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
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
//! Error management
//!
//! Parsers are generic over their error type, requiring that it implements
//! the `error::ParseError<Input>` trait.

use crate::internal::Parser;
use crate::lib::std::fmt;

/// This trait must be implemented by the error type of a nom parser.
///
/// There are already implementations of it for `(Input, ErrorKind)`
/// and `VerboseError<Input>`.
///
/// It provides methods to create an error from some combinators,
/// and combine existing errors in combinators like `alt`.
pub trait ParseError<I>: Sized {
  /// Creates an error from the input position and an [ErrorKind]
  fn from_error_kind(input: I, kind: ErrorKind) -> Self;

  /// Combines an existing error with a new one created from the input
  /// position and an [ErrorKind]. This is useful when backtracking
  /// through a parse tree, accumulating error context on the way
  fn append(input: I, kind: ErrorKind, other: Self) -> Self;

  /// Creates an error from an input position and an expected character
  fn from_char(input: I, _: char) -> Self {
    Self::from_error_kind(input, ErrorKind::Char)
  }

  /// Combines two existing errors. This function is used to compare errors
  /// generated in various branches of `alt`.
  fn or(self, other: Self) -> Self {
    other
  }
}

/// This trait is required by the `context` combinator to add a static string
/// to an existing error
pub trait ContextError<I>: Sized {
  /// Creates a new error from an input position, a static string and an existing error.
  /// This is used mainly in the [context] combinator, to add user friendly information
  /// to errors when backtracking through a parse tree
  fn add_context(_input: I, _ctx: &'static str, other: Self) -> Self {
    other
  }
}

/// This trait is required by the `map_res` combinator to integrate
/// error types from external functions, like [std::str::FromStr]
pub trait FromExternalError<I, E> {
  /// Creates a new error from an input position, an [ErrorKind] indicating the
  /// wrapping parser, and an external error
  fn from_external_error(input: I, kind: ErrorKind, e: E) -> Self;
}

/// default error type, only contains the error' location and code
#[derive(Debug, PartialEq)]
pub struct Error<I> {
  /// position of the error in the input data
  pub input: I,
  /// nom error code
  pub code: ErrorKind,
}

impl<I> Error<I> {
  /// creates a new basic error
  pub fn new(input: I, code: ErrorKind) -> Error<I> {
    Error { input, code }
  }
}

impl<I> ParseError<I> for Error<I> {
  fn from_error_kind(input: I, kind: ErrorKind) -> Self {
    Error { input, code: kind }
  }

  fn append(_: I, _: ErrorKind, other: Self) -> Self {
    other
  }
}

impl<I> ContextError<I> for Error<I> {}

impl<I, E> FromExternalError<I, E> for Error<I> {
  /// Create a new error from an input position and an external error
  fn from_external_error(input: I, kind: ErrorKind, _e: E) -> Self {
    Error { input, code: kind }
  }
}

/// The Display implementation allows the std::error::Error implementation
impl<I: fmt::Display> fmt::Display for Error<I> {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    write!(f, "error {:?} at: {}", self.code, self.input)
  }
}

#[cfg(feature = "std")]
impl<I: fmt::Debug + fmt::Display> std::error::Error for Error<I> {}

// for backward compatibility, keep those trait implementations
// for the previously used error type
impl<I> ParseError<I> for (I, ErrorKind) {
  fn from_error_kind(input: I, kind: ErrorKind) -> Self {
    (input, kind)
  }

  fn append(_: I, _: ErrorKind, other: Self) -> Self {
    other
  }
}

impl<I> ContextError<I> for (I, ErrorKind) {}

impl<I, E> FromExternalError<I, E> for (I, ErrorKind) {
  fn from_external_error(input: I, kind: ErrorKind, _e: E) -> Self {
    (input, kind)
  }
}

impl<I> ParseError<I> for () {
  fn from_error_kind(_: I, _: ErrorKind) -> Self {}

  fn append(_: I, _: ErrorKind, _: Self) -> Self {}
}

impl<I> ContextError<I> for () {}

impl<I, E> FromExternalError<I, E> for () {
  fn from_external_error(_input: I, _kind: ErrorKind, _e: E) -> Self {}
}

/// Creates an error from the input position and an [ErrorKind]
pub fn make_error<I, E: ParseError<I>>(input: I, kind: ErrorKind) -> E {
  E::from_error_kind(input, kind)
}

/// Combines an existing error with a new one created from the input
/// position and an [ErrorKind]. This is useful when backtracking
/// through a parse tree, accumulating error context on the way
pub fn append_error<I, E: ParseError<I>>(input: I, kind: ErrorKind, other: E) -> E {
  E::append(input, kind, other)
}

/// This error type accumulates errors and their position when backtracking
/// through a parse tree. With some post processing (cf `examples/json.rs`),
/// it can be used to display user friendly error messages
#[cfg(feature = "alloc")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
#[derive(Clone, Debug, PartialEq)]
pub struct VerboseError<I> {
  /// List of errors accumulated by `VerboseError`, containing the affected
  /// part of input data, and some context
  pub errors: crate::lib::std::vec::Vec<(I, VerboseErrorKind)>,
}

#[cfg(feature = "alloc")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
#[derive(Clone, Debug, PartialEq)]
/// Error context for `VerboseError`
pub enum VerboseErrorKind {
  /// Static string added by the `context` function
  Context(&'static str),
  /// Indicates which character was expected by the `char` function
  Char(char),
  /// Error kind given by various nom parsers
  Nom(ErrorKind),
}

#[cfg(feature = "alloc")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
impl<I> ParseError<I> for VerboseError<I> {
  fn from_error_kind(input: I, kind: ErrorKind) -> Self {
    VerboseError {
      errors: vec![(input, VerboseErrorKind::Nom(kind))],
    }
  }

  fn append(input: I, kind: ErrorKind, mut other: Self) -> Self {
    other.errors.push((input, VerboseErrorKind::Nom(kind)));
    other
  }

  fn from_char(input: I, c: char) -> Self {
    VerboseError {
      errors: vec![(input, VerboseErrorKind::Char(c))],
    }
  }
}

#[cfg(feature = "alloc")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
impl<I> ContextError<I> for VerboseError<I> {
  fn add_context(input: I, ctx: &'static str, mut other: Self) -> Self {
    other.errors.push((input, VerboseErrorKind::Context(ctx)));
    other
  }
}

#[cfg(feature = "alloc")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
impl<I, E> FromExternalError<I, E> for VerboseError<I> {
  /// Create a new error from an input position and an external error
  fn from_external_error(input: I, kind: ErrorKind, _e: E) -> Self {
    Self::from_error_kind(input, kind)
  }
}

#[cfg(feature = "alloc")]
impl<I: fmt::Display> fmt::Display for VerboseError<I> {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    writeln!(f, "Parse error:")?;
    for (input, error) in &self.errors {
      match error {
        VerboseErrorKind::Nom(e) => writeln!(f, "{:?} at: {}", e, input)?,
        VerboseErrorKind::Char(c) => writeln!(f, "expected '{}' at: {}", c, input)?,
        VerboseErrorKind::Context(s) => writeln!(f, "in section '{}', at: {}", s, input)?,
      }
    }

    Ok(())
  }
}

#[cfg(feature = "std")]
impl<I: fmt::Debug + fmt::Display> std::error::Error for VerboseError<I> {}

use crate::internal::{Err, IResult};

/// Create a new error from an input position, a static string and an existing error.
/// This is used mainly in the [context] combinator, to add user friendly information
/// to errors when backtracking through a parse tree
pub fn context<I: Clone, E: ContextError<I>, F, O>(
  context: &'static str,
  mut f: F,
) -> impl FnMut(I) -> IResult<I, O, E>
where
  F: Parser<I, O, E>,
{
  move |i: I| match f.parse(i.clone()) {
    Ok(o) => Ok(o),
    Err(Err::Incomplete(i)) => Err(Err::Incomplete(i)),
    Err(Err::Error(e)) => Err(Err::Error(E::add_context(i, context, e))),
    Err(Err::Failure(e)) => Err(Err::Failure(E::add_context(i, context, e))),
  }
}

/// Transforms a `VerboseError` into a trace with input position information
#[cfg(feature = "alloc")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "alloc")))]
pub fn convert_error<I: core::ops::Deref<Target = str>>(
  input: I,
  e: VerboseError<I>,
) -> crate::lib::std::string::String {
  use crate::lib::std::fmt::Write;
  use crate::traits::Offset;

  let mut result = crate::lib::std::string::String::new();

  for (i, (substring, kind)) in e.errors.iter().enumerate() {
    let offset = input.offset(substring);

    if input.is_empty() {
      match kind {
        VerboseErrorKind::Char(c) => {
          write!(&mut result, "{}: expected '{}', got empty input\n\n", i, c)
        }
        VerboseErrorKind::Context(s) => write!(&mut result, "{}: in {}, got empty input\n\n", i, s),
        VerboseErrorKind::Nom(e) => write!(&mut result, "{}: in {:?}, got empty input\n\n", i, e),
      }
    } else {
      let prefix = &input.as_bytes()[..offset];

      // Count the number of newlines in the first `offset` bytes of input
      let line_number = prefix.iter().filter(|&&b| b == b'\n').count() + 1;

      // Find the line that includes the subslice:
      // Find the *last* newline before the substring starts
      let line_begin = prefix
        .iter()
        .rev()
        .position(|&b| b == b'\n')
        .map(|pos| offset - pos)
        .unwrap_or(0);

      // Find the full line after that newline
      let line = input[line_begin..]
        .lines()
        .next()
        .unwrap_or(&input[line_begin..])
        .trim_end();

      // The (1-indexed) column number is the offset of our substring into that line
      let column_number = line.offset(substring) + 1;

      match kind {
        VerboseErrorKind::Char(c) => {
          if let Some(actual) = substring.chars().next() {
            write!(
              &mut result,
              "{i}: at line {line_number}:\n\
               {line}\n\
               {caret:>column$}\n\
               expected '{expected}', found {actual}\n\n",
              i = i,
              line_number = line_number,
              line = line,
              caret = '^',
              column = column_number,
              expected = c,
              actual = actual,
            )
          } else {
            write!(
              &mut result,
              "{i}: at line {line_number}:\n\
               {line}\n\
               {caret:>column$}\n\
               expected '{expected}', got end of input\n\n",
              i = i,
              line_number = line_number,
              line = line,
              caret = '^',
              column = column_number,
              expected = c,
            )
          }
        }
        VerboseErrorKind::Context(s) => write!(
          &mut result,
          "{i}: at line {line_number}, in {context}:\n\
             {line}\n\
             {caret:>column$}\n\n",
          i = i,
          line_number = line_number,
          context = s,
          line = line,
          caret = '^',
          column = column_number,
        ),
        VerboseErrorKind::Nom(e) => write!(
          &mut result,
          "{i}: at line {line_number}, in {nom_err:?}:\n\
             {line}\n\
             {caret:>column$}\n\n",
          i = i,
          line_number = line_number,
          nom_err = e,
          line = line,
          caret = '^',
          column = column_number,
        ),
      }
    }
    // Because `write!` to a `String` is infallible, this `unwrap` is fine.
    .unwrap();
  }

  result
}

/// Indicates which parser returned an error
#[rustfmt::skip]
#[derive(Debug,PartialEq,Eq,Hash,Clone,Copy)]
#[allow(deprecated,missing_docs)]
pub enum ErrorKind {
  Tag,
  MapRes,
  MapOpt,
  Alt,
  IsNot,
  IsA,
  SeparatedList,
  SeparatedNonEmptyList,
  Many0,
  Many1,
  ManyTill,
  Count,
  TakeUntil,
  LengthValue,
  TagClosure,
  Alpha,
  Digit,
  HexDigit,
  OctDigit,
  AlphaNumeric,
  Space,
  MultiSpace,
  LengthValueFn,
  Eof,
  Switch,
  TagBits,
  OneOf,
  NoneOf,
  Char,
  CrLf,
  RegexpMatch,
  RegexpMatches,
  RegexpFind,
  RegexpCapture,
  RegexpCaptures,
  TakeWhile1,
  Complete,
  Fix,
  Escaped,
  EscapedTransform,
  NonEmpty,
  ManyMN,
  Not,
  Permutation,
  Verify,
  TakeTill1,
  TakeWhileMN,
  TooLarge,
  Many0Count,
  Many1Count,
  Float,
  Satisfy,
  Fail,
}

#[rustfmt::skip]
#[allow(deprecated)]
/// Converts an ErrorKind to a number
pub fn error_to_u32(e: &ErrorKind) -> u32 {
  match *e {
    ErrorKind::Tag                       => 1,
    ErrorKind::MapRes                    => 2,
    ErrorKind::MapOpt                    => 3,
    ErrorKind::Alt                       => 4,
    ErrorKind::IsNot                     => 5,
    ErrorKind::IsA                       => 6,
    ErrorKind::SeparatedList             => 7,
    ErrorKind::SeparatedNonEmptyList     => 8,
    ErrorKind::Many1                     => 9,
    ErrorKind::Count                     => 10,
    ErrorKind::TakeUntil                 => 12,
    ErrorKind::LengthValue               => 15,
    ErrorKind::TagClosure                => 16,
    ErrorKind::Alpha                     => 17,
    ErrorKind::Digit                     => 18,
    ErrorKind::AlphaNumeric              => 19,
    ErrorKind::Space                     => 20,
    ErrorKind::MultiSpace                => 21,
    ErrorKind::LengthValueFn             => 22,
    ErrorKind::Eof                       => 23,
    ErrorKind::Switch                    => 27,
    ErrorKind::TagBits                   => 28,
    ErrorKind::OneOf                     => 29,
    ErrorKind::NoneOf                    => 30,
    ErrorKind::Char                      => 40,
    ErrorKind::CrLf                      => 41,
    ErrorKind::RegexpMatch               => 42,
    ErrorKind::RegexpMatches             => 43,
    ErrorKind::RegexpFind                => 44,
    ErrorKind::RegexpCapture             => 45,
    ErrorKind::RegexpCaptures            => 46,
    ErrorKind::TakeWhile1                => 47,
    ErrorKind::Complete                  => 48,
    ErrorKind::Fix                       => 49,
    ErrorKind::Escaped                   => 50,
    ErrorKind::EscapedTransform          => 51,
    ErrorKind::NonEmpty                  => 56,
    ErrorKind::ManyMN                    => 57,
    ErrorKind::HexDigit                  => 59,
    ErrorKind::OctDigit                  => 61,
    ErrorKind::Many0                     => 62,
    ErrorKind::Not                       => 63,
    ErrorKind::Permutation               => 64,
    ErrorKind::ManyTill                  => 65,
    ErrorKind::Verify                    => 66,
    ErrorKind::TakeTill1                 => 67,
    ErrorKind::TakeWhileMN               => 69,
    ErrorKind::TooLarge                  => 70,
    ErrorKind::Many0Count                => 71,
    ErrorKind::Many1Count                => 72,
    ErrorKind::Float                     => 73,
    ErrorKind::Satisfy                   => 74,
    ErrorKind::Fail                      => 75,
  }
}

impl ErrorKind {
  #[rustfmt::skip]
  #[allow(deprecated)]
  /// Converts an ErrorKind to a text description
  pub fn description(&self) -> &str {
    match *self {
      ErrorKind::Tag                       => "Tag",
      ErrorKind::MapRes                    => "Map on Result",
      ErrorKind::MapOpt                    => "Map on Option",
      ErrorKind::Alt                       => "Alternative",
      ErrorKind::IsNot                     => "IsNot",
      ErrorKind::IsA                       => "IsA",
      ErrorKind::SeparatedList             => "Separated list",
      ErrorKind::SeparatedNonEmptyList     => "Separated non empty list",
      ErrorKind::Many0                     => "Many0",
      ErrorKind::Many1                     => "Many1",
      ErrorKind::Count                     => "Count",
      ErrorKind::TakeUntil                 => "Take until",
      ErrorKind::LengthValue               => "Length followed by value",
      ErrorKind::TagClosure                => "Tag closure",
      ErrorKind::Alpha                     => "Alphabetic",
      ErrorKind::Digit                     => "Digit",
      ErrorKind::AlphaNumeric              => "AlphaNumeric",
      ErrorKind::Space                     => "Space",
      ErrorKind::MultiSpace                => "Multiple spaces",
      ErrorKind::LengthValueFn             => "LengthValueFn",
      ErrorKind::Eof                       => "End of file",
      ErrorKind::Switch                    => "Switch",
      ErrorKind::TagBits                   => "Tag on bitstream",
      ErrorKind::OneOf                     => "OneOf",
      ErrorKind::NoneOf                    => "NoneOf",
      ErrorKind::Char                      => "Char",
      ErrorKind::CrLf                      => "CrLf",
      ErrorKind::RegexpMatch               => "RegexpMatch",
      ErrorKind::RegexpMatches             => "RegexpMatches",
      ErrorKind::RegexpFind                => "RegexpFind",
      ErrorKind::RegexpCapture             => "RegexpCapture",
      ErrorKind::RegexpCaptures            => "RegexpCaptures",
      ErrorKind::TakeWhile1                => "TakeWhile1",
      ErrorKind::Complete                  => "Complete",
      ErrorKind::Fix                       => "Fix",
      ErrorKind::Escaped                   => "Escaped",
      ErrorKind::EscapedTransform          => "EscapedTransform",
      ErrorKind::NonEmpty                  => "NonEmpty",
      ErrorKind::ManyMN                    => "Many(m, n)",
      ErrorKind::HexDigit                  => "Hexadecimal Digit",
      ErrorKind::OctDigit                  => "Octal digit",
      ErrorKind::Not                       => "Negation",
      ErrorKind::Permutation               => "Permutation",
      ErrorKind::ManyTill                  => "ManyTill",
      ErrorKind::Verify                    => "predicate verification",
      ErrorKind::TakeTill1                 => "TakeTill1",
      ErrorKind::TakeWhileMN               => "TakeWhileMN",
      ErrorKind::TooLarge                  => "Needed data size is too large",
      ErrorKind::Many0Count                => "Count occurrence of >=0 patterns",
      ErrorKind::Many1Count                => "Count occurrence of >=1 patterns",
      ErrorKind::Float                     => "Float",
      ErrorKind::Satisfy                   => "Satisfy",
      ErrorKind::Fail                      => "Fail",
    }
  }
}

/// Creates a parse error from a `nom::ErrorKind`
/// and the position in the input
#[allow(unused_variables)]
#[macro_export(local_inner_macros)]
macro_rules! error_position(
  ($input:expr, $code:expr) => ({
    $crate::error::make_error($input, $code)
  });
);

/// Creates a parse error from a `nom::ErrorKind`,
/// the position in the input and the next error in
/// the parsing tree
#[allow(unused_variables)]
#[macro_export(local_inner_macros)]
macro_rules! error_node_position(
  ($input:expr, $code:expr, $next:expr) => ({
    $crate::error::append_error($input, $code, $next)
  });
);

/// Prints a message and the input if the parser fails.
///
/// The message prints the `Error` or `Incomplete`
/// and the parser's calling code.
///
/// It also displays the input in hexdump format
///
/// ```rust
/// use nom::{IResult, error::dbg_dmp, bytes::complete::tag};
///
/// fn f(i: &[u8]) -> IResult<&[u8], &[u8]> {
///   dbg_dmp(tag("abcd"), "tag")(i)
/// }
///
///   let a = &b"efghijkl"[..];
///
/// // Will print the following message:
/// // Error(Position(0, [101, 102, 103, 104, 105, 106, 107, 108])) at l.5 by ' tag ! ( "abcd" ) '
/// // 00000000        65 66 67 68 69 6a 6b 6c         efghijkl
/// f(a);
/// ```
#[cfg(feature = "std")]
#[cfg_attr(feature = "docsrs", doc(cfg(feature = "std")))]
pub fn dbg_dmp<'a, F, O, E: std::fmt::Debug>(
  f: F,
  context: &'static str,
) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], O, E>
where
  F: Fn(&'a [u8]) -> IResult<&'a [u8], O, E>,
{
  use crate::HexDisplay;
  move |i: &'a [u8]| match f(i) {
    Err(e) => {
      println!("{}: Error({:?}) at:\n{}", context, e, i.to_hex(8));
      Err(e)
    }
    a => a,
  }
}

#[cfg(test)]
#[cfg(feature = "alloc")]
mod tests {
  use super::*;
  use crate::character::complete::char;

  #[test]
  fn convert_error_panic() {
    let input = "";

    let _result: IResult<_, _, VerboseError<&str>> = char('x')(input);
  }
}

/*
#[cfg(feature = "alloc")]
use lib::std::{vec::Vec, collections::HashMap};

#[cfg(feature = "std")]
use lib::std::hash::Hash;

#[cfg(feature = "std")]
pub fn add_error_pattern<'a, I: Clone + Hash + Eq, O, E: Clone + Hash + Eq>(
  h: &mut HashMap<VerboseError<I>, &'a str>,
  e: VerboseError<I>,
  message: &'a str,
) -> bool {
  h.insert(e, message);
  true
}

pub fn slice_to_offsets(input: &[u8], s: &[u8]) -> (usize, usize) {
  let start = input.as_ptr();
  let off1 = s.as_ptr() as usize - start as usize;
  let off2 = off1 + s.len();
  (off1, off2)
}

#[cfg(feature = "std")]
pub fn prepare_errors<O, E: Clone>(input: &[u8], e: VerboseError<&[u8]>) -> Option<Vec<(ErrorKind, usize, usize)>> {
  let mut v: Vec<(ErrorKind, usize, usize)> = Vec::new();

  for (p, kind) in e.errors.drain(..) {
    let (o1, o2) = slice_to_offsets(input, p);
    v.push((kind, o1, o2));
  }

  v.reverse();
  Some(v)
}

#[cfg(feature = "std")]
pub fn print_error<O, E: Clone>(input: &[u8], res: VerboseError<&[u8]>) {
  if let Some(v) = prepare_errors(input, res) {
    let colors = generate_colors(&v);
    println!("parser codes: {}", print_codes(&colors, &HashMap::new()));
    println!("{}", print_offsets(input, 0, &v));
  } else {
    println!("not an error");
  }
}

#[cfg(feature = "std")]
pub fn generate_colors<E>(v: &[(ErrorKind, usize, usize)]) -> HashMap<u32, u8> {
  let mut h: HashMap<u32, u8> = HashMap::new();
  let mut color = 0;

  for &(ref c, _, _) in v.iter() {
    h.insert(error_to_u32(c), color + 31);
    color = color + 1 % 7;
  }

  h
}

pub fn code_from_offset(v: &[(ErrorKind, usize, usize)], offset: usize) -> Option<u32> {
  let mut acc: Option<(u32, usize, usize)> = None;
  for &(ref ek, s, e) in v.iter() {
    let c = error_to_u32(ek);
    if s <= offset && offset <= e {
      if let Some((_, start, end)) = acc {
        if start <= s && e <= end {
          acc = Some((c, s, e));
        }
      } else {
        acc = Some((c, s, e));
      }
    }
  }
  if let Some((code, _, _)) = acc {
    return Some(code);
  } else {
    return None;
  }
}

#[cfg(feature = "alloc")]
pub fn reset_color(v: &mut Vec<u8>) {
  v.push(0x1B);
  v.push(b'[');
  v.push(0);
  v.push(b'm');
}

#[cfg(feature = "alloc")]
pub fn write_color(v: &mut Vec<u8>, color: u8) {
  v.push(0x1B);
  v.push(b'[');
  v.push(1);
  v.push(b';');
  let s = color.to_string();
  let bytes = s.as_bytes();
  v.extend(bytes.iter().cloned());
  v.push(b'm');
}

#[cfg(feature = "std")]
#[cfg_attr(feature = "cargo-clippy", allow(implicit_hasher))]
pub fn print_codes(colors: &HashMap<u32, u8>, names: &HashMap<u32, &str>) -> String {
  let mut v = Vec::new();
  for (code, &color) in colors {
    if let Some(&s) = names.get(code) {
      let bytes = s.as_bytes();
      write_color(&mut v, color);
      v.extend(bytes.iter().cloned());
    } else {
      let s = code.to_string();
      let bytes = s.as_bytes();
      write_color(&mut v, color);
      v.extend(bytes.iter().cloned());
    }
    reset_color(&mut v);
    v.push(b' ');
  }
  reset_color(&mut v);

  String::from_utf8_lossy(&v[..]).into_owned()
}

#[cfg(feature = "std")]
pub fn print_offsets(input: &[u8], from: usize, offsets: &[(ErrorKind, usize, usize)]) -> String {
  let mut v = Vec::with_capacity(input.len() * 3);
  let mut i = from;
  let chunk_size = 8;
  let mut current_code: Option<u32> = None;
  let mut current_code2: Option<u32> = None;

  let colors = generate_colors(&offsets);

  for chunk in input.chunks(chunk_size) {
    let s = format!("{:08x}", i);
    for &ch in s.as_bytes().iter() {
      v.push(ch);
    }
    v.push(b'\t');

    let mut k = i;
    let mut l = i;
    for &byte in chunk {
      if let Some(code) = code_from_offset(&offsets, k) {
        if let Some(current) = current_code {
          if current != code {
            reset_color(&mut v);
            current_code = Some(code);
            if let Some(&color) = colors.get(&code) {
              write_color(&mut v, color);
            }
          }
        } else {
          current_code = Some(code);
          if let Some(&color) = colors.get(&code) {
            write_color(&mut v, color);
          }
        }
      }
      v.push(CHARS[(byte >> 4) as usize]);
      v.push(CHARS[(byte & 0xf) as usize]);
      v.push(b' ');
      k = k + 1;
    }

    reset_color(&mut v);

    if chunk_size > chunk.len() {
      for _ in 0..(chunk_size - chunk.len()) {
        v.push(b' ');
        v.push(b' ');
        v.push(b' ');
      }
    }
    v.push(b'\t');

    for &byte in chunk {
      if let Some(code) = code_from_offset(&offsets, l) {
        if let Some(current) = current_code2 {
          if current != code {
            reset_color(&mut v);
            current_code2 = Some(code);
            if let Some(&color) = colors.get(&code) {
              write_color(&mut v, color);
            }
          }
        } else {
          current_code2 = Some(code);
          if let Some(&color) = colors.get(&code) {
            write_color(&mut v, color);
          }
        }
      }
      if (byte >= 32 && byte <= 126) || byte >= 128 {
        v.push(byte);
      } else {
        v.push(b'.');
      }
      l = l + 1;
    }
    reset_color(&mut v);

    v.push(b'\n');
    i = i + chunk_size;
  }

  String::from_utf8_lossy(&v[..]).into_owned()
}
*/