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//! Basic types to build the parsers use self::Needed::*; use 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 an enum 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 appling 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()), } } } /* #[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 { write!(f, "{:?}", self) } } #[cfg(feature = "std")] use std::error::Error; #[cfg(feature = "std")] impl<E> Error for Err<E> where I: fmt::Debug, E: fmt::Debug, { fn description(&self) -> &str { match self { &Err::Incomplete(..) => "there was not enough data", &Err::Error(Context::Code(_, ref error_kind)) | &Err::Failure(Context::Code(_, ref error_kind)) => error_kind.description(), } } fn cause(&self) -> Option<&Error> { None } } */ #[cfg(test)] mod tests { use super::*; use error::ErrorKind; #[doc(hidden)] #[macro_export] macro_rules! assert_size ( ($t:ty, $sz:expr) => ( assert_eq!(::lib::std::mem::size_of::<$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); } }