go-neb/pkg/unicode/utf8/index.html

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  <h1>Package utf8</h1>


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			<dd><code>import "unicode/utf8"</code></dd>
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				<p>
Package utf8 implements functions and constants to support text encoded in
UTF-8. It includes functions to translate between runes and UTF-8 byte sequences.
</p>

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				<dd><a href="index.html#pkg-constants">Constants</a></dd>
			
			
				<dd><a href="index.html#DecodeLastRune">func DecodeLastRune(p []byte) (r rune, size int)</a></dd>
			
				
				<dd><a href="index.html#DecodeLastRuneInString">func DecodeLastRuneInString(s string) (r rune, size int)</a></dd>
			
				
				<dd><a href="index.html#DecodeRune">func DecodeRune(p []byte) (r rune, size int)</a></dd>
			
				
				<dd><a href="index.html#DecodeRuneInString">func DecodeRuneInString(s string) (r rune, size int)</a></dd>
			
				
				<dd><a href="index.html#EncodeRune">func EncodeRune(p []byte, r rune) int</a></dd>
			
				
				<dd><a href="index.html#FullRune">func FullRune(p []byte) bool</a></dd>
			
				
				<dd><a href="index.html#FullRuneInString">func FullRuneInString(s string) bool</a></dd>
			
				
				<dd><a href="index.html#RuneCount">func RuneCount(p []byte) int</a></dd>
			
				
				<dd><a href="index.html#RuneCountInString">func RuneCountInString(s string) (n int)</a></dd>
			
				
				<dd><a href="index.html#RuneLen">func RuneLen(r rune) int</a></dd>
			
				
				<dd><a href="index.html#RuneStart">func RuneStart(b byte) bool</a></dd>
			
				
				<dd><a href="index.html#Valid">func Valid(p []byte) bool</a></dd>
			
				
				<dd><a href="index.html#ValidRune">func ValidRune(r rune) bool</a></dd>
			
				
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			<dd><a class="exampleLink" href="index.html#example_DecodeLastRune">DecodeLastRune</a></dd>
			
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			<dd><a class="exampleLink" href="index.html#example_FullRune">FullRune</a></dd>
			
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			<dd><a class="exampleLink" href="index.html#example_RuneStart">RuneStart</a></dd>
			
			<dd><a class="exampleLink" href="index.html#example_Valid">Valid</a></dd>
			
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			<h4>Package files</h4>
			<p>
			<span style="font-size:90%">
			
				<a href="http://localhost:6060/src/unicode/utf8/utf8.go">utf8.go</a>
			
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			  In the call graph viewer below, each node
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			<h2 id="pkg-constants">Constants</h2>
			
				<pre>const (
    <span id="RuneError">RuneError</span> = &#39;\uFFFD&#39;     <span class="comment">// the &#34;error&#34; Rune or &#34;Unicode replacement character&#34;</span>
    <span id="RuneSelf">RuneSelf</span>  = 0x80         <span class="comment">// characters below Runeself are represented as themselves in a single byte.</span>
    <span id="MaxRune">MaxRune</span>   = &#39;\U0010FFFF&#39; <span class="comment">// Maximum valid Unicode code point.</span>
    <span id="UTFMax">UTFMax</span>    = 4            <span class="comment">// maximum number of bytes of a UTF-8 encoded Unicode character.</span>
)</pre>
				<p>
Numbers fundamental to the encoding.
</p>

			
			<h2 id="DecodeLastRune">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=8153:8201#L239">DecodeLastRune</a></h2>
			<pre>func DecodeLastRune(p []<a href="../../builtin/index.html#byte">byte</a>) (r <a href="../../builtin/index.html#rune">rune</a>, size <a href="../../builtin/index.html#int">int</a>)</pre>
			<p>
DecodeLastRune unpacks the last UTF-8 encoding in p and returns the rune and
its width in bytes. If p is empty it returns (RuneError, 0). Otherwise, if
the encoding is invalid, it returns (RuneError, 1). Both are impossible
results for correct, non-empty UTF-8.
</p>
<p>
An encoding is invalid if it is incorrect UTF-8, encodes a rune that is
out of range, or is not the shortest possible UTF-8 encoding for the
value. No other validation is performed.
</p>

			<div id="example_DecodeLastRune" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">b := []byte(&#34;Hello, 世界&#34;)

for len(b) &gt; 0 {
    r, size := utf8.DecodeLastRune(b)
    fmt.Printf(&#34;%c %v\n&#34;, r, size)

    b = b[:len(b)-size]
}
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">界 3
世 3
  1
, 1
o 1
l 1
l 1
e 1
H 1
</pre>
			
		
	</div>
</div>

			
			<h2 id="DecodeLastRuneInString">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=9163:9219#L279">DecodeLastRuneInString</a></h2>
			<pre>func DecodeLastRuneInString(s <a href="../../builtin/index.html#string">string</a>) (r <a href="../../builtin/index.html#rune">rune</a>, size <a href="../../builtin/index.html#int">int</a>)</pre>
			<p>
DecodeLastRuneInString is like DecodeLastRune but its input is a string. If
s is empty it returns (RuneError, 0). Otherwise, if the encoding is invalid,
it returns (RuneError, 1). Both are impossible results for correct,
non-empty UTF-8.
</p>
<p>
An encoding is invalid if it is incorrect UTF-8, encodes a rune that is
out of range, or is not the shortest possible UTF-8 encoding for the
value. No other validation is performed.
</p>

			<div id="example_DecodeLastRuneInString" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">str := &#34;Hello, 世界&#34;

for len(str) &gt; 0 {
    r, size := utf8.DecodeLastRuneInString(str)
    fmt.Printf(&#34;%c %v\n&#34;, r, size)

    str = str[:len(str)-size]
}
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">界 3
世 3
  1
, 1
o 1
l 1
l 1
e 1
H 1
</pre>
			
		
	</div>
</div>

			
			<h2 id="DecodeRune">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=5307:5351#L143">DecodeRune</a></h2>
			<pre>func DecodeRune(p []<a href="../../builtin/index.html#byte">byte</a>) (r <a href="../../builtin/index.html#rune">rune</a>, size <a href="../../builtin/index.html#int">int</a>)</pre>
			<p>
DecodeRune unpacks the first UTF-8 encoding in p and returns the rune and
its width in bytes. If p is empty it returns (RuneError, 0). Otherwise, if
the encoding is invalid, it returns (RuneError, 1). Both are impossible
results for correct, non-empty UTF-8.
</p>
<p>
An encoding is invalid if it is incorrect UTF-8, encodes a rune that is
out of range, or is not the shortest possible UTF-8 encoding for the
value. No other validation is performed.
</p>

			<div id="example_DecodeRune" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">b := []byte(&#34;Hello, 世界&#34;)

for len(b) &gt; 0 {
    r, size := utf8.DecodeRune(b)
    fmt.Printf(&#34;%c %v\n&#34;, r, size)

    b = b[size:]
}
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">H 1
e 1
l 1
l 1
o 1
, 1
  1
世 3
界 3
</pre>
			
		
	</div>
</div>

			
			<h2 id="DecodeRuneInString">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=6710:6762#L191">DecodeRuneInString</a></h2>
			<pre>func DecodeRuneInString(s <a href="../../builtin/index.html#string">string</a>) (r <a href="../../builtin/index.html#rune">rune</a>, size <a href="../../builtin/index.html#int">int</a>)</pre>
			<p>
DecodeRuneInString is like DecodeRune but its input is a string. If s is
empty it returns (RuneError, 0). Otherwise, if the encoding is invalid, it
returns (RuneError, 1). Both are impossible results for correct, non-empty
UTF-8.
</p>
<p>
An encoding is invalid if it is incorrect UTF-8, encodes a rune that is
out of range, or is not the shortest possible UTF-8 encoding for the
value. No other validation is performed.
</p>

			<div id="example_DecodeRuneInString" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">str := &#34;Hello, 世界&#34;

for len(str) &gt; 0 {
    r, size := utf8.DecodeRuneInString(str)
    fmt.Printf(&#34;%c %v\n&#34;, r, size)

    str = str[size:]
}
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">H 1
e 1
l 1
l 1
o 1
, 1
  1
世 3
界 3
</pre>
			
		
	</div>
</div>

			
			<h2 id="EncodeRune">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=10279:10316#L333">EncodeRune</a></h2>
			<pre>func EncodeRune(p []<a href="../../builtin/index.html#byte">byte</a>, r <a href="../../builtin/index.html#rune">rune</a>) <a href="../../builtin/index.html#int">int</a></pre>
			<p>
EncodeRune writes into p (which must be large enough) the UTF-8 encoding of the rune.
It returns the number of bytes written.
</p>

			<div id="example_EncodeRune" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">r := &#39;世&#39;
buf := make([]byte, 3)

n := utf8.EncodeRune(buf, r)

fmt.Println(buf)
fmt.Println(n)
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">[228 184 150]
3
</pre>
			
		
	</div>
</div>

			
			<h2 id="FullRune">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=3999:4027#L92">FullRune</a></h2>
			<pre>func FullRune(p []<a href="../../builtin/index.html#byte">byte</a>) <a href="../../builtin/index.html#bool">bool</a></pre>
			<p>
FullRune reports whether the bytes in p begin with a full UTF-8 encoding of a rune.
An invalid encoding is considered a full Rune since it will convert as a width-1 error rune.
</p>

			<div id="example_FullRune" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">buf := []byte{228, 184, 150} <span class="comment">// 世</span>
fmt.Println(utf8.FullRune(buf))
fmt.Println(utf8.FullRune(buf[:2]))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">true
false
</pre>
			
		
	</div>
</div>

			
			<h2 id="FullRuneInString">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=4448:4484#L114">FullRuneInString</a></h2>
			<pre>func FullRuneInString(s <a href="../../builtin/index.html#string">string</a>) <a href="../../builtin/index.html#bool">bool</a></pre>
			<p>
FullRuneInString is like FullRune but its input is a string.
</p>

			<div id="example_FullRuneInString" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">str := &#34;世&#34;
fmt.Println(utf8.FullRuneInString(str))
fmt.Println(utf8.FullRuneInString(str[:2]))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">true
false
</pre>
			
		
	</div>
</div>

			
			<h2 id="RuneCount">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=11033:11061#L362">RuneCount</a></h2>
			<pre>func RuneCount(p []<a href="../../builtin/index.html#byte">byte</a>) <a href="../../builtin/index.html#int">int</a></pre>
			<p>
RuneCount returns the number of runes in p.  Erroneous and short
encodings are treated as single runes of width 1 byte.
</p>

			<div id="example_RuneCount" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">buf := []byte(&#34;Hello, 世界&#34;)
fmt.Println(&#34;bytes =&#34;, len(buf))
fmt.Println(&#34;runes =&#34;, utf8.RuneCount(buf))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">bytes = 13
runes = 9
</pre>
			
		
	</div>
</div>

			
			<h2 id="RuneCountInString">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=11705:11745#L399">RuneCountInString</a></h2>
			<pre>func RuneCountInString(s <a href="../../builtin/index.html#string">string</a>) (n <a href="../../builtin/index.html#int">int</a>)</pre>
			<p>
RuneCountInString is like RuneCount but its input is a string.
</p>

			<div id="example_RuneCountInString" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">str := &#34;Hello, 世界&#34;
fmt.Println(&#34;bytes =&#34;, len(str))
fmt.Println(&#34;runes =&#34;, utf8.RuneCountInString(str))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">bytes = 13
runes = 9
</pre>
			
		
	</div>
</div>

			
			<h2 id="RuneLen">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=9883:9907#L313">RuneLen</a></h2>
			<pre>func RuneLen(r <a href="../../builtin/index.html#rune">rune</a>) <a href="../../builtin/index.html#int">int</a></pre>
			<p>
RuneLen returns the number of bytes required to encode the rune.
It returns -1 if the rune is not a valid value to encode in UTF-8.
</p>

			<div id="example_RuneLen" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">fmt.Println(utf8.RuneLen(&#39;a&#39;))
fmt.Println(utf8.RuneLen(&#39;界&#39;))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">1
3
</pre>
			
		
	</div>
</div>

			
			<h2 id="RuneStart">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=12485:12512#L436">RuneStart</a></h2>
			<pre>func RuneStart(b <a href="../../builtin/index.html#byte">byte</a>) <a href="../../builtin/index.html#bool">bool</a></pre>
			<p>
RuneStart reports whether the byte could be the first byte of an encoded,
possibly invalid rune.  Second and subsequent bytes always have the top two
bits set to 10.
</p>

			<div id="example_RuneStart" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">buf := []byte(&#34;a界&#34;)
fmt.Println(utf8.RuneStart(buf[0]))
fmt.Println(utf8.RuneStart(buf[1]))
fmt.Println(utf8.RuneStart(buf[2]))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">true
true
false
</pre>
			
		
	</div>
</div>

			
			<h2 id="Valid">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=12615:12640#L439">Valid</a></h2>
			<pre>func Valid(p []<a href="../../builtin/index.html#byte">byte</a>) <a href="../../builtin/index.html#bool">bool</a></pre>
			<p>
Valid reports whether p consists entirely of valid UTF-8-encoded runes.
</p>

			<div id="example_Valid" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">valid := []byte(&#34;Hello, 世界&#34;)
invalid := []byte{0xff, 0xfe, 0xfd}

fmt.Println(utf8.Valid(valid))
fmt.Println(utf8.Valid(invalid))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">true
false
</pre>
			
		
	</div>
</div>

			
			<h2 id="ValidRune">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=14008:14035#L504">ValidRune</a></h2>
			<pre>func ValidRune(r <a href="../../builtin/index.html#rune">rune</a>) <a href="../../builtin/index.html#bool">bool</a></pre>
			<p>
ValidRune reports whether r can be legally encoded as UTF-8.
Code points that are out of range or a surrogate half are illegal.
</p>

			<div id="example_ValidRune" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">valid := &#39;a&#39;
invalid := rune(0xfffffff)

fmt.Println(utf8.ValidRune(valid))
fmt.Println(utf8.ValidRune(invalid))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">true
false
</pre>
			
		
	</div>
</div>

			
			<h2 id="ValidString">func <a href="http://localhost:6060/src/unicode/utf8/utf8.go?s=13282:13313#L471">ValidString</a></h2>
			<pre>func ValidString(s <a href="../../builtin/index.html#string">string</a>) <a href="../../builtin/index.html#bool">bool</a></pre>
			<p>
ValidString reports whether s consists entirely of valid UTF-8-encoded runes.
</p>

			<div id="example_ValidString" class="toggle">
	<div class="collapsed">
		<p class="exampleHeading toggleButton">▹ <span class="text">Example</span></p>
	</div>
	<div class="expanded">
		<p class="exampleHeading toggleButton">▾ <span class="text">Example</span></p>
		
		
			<p>Code:</p>
			<pre class="code">valid := &#34;Hello, 世界&#34;
invalid := string([]byte{0xff, 0xfe, 0xfd})

fmt.Println(utf8.ValidString(valid))
fmt.Println(utf8.ValidString(invalid))
<span class="comment"></pre>
			
			<p>Output:</p>
			<pre class="output">true
false
</pre>
			
		
	</div>
</div>

			
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