1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172

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::concat2` 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,
}