blob: aae5623efa1a7953796b76eb6da435709ac6b83f [file] [log] [blame]
use core::mem;
use core::fmt::{Debug, Formatter, Result as FmtResult};
use core::default::Default;
use {Poll, Async};
use future::Future;
use stream::Stream;
/// A stream combinator to concatenate the results of a stream into the first
/// yielded item.
///
/// This structure is produced by the `Stream::concat` method.
#[must_use = "streams do nothing unless polled"]
pub struct Concat2<S>
where S: Stream,
{
inner: ConcatSafe<S>
}
impl<S: Debug> Debug for Concat2<S> where S: Stream, S::Item: Debug {
fn fmt(&self, fmt: &mut Formatter) -> FmtResult {
fmt.debug_struct("Concat2")
.field("inner", &self.inner)
.finish()
}
}
pub fn new2<S>(s: S) -> Concat2<S>
where S: Stream,
S::Item: Extend<<<S as Stream>::Item as IntoIterator>::Item> + IntoIterator + Default,
{
Concat2 {
inner: new_safe(s)
}
}
impl<S> Future for Concat2<S>
where S: Stream,
S::Item: Extend<<<S as Stream>::Item as IntoIterator>::Item> + IntoIterator + Default,
{
type Item = S::Item;
type Error = S::Error;
fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
self.inner.poll().map(|a| {
match a {
Async::NotReady => Async::NotReady,
Async::Ready(None) => Async::Ready(Default::default()),
Async::Ready(Some(e)) => Async::Ready(e)
}
})
}
}
/// A stream combinator to concatenate the results of a stream into the first
/// yielded item.
///
/// This structure is produced by the `Stream::concat` method.
#[deprecated(since="0.1.18", note="please use `Stream::Concat2` instead")]
#[must_use = "streams do nothing unless polled"]
pub struct Concat<S>
where S: Stream,
{
inner: ConcatSafe<S>
}
#[allow(deprecated)]
impl<S: Debug> Debug for Concat<S> where S: Stream, S::Item: Debug {
fn fmt(&self, fmt: &mut Formatter) -> FmtResult {
fmt.debug_struct("Concat")
.field("inner", &self.inner)
.finish()
}
}
#[allow(deprecated)]
pub fn new<S>(s: S) -> Concat<S>
where S: Stream,
S::Item: Extend<<<S as Stream>::Item as IntoIterator>::Item> + IntoIterator,
{
Concat {
inner: new_safe(s)
}
}
#[allow(deprecated)]
impl<S> Future for Concat<S>
where S: Stream,
S::Item: Extend<<<S as Stream>::Item as IntoIterator>::Item> + IntoIterator,
{
type Item = S::Item;
type Error = S::Error;
fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
self.inner.poll().map(|a| {
match a {
Async::NotReady => Async::NotReady,
Async::Ready(None) => panic!("attempted concatenation of empty stream"),
Async::Ready(Some(e)) => Async::Ready(e)
}
})
}
}
#[derive(Debug)]
struct ConcatSafe<S>
where S: Stream,
{
stream: S,
extend: Inner<S::Item>,
}
fn new_safe<S>(s: S) -> ConcatSafe<S>
where S: Stream,
S::Item: Extend<<<S as Stream>::Item as IntoIterator>::Item> + IntoIterator,
{
ConcatSafe {
stream: s,
extend: Inner::First,
}
}
impl<S> Future for ConcatSafe<S>
where S: Stream,
S::Item: Extend<<<S as Stream>::Item as IntoIterator>::Item> + IntoIterator,
{
type Item = Option<S::Item>;
type Error = S::Error;
fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
loop {
match self.stream.poll() {
Ok(Async::Ready(Some(i))) => {
match self.extend {
Inner::First => {
self.extend = Inner::Extending(i);
},
Inner::Extending(ref mut e) => {
e.extend(i);
},
Inner::Done => unreachable!(),
}
},
Ok(Async::Ready(None)) => {
match mem::replace(&mut self.extend, Inner::Done) {
Inner::First => return Ok(Async::Ready(None)),
Inner::Extending(e) => return Ok(Async::Ready(Some(e))),
Inner::Done => panic!("cannot poll Concat again")
}
},
Ok(Async::NotReady) => return Ok(Async::NotReady),
Err(e) => {
self.extend = Inner::Done;
return Err(e)
}
}
}
}
}
#[derive(Debug)]
enum Inner<E> {
First,
Extending(E),
Done,
}