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  <h1>Package unicode</h1>


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			<dl>
			<dd><code>import "golang.org/x/text/encoding/unicode"</code></dd>
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				<p>
Package unicode provides Unicode encodings such as UTF-16.
</p>

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			<dl>
			
			
				<dd><a href="index.html#pkg-variables">Variables</a></dd>
			
			
				<dd><a href="index.html#BOMOverride">func BOMOverride(fallback transform.Transformer) transform.Transformer</a></dd>
			
				
				<dd><a href="index.html#UTF16">func UTF16(e Endianness, b BOMPolicy) encoding.Encoding</a></dd>
			
			
				<dd><a href="index.html#BOMPolicy">type BOMPolicy</a></dd>
				
				
				<dd><a href="index.html#Endianness">type Endianness</a></dd>
				
				
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			<h4>Package files</h4>
			<p>
			<span style="font-size:90%">
			
				<a href="http://localhost:6060/src/golang.org/x/text/encoding/unicode/override.go">override.go</a>
			
				<a href="http://localhost:6060/src/golang.org/x/text/encoding/unicode/unicode.go">unicode.go</a>
			
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			  In the call graph viewer below, each node
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			<h2 id="pkg-variables">Variables</h2>
			
				<pre>var <span id="All">All</span> = []<a href="../index.html">encoding</a>.<a href="../index.html#Encoding">Encoding</a>{
    <a href="index.html#UTF8">UTF8</a>,
    <a href="index.html#UTF16">UTF16</a>(<a href="index.html#BigEndian">BigEndian</a>, <a href="index.html#UseBOM">UseBOM</a>),
    <a href="index.html#UTF16">UTF16</a>(<a href="index.html#BigEndian">BigEndian</a>, <a href="index.html#IgnoreBOM">IgnoreBOM</a>),
    <a href="index.html#UTF16">UTF16</a>(<a href="index.html#LittleEndian">LittleEndian</a>, <a href="index.html#IgnoreBOM">IgnoreBOM</a>),
}</pre>
				<p>
All lists a configuration for each IANA-defined UTF-16 variant.
</p>

			
				<pre>var <span id="ErrMissingBOM">ErrMissingBOM</span> = <a href="../../../../../errors/index.html">errors</a>.<a href="../../../../../errors/index.html#New">New</a>(&#34;encoding: missing byte order mark&#34;)</pre>
				<p>
ErrMissingBOM means that decoding UTF-16 input with ExpectBOM did not find a
starting byte order mark.
</p>

			
				<pre>var <span id="UTF8">UTF8</span> <a href="../index.html">encoding</a>.<a href="../index.html#Encoding">Encoding</a> = utf8enc</pre>
				<p>
UTF8 is the UTF-8 encoding.
</p>

			
			<h2 id="BOMOverride">func <a href="http://localhost:6060/src/golang.org/x/text/encoding/unicode/override.go?s=1109:1179#L17">BOMOverride</a></h2>
			<pre>func BOMOverride(fallback <a href="../../transform/index.html">transform</a>.<a href="../../transform/index.html#Transformer">Transformer</a>) <a href="../../transform/index.html">transform</a>.<a href="../../transform/index.html#Transformer">Transformer</a></pre>
			<p>
BOMOverride returns a new decoder transformer that is identical to fallback,
except that the presence of a Byte Order Mark at the start of the input
causes it to switch to the corresponding Unicode decoding. It will only
consider BOMs for UTF-8, UTF-16BE, and UTF-16LE.
</p>
<p>
This differs from using ExpectBOM by allowing a BOM to switch to UTF-8, not
just UTF-16 variants, and allowing falling back to any encoding scheme.
</p>
<p>
This technique is recommended by the W3C for use in HTML 5: &#34;For
compatibility with deployed content, the byte order mark (also known as BOM)
is considered more authoritative than anything else.&#34;
<a href="http://www.w3.org/TR/encoding/#specification-hooks">http://www.w3.org/TR/encoding/#specification-hooks</a>
</p>
<p>
Using BOMOverride is mostly intended for use cases where the first characters
of a fallback encoding are known to not be a BOM, for example, for valid HTML
and most encodings.
</p>

			
			<h2 id="UTF16">func <a href="http://localhost:6060/src/golang.org/x/text/encoding/unicode/unicode.go?s=5459:5514#L142">UTF16</a></h2>
			<pre>func UTF16(e <a href="index.html#Endianness">Endianness</a>, b <a href="index.html#BOMPolicy">BOMPolicy</a>) <a href="../index.html">encoding</a>.<a href="../index.html#Encoding">Encoding</a></pre>
			<p>
UTF16 returns a UTF-16 Encoding for the given default endianness and byte
order mark (BOM) policy.
</p>
<p>
When decoding from UTF-16 to UTF-8, if the BOMPolicy is IgnoreBOM then
neither BOMs U+FEFF nor noncharacters U+FFFE in the input stream will affect
the endianness used for decoding, and will instead be output as their
standard UTF-8 encodings: &#34;\xef\xbb\xbf&#34; and &#34;\xef\xbf\xbe&#34;. If the BOMPolicy
is UseBOM or ExpectBOM a staring BOM is not written to the UTF-8 output.
Instead, it overrides the default endianness e for the remainder of the
transformation. Any subsequent BOMs U+FEFF or noncharacters U+FFFE will not
affect the endianness used, and will instead be output as their standard
UTF-8 encodings. For UseBOM, if there is no starting BOM, it will proceed
with the default Endianness. For ExpectBOM, in that case, the transformation
will return early with an ErrMissingBOM error.
</p>
<p>
When encoding from UTF-8 to UTF-16, a BOM will be inserted at the start of
the output if the BOMPolicy is UseBOM or ExpectBOM. Otherwise, a BOM will not
be inserted. The UTF-8 input does not need to contain a BOM.
</p>
<p>
There is no concept of a &#39;native&#39; endianness. If the UTF-16 data is produced
and consumed in a greater context that implies a certain endianness, use
IgnoreBOM. Otherwise, use ExpectBOM and always produce and consume a BOM.
</p>
<p>
In the language of <a href="http://www.unicode.org/faq/utf_bom.html#bom10">http://www.unicode.org/faq/utf_bom.html#bom10</a>, IgnoreBOM
corresponds to &#34;Where the precise type of the data stream is known... the
BOM should not be used&#34; and ExpectBOM corresponds to &#34;A particular
protocol... may require use of the BOM&#34;.
</p>

			
			<h2 id="BOMPolicy">type <a href="http://localhost:6060/src/golang.org/x/text/encoding/unicode/unicode.go?s=6708:6728#L173">BOMPolicy</a></h2>
			<pre>type BOMPolicy <a href="../../../../../builtin/index.html#uint8">uint8</a></pre>
			<p>
BOMPolicy is a UTF-16 encoding&#39;s byte order mark policy.
</p>


				<pre>const (

    <span class="comment">// IgnoreBOM means to ignore any byte order marks.</span>
    <span id="IgnoreBOM">IgnoreBOM</span> <a href="index.html#BOMPolicy">BOMPolicy</a> = 0

    <span class="comment">// UseBOM means that the UTF-16 form may start with a byte order mark, which</span>
    <span class="comment">// will be used to override the default encoding.</span>
    <span id="UseBOM">UseBOM</span> <a href="index.html#BOMPolicy">BOMPolicy</a> = writeBOM | acceptBOM

    <span class="comment">// ExpectBOM means that the UTF-16 form must start with a byte order mark,</span>
    <span class="comment">// which will be used to override the default encoding.</span>
    <span id="ExpectBOM">ExpectBOM</span> <a href="index.html#BOMPolicy">BOMPolicy</a> = writeBOM | acceptBOM | requireBOM
)</pre>
				
			
			<h2 id="Endianness">type <a href="http://localhost:6060/src/golang.org/x/text/encoding/unicode/unicode.go?s=8326:8346#L212">Endianness</a></h2>
			<pre>type Endianness <a href="../../../../../builtin/index.html#bool">bool</a></pre>
			<p>
Endianness is a UTF-16 encoding&#39;s default endianness.
</p>


				<pre>const (
    <span class="comment">// BigEndian is UTF-16BE.</span>
    <span id="BigEndian">BigEndian</span> <a href="index.html#Endianness">Endianness</a> = <a href="../../../../../builtin/index.html#false">false</a>
    <span class="comment">// LittleEndian is UTF-16LE.</span>
    <span id="LittleEndian">LittleEndian</span> <a href="index.html#Endianness">Endianness</a> = <a href="../../../../../builtin/index.html#true">true</a>
)</pre>
				
			
		<h2 id="pkg-subdirectories">Subdirectories</h2>
	
	
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						<td class="pkg-name" style="padding-left: 0px;">
							<a href="utf32/index.html">utf32</a>
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						<td class="pkg-synopsis">
							Package utf32 provides the UTF-32 Unicode encoding.
						</td>
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