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
//! Basic types to build the parsers

use self::Needed::*;
use crate::error::ErrorKind;

/// Holds the result of parsing functions
///
/// It depends on I, the input type, O, the output type, and E, the error type (by default u32)
///
/// The `Ok` side is a pair containing the remainder of the input (the part of the data that
/// was not parsed) and the produced value. The `Err` side contains an instance of `nom::Err`.
///
pub type IResult<I, O, E=(I,ErrorKind)> = Result<(I, O), Err<E>>;

/// Contains information on needed data if a parser returned `Incomplete`
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum Needed {
  /// needs more data, but we do not know how much
  Unknown,
  /// contains the required data size
  Size(usize),
}

impl Needed {
  /// indicates if we know how many bytes we need
  pub fn is_known(&self) -> bool {
    *self != Unknown
  }

  /// Maps a `Needed` to `Needed` by applying a function to a contained `Size` value.
  #[inline]
  pub fn map<F: Fn(usize) -> usize>(self, f: F) -> Needed {
    match self {
      Unknown => Unknown,
      Size(n) => Size(f(n)),
    }
  }
}

/// The `Err` enum indicates the parser was not successful
///
/// It has three cases:
///
/// * `Incomplete` indicates that more data is needed to decide. The `Needed` enum
/// can contain how many additional bytes are necessary. If you are sure your parser
/// is working on full data, you can wrap your parser with the `complete` combinator
/// to transform that case in `Error`
/// * `Error` means some parser did not succeed, but another one might (as an example,
/// when testing different branches of an `alt` combinator)
/// * `Failure` indicates an unrecoverable error. As an example, if you recognize a prefix
/// to decide on the next parser to apply, and that parser fails, you know there's no need
/// to try other parsers, you were already in the right branch, so the data is invalid
///
#[derive(Debug, Clone, PartialEq)]
pub enum Err<E> {
  /// There was not enough data
  Incomplete(Needed),
  /// The parser had an error (recoverable)
  Error(E),
  /// The parser had an unrecoverable error: we got to the right
  /// branch and we know other branches won't work, so backtrack
  /// as fast as possible
  Failure(E),
}

impl<E> Err<E> {
  /// tests if the result is Incomplete
  pub fn is_incomplete(&self) -> bool {
    if let Err::Incomplete(_) = self {
      true
    } else {
      false
    }
  }

  /// automatically converts between errors if the underlying type supports it
  pub fn convert<F>(e: Err<F>) -> Self
    where E: From<F> {
    match e {
      Err::Incomplete(n) => Err::Incomplete(n),
      Err::Failure(c) => Err::Failure(c.into()),
      Err::Error(c) => Err::Error(c.into()),
    }
  }
}

impl<T> Err<(T, ErrorKind)> {
  /// maps `Err<(T, ErrorKind)>` to `Err<(U, ErrorKind)>` with the given F: T -> U
  pub fn map_input<U, F>(self, f: F) -> Err<(U, ErrorKind)>
    where F: FnOnce(T) -> U {
    match self {
      Err::Incomplete(n) => Err::Incomplete(n),
      Err::Failure((input, k)) => Err::Failure((f(input), k)),
      Err::Error((input, k)) => Err::Error((f(input), k)),
    }
  }
}

#[cfg(feature = "std")]
impl Err<(&[u8], ErrorKind)> {
  /// Obtaining ownership
  pub fn to_owned(self) -> Err<(Vec<u8>, ErrorKind)> {
    self.map_input(ToOwned::to_owned)
  }
}

#[cfg(feature = "std")]
impl Err<(&str, ErrorKind)> {
  /// automatically converts between errors if the underlying type supports it
  pub fn to_owned(self) -> Err<(String, ErrorKind)> {
    self.map_input(ToOwned::to_owned)
  }
}

impl<E: Eq> Eq for Err<E> {}

#[cfg(feature = "std")]
use std::fmt;

#[cfg(feature = "std")]
impl<E> fmt::Display for Err<E>
where
  E: fmt::Debug,
{
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    match self {
      Err::Incomplete(Needed::Size(u)) => write!(f, "Parsing requires {} bytes/chars", u),
      Err::Incomplete(Needed::Unknown) => write!(f, "Parsing requires more data"),
      Err::Failure(c) => write!(f, "Parsing Failure: {:?}", c),
      Err::Error(c) => write!(f, "Parsing Error: {:?}", c),
    }
  }
}

#[cfg(feature = "std")]
use std::error::Error;

#[cfg(feature = "std")]
impl<E> Error for Err<E>
where
  E: fmt::Debug,
{
  fn source(&self) -> Option<&(dyn Error + 'static)> {
    None // no underlying error
  }
}

#[cfg(test)]
mod tests {
  use super::*;
  use crate::error::ErrorKind;

  #[doc(hidden)]
  #[macro_export]
  macro_rules! assert_size (
    ($t:ty, $sz:expr) => (
      assert_eq!(crate::lib::std::mem::size_of::<$t>(), $sz);
    );
  );

  #[test]
  #[cfg(target_pointer_width = "64")]
  fn size_test() {
    assert_size!(IResult<&[u8], &[u8], (&[u8], u32)>, 40);
    assert_size!(IResult<&str, &str, u32>, 40);
    assert_size!(Needed, 16);
    assert_size!(Err<u32>, 24);
    assert_size!(ErrorKind, 1);
  }

}