .process::<OutputM<Emit, OM::Error, OM::Incomplete>>(i)?;
701
702    let (_, o2) = self.g.process::<OM>(o1)?;
703    Ok((input, o2))
704  }
705}
706
707/// Implementation of `Parser::and`
708pub struct And<F, G> {
709  f: F,
710  g: G,
711}
712
713impl<I, E: ParseError<I>, F: Parser<I, Error = E>, G: Parser<I, Error = E>> Parser<I>
714  for And<F, G>
715{
716  type Output = (<F as Parser<I>>::Output, <G as Parser<I>>::Output);
717  type Error = E;
718
719  #[inline(always)]
720  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
721    let (i, o1) = self.f.process::<OM>(i)?;
722    let (i, o2) = self.g.process::<OM>(i)?;
723
724    Ok((i, OM::Output::combine(o1, o2, |o1, o2| (o1, o2))))
725  }
726}
727
728/// Implementation of `Parser::or`
729pub struct Or<F, G> {
730  f: F,
731  g: G,
732}
733
734impl<
735    I: Clone,
736    O,
737    E: ParseError<I>,
738    F: Parser<I, Output = O, Error = E>,
739    G: Parser<I, Output = O, Error = E>,
740  > Parser<I> for Or<F, G>
741{
742  type Output = <F as Parser<I>>::Output;
743  type Error = <F as Parser<I>>::Error;
744
745  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
746    match self.f.process::<OM>(i.clone()) {
747      Err(Err::Error(e1)) => match self.g.process::<OM>(i) {
748        Err(Err::Error(e2)) => Err(Err::Error(OM::Error::combine(e1, e2, |e1, e2| e1.or(e2)))),
749        res => res,
750      },
751      res => res,
752    }
753  }
754}
755
756/// Implementation of `Parser::into`
757pub struct Into<F, O2, E2> {
758  f: F,
759  phantom_out2: core::marker::PhantomData<O2>,
760  phantom_err2: core::marker::PhantomData<E2>,
761}
762
763impl<
764    I,
765    O2: From<<F as Parser<I>>::Output>,
766    E2: crate::error::ParseError<I> + From<<F as Parser<I>>::Error>,
767    F: Parser<I>,
768  > Parser<I> for Into<F, O2, E2>
769{
770  type Output = O2;
771  type Error = E2;
772
773  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
774    match self.f.process::<OM>(i) {
775      Ok((i, o)) => Ok((i, OM::Output::map(o, |o| o.into()))),
776      Err(Err::Error(e)) => Err(Err::Error(OM::Error::map(e, |e| e.into()))),
777      Err(Err::Failure(e)) => Err(Err::Failure(e.into())),
778      Err(Err::Incomplete(e)) => Err(Err::Incomplete(e)),
779    }
780  }
781}
782
783/// Alternate between two Parser implementations with the same result type.
784pub(crate) enum Either<F, G> {
785  Left(F),
786  Right(G),
787}
788
789impl<
790    I,
791    F: Parser<I>,
792    G: Parser<I, Output = <F as Parser<I>>::Output, Error = <F as Parser<I>>::Error>,
793  > Parser<I> for Either<F, G>
794{
795  type Output = <F as Parser<I>>::Output;
796  type Error = <F as Parser<I>>::Error;
797
798  #[inline]
799  fn process<OM: OutputMode>(&mut self, i: I) -> PResult<OM, I, Self::Output, Self::Error> {
800    match self {
801      Either::Left(f) => f.process::<OM>(i),
802      Either::Right(g) => g.process::<OM>(i),
803    }
804  }
805}
806
807#[cfg(test)]
808mod tests {
809  use super::*;
810  use crate::error::ErrorKind;
811
812  use crate::bytes::streaming::{tag, take};
813  use crate::number::streaming::be_u16;
814  use crate::sequence::terminated;
815
816  #[doc(hidden)]
817  #[macro_export]
818  macro_rules! assert_size (
819    ($t:ty, $sz:expr) => (
820      assert_eq!($crate::lib::std::mem::size_of::<$t>(), $sz);
821    );
822  );
823
824  #[test]
825  #[cfg(target_pointer_width = "64")]
826  fn size_test() {
827    assert_size!(IResult<&[u8], &[u8], (&[u8], u32)>, 40);
828    //FIXME: since rust 1.65, this is now 32 bytes, likely thanks to https://github.com/rust-lang/rust/pull/94075
829    // deactivating that test for now because it'll have different values depending on the rust version
830    // assert_size!(IResult<&str, &str, u32>, 40);
831    assert_size!(Needed, 8);
832    assert_size!(Err<u32>, 16);
833    assert_size!(ErrorKind, 1);
834  }
835
836  #[test]
837  fn err_map_test() {
838    let e = Err::Error(1);
839    assert_eq!(e.map(|v| v + 1), Err::Error(2));
840  }
841
842  #[test]
843  fn native_tuple_test() {
844    fn tuple_3(i: &[u8]) -> IResult<&[u8], (u16, &[u8])> {
845      terminated((be_u16, take(3u8)), tag("fg")).parse(i)
846    }
847
848    assert_eq!(
849      tuple_3(&b"abcdefgh"[..]),
850      Ok((&b"h"[..], (0x6162u16, &b"cde"[..])))
851    );
852    assert_eq!(tuple_3(&b"abcd"[..]), Err(Err::Incomplete(Needed::new(1))));
853    assert_eq!(tuple_3(&b"abcde"[..]), Err(Err::Incomplete(Needed::new(2))));
854    assert_eq!(
855      tuple_3(&b"abcdejk"[..]),
856      Err(Err::Error(error_position!(&b"jk"[..], ErrorKind::Tag)))
857    );
858  }
859}
nom/internal.rs

nom/
internal.rs
