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<p class='location'>Trait DecoderHelpers</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#required-methods">Required Methods</a><div class="sidebar-links"><a href="#tymethod.read_to_vec">read_to_vec</a></div><a class="sidebar-title" href="#implementors">Implementors</a></div><p class='location'><a href='index.html'>rustc_serialize</a></p><script>window.sidebarCurrent = {name: 'DecoderHelpers', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script></div>
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<h1 class='fqn'><span class='in-band'>Trait <a href='index.html'>rustc_serialize</a>::<wbr><a class="trait" href=''>DecoderHelpers</a></span><span class='out-of-band'><span id='render-detail'>
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</span><a class='srclink' href='../src/rustc_serialize/serialize.rs.html#1515-1548' title='goto source code'>[src]</a></span></h1>
<pre class='rust trait'>pub trait DecoderHelpers: <a class="trait" href="../rustc_serialize/trait.Decoder.html" title="trait rustc_serialize::Decoder">Decoder</a> {
fn <a href='#tymethod.read_to_vec' class='fnname'>read_to_vec</a>&lt;T, F&gt;(&amp;mut self, f: F) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;<a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a>&lt;T&gt;, Self::<a class="type" href="../rustc_serialize/trait.Decoder.html#associatedtype.Error" title="type rustc_serialize::Decoder::Error">Error</a>&gt;<br>&nbsp;&nbsp;&nbsp; <span class="where">where<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;F: <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/function/trait.FnMut.html" title="trait core::ops::function::FnMut">FnMut</a>(<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>Self) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;T, Self::<a class="type" href="../rustc_serialize/trait.Decoder.html#associatedtype.Error" title="type rustc_serialize::Decoder::Error">Error</a>&gt;</span>;
}</pre><div class='docblock'><p>Trait with helper functions for implementing <code>Decodable</code>.</p>
<p>This trait is implemented for everything that implements <code>Decoder</code>.
<code>Decodable</code> implementations can make use of it to make their implementations
easier.</p>
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Required Methods<a href='#required-methods' class='anchor'></a>
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<h3 id='tymethod.read_to_vec' class='method'><span id='read_to_vec.v' class='invisible'><code>fn <a href='#tymethod.read_to_vec' class='fnname'>read_to_vec</a>&lt;T, F&gt;(&amp;mut self, f: F) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;<a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a>&lt;T&gt;, Self::<a class="type" href="../rustc_serialize/trait.Decoder.html#associatedtype.Error" title="type rustc_serialize::Decoder::Error">Error</a>&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;F: <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/function/trait.FnMut.html" title="trait core::ops::function::FnMut">FnMut</a>(<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>Self) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;T, Self::<a class="type" href="../rustc_serialize/trait.Decoder.html#associatedtype.Error" title="type rustc_serialize::Decoder::Error">Error</a>&gt;,&nbsp;</span></code></span></h3><div class='docblock'><p>Read a sequence into a vector.</p>
<p>Storing sequences as vectors is a common pattern. This method makes
deserializing such sequences easier by wrapping the calls to
<code>Decoder::read_seq</code> and <code>Decoder::read_seq_elt</code>.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">rustc_serialize</span>::<span class="ident">Decodable</span>;
<span class="kw">use</span> <span class="ident">rustc_serialize</span>::<span class="ident">Decoder</span>;
<span class="kw">use</span> <span class="ident">rustc_serialize</span>::<span class="ident">DecoderHelpers</span>;
<span class="kw">struct</span> <span class="ident">NumberSequence</span> {
<span class="ident">elements</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="ident">i32</span><span class="op">&gt;</span>,
}
<span class="kw">impl</span> <span class="ident">Decodable</span> <span class="kw">for</span> <span class="ident">NumberSequence</span> {
<span class="kw">fn</span> <span class="ident">decode</span><span class="op">&lt;</span><span class="ident">D</span>: <span class="ident">Decoder</span><span class="op">&gt;</span>(<span class="ident">d</span>: <span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">D</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">NumberSequence</span>, <span class="ident">D</span>::<span class="ident">Error</span><span class="op">&gt;</span> {
<span class="ident">d</span>.<span class="ident">read_struct</span>(<span class="string">&quot;NumberSequence&quot;</span>, <span class="number">2</span>, <span class="op">|</span><span class="ident">d</span><span class="op">|</span> {
<span class="prelude-val">Ok</span>(<span class="ident">NumberSequence</span>{
<span class="ident">elements</span>: <span class="macro">try</span><span class="macro">!</span>(<span class="ident">d</span>.<span class="ident">read_struct_field</span>(<span class="string">&quot;elements&quot;</span>, <span class="number">0</span>, <span class="op">|</span><span class="ident">d</span><span class="op">|</span> {
<span class="ident">d</span>.<span class="ident">read_to_vec</span>(<span class="op">|</span><span class="ident">d</span><span class="op">|</span> { <span class="ident">d</span>.<span class="ident">read_i32</span>() })
}))
})
})
}
}</pre>
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<li><div class='out-of-band'><a class='srclink' href='../src/rustc_serialize/serialize.rs.html#1550-1562' title='goto source code'>[src]</a></div><code>impl&lt;D:&nbsp;<a class="trait" href="../rustc_serialize/trait.Decoder.html" title="trait rustc_serialize::Decoder">Decoder</a>&gt; DecoderHelpers for D</code></li>
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