scroll 0.6.0

A suite of powerful, extensible, generic, endian-aware Read/Write traits and contextual conversion traits
Documentation 
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use core::fmt::{self, Display};
use core::result;
use core::ops::Range;

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

#[derive(Debug)]
/// A custom Scroll error
pub enum Error {
    /// The requested offset to read/write at is invalid
    BadOffset(usize),
    /// The requested range to read/write at is invalid for the size of the provided object
    BadRange { range: Range<usize>, size: usize },
    /// The data at the given range is invalid
    BadInput { range: Range<usize>, size: usize, msg: &'static str },
    #[cfg(feature = "std")]
    /// A custom Scroll error for reporting messages to clients
    Custom(String),
    #[cfg(feature = "std")]
    /// Returned when IO based errors are encountered
    IO(io::Error),
}

#[cfg(feature = "std")]
impl error::Error for Error {
    fn description(&self) -> &str {
        match *self {
            Error::BadOffset(_) => { "BadOffset" }
            Error::BadRange{ .. } => { "BadRange" }
            Error::BadInput{ .. } => { "BadInput" }
            Error::Custom(_) => { "Custom" }
            Error::IO(_) => { "IO" }
        }
    }
    fn cause(&self) -> Option<&error::Error> {
        match *self {
            Error::BadOffset(_) => { None }
            Error::BadRange{ .. } => { None }
            Error::BadInput{ .. }=> { None }
            Error::Custom(_) => { None }
            Error::IO(ref io) => { io.cause() }
        }
    }
}

#[cfg(feature = "std")]
impl From<io::Error> for Error {
    fn from(err: io::Error) -> Error {
        Error::IO(err)
    }
}

impl Display for Error {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Error::BadOffset(ref offset) => { write! (fmt, "bad offset {}", offset) },
            Error::BadRange{ ref range, ref size} => {
                write!(fmt, "requested range [{}..{}) from object of len {}", range.start, range.end, size)
            },
            Error::BadInput{ref range, ref size, msg} => {
                write!(fmt, "{} - range [{}..{}), len {}", msg, range.start, range.end, size)
            },
            #[cfg(feature = "std")]
            Error::Custom(ref msg) => { write! (fmt, "{}", msg) },
            #[cfg(feature = "std")]
            Error::IO(ref err) => { write!(fmt, "{}", err) },
        }
    }
}

pub type Result<T> = result::Result<T, Error>;