rust-libp2p/core/src/upgrade/map.rs

// Copyright 2017 Parity Technologies (UK) Ltd.
//
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// copy of this software and associated documentation files (the "Software"),
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// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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use std::io::Error as IoError;
use futures::prelude::*;
use tokio_io::{AsyncRead, AsyncWrite};
use upgrade::{ConnectionUpgrade, Endpoint};

/// Applies a closure on the output of a connection upgrade.
#[inline]
pub fn map<U, F>(upgrade: U, map: F) -> Map<U, F> {
    Map { upgrade, map }
}

/// Application of a closure on the output of a connection upgrade.
#[derive(Debug, Copy, Clone)]
pub struct Map<U, F> {
    upgrade: U,
    map: F,
}

impl<C, U, F, O> ConnectionUpgrade<C> for Map<U, F>
where
    U: ConnectionUpgrade<C>,
    U::Future: Send + 'static,     // TODO: 'static :(
    C: AsyncRead + AsyncWrite,
    F: FnOnce(U::Output) -> O + Send + 'static,     // TODO: 'static :(
{
    type NamesIter = U::NamesIter;
    type UpgradeIdentifier = U::UpgradeIdentifier;

    fn protocol_names(&self) -> Self::NamesIter {
        self.upgrade.protocol_names()
    }

    type Output = O;
    type Future = Box<Future<Item = O, Error = IoError> + Send>;

    fn upgrade(
        self,
        socket: C,
        id: Self::UpgradeIdentifier,
        ty: Endpoint,
    ) -> Self::Future {
        let map = self.map;
        let fut = self.upgrade
            .upgrade(socket, id, ty)
            .map(map);
        Box::new(fut) as Box<_>
    }
}