Split InputModify and ParseResultModify into more specialized traits

[m4rw3r]

Problem

internal::InputModify and internal::ParseResultModify contain too many methods, making it hard to see what a part is actually doing with the Input and ParseResult types.

Proposed solution

Remove ParseResultModify and InputModify and replace with the following traits:

Note: ParseResultModify::modify does not need any corresponding trait, it is unused.

• Replace all uses of InputModify::modify with buffer() + replace(buffer).

IntoInner trait

pub trait IntoInner {
    type Inner;

    fn into_inner() -> Self::Inner;
}

• Input -> (InputState, &[I])
• ParseResult -> State

ParseResultChain for ParseResult

Is this really useful? It is used in two spots in combinators.rs.

pub trait ParseResultChain {
    fn chain<F, T, E>(self, F) -> ParseResult<'a, Self::Input, T, E>
      where F: FnOnce(State<'a, Self::Input, Self::Data, Self::Error>)
               ...;
}

InputClone

pub trait InputClone {
    fn clone_input(&self) -> Self;
}

InputBuffer

pub trait InputBuffer<'a> {
    fn buffer(&self) -> &'a [Self::Type]
      where <Self as InputModify<'a>>::Type: 'a;
    fn replace(self, &'a [Self::Type]) -> Self
      where <Self as InputModify<'a>>::Type: 'a;
    fn is_last_slice(&self) -> bool;
}

replace is never used without buffer (except for in one case combined with parse), and same goes for is_last_slice.

InputIncomplete

pub trait InputIncomplete {
    fn incomplete<T, E>(self, usize) -> ParseResult<'a, Self::Type, T, E>;
}