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oxipng/doc/bitflags/__core/io/trait.Read.html
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2016-04-20 15:59:23 -04:00

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<h1 class='fqn'><span class='in-band'>Trait <a href='../../index.html'>bitflags</a>::<wbr><a href='../index.html'>__core</a>::<wbr><a href='index.html'>io</a>::<wbr><a class='trait' href=''>Read</a></span><span class='out-of-band'><span id='render-detail'>
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</span><a id='src-4892' class='srclink' href='https://doc.rust-lang.org/nightly/std/io/trait.Read.html?gotosrc=4892' title='goto source code'>[src]</a></span></h1>
<pre class='rust trait'>pub trait Read {
fn <a href='#tymethod.read' class='fnname'>read</a>(&amp;mut self, buf: <a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>&amp;mut [</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u8.html'>u8</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>]</a>) -&gt; <a class='enum' href='../../../bitflags/__core/result/enum.Result.html' title='bitflags::__core::result::Result'>Result</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.usize.html'>usize</a>, <a class='struct' href='../../../bitflags/__core/io/struct.Error.html' title='bitflags::__core::io::Error'>Error</a>&gt;;
fn <a href='#method.read_to_end' class='fnname'>read_to_end</a>(&amp;mut self, buf: &amp;mut <a class='struct' href='../../../bitflags/__core/vec/struct.Vec.html' title='bitflags::__core::vec::Vec'>Vec</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u8.html'>u8</a>&gt;) -&gt; <a class='enum' href='../../../bitflags/__core/result/enum.Result.html' title='bitflags::__core::result::Result'>Result</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.usize.html'>usize</a>, <a class='struct' href='../../../bitflags/__core/io/struct.Error.html' title='bitflags::__core::io::Error'>Error</a>&gt; { ... }
fn <a href='#method.read_to_string' class='fnname'>read_to_string</a>(&amp;mut self, buf: &amp;mut <a class='struct' href='../../../bitflags/__core/string/struct.String.html' title='bitflags::__core::string::String'>String</a>) -&gt; <a class='enum' href='../../../bitflags/__core/result/enum.Result.html' title='bitflags::__core::result::Result'>Result</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.usize.html'>usize</a>, <a class='struct' href='../../../bitflags/__core/io/struct.Error.html' title='bitflags::__core::io::Error'>Error</a>&gt; { ... }
fn <a href='#method.read_exact' class='fnname'>read_exact</a>(&amp;mut self, buf: <a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>&amp;mut [</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u8.html'>u8</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>]</a>) -&gt; <a class='enum' href='../../../bitflags/__core/result/enum.Result.html' title='bitflags::__core::result::Result'>Result</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.tuple.html'>()</a>, <a class='struct' href='../../../bitflags/__core/io/struct.Error.html' title='bitflags::__core::io::Error'>Error</a>&gt; { ... }
fn <a href='#method.by_ref' class='fnname'>by_ref</a>(&amp;mut self) -&gt; &amp;mut Self { ... }
fn <a href='#method.bytes' class='fnname'>bytes</a>(self) -&gt; <a class='struct' href='../../../bitflags/__core/io/struct.Bytes.html' title='bitflags::__core::io::Bytes'>Bytes</a>&lt;Self&gt; { ... }
fn <a href='#method.chars' class='fnname'>chars</a>(self) -&gt; <a class='struct' href='../../../bitflags/__core/io/struct.Chars.html' title='bitflags::__core::io::Chars'>Chars</a>&lt;Self&gt; { ... }
fn <a href='#method.chain' class='fnname'>chain</a>&lt;R&gt;(self, next: R) -&gt; <a class='struct' href='../../../bitflags/__core/io/struct.Chain.html' title='bitflags::__core::io::Chain'>Chain</a>&lt;Self, R&gt; <span class='where'>where R: <a class='trait' href='../../../bitflags/__core/io/trait.Read.html' title='bitflags::__core::io::Read'>Read</a></span> { ... }
fn <a href='#method.take' class='fnname'>take</a>(self, limit: <a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u64.html'>u64</a>) -&gt; <a class='struct' href='../../../bitflags/__core/io/struct.Take.html' title='bitflags::__core::io::Take'>Take</a>&lt;Self&gt; { ... }
}</pre><div class='docblock'><p>The <code>Read</code> trait allows for reading bytes from a source.</p>
<p>Implementors of the <code>Read</code> trait are sometimes called &#39;readers&#39;.</p>
<p>Readers are defined by one required method, <code>read()</code>. Each call to <code>read</code>
will attempt to pull bytes from this source into a provided buffer. A
number of other methods are implemented in terms of <code>read()</code>, giving
implementors a number of ways to read bytes while only needing to implement
a single method.</p>
<p>Readers are intended to be composable with one another. Many implementors
throughout <code>std::io</code> take and provide types which implement the <code>Read</code>
trait.</p>
<p>Please note that each call to <code>read</code> may involve a system call, and
therefore, using something that implements <a href="trait.BufRead.html"><code>BufRead</code></a>, such as
<a href="struct.BufReader.html"><code>BufReader</code></a>, will be more efficient.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> [<span class='number'>0</span>; <span class='number'>10</span>];
<span class='comment'>// read up to 10 bytes</span>
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>f</span>.<span class='ident'>read</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> <span class='macro'>vec</span><span class='macro'>!</span>[<span class='number'>0</span>; <span class='number'>10</span>];
<span class='comment'>// read the whole file</span>
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>f</span>.<span class='ident'>read_to_end</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));
<span class='comment'>// read into a String, so that you don&#39;t need to do the conversion.</span>
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> <span class='ident'>String</span>::<span class='ident'>new</span>();
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>f</span>.<span class='ident'>read_to_string</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));
<span class='comment'>// and more! See the other methods for more details.</span></pre>
</div>
<h2 id='required-methods'>Required Methods</h2>
<div class='methods'>
<h3 id='tymethod.read' class='method stab '><code>fn <a href='#tymethod.read' class='fnname'>read</a>(&amp;mut self, buf: <a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>&amp;mut [</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u8.html'>u8</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>]</a>) -&gt; <a class='enum' href='../../../bitflags/__core/result/enum.Result.html' title='bitflags::__core::result::Result'>Result</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.usize.html'>usize</a>, <a class='struct' href='../../../bitflags/__core/io/struct.Error.html' title='bitflags::__core::io::Error'>Error</a>&gt;</code></h3><div class='docblock'><p>Pull some bytes from this source into the specified buffer, returning
how many bytes were read.</p>
<p>This function does not provide any guarantees about whether it blocks
waiting for data, but if an object needs to block for a read but cannot
it will typically signal this via an <code>Err</code> return value.</p>
<p>If the return value of this method is <code>Ok(n)</code>, then it must be
guaranteed that <code>0 &lt;= n &lt;= buf.len()</code>. A nonzero <code>n</code> value indicates
that the buffer <code>buf</code> has been filled in with <code>n</code> bytes of data from this
source. If <code>n</code> is <code>0</code>, then it can indicate one of two scenarios:</p>
<ol>
<li>This reader has reached its &quot;end of file&quot; and will likely no longer
be able to produce bytes. Note that this does not mean that the
reader will <em>always</em> no longer be able to produce bytes.</li>
<li>The buffer specified was 0 bytes in length.</li>
</ol>
<p>No guarantees are provided about the contents of <code>buf</code> when this
function is called, implementations cannot rely on any property of the
contents of <code>buf</code> being true. It is recommended that implementations
only write data to <code>buf</code> instead of reading its contents.</p>
<h1 id='errors' class='section-header'><a href='#errors'>Errors</a></h1>
<p>If this function encounters any form of I/O or other error, an error
variant will be returned. If an error is returned then it must be
guaranteed that no bytes were read.</p>
<h1 id='examples-1' class='section-header'><a href='#examples-1'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> [<span class='number'>0</span>; <span class='number'>10</span>];
<span class='comment'>// read 10 bytes</span>
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>f</span>.<span class='ident'>read</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>[..]));</pre>
</div></div>
<h2 id='provided-methods'>Provided Methods</h2>
<div class='methods'>
<h3 id='method.read_to_end' class='method stab '><code>fn <a href='#method.read_to_end' class='fnname'>read_to_end</a>(&amp;mut self, buf: &amp;mut <a class='struct' href='../../../bitflags/__core/vec/struct.Vec.html' title='bitflags::__core::vec::Vec'>Vec</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u8.html'>u8</a>&gt;) -&gt; <a class='enum' href='../../../bitflags/__core/result/enum.Result.html' title='bitflags::__core::result::Result'>Result</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.usize.html'>usize</a>, <a class='struct' href='../../../bitflags/__core/io/struct.Error.html' title='bitflags::__core::io::Error'>Error</a>&gt;</code></h3><div class='docblock'><p>Read all bytes until EOF in this source, placing them into <code>buf</code>.</p>
<p>All bytes read from this source will be appended to the specified buffer
<code>buf</code>. This function will continuously call <code>read</code> to append more data to
<code>buf</code> until <code>read</code> returns either <code>Ok(0)</code> or an error of
non-<code>ErrorKind::Interrupted</code> kind.</p>
<p>If successful, this function will return the total number of bytes read.</p>
<h1 id='errors-1' class='section-header'><a href='#errors-1'>Errors</a></h1>
<p>If this function encounters an error of the kind
<code>ErrorKind::Interrupted</code> then the error is ignored and the operation
will continue.</p>
<p>If any other read error is encountered then this function immediately
returns. Any bytes which have already been read will be appended to
<code>buf</code>.</p>
<h1 id='examples-2' class='section-header'><a href='#examples-2'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> <span class='ident'>Vec</span>::<span class='ident'>new</span>();
<span class='comment'>// read the whole file</span>
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>f</span>.<span class='ident'>read_to_end</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));</pre>
</div><h3 id='method.read_to_string' class='method stab '><code>fn <a href='#method.read_to_string' class='fnname'>read_to_string</a>(&amp;mut self, buf: &amp;mut <a class='struct' href='../../../bitflags/__core/string/struct.String.html' title='bitflags::__core::string::String'>String</a>) -&gt; <a class='enum' href='../../../bitflags/__core/result/enum.Result.html' title='bitflags::__core::result::Result'>Result</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.usize.html'>usize</a>, <a class='struct' href='../../../bitflags/__core/io/struct.Error.html' title='bitflags::__core::io::Error'>Error</a>&gt;</code></h3><div class='docblock'><p>Read all bytes until EOF in this source, placing them into <code>buf</code>.</p>
<p>If successful, this function returns the number of bytes which were read
and appended to <code>buf</code>.</p>
<h1 id='errors-2' class='section-header'><a href='#errors-2'>Errors</a></h1>
<p>If the data in this stream is <em>not</em> valid UTF-8 then an error is
returned and <code>buf</code> is unchanged.</p>
<p>See <a href="#method.read_to_end"><code>read_to_end()</code></a> for other error semantics.</p>
<h1 id='examples-3' class='section-header'><a href='#examples-3'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> <span class='ident'>String</span>::<span class='ident'>new</span>();
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>f</span>.<span class='ident'>read_to_string</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));</pre>
</div><h3 id='method.read_exact' class='method stab '><code>fn <a href='#method.read_exact' class='fnname'>read_exact</a>(&amp;mut self, buf: <a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>&amp;mut [</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u8.html'>u8</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>]</a>) -&gt; <a class='enum' href='../../../bitflags/__core/result/enum.Result.html' title='bitflags::__core::result::Result'>Result</a>&lt;<a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.tuple.html'>()</a>, <a class='struct' href='../../../bitflags/__core/io/struct.Error.html' title='bitflags::__core::io::Error'>Error</a>&gt;</code><span class="since">1.6.0</span></h3><div class='docblock'><p>Read the exact number of bytes required to fill <code>buf</code>.</p>
<p>This function reads as many bytes as necessary to completely fill the
specified buffer <code>buf</code>.</p>
<p>No guarantees are provided about the contents of <code>buf</code> when this
function is called, implementations cannot rely on any property of the
contents of <code>buf</code> being true. It is recommended that implementations
only write data to <code>buf</code> instead of reading its contents.</p>
<h1 id='errors-3' class='section-header'><a href='#errors-3'>Errors</a></h1>
<p>If this function encounters an error of the kind
<code>ErrorKind::Interrupted</code> then the error is ignored and the operation
will continue.</p>
<p>If this function encounters an &quot;end of file&quot; before completely filling
the buffer, it returns an error of the kind <code>ErrorKind::UnexpectedEof</code>.
The contents of <code>buf</code> are unspecified in this case.</p>
<p>If any other read error is encountered then this function immediately
returns. The contents of <code>buf</code> are unspecified in this case.</p>
<p>If this function returns an error, it is unspecified how many bytes it
has read, but it will never read more than would be necessary to
completely fill the buffer.</p>
<h1 id='examples-4' class='section-header'><a href='#examples-4'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> [<span class='number'>0</span>; <span class='number'>10</span>];
<span class='comment'>// read exactly 10 bytes</span>
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>f</span>.<span class='ident'>read_exact</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));</pre>
</div><h3 id='method.by_ref' class='method stab '><code>fn <a href='#method.by_ref' class='fnname'>by_ref</a>(&amp;mut self) -&gt; &amp;mut Self</code></h3><div class='docblock'><p>Creates a &quot;by reference&quot; adaptor for this instance of <code>Read</code>.</p>
<p>The returned adaptor also implements <code>Read</code> and will simply borrow this
current reader.</p>
<h1 id='examples-5' class='section-header'><a href='#examples-5'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>Read</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> <span class='ident'>Vec</span>::<span class='ident'>new</span>();
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>other_buffer</span> <span class='op'>=</span> <span class='ident'>Vec</span>::<span class='ident'>new</span>();
{
<span class='kw'>let</span> <span class='ident'>reference</span> <span class='op'>=</span> <span class='ident'>f</span>.<span class='ident'>by_ref</span>();
<span class='comment'>// read at most 5 bytes</span>
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>reference</span>.<span class='ident'>take</span>(<span class='number'>5</span>).<span class='ident'>read_to_end</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));
} <span class='comment'>// drop our &amp;mut reference so we can use f again</span>
<span class='comment'>// original file still usable, read the rest</span>
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>f</span>.<span class='ident'>read_to_end</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>other_buffer</span>));</pre>
</div><h3 id='method.bytes' class='method stab '><code>fn <a href='#method.bytes' class='fnname'>bytes</a>(self) -&gt; <a class='struct' href='../../../bitflags/__core/io/struct.Bytes.html' title='bitflags::__core::io::Bytes'>Bytes</a>&lt;Self&gt;</code></h3><div class='docblock'><p>Transforms this <code>Read</code> instance to an <code>Iterator</code> over its bytes.</p>
<p>The returned type implements <code>Iterator</code> where the <code>Item</code> is <code>Result&lt;u8, R::Err&gt;</code>. The yielded item is <code>Ok</code> if a byte was successfully read and
<code>Err</code> otherwise for I/O errors. EOF is mapped to returning <code>None</code> from
this iterator.</p>
<h1 id='examples-6' class='section-header'><a href='#examples-6'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>for</span> <span class='ident'>byte</span> <span class='kw'>in</span> <span class='ident'>f</span>.<span class='ident'>bytes</span>() {
<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>&quot;{}&quot;</span>, <span class='ident'>byte</span>.<span class='ident'>unwrap</span>());
}</pre>
</div><h3 id='method.chars' class='method stab unstable'><code>fn <a href='#method.chars' class='fnname'>chars</a>(self) -&gt; <a class='struct' href='../../../bitflags/__core/io/struct.Chars.html' title='bitflags::__core::io::Chars'>Chars</a>&lt;Self&gt;</code></h3><div class='stability'><em class='stab unstable'>Unstable (<code>io</code>)<p>: the semantics of a partial read/write of where errors happen is currently unclear and may change</p>
</em></div><div class='docblock'><p>Transforms this <code>Read</code> instance to an <code>Iterator</code> over <code>char</code>s.</p>
<p>This adaptor will attempt to interpret this reader as a UTF-8 encoded
sequence of characters. The returned iterator will return <code>None</code> once
EOF is reached for this reader. Otherwise each element yielded will be a
<code>Result&lt;char, E&gt;</code> where <code>E</code> may contain information about what I/O error
occurred or where decoding failed.</p>
<p>Currently this adaptor will discard intermediate data read, and should
be avoided if this is not desired.</p>
<h1 id='examples-7' class='section-header'><a href='#examples-7'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='attribute'>#<span class='op'>!</span>[<span class='ident'>feature</span>(<span class='ident'>io</span>)]</span>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>for</span> <span class='ident'>c</span> <span class='kw'>in</span> <span class='ident'>f</span>.<span class='ident'>chars</span>() {
<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>&quot;{}&quot;</span>, <span class='ident'>c</span>.<span class='ident'>unwrap</span>());
}</pre>
</div><h3 id='method.chain' class='method stab '><code>fn <a href='#method.chain' class='fnname'>chain</a>&lt;R&gt;(self, next: R) -&gt; <a class='struct' href='../../../bitflags/__core/io/struct.Chain.html' title='bitflags::__core::io::Chain'>Chain</a>&lt;Self, R&gt; <span class='where'>where R: <a class='trait' href='../../../bitflags/__core/io/trait.Read.html' title='bitflags::__core::io::Read'>Read</a></span></code></h3><div class='docblock'><p>Creates an adaptor which will chain this stream with another.</p>
<p>The returned <code>Read</code> instance will first read all bytes from this object
until EOF is encountered. Afterwards the output is equivalent to the
output of <code>next</code>.</p>
<h1 id='examples-8' class='section-header'><a href='#examples-8'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f1</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f2</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;bar.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>handle</span> <span class='op'>=</span> <span class='ident'>f1</span>.<span class='ident'>chain</span>(<span class='ident'>f2</span>);
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> <span class='ident'>String</span>::<span class='ident'>new</span>();
<span class='comment'>// read the value into a String. We could use any Read method here,</span>
<span class='comment'>// this is just one example.</span>
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>handle</span>.<span class='ident'>read_to_string</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));</pre>
</div><h3 id='method.take' class='method stab '><code>fn <a href='#method.take' class='fnname'>take</a>(self, limit: <a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u64.html'>u64</a>) -&gt; <a class='struct' href='../../../bitflags/__core/io/struct.Take.html' title='bitflags::__core::io::Take'>Take</a>&lt;Self&gt;</code></h3><div class='docblock'><p>Creates an adaptor which will read at most <code>limit</code> bytes from it.</p>
<p>This function returns a new instance of <code>Read</code> which will read at most
<code>limit</code> bytes, after which it will always return EOF (<code>Ok(0)</code>). Any
read errors will not count towards the number of bytes read and future
calls to <code>read</code> may succeed.</p>
<h1 id='examples-9' class='section-header'><a href='#examples-9'>Examples</a></h1>
<p><a href="../fs/struct.File.html"><code>File</code></a>s implement <code>Read</code>:</p>
<pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>io</span>::<span class='ident'>prelude</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>fs</span>::<span class='ident'>File</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>f</span> <span class='op'>=</span> <span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>File</span>::<span class='ident'>open</span>(<span class='string'>&quot;foo.txt&quot;</span>));
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>buffer</span> <span class='op'>=</span> [<span class='number'>0</span>; <span class='number'>5</span>];
<span class='comment'>// read at most five bytes</span>
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>handle</span> <span class='op'>=</span> <span class='ident'>f</span>.<span class='ident'>take</span>(<span class='number'>5</span>);
<span class='macro'>try</span><span class='macro'>!</span>(<span class='ident'>handle</span>.<span class='ident'>read</span>(<span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='ident'>buffer</span>));</pre>
</div></div>
<h2 id='implementors'>Implementors</h2>
<ul class='item-list' id='implementors-list'>
<li><code>impl&lt;'a&gt; Read for <a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>&amp;'a [</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.u8.html'>u8</a><a class='primitive' href='https://doc.rust-lang.org/nightly/bitflags/primitive.slice.html'>]</a></code></li>
</ul><script type="text/javascript" async
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