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320 lines
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</pre><pre class="rust"><code><span class="doccomment">/// Compute the display width of `text`</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// # Examples</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// **Note:** When the `unicode` Cargo feature is disabled, all characters are presumed to take up</span>
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<span class="doccomment">/// 1 width. With the feature enabled, function will correctly deal with [combining characters] in</span>
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<span class="doccomment">/// their decomposed form (see [Unicode equivalence]).</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// An example of a decomposed character is “é”, which can be decomposed into: “e” followed by a</span>
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<span class="doccomment">/// combining acute accent: “◌́”. Without the `unicode` Cargo feature, every `char` has a width of</span>
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<span class="doccomment">/// 1. This includes the combining accent:</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// ## Emojis and CJK Characters</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// Characters such as emojis and [CJK characters] used in the</span>
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<span class="doccomment">/// Chinese, Japanese, and Korean languages are seen as double-width,</span>
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<span class="doccomment">/// even if the `unicode-width` feature is disabled:</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// # Limitations</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// The displayed width of a string cannot always be computed from the</span>
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<span class="doccomment">/// string alone. This is because the width depends on the rendering</span>
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<span class="doccomment">/// engine used. This is particularly visible with [emoji modifier</span>
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<span class="doccomment">/// sequences] where a base emoji is modified with, e.g., skin tone or</span>
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<span class="doccomment">/// hair color modifiers. It is up to the rendering engine to detect</span>
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<span class="doccomment">/// this and to produce a suitable emoji.</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// A simple example is “❤️”, which consists of “❤” (U+2764: Black</span>
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<span class="doccomment">/// Heart Symbol) followed by U+FE0F (Variation Selector-16). By</span>
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<span class="doccomment">/// itself, “❤” is a black heart, but if you follow it with the</span>
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<span class="doccomment">/// variant selector, you may get a wider red heart.</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// A more complex example would be “👨🦰” which should depict a man</span>
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<span class="doccomment">/// with red hair. Here the computed width is too large — and the</span>
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<span class="doccomment">/// width differs depending on the use of the `unicode-width` feature:</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// This happens because the grapheme consists of three code points:</span>
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<span class="doccomment">/// “👨” (U+1F468: Man), Zero Width Joiner (U+200D), and “🦰”</span>
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<span class="doccomment">/// (U+1F9B0: Red Hair). You can see them above in the test. With</span>
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<span class="doccomment">/// `unicode-width` enabled, the ZWJ is correctly seen as having zero</span>
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<span class="doccomment">/// width, without it is counted as a double-width character.</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// ## Terminal Support</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// Modern browsers typically do a great job at combining characters</span>
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<span class="doccomment">/// as shown above, but terminals often struggle more. As an example,</span>
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<span class="doccomment">/// Gnome Terminal version 3.38.1, shows “❤️” as a big red heart, but</span>
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<span class="doccomment">/// shows "👨🦰" as “👨🦰”.</span>
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<span class="doccomment">///</span>
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<span class="doccomment">/// [combining characters]: https://en.wikipedia.org/wiki/Combining_character</span>
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<span class="doccomment">/// [Unicode equivalence]: https://en.wikipedia.org/wiki/Unicode_equivalence</span>
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<span class="doccomment">/// [CJK characters]: https://en.wikipedia.org/wiki/CJK_characters</span>
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<span class="doccomment">/// [emoji modifier sequences]: https://unicode.org/emoji/charts/full-emoji-modifiers.html</span>
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<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">never</span>)]</span>
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<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">display_width</span>(<span class="ident">text</span>: <span class="kw-2">&</span><span class="ident">str</span>) -> <span class="ident">usize</span> {
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<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">width</span> <span class="op">=</span> <span class="number">0</span>;
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<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">control_sequence</span> <span class="op">=</span> <span class="bool-val">false</span>;
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<span class="kw">let</span> <span class="ident">control_terminate</span>: <span class="ident">char</span> <span class="op">=</span> <span class="string">'m'</span>;
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<span class="kw">for</span> <span class="ident">ch</span> <span class="kw">in</span> <span class="ident">text</span>.<span class="ident">chars</span>() {
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<span class="kw">if</span> <span class="ident">ch</span>.<span class="ident">is_ascii_control</span>() {
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<span class="ident">control_sequence</span> <span class="op">=</span> <span class="bool-val">true</span>;
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} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">control_sequence</span> <span class="op">&&</span> <span class="ident">ch</span> <span class="op">==</span> <span class="ident">control_terminate</span> {
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<span class="ident">control_sequence</span> <span class="op">=</span> <span class="bool-val">false</span>;
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<span class="kw">continue</span>;
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}
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<span class="kw">if</span> <span class="op">!</span><span class="ident">control_sequence</span> {
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<span class="ident">width</span> <span class="op">+</span><span class="op">=</span> <span class="ident">ch_width</span>(<span class="ident">ch</span>);
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}
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}
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<span class="ident">width</span>
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}
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>)]</span>
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<span class="kw">fn</span> <span class="ident">ch_width</span>(<span class="ident">ch</span>: <span class="ident">char</span>) -> <span class="ident">usize</span> {
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<span class="ident">unicode_width::UnicodeWidthChar::width</span>(<span class="ident">ch</span>).<span class="ident">unwrap_or</span>(<span class="number">0</span>)
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}
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>))]</span>
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<span class="kw">fn</span> <span class="ident">ch_width</span>(<span class="kw">_</span>: <span class="ident">char</span>) -> <span class="ident">usize</span> {
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<span class="number">1</span>
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}
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
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<span class="kw">mod</span> <span class="ident">tests</span> {
|
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<span class="kw">use</span> <span class="kw">super</span>::<span class="kw-2">*</span>;
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>)]</span>
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<span class="kw">use</span> <span class="ident">unicode_width::UnicodeWidthChar</span>;
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<span class="attribute">#[<span class="ident">test</span>]</span>
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<span class="kw">fn</span> <span class="ident">emojis_have_correct_width</span>() {
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<span class="kw">use</span> <span class="ident">unic_emoji_char::is_emoji</span>;
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<span class="comment">// Emojis in the Basic Latin (ASCII) and Latin-1 Supplement</span>
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<span class="comment">// blocks all have a width of 1 column. This includes</span>
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<span class="comment">// characters such as '#' and '©'.</span>
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<span class="kw">for</span> <span class="ident">ch</span> <span class="kw">in</span> <span class="string">'\u{1}'</span>..<span class="string">'\u{FF}'</span> {
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<span class="kw">if</span> <span class="ident">is_emoji</span>(<span class="ident">ch</span>) {
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<span class="kw">let</span> <span class="ident">desc</span> <span class="op">=</span> <span class="macro">format!</span>(<span class="string">"{:?} U+{:04X}"</span>, <span class="ident">ch</span>, <span class="ident">ch</span> <span class="kw">as</span> <span class="ident">u32</span>);
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||
|
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>)]</span>
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<span class="macro">assert_eq!</span>(<span class="ident">ch</span>.<span class="ident">width</span>().<span class="ident">unwrap</span>(), <span class="number">1</span>, <span class="string">"char: {}"</span>, <span class="ident">desc</span>);
|
||
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>))]</span>
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<span class="macro">assert_eq!</span>(<span class="ident">ch_width</span>(<span class="ident">ch</span>), <span class="number">1</span>, <span class="string">"char: {}"</span>, <span class="ident">desc</span>);
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}
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}
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||
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<span class="comment">// Emojis in the remaining blocks of the Basic Multilingual</span>
|
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<span class="comment">// Plane (BMP), in the Supplementary Multilingual Plane (SMP),</span>
|
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<span class="comment">// and in the Supplementary Ideographic Plane (SIP), are all 1</span>
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<span class="comment">// or 2 columns wide when unicode-width is used, and always 2</span>
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<span class="comment">// columns wide otherwise. This includes all of our favorite</span>
|
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<span class="comment">// emojis such as 😊.</span>
|
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<span class="kw">for</span> <span class="ident">ch</span> <span class="kw">in</span> <span class="string">'\u{FF}'</span>..<span class="string">'\u{2FFFF}'</span> {
|
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<span class="kw">if</span> <span class="ident">is_emoji</span>(<span class="ident">ch</span>) {
|
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<span class="kw">let</span> <span class="ident">desc</span> <span class="op">=</span> <span class="macro">format!</span>(<span class="string">"{:?} U+{:04X}"</span>, <span class="ident">ch</span>, <span class="ident">ch</span> <span class="kw">as</span> <span class="ident">u32</span>);
|
||
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>)]</span>
|
||
<span class="macro">assert!</span>(<span class="ident">ch</span>.<span class="ident">width</span>().<span class="ident">unwrap</span>() <span class="op"><</span><span class="op">=</span> <span class="number">2</span>, <span class="string">"char: {}"</span>, <span class="ident">desc</span>);
|
||
|
||
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>))]</span>
|
||
<span class="macro">assert_eq!</span>(<span class="ident">ch_width</span>(<span class="ident">ch</span>), <span class="number">1</span>, <span class="string">"char: {}"</span>, <span class="ident">desc</span>);
|
||
}
|
||
}
|
||
|
||
<span class="comment">// The remaining planes contain almost no assigned code points</span>
|
||
<span class="comment">// and thus also no emojis.</span>
|
||
}
|
||
|
||
<span class="attribute">#[<span class="ident">test</span>]</span>
|
||
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>)]</span>
|
||
<span class="kw">fn</span> <span class="ident">display_width_works</span>() {
|
||
<span class="macro">assert_eq!</span>(<span class="string">"Café Plain"</span>.<span class="ident">len</span>(), <span class="number">11</span>); <span class="comment">// “é” is two bytes</span>
|
||
<span class="macro">assert_eq!</span>(<span class="ident">display_width</span>(<span class="string">"Café Plain"</span>), <span class="number">10</span>);
|
||
}
|
||
|
||
<span class="attribute">#[<span class="ident">test</span>]</span>
|
||
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>)]</span>
|
||
<span class="kw">fn</span> <span class="ident">display_width_narrow_emojis</span>() {
|
||
<span class="macro">assert_eq!</span>(<span class="ident">display_width</span>(<span class="string">"⁉"</span>), <span class="number">1</span>);
|
||
}
|
||
|
||
<span class="attribute">#[<span class="ident">test</span>]</span>
|
||
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>)]</span>
|
||
<span class="kw">fn</span> <span class="ident">display_width_narrow_emojis_variant_selector</span>() {
|
||
<span class="macro">assert_eq!</span>(<span class="ident">display_width</span>(<span class="string">"⁉\u{fe0f}"</span>), <span class="number">1</span>);
|
||
}
|
||
|
||
<span class="attribute">#[<span class="ident">test</span>]</span>
|
||
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unicode"</span>)]</span>
|
||
<span class="kw">fn</span> <span class="ident">display_width_emojis</span>() {
|
||
<span class="macro">assert_eq!</span>(<span class="ident">display_width</span>(<span class="string">"😂😭🥺🤣✨😍🙏🥰😊🔥"</span>), <span class="number">20</span>);
|
||
}
|
||
}
|
||
</code></pre></div>
|
||
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