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</pre><pre class="rust ">
<span class="kw">use</span> {<span class="ident">Poll</span>, <span class="ident">Async</span>, <span class="ident">Future</span>, <span class="ident">AsyncSink</span>};
<span class="kw">use</span> <span class="ident">stream</span>::{<span class="ident">Stream</span>, <span class="ident">Fuse</span>};
<span class="kw">use</span> <span class="ident">sink</span>::<span class="ident">Sink</span>;
<span class="doccomment">/// Future for the `Stream::forward` combinator, which sends a stream of values</span>
<span class="doccomment">/// to a sink and then waits until the sink has fully flushed those values.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"futures do nothing unless polled"</span>]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Forward</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Stream</span>, <span class="ident">U</span><span class="op">></span> {
<span class="ident">sink</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">U</span><span class="op">></span>,
<span class="ident">stream</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Fuse</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span>,
<span class="ident">buffered</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span>::<span class="ident">Item</span><span class="op">></span>,
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">U</span><span class="op">></span>(<span class="ident">stream</span>: <span class="ident">T</span>, <span class="ident">sink</span>: <span class="ident">U</span>) <span class="op">-></span> <span class="ident">Forward</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">U</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">U</span>: <span class="ident">Sink</span><span class="op"><</span><span class="ident">SinkItem</span><span class="op">=</span><span class="ident">T</span>::<span class="ident">Item</span><span class="op">></span>,
<span class="ident">T</span>: <span class="ident">Stream</span>,
<span class="ident">T</span>::<span class="ident">Error</span>: <span class="ident">From</span><span class="op"><</span><span class="ident">U</span>::<span class="ident">SinkError</span><span class="op">></span>,
{
<span class="ident">Forward</span> {
<span class="ident">sink</span>: <span class="prelude-val">Some</span>(<span class="ident">sink</span>),
<span class="ident">stream</span>: <span class="prelude-val">Some</span>(<span class="ident">stream</span>.<span class="ident">fuse</span>()),
<span class="ident">buffered</span>: <span class="prelude-val">None</span>,
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">U</span><span class="op">></span> <span class="ident">Forward</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">U</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">U</span>: <span class="ident">Sink</span><span class="op"><</span><span class="ident">SinkItem</span><span class="op">=</span><span class="ident">T</span>::<span class="ident">Item</span><span class="op">></span>,
<span class="ident">T</span>: <span class="ident">Stream</span>,
<span class="ident">T</span>::<span class="ident">Error</span>: <span class="ident">From</span><span class="op"><</span><span class="ident">U</span>::<span class="ident">SinkError</span><span class="op">></span>,
{
<span class="doccomment">/// Get a shared reference to the inner sink.</span>
<span class="doccomment">/// If this combinator has already been polled to completion, None will be returned.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">sink_ref</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">U</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">sink</span>.<span class="ident">as_ref</span>()
}
<span class="doccomment">/// Get a mutable reference to the inner sink.</span>
<span class="doccomment">/// If this combinator has already been polled to completion, None will be returned.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">sink_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">U</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">sink</span>.<span class="ident">as_mut</span>()
}
<span class="doccomment">/// Get a shared reference to the inner stream.</span>
<span class="doccomment">/// If this combinator has already been polled to completion, None will be returned.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">stream_ref</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">T</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">stream</span>.<span class="ident">as_ref</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">get_ref</span>())
}
<span class="doccomment">/// Get a mutable reference to the inner stream.</span>
<span class="doccomment">/// If this combinator has already been polled to completion, None will be returned.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">stream_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">T</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">stream</span>.<span class="ident">as_mut</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">get_mut</span>())
}
<span class="kw">fn</span> <span class="ident">take_result</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> (<span class="ident">T</span>, <span class="ident">U</span>) {
<span class="kw">let</span> <span class="ident">sink</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">sink</span>.<span class="ident">take</span>()
.<span class="ident">expect</span>(<span class="string">"Attempted to poll Forward after completion"</span>);
<span class="kw">let</span> <span class="ident">fuse</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">stream</span>.<span class="ident">take</span>()
.<span class="ident">expect</span>(<span class="string">"Attempted to poll Forward after completion"</span>);
(<span class="ident">fuse</span>.<span class="ident">into_inner</span>(), <span class="ident">sink</span>)
}
<span class="kw">fn</span> <span class="ident">try_start_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">item</span>: <span class="ident">T</span>::<span class="ident">Item</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">U</span>::<span class="ident">SinkError</span><span class="op">></span> {
<span class="macro">debug_assert</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">buffered</span>.<span class="ident">is_none</span>());
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">AsyncSink</span>::<span class="ident">NotReady</span>(<span class="ident">item</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">sink_mut</span>()
.<span class="ident">take</span>().<span class="ident">expect</span>(<span class="string">"Attempted to poll Forward after completion"</span>)
.<span class="ident">start_send</span>(<span class="ident">item</span>)<span class="question-mark">?</span>
{
<span class="self">self</span>.<span class="ident">buffered</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">item</span>);
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>)
}
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">U</span><span class="op">></span> <span class="ident">Future</span> <span class="kw">for</span> <span class="ident">Forward</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">U</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">U</span>: <span class="ident">Sink</span><span class="op"><</span><span class="ident">SinkItem</span><span class="op">=</span><span class="ident">T</span>::<span class="ident">Item</span><span class="op">></span>,
<span class="ident">T</span>: <span class="ident">Stream</span>,
<span class="ident">T</span>::<span class="ident">Error</span>: <span class="ident">From</span><span class="op"><</span><span class="ident">U</span>::<span class="ident">SinkError</span><span class="op">></span>,
{
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> (<span class="ident">T</span>, <span class="ident">U</span>);
<span class="kw">type</span> <span class="ident">Error</span> <span class="op">=</span> <span class="ident">T</span>::<span class="ident">Error</span>;
<span class="kw">fn</span> <span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(<span class="ident">T</span>, <span class="ident">U</span>), <span class="ident">T</span>::<span class="ident">Error</span><span class="op">></span> {
<span class="comment">// If we've got an item buffered already, we need to write it to the</span>
<span class="comment">// sink before we can do anything else</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">item</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">buffered</span>.<span class="ident">take</span>() {
<span class="macro">try_ready</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">try_start_send</span>(<span class="ident">item</span>))
}
<span class="kw">loop</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">stream_mut</span>()
.<span class="ident">take</span>().<span class="ident">expect</span>(<span class="string">"Attempted to poll Forward after completion"</span>)
.<span class="ident">poll</span>()<span class="question-mark">?</span>
{
<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">Some</span>(<span class="ident">item</span>)) <span class="op">=></span> <span class="macro">try_ready</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">try_start_send</span>(<span class="ident">item</span>)),
<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">None</span>) <span class="op">=></span> {
<span class="macro">try_ready</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">sink_mut</span>().<span class="ident">take</span>().<span class="ident">expect</span>(<span class="string">"Attempted to poll Forward after completion"</span>).<span class="ident">close</span>());
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="self">self</span>.<span class="ident">take_result</span>()))
}
<span class="ident">Async</span>::<span class="ident">NotReady</span> <span class="op">=></span> {
<span class="macro">try_ready</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">sink_mut</span>().<span class="ident">take</span>().<span class="ident">expect</span>(<span class="string">"Attempted to poll Forward after completion"</span>).<span class="ident">poll_complete</span>());
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>)
}
}
}
}
}
</pre>
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