rust-libp2p/misc/multistream-select/src/error.rs

// Copyright 2017 Parity Technologies (UK) Ltd.
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//! Main `ProtocolChoiceError` error.

use protocol::MultistreamSelectError;
use std::error;
use std::fmt;
use std::io::Error as IoError;

/// Error that can happen when negotiating a protocol with the remote.
#[derive(Debug)]
pub enum ProtocolChoiceError {
    /// Error in the protocol.
    MultistreamSelectError(MultistreamSelectError),

    /// Received a message from the remote that makes no sense in the current context.
    UnexpectedMessage,

    /// We don't support any protocol in common with the remote.
    NoProtocolFound,
}

impl From<MultistreamSelectError> for ProtocolChoiceError {
    #[inline]
    fn from(err: MultistreamSelectError) -> ProtocolChoiceError {
        ProtocolChoiceError::MultistreamSelectError(err)
    }
}

impl From<IoError> for ProtocolChoiceError {
    #[inline]
    fn from(err: IoError) -> ProtocolChoiceError {
        MultistreamSelectError::from(err).into()
    }
}

impl error::Error for ProtocolChoiceError {
    #[inline]
    fn description(&self) -> &str {
        match *self {
            ProtocolChoiceError::MultistreamSelectError(_) => "error in the protocol",
            ProtocolChoiceError::UnexpectedMessage => {
                "received a message from the remote that makes no sense in the current context"
            }
            ProtocolChoiceError::NoProtocolFound => {
                "we don't support any protocol in common with the remote"
            }
        }
    }

    fn cause(&self) -> Option<&error::Error> {
        match *self {
            ProtocolChoiceError::MultistreamSelectError(ref err) => Some(err),
            _ => None,
        }
    }
}

impl fmt::Display for ProtocolChoiceError {
    #[inline]
    fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        write!(fmt, "{}", error::Error::description(self))
    }
}