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
use core::fmt;
use core::pin::Pin;
use futures_core::future::TryFuture;
use futures_core::stream::{Stream, TryStream, FusedStream};
use futures_core::task::{Context, Poll};
#[cfg(feature = "sink")]
use futures_sink::Sink;
use pin_utils::{unsafe_pinned, unsafe_unpinned};
#[must_use = "streams do nothing unless polled"]
pub struct TrySkipWhile<St, Fut, F> where St: TryStream {
stream: St,
f: F,
pending_fut: Option<Fut>,
pending_item: Option<St::Ok>,
done_skipping: bool,
}
impl<St: Unpin + TryStream, Fut: Unpin, F> Unpin for TrySkipWhile<St, Fut, F> {}
impl<St, Fut, F> fmt::Debug for TrySkipWhile<St, Fut, F>
where
St: TryStream + fmt::Debug,
St::Ok: fmt::Debug,
Fut: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("TrySkipWhile")
.field("stream", &self.stream)
.field("pending_fut", &self.pending_fut)
.field("pending_item", &self.pending_item)
.field("done_skipping", &self.done_skipping)
.finish()
}
}
impl<St, Fut, F> TrySkipWhile<St, Fut, F>
where St: TryStream,
{
unsafe_pinned!(stream: St);
}
impl<St, Fut, F> TrySkipWhile<St, Fut, F>
where St: TryStream,
F: FnMut(&St::Ok) -> Fut,
Fut: TryFuture<Ok = bool, Error = St::Error>,
{
unsafe_unpinned!(f: F);
unsafe_pinned!(pending_fut: Option<Fut>);
unsafe_unpinned!(pending_item: Option<St::Ok>);
unsafe_unpinned!(done_skipping: bool);
pub(super) fn new(stream: St, f: F) -> TrySkipWhile<St, Fut, F> {
TrySkipWhile {
stream,
f,
pending_fut: None,
pending_item: None,
done_skipping: false,
}
}
pub fn get_ref(&self) -> &St {
&self.stream
}
pub fn get_mut(&mut self) -> &mut St {
&mut self.stream
}
pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut St> {
self.stream()
}
pub fn into_inner(self) -> St {
self.stream
}
}
impl<St, Fut, F> Stream for TrySkipWhile<St, Fut, F>
where St: TryStream,
F: FnMut(&St::Ok) -> Fut,
Fut: TryFuture<Ok = bool, Error = St::Error>,
{
type Item = Result<St::Ok, St::Error>;
fn poll_next(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<Self::Item>> {
if self.done_skipping {
return self.as_mut().stream().try_poll_next(cx);
}
loop {
if self.pending_item.is_none() {
let item = match ready!(self.as_mut().stream().try_poll_next(cx)?) {
Some(e) => e,
None => return Poll::Ready(None),
};
let fut = (self.as_mut().f())(&item);
self.as_mut().pending_fut().set(Some(fut));
*self.as_mut().pending_item() = Some(item);
}
let skipped = ready!(self.as_mut().pending_fut().as_pin_mut().unwrap().try_poll(cx)?);
let item = self.as_mut().pending_item().take().unwrap();
self.as_mut().pending_fut().set(None);
if !skipped {
*self.as_mut().done_skipping() = true;
return Poll::Ready(Some(Ok(item)))
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let pending_len = if self.pending_item.is_some() { 1 } else { 0 };
let (_, upper) = self.stream.size_hint();
let upper = match upper {
Some(x) => x.checked_add(pending_len),
None => None,
};
(0, upper)
}
}
impl<St, Fut, F> FusedStream for TrySkipWhile<St, Fut, F>
where St: TryStream + FusedStream,
F: FnMut(&St::Ok) -> Fut,
Fut: TryFuture<Ok = bool, Error = St::Error>,
{
fn is_terminated(&self) -> bool {
self.pending_item.is_none() && self.stream.is_terminated()
}
}
#[cfg(feature = "sink")]
impl<S, Fut, F, Item, E> Sink<Item> for TrySkipWhile<S, Fut, F>
where S: TryStream + Sink<Item, Error = E>,
{
type Error = E;
delegate_sink!(stream, Item);
}