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<section id='main' class="content"><pre class="line-numbers"><span id="1"> 1</span>
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</pre><pre class="rust ">
<span class="comment">// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT</span>
<span class="comment">// file at the top-level directory of this distribution and at</span>
<span class="comment">// http://rust-lang.org/COPYRIGHT.</span>
<span class="comment">//</span>
<span class="comment">// Licensed under the Apache License, Version 2.0 &lt;LICENSE-APACHE or</span>
<span class="comment">// http://www.apache.org/licenses/LICENSE-2.0&gt; or the MIT license</span>
<span class="comment">// &lt;LICENSE-MIT or http://opensource.org/licenses/MIT&gt;, at your</span>
<span class="comment">// option. This file may not be copied, modified, or distributed</span>
<span class="comment">// except according to those terms.</span>
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">cmp</span>;
<span class="kw">use</span> <span class="ident">tables</span>::<span class="ident">grapheme</span>::<span class="ident">GraphemeCat</span>;
<span class="doccomment">/// External iterator for grapheme clusters and byte offsets.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">GraphemeIndices</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> {
<span class="ident">start_offset</span>: <span class="ident">usize</span>,
<span class="ident">iter</span>: <span class="ident">Graphemes</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span>,
}
<span class="kw">impl</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> <span class="ident">GraphemeIndices</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="doccomment">/// View the underlying data (the part yet to be iterated) as a slice of the original string.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::UnicodeSegmentation;</span>
<span class="doccomment">/// let mut iter = &quot;abc&quot;.grapheme_indices(true);</span>
<span class="doccomment">/// assert_eq!(iter.as_str(), &quot;abc&quot;);</span>
<span class="doccomment">/// iter.next();</span>
<span class="doccomment">/// assert_eq!(iter.as_str(), &quot;bc&quot;);</span>
<span class="doccomment">/// iter.next();</span>
<span class="doccomment">/// iter.next();</span>
<span class="doccomment">/// assert_eq!(iter.as_str(), &quot;&quot;);</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">as_str</span>(<span class="kw-2">&amp;</span><span class="self">self</span>) <span class="op">-&gt;</span> <span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">as_str</span>()
}
}
<span class="kw">impl</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">GraphemeIndices</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> (<span class="ident">usize</span>, <span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span>);
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Option</span><span class="op">&lt;</span>(<span class="ident">usize</span>, <span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span>)<span class="op">&gt;</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">s</span><span class="op">|</span> (<span class="ident">s</span>.<span class="ident">as_ptr</span>() <span class="kw">as</span> <span class="ident">usize</span> <span class="op">-</span> <span class="self">self</span>.<span class="ident">start_offset</span>, <span class="ident">s</span>))
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&amp;</span><span class="self">self</span>) <span class="op">-&gt;</span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span>) {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">size_hint</span>()
}
}
<span class="kw">impl</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">GraphemeIndices</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Option</span><span class="op">&lt;</span>(<span class="ident">usize</span>, <span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span>)<span class="op">&gt;</span> {
<span class="self">self</span>.<span class="ident">iter</span>.<span class="ident">next_back</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">s</span><span class="op">|</span> (<span class="ident">s</span>.<span class="ident">as_ptr</span>() <span class="kw">as</span> <span class="ident">usize</span> <span class="op">-</span> <span class="self">self</span>.<span class="ident">start_offset</span>, <span class="ident">s</span>))
}
}
<span class="doccomment">/// External iterator for a string&#39;s</span>
<span class="doccomment">/// [grapheme clusters](http://www.unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries).</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Graphemes</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> {
<span class="ident">string</span>: <span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span>,
<span class="ident">cursor</span>: <span class="ident">GraphemeCursor</span>,
<span class="ident">cursor_back</span>: <span class="ident">GraphemeCursor</span>,
}
<span class="kw">impl</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> <span class="ident">Graphemes</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="doccomment">/// View the underlying data (the part yet to be iterated) as a slice of the original string.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::UnicodeSegmentation;</span>
<span class="doccomment">/// let mut iter = &quot;abc&quot;.graphemes(true);</span>
<span class="doccomment">/// assert_eq!(iter.as_str(), &quot;abc&quot;);</span>
<span class="doccomment">/// iter.next();</span>
<span class="doccomment">/// assert_eq!(iter.as_str(), &quot;bc&quot;);</span>
<span class="doccomment">/// iter.next();</span>
<span class="doccomment">/// iter.next();</span>
<span class="doccomment">/// assert_eq!(iter.as_str(), &quot;&quot;);</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">as_str</span>(<span class="kw-2">&amp;</span><span class="self">self</span>) <span class="op">-&gt;</span> <span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span> {
<span class="kw-2">&amp;</span><span class="self">self</span>.<span class="ident">string</span>[<span class="self">self</span>.<span class="ident">cursor</span>.<span class="ident">cur_cursor</span>()..<span class="self">self</span>.<span class="ident">cursor_back</span>.<span class="ident">cur_cursor</span>()]
}
}
<span class="kw">impl</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Graphemes</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">size_hint</span>(<span class="kw-2">&amp;</span><span class="self">self</span>) <span class="op">-&gt;</span> (<span class="ident">usize</span>, <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span>) {
<span class="kw">let</span> <span class="ident">slen</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">cursor_back</span>.<span class="ident">cur_cursor</span>() <span class="op">-</span> <span class="self">self</span>.<span class="ident">cursor</span>.<span class="ident">cur_cursor</span>();
(<span class="ident">cmp</span>::<span class="ident">min</span>(<span class="ident">slen</span>, <span class="number">1</span>), <span class="prelude-val">Some</span>(<span class="ident">slen</span>))
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span><span class="op">&gt;</span> {
<span class="kw">let</span> <span class="ident">start</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">cursor</span>.<span class="ident">cur_cursor</span>();
<span class="kw">if</span> <span class="ident">start</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">cursor_back</span>.<span class="ident">cur_cursor</span>() {
<span class="kw">return</span> <span class="prelude-val">None</span>;
}
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">cursor</span>.<span class="ident">next_boundary</span>(<span class="self">self</span>.<span class="ident">string</span>, <span class="number">0</span>).<span class="ident">unwrap</span>().<span class="ident">unwrap</span>();
<span class="prelude-val">Some</span>(<span class="kw-2">&amp;</span><span class="self">self</span>.<span class="ident">string</span>[<span class="ident">start</span>..<span class="ident">next</span>])
}
}
<span class="kw">impl</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> <span class="ident">DoubleEndedIterator</span> <span class="kw">for</span> <span class="ident">Graphemes</span><span class="op">&lt;</span><span class="lifetime">&#39;a</span><span class="op">&gt;</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_back</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> <span class="ident">str</span><span class="op">&gt;</span> {
<span class="kw">let</span> <span class="ident">end</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">cursor_back</span>.<span class="ident">cur_cursor</span>();
<span class="kw">if</span> <span class="ident">end</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">cursor</span>.<span class="ident">cur_cursor</span>() {
<span class="kw">return</span> <span class="prelude-val">None</span>;
}
<span class="kw">let</span> <span class="ident">prev</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">cursor_back</span>.<span class="ident">prev_boundary</span>(<span class="self">self</span>.<span class="ident">string</span>, <span class="number">0</span>).<span class="ident">unwrap</span>().<span class="ident">unwrap</span>();
<span class="prelude-val">Some</span>(<span class="kw-2">&amp;</span><span class="self">self</span>.<span class="ident">string</span>[<span class="ident">prev</span>..<span class="ident">end</span>])
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new_graphemes</span><span class="op">&lt;</span><span class="lifetime">&#39;b</span><span class="op">&gt;</span>(<span class="ident">s</span>: <span class="kw-2">&amp;</span><span class="lifetime">&#39;b</span> <span class="ident">str</span>, <span class="ident">is_extended</span>: <span class="ident">bool</span>) <span class="op">-&gt;</span> <span class="ident">Graphemes</span><span class="op">&lt;</span><span class="lifetime">&#39;b</span><span class="op">&gt;</span> {
<span class="kw">let</span> <span class="ident">len</span> <span class="op">=</span> <span class="ident">s</span>.<span class="ident">len</span>();
<span class="ident">Graphemes</span> {
<span class="ident">string</span>: <span class="ident">s</span>,
<span class="ident">cursor</span>: <span class="ident">GraphemeCursor</span>::<span class="ident">new</span>(<span class="number">0</span>, <span class="ident">len</span>, <span class="ident">is_extended</span>),
<span class="ident">cursor_back</span>: <span class="ident">GraphemeCursor</span>::<span class="ident">new</span>(<span class="ident">len</span>, <span class="ident">len</span>, <span class="ident">is_extended</span>),
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new_grapheme_indices</span><span class="op">&lt;</span><span class="lifetime">&#39;b</span><span class="op">&gt;</span>(<span class="ident">s</span>: <span class="kw-2">&amp;</span><span class="lifetime">&#39;b</span> <span class="ident">str</span>, <span class="ident">is_extended</span>: <span class="ident">bool</span>) <span class="op">-&gt;</span> <span class="ident">GraphemeIndices</span><span class="op">&lt;</span><span class="lifetime">&#39;b</span><span class="op">&gt;</span> {
<span class="ident">GraphemeIndices</span> { <span class="ident">start_offset</span>: <span class="ident">s</span>.<span class="ident">as_ptr</span>() <span class="kw">as</span> <span class="ident">usize</span>, <span class="ident">iter</span>: <span class="ident">new_graphemes</span>(<span class="ident">s</span>, <span class="ident">is_extended</span>) }
}
<span class="comment">// maybe unify with PairResult?</span>
<span class="comment">// An enum describing information about a potential boundary.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">PartialEq</span>, <span class="ident">Eq</span>, <span class="ident">Clone</span>)]</span>
<span class="kw">enum</span> <span class="ident">GraphemeState</span> {
<span class="comment">// No information is known.</span>
<span class="ident">Unknown</span>,
<span class="comment">// It is known to not be a boundary.</span>
<span class="ident">NotBreak</span>,
<span class="comment">// It is known to be a boundary.</span>
<span class="ident">Break</span>,
<span class="comment">// The codepoint after is a Regional Indicator Symbol, so a boundary iff</span>
<span class="comment">// it is preceded by an even number of RIS codepoints. (GB12, GB13)</span>
<span class="ident">Regional</span>,
<span class="comment">// The codepoint after is in the E_Modifier category, so whether it&#39;s a boundary</span>
<span class="comment">// depends on pre-context according to GB10.</span>
<span class="ident">Emoji</span>,
}
<span class="doccomment">/// Cursor-based segmenter for grapheme clusters.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">GraphemeCursor</span> {
<span class="comment">// Current cursor position.</span>
<span class="ident">offset</span>: <span class="ident">usize</span>,
<span class="comment">// Total length of the string.</span>
<span class="ident">len</span>: <span class="ident">usize</span>,
<span class="comment">// A config flag indicating whether this cursor computes legacy or extended</span>
<span class="comment">// grapheme cluster boundaries (enables GB9a and GB9b if set).</span>
<span class="ident">is_extended</span>: <span class="ident">bool</span>,
<span class="comment">// Information about the potential boundary at `offset`</span>
<span class="ident">state</span>: <span class="ident">GraphemeState</span>,
<span class="comment">// Category of codepoint immediately preceding cursor, if known.</span>
<span class="ident">cat_before</span>: <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">GraphemeCat</span><span class="op">&gt;</span>,
<span class="comment">// Category of codepoint immediately after cursor, if known.</span>
<span class="ident">cat_after</span>: <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">GraphemeCat</span><span class="op">&gt;</span>,
<span class="comment">// If set, at least one more codepoint immediately preceding this offset</span>
<span class="comment">// is needed to resolve whether there&#39;s a boundary at `offset`.</span>
<span class="ident">pre_context_offset</span>: <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span>,
<span class="comment">// The number of RIS codepoints preceding `offset`. If `pre_context_offset`</span>
<span class="comment">// is set, then counts the number of RIS between that and `offset`, otherwise</span>
<span class="comment">// is an accurate count relative to the string.</span>
<span class="ident">ris_count</span>: <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span>,
<span class="comment">// Set if a call to `prev_boundary` or `next_boundary` was suspended due</span>
<span class="comment">// to needing more input.</span>
<span class="ident">resuming</span>: <span class="ident">bool</span>,
}
<span class="doccomment">/// An error return indicating that not enough content was available in the</span>
<span class="doccomment">/// provided chunk to satisfy the query, and that more content must be provided.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">PartialEq</span>, <span class="ident">Eq</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">GraphemeIncomplete</span> {
<span class="doccomment">/// More pre-context is needed. The caller should call `provide_context`</span>
<span class="doccomment">/// with a chunk ending at the offset given, then retry the query. This</span>
<span class="doccomment">/// will only be returned if the `chunk_start` parameter is nonzero.</span>
<span class="ident">PreContext</span>(<span class="ident">usize</span>),
<span class="doccomment">/// When requesting `prev_boundary`, the cursor is moving past the beginning</span>
<span class="doccomment">/// of the current chunk, so the chunk before that is requested. This will</span>
<span class="doccomment">/// only be returned if the `chunk_start` parameter is nonzero.</span>
<span class="ident">PrevChunk</span>,
<span class="doccomment">/// When requesting `next_boundary`, the cursor is moving past the end of the</span>
<span class="doccomment">/// current chunk, so the chunk after that is requested. This will only be</span>
<span class="doccomment">/// returned if the chunk ends before the `len` parameter provided on</span>
<span class="doccomment">/// creation of the cursor.</span>
<span class="ident">NextChunk</span>, <span class="comment">// requesting chunk following the one given</span>
<span class="doccomment">/// An error returned when the chunk given does not contain the cursor position.</span>
<span class="ident">InvalidOffset</span>,
}
<span class="comment">// An enum describing the result from lookup of a pair of categories.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">PartialEq</span>, <span class="ident">Eq</span>)]</span>
<span class="kw">enum</span> <span class="ident">PairResult</span> {
<span class="ident">NotBreak</span>, <span class="comment">// definitely not a break</span>
<span class="ident">Break</span>, <span class="comment">// definitely a break</span>
<span class="ident">Extended</span>, <span class="comment">// a break iff not in extended mode</span>
<span class="ident">Regional</span>, <span class="comment">// a break if preceded by an even number of RIS</span>
<span class="ident">Emoji</span>, <span class="comment">// a break if preceded by emoji base and (Extend)*</span>
}
<span class="kw">fn</span> <span class="ident">check_pair</span>(<span class="ident">before</span>: <span class="ident">GraphemeCat</span>, <span class="ident">after</span>: <span class="ident">GraphemeCat</span>) <span class="op">-&gt;</span> <span class="ident">PairResult</span> {
<span class="kw">use</span> <span class="ident">tables</span>::<span class="ident">grapheme</span>::<span class="ident">GraphemeCat</span>::<span class="kw-2">*</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">PairResult</span>::<span class="kw-2">*</span>;
<span class="kw">match</span> (<span class="ident">before</span>, <span class="ident">after</span>) {
(<span class="ident">GC_CR</span>, <span class="ident">GC_LF</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB3</span>
(<span class="ident">GC_Control</span>, _) <span class="op">=&gt;</span> <span class="ident">Break</span>, <span class="comment">// GB4</span>
(<span class="ident">GC_CR</span>, _) <span class="op">=&gt;</span> <span class="ident">Break</span>, <span class="comment">// GB4</span>
(<span class="ident">GC_LF</span>, _) <span class="op">=&gt;</span> <span class="ident">Break</span>, <span class="comment">// GB4</span>
(_, <span class="ident">GC_Control</span>) <span class="op">=&gt;</span> <span class="ident">Break</span>, <span class="comment">// GB5</span>
(_, <span class="ident">GC_CR</span>) <span class="op">=&gt;</span> <span class="ident">Break</span>, <span class="comment">// GB5</span>
(_, <span class="ident">GC_LF</span>) <span class="op">=&gt;</span> <span class="ident">Break</span>, <span class="comment">// GB5</span>
(<span class="ident">GC_L</span>, <span class="ident">GC_L</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB6</span>
(<span class="ident">GC_L</span>, <span class="ident">GC_V</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB6</span>
(<span class="ident">GC_L</span>, <span class="ident">GC_LV</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB6</span>
(<span class="ident">GC_L</span>, <span class="ident">GC_LVT</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB6</span>
(<span class="ident">GC_LV</span>, <span class="ident">GC_V</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB7</span>
(<span class="ident">GC_LV</span>, <span class="ident">GC_T</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB7</span>
(<span class="ident">GC_V</span>, <span class="ident">GC_V</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB7</span>
(<span class="ident">GC_V</span>, <span class="ident">GC_T</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB7</span>
(<span class="ident">GC_LVT</span>, <span class="ident">GC_T</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB8</span>
(<span class="ident">GC_T</span>, <span class="ident">GC_T</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB8</span>
(_, <span class="ident">GC_Extend</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB9</span>
(_, <span class="ident">GC_ZWJ</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB9</span>
(_, <span class="ident">GC_SpacingMark</span>) <span class="op">=&gt;</span> <span class="ident">Extended</span>, <span class="comment">// GB9a</span>
(<span class="ident">GC_Prepend</span>, _) <span class="op">=&gt;</span> <span class="ident">Extended</span>, <span class="comment">// GB9b</span>
(<span class="ident">GC_E_Base</span>, <span class="ident">GC_E_Modifier</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB10</span>
(<span class="ident">GC_E_Base_GAZ</span>, <span class="ident">GC_E_Modifier</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB10</span>
(<span class="ident">GC_Extend</span>, <span class="ident">GC_E_Modifier</span>) <span class="op">=&gt;</span> <span class="ident">Emoji</span>, <span class="comment">// GB10</span>
(<span class="ident">GC_ZWJ</span>, <span class="ident">GC_Glue_After_Zwj</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB11</span>
(<span class="ident">GC_ZWJ</span>, <span class="ident">GC_E_Base_GAZ</span>) <span class="op">=&gt;</span> <span class="ident">NotBreak</span>, <span class="comment">// GB11</span>
(<span class="ident">GC_Regional_Indicator</span>, <span class="ident">GC_Regional_Indicator</span>) <span class="op">=&gt;</span> <span class="ident">Regional</span>, <span class="comment">// GB12, GB13</span>
(_, _) <span class="op">=&gt;</span> <span class="ident">Break</span>, <span class="comment">// GB999</span>
}
}
<span class="kw">impl</span> <span class="ident">GraphemeCursor</span> {
<span class="doccomment">/// Create a new cursor. The string and initial offset are given at creation</span>
<span class="doccomment">/// time, but the contents of the string are not. The `is_extended` parameter</span>
<span class="doccomment">/// controls whether extended grapheme clusters are selected.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The `offset` parameter must be on a codepoint boundary.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::GraphemeCursor;</span>
<span class="doccomment">/// let s = &quot;हिन्दी&quot;;</span>
<span class="doccomment">/// let mut legacy = GraphemeCursor::new(0, s.len(), false);</span>
<span class="doccomment">/// assert_eq!(legacy.next_boundary(s, 0), Ok(Some(&quot;ह&quot;.len())));</span>
<span class="doccomment">/// let mut extended = GraphemeCursor::new(0, s.len(), true);</span>
<span class="doccomment">/// assert_eq!(extended.next_boundary(s, 0), Ok(Some(&quot;हि&quot;.len())));</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">offset</span>: <span class="ident">usize</span>, <span class="ident">len</span>: <span class="ident">usize</span>, <span class="ident">is_extended</span>: <span class="ident">bool</span>) <span class="op">-&gt;</span> <span class="ident">GraphemeCursor</span> {
<span class="kw">let</span> <span class="ident">state</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">offset</span> <span class="op">==</span> <span class="number">0</span> <span class="op">||</span> <span class="ident">offset</span> <span class="op">==</span> <span class="ident">len</span> {
<span class="ident">GraphemeState</span>::<span class="ident">Break</span>
} <span class="kw">else</span> {
<span class="ident">GraphemeState</span>::<span class="ident">Unknown</span>
};
<span class="ident">GraphemeCursor</span> {
<span class="ident">offset</span>: <span class="ident">offset</span>,
<span class="ident">len</span>: <span class="ident">len</span>,
<span class="ident">state</span>: <span class="ident">state</span>,
<span class="ident">is_extended</span>: <span class="ident">is_extended</span>,
<span class="ident">cat_before</span>: <span class="prelude-val">None</span>,
<span class="ident">cat_after</span>: <span class="prelude-val">None</span>,
<span class="ident">pre_context_offset</span>: <span class="prelude-val">None</span>,
<span class="ident">ris_count</span>: <span class="prelude-val">None</span>,
<span class="ident">resuming</span>: <span class="bool-val">false</span>,
}
}
<span class="comment">// Not sure I&#39;m gonna keep this, the advantage over new() seems thin.</span>
<span class="doccomment">/// Set the cursor to a new location in the same string.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::GraphemeCursor;</span>
<span class="doccomment">/// let s = &quot;abcd&quot;;</span>
<span class="doccomment">/// let mut cursor = GraphemeCursor::new(0, s.len(), false);</span>
<span class="doccomment">/// assert_eq!(cursor.cur_cursor(), 0);</span>
<span class="doccomment">/// cursor.set_cursor(2);</span>
<span class="doccomment">/// assert_eq!(cursor.cur_cursor(), 2);</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">set_cursor</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">offset</span>: <span class="ident">usize</span>) {
<span class="kw">if</span> <span class="ident">offset</span> <span class="op">!=</span> <span class="self">self</span>.<span class="ident">offset</span> {
<span class="self">self</span>.<span class="ident">offset</span> <span class="op">=</span> <span class="ident">offset</span>;
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">offset</span> <span class="op">==</span> <span class="number">0</span> <span class="op">||</span> <span class="ident">offset</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">len</span> {
<span class="ident">GraphemeState</span>::<span class="ident">Break</span>
} <span class="kw">else</span> {
<span class="ident">GraphemeState</span>::<span class="ident">Unknown</span>
};
<span class="comment">// reset state derived from text around cursor</span>
<span class="self">self</span>.<span class="ident">cat_before</span> <span class="op">=</span> <span class="prelude-val">None</span>;
<span class="self">self</span>.<span class="ident">cat_after</span> <span class="op">=</span> <span class="prelude-val">None</span>;
<span class="self">self</span>.<span class="ident">ris_count</span> <span class="op">=</span> <span class="prelude-val">None</span>;
}
}
<span class="doccomment">/// The current offset of the cursor. Equal to the last value provided to</span>
<span class="doccomment">/// `new()` or `set_cursor()`, or returned from `next_boundary()` or</span>
<span class="doccomment">/// `prev_boundary()`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::GraphemeCursor;</span>
<span class="doccomment">/// // Two flags (🇷🇸🇮🇴), each flag is two RIS codepoints, each RIS is 4 bytes.</span>
<span class="doccomment">/// let flags = &quot;\u{1F1F7}\u{1F1F8}\u{1F1EE}\u{1F1F4}&quot;;</span>
<span class="doccomment">/// let mut cursor = GraphemeCursor::new(4, flags.len(), false);</span>
<span class="doccomment">/// assert_eq!(cursor.cur_cursor(), 4);</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(flags, 0), Ok(Some(8)));</span>
<span class="doccomment">/// assert_eq!(cursor.cur_cursor(), 8);</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">cur_cursor</span>(<span class="kw-2">&amp;</span><span class="self">self</span>) <span class="op">-&gt;</span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">offset</span>
}
<span class="doccomment">/// Provide additional pre-context when it is needed to decide a boundary.</span>
<span class="doccomment">/// The end of the chunk must coincide with the value given in the</span>
<span class="doccomment">/// `GraphemeIncomplete::PreContext` request.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::{GraphemeCursor, GraphemeIncomplete};</span>
<span class="doccomment">/// let flags = &quot;\u{1F1F7}\u{1F1F8}\u{1F1EE}\u{1F1F4}&quot;;</span>
<span class="doccomment">/// let mut cursor = GraphemeCursor::new(8, flags.len(), false);</span>
<span class="doccomment">/// // Not enough pre-context to decide if there&#39;s a boundary between the two flags.</span>
<span class="doccomment">/// assert_eq!(cursor.is_boundary(&amp;flags[8..], 8), Err(GraphemeIncomplete::PreContext(8)));</span>
<span class="doccomment">/// // Provide one more Regional Indicator Symbol of pre-context</span>
<span class="doccomment">/// cursor.provide_context(&amp;flags[4..8], 4);</span>
<span class="doccomment">/// // Still not enough context to decide.</span>
<span class="doccomment">/// assert_eq!(cursor.is_boundary(&amp;flags[8..], 8), Err(GraphemeIncomplete::PreContext(4)));</span>
<span class="doccomment">/// // Provide additional requested context.</span>
<span class="doccomment">/// cursor.provide_context(&amp;flags[0..4], 0);</span>
<span class="doccomment">/// // That&#39;s enough to decide (it always is when context goes to the start of the string)</span>
<span class="doccomment">/// assert_eq!(cursor.is_boundary(&amp;flags[8..], 8), Ok(true));</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">provide_context</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">chunk</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>, <span class="ident">chunk_start</span>: <span class="ident">usize</span>) {
<span class="kw">use</span> <span class="ident">tables</span>::<span class="ident">grapheme</span> <span class="kw">as</span> <span class="ident">gr</span>;
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">chunk_start</span> <span class="op">+</span> <span class="ident">chunk</span>.<span class="ident">len</span>() <span class="op">==</span> <span class="self">self</span>.<span class="ident">pre_context_offset</span>.<span class="ident">unwrap</span>());
<span class="self">self</span>.<span class="ident">pre_context_offset</span> <span class="op">=</span> <span class="prelude-val">None</span>;
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_extended</span> <span class="op">&amp;&amp;</span> <span class="ident">chunk_start</span> <span class="op">+</span> <span class="ident">chunk</span>.<span class="ident">len</span>() <span class="op">==</span> <span class="self">self</span>.<span class="ident">offset</span> {
<span class="kw">let</span> <span class="ident">ch</span> <span class="op">=</span> <span class="ident">chunk</span>.<span class="ident">chars</span>().<span class="ident">rev</span>().<span class="ident">next</span>().<span class="ident">unwrap</span>();
<span class="kw">if</span> <span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>) <span class="op">==</span> <span class="ident">gr</span>::<span class="ident">GC_Prepend</span> {
<span class="self">self</span>.<span class="ident">decide</span>(<span class="bool-val">false</span>); <span class="comment">// GB9b</span>
<span class="kw">return</span>;
}
}
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">GraphemeState</span>::<span class="ident">Regional</span> <span class="op">=&gt;</span> <span class="self">self</span>.<span class="ident">handle_regional</span>(<span class="ident">chunk</span>, <span class="ident">chunk_start</span>),
<span class="ident">GraphemeState</span>::<span class="ident">Emoji</span> <span class="op">=&gt;</span> <span class="self">self</span>.<span class="ident">handle_emoji</span>(<span class="ident">chunk</span>, <span class="ident">chunk_start</span>),
_ <span class="op">=&gt;</span> <span class="macro">panic</span><span class="macro">!</span>(<span class="string">&quot;invalid state&quot;</span>)
}
}
<span class="kw">fn</span> <span class="ident">decide</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">is_break</span>: <span class="ident">bool</span>) {
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">is_break</span> {
<span class="ident">GraphemeState</span>::<span class="ident">Break</span>
} <span class="kw">else</span> {
<span class="ident">GraphemeState</span>::<span class="ident">NotBreak</span>
};
}
<span class="kw">fn</span> <span class="ident">decision</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">is_break</span>: <span class="ident">bool</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">bool</span>, <span class="ident">GraphemeIncomplete</span><span class="op">&gt;</span> {
<span class="self">self</span>.<span class="ident">decide</span>(<span class="ident">is_break</span>);
<span class="prelude-val">Ok</span>(<span class="ident">is_break</span>)
}
<span class="kw">fn</span> <span class="ident">is_boundary_result</span>(<span class="kw-2">&amp;</span><span class="self">self</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">bool</span>, <span class="ident">GraphemeIncomplete</span><span class="op">&gt;</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">state</span> <span class="op">==</span> <span class="ident">GraphemeState</span>::<span class="ident">Break</span> {
<span class="prelude-val">Ok</span>(<span class="bool-val">true</span>)
} <span class="kw">else</span> <span class="kw">if</span> <span class="self">self</span>.<span class="ident">state</span> <span class="op">==</span> <span class="ident">GraphemeState</span>::<span class="ident">NotBreak</span> {
<span class="prelude-val">Ok</span>(<span class="bool-val">false</span>)
} <span class="kw">else</span> <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">pre_context_offset</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">pre_context_offset</span> {
<span class="prelude-val">Err</span>(<span class="ident">GraphemeIncomplete</span>::<span class="ident">PreContext</span>(<span class="ident">pre_context_offset</span>))
} <span class="kw">else</span> {
<span class="macro">unreachable</span><span class="macro">!</span>(<span class="string">&quot;inconsistent state&quot;</span>);
}
}
<span class="kw">fn</span> <span class="ident">handle_regional</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">chunk</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>, <span class="ident">chunk_start</span>: <span class="ident">usize</span>) {
<span class="kw">use</span> <span class="ident">tables</span>::<span class="ident">grapheme</span> <span class="kw">as</span> <span class="ident">gr</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ris_count</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">ris_count</span>.<span class="ident">unwrap_or</span>(<span class="number">0</span>);
<span class="kw">for</span> <span class="ident">ch</span> <span class="kw">in</span> <span class="ident">chunk</span>.<span class="ident">chars</span>().<span class="ident">rev</span>() {
<span class="kw">if</span> <span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>) <span class="op">!=</span> <span class="ident">gr</span>::<span class="ident">GC_Regional_Indicator</span> {
<span class="self">self</span>.<span class="ident">ris_count</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">ris_count</span>);
<span class="self">self</span>.<span class="ident">decide</span>((<span class="ident">ris_count</span> <span class="op">%</span> <span class="number">2</span>) <span class="op">==</span> <span class="number">0</span>);
<span class="kw">return</span>;
}
<span class="ident">ris_count</span> <span class="op">+=</span> <span class="number">1</span>;
}
<span class="self">self</span>.<span class="ident">ris_count</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">ris_count</span>);
<span class="kw">if</span> <span class="ident">chunk_start</span> <span class="op">==</span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">decide</span>((<span class="ident">ris_count</span> <span class="op">%</span> <span class="number">2</span>) <span class="op">==</span> <span class="number">0</span>);
<span class="kw">return</span>;
}
<span class="self">self</span>.<span class="ident">pre_context_offset</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">chunk_start</span>);
}
<span class="kw">fn</span> <span class="ident">handle_emoji</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">chunk</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>, <span class="ident">chunk_start</span>: <span class="ident">usize</span>) {
<span class="kw">use</span> <span class="ident">tables</span>::<span class="ident">grapheme</span> <span class="kw">as</span> <span class="ident">gr</span>;
<span class="kw">for</span> <span class="ident">ch</span> <span class="kw">in</span> <span class="ident">chunk</span>.<span class="ident">chars</span>().<span class="ident">rev</span>() {
<span class="kw">match</span> <span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>) {
<span class="ident">gr</span>::<span class="ident">GC_Extend</span> <span class="op">=&gt;</span> (),
<span class="ident">gr</span>::<span class="ident">GC_E_Base</span> <span class="op">|</span> <span class="ident">gr</span>::<span class="ident">GC_E_Base_GAZ</span> <span class="op">=&gt;</span> {
<span class="self">self</span>.<span class="ident">decide</span>(<span class="bool-val">false</span>);
<span class="kw">return</span>;
}
_ <span class="op">=&gt;</span> {
<span class="self">self</span>.<span class="ident">decide</span>(<span class="bool-val">true</span>);
<span class="kw">return</span>;
}
}
}
<span class="kw">if</span> <span class="ident">chunk_start</span> <span class="op">==</span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">decide</span>(<span class="bool-val">true</span>);
<span class="kw">return</span>;
}
<span class="self">self</span>.<span class="ident">pre_context_offset</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">chunk_start</span>);
}
<span class="doccomment">/// Determine whether the current cursor location is a grapheme cluster boundary.</span>
<span class="doccomment">/// Only a part of the string need be supplied. If `chunk_start` is nonzero or</span>
<span class="doccomment">/// the length of `chunk` is not equal to `len` on creation, then this method</span>
<span class="doccomment">/// may return `GraphemeIncomplete::PreContext`. The caller should then</span>
<span class="doccomment">/// call `provide_context` with the requested chunk, then retry calling this</span>
<span class="doccomment">/// method.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// For partial chunks, if the cursor is not at the beginning or end of the</span>
<span class="doccomment">/// string, the chunk should contain at least the codepoint following the cursor.</span>
<span class="doccomment">/// If the string is nonempty, the chunk must be nonempty.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// All calls should have consistent chunk contents (ie, if a chunk provides</span>
<span class="doccomment">/// content for a given slice, all further chunks covering that slice must have</span>
<span class="doccomment">/// the same content for it).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::GraphemeCursor;</span>
<span class="doccomment">/// let flags = &quot;\u{1F1F7}\u{1F1F8}\u{1F1EE}\u{1F1F4}&quot;;</span>
<span class="doccomment">/// let mut cursor = GraphemeCursor::new(8, flags.len(), false);</span>
<span class="doccomment">/// assert_eq!(cursor.is_boundary(flags, 0), Ok(true));</span>
<span class="doccomment">/// cursor.set_cursor(12);</span>
<span class="doccomment">/// assert_eq!(cursor.is_boundary(flags, 0), Ok(false));</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">is_boundary</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">chunk</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>, <span class="ident">chunk_start</span>: <span class="ident">usize</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">bool</span>, <span class="ident">GraphemeIncomplete</span><span class="op">&gt;</span> {
<span class="kw">use</span> <span class="ident">tables</span>::<span class="ident">grapheme</span> <span class="kw">as</span> <span class="ident">gr</span>;
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">state</span> <span class="op">==</span> <span class="ident">GraphemeState</span>::<span class="ident">Break</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="bool-val">true</span>)
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">state</span> <span class="op">==</span> <span class="ident">GraphemeState</span>::<span class="ident">NotBreak</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="bool-val">false</span>)
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">&lt;</span> <span class="ident">chunk_start</span> <span class="op">||</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">&gt;=</span> <span class="ident">chunk_start</span> <span class="op">+</span> <span class="ident">chunk</span>.<span class="ident">len</span>() {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">&gt;</span> <span class="ident">chunk_start</span> <span class="op">+</span> <span class="ident">chunk</span>.<span class="ident">len</span>() <span class="op">||</span> <span class="self">self</span>.<span class="ident">cat_after</span>.<span class="ident">is_none</span>() {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">GraphemeIncomplete</span>::<span class="ident">InvalidOffset</span>)
}
}
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">pre_context_offset</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">pre_context_offset</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">GraphemeIncomplete</span>::<span class="ident">PreContext</span>(<span class="ident">pre_context_offset</span>));
}
<span class="kw">let</span> <span class="ident">offset_in_chunk</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">-</span> <span class="ident">chunk_start</span>;
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">cat_after</span>.<span class="ident">is_none</span>() {
<span class="kw">let</span> <span class="ident">ch</span> <span class="op">=</span> <span class="ident">chunk</span>[<span class="ident">offset_in_chunk</span>..].<span class="ident">chars</span>().<span class="ident">next</span>().<span class="ident">unwrap</span>();
<span class="self">self</span>.<span class="ident">cat_after</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>));
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">==</span> <span class="ident">chunk_start</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">need_pre_context</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">cat_after</span>.<span class="ident">unwrap</span>() {
<span class="ident">gr</span>::<span class="ident">GC_Regional_Indicator</span> <span class="op">=&gt;</span> <span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">GraphemeState</span>::<span class="ident">Regional</span>,
<span class="ident">gr</span>::<span class="ident">GC_E_Modifier</span> <span class="op">=&gt;</span> <span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">GraphemeState</span>::<span class="ident">Emoji</span>,
_ <span class="op">=&gt;</span> <span class="ident">need_pre_context</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">cat_before</span>.<span class="ident">is_none</span>(),
}
<span class="kw">if</span> <span class="ident">need_pre_context</span> {
<span class="self">self</span>.<span class="ident">pre_context_offset</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">chunk_start</span>);
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">GraphemeIncomplete</span>::<span class="ident">PreContext</span>(<span class="ident">chunk_start</span>));
}
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">cat_before</span>.<span class="ident">is_none</span>() {
<span class="kw">let</span> <span class="ident">ch</span> <span class="op">=</span> <span class="ident">chunk</span>[..<span class="ident">offset_in_chunk</span>].<span class="ident">chars</span>().<span class="ident">rev</span>().<span class="ident">next</span>().<span class="ident">unwrap</span>();
<span class="self">self</span>.<span class="ident">cat_before</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>));
}
<span class="kw">match</span> <span class="ident">check_pair</span>(<span class="self">self</span>.<span class="ident">cat_before</span>.<span class="ident">unwrap</span>(), <span class="self">self</span>.<span class="ident">cat_after</span>.<span class="ident">unwrap</span>()) {
<span class="ident">PairResult</span>::<span class="ident">NotBreak</span> <span class="op">=&gt;</span> <span class="kw">return</span> <span class="self">self</span>.<span class="ident">decision</span>(<span class="bool-val">false</span>),
<span class="ident">PairResult</span>::<span class="ident">Break</span> <span class="op">=&gt;</span> <span class="kw">return</span> <span class="self">self</span>.<span class="ident">decision</span>(<span class="bool-val">true</span>),
<span class="ident">PairResult</span>::<span class="ident">Extended</span> <span class="op">=&gt;</span> {
<span class="kw">let</span> <span class="ident">is_extended</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">is_extended</span>;
<span class="kw">return</span> <span class="self">self</span>.<span class="ident">decision</span>(<span class="op">!</span><span class="ident">is_extended</span>);
}
<span class="ident">PairResult</span>::<span class="ident">Regional</span> <span class="op">=&gt;</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">ris_count</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">ris_count</span> {
<span class="kw">return</span> <span class="self">self</span>.<span class="ident">decision</span>((<span class="ident">ris_count</span> <span class="op">%</span> <span class="number">2</span>) <span class="op">==</span> <span class="number">0</span>);
}
<span class="self">self</span>.<span class="ident">handle_regional</span>(<span class="kw-2">&amp;</span><span class="ident">chunk</span>[..<span class="ident">offset_in_chunk</span>], <span class="ident">chunk_start</span>);
<span class="self">self</span>.<span class="ident">is_boundary_result</span>()
}
<span class="ident">PairResult</span>::<span class="ident">Emoji</span> <span class="op">=&gt;</span> {
<span class="self">self</span>.<span class="ident">handle_emoji</span>(<span class="kw-2">&amp;</span><span class="ident">chunk</span>[..<span class="ident">offset_in_chunk</span>], <span class="ident">chunk_start</span>);
<span class="self">self</span>.<span class="ident">is_boundary_result</span>()
}
}
}
<span class="doccomment">/// Find the next boundary after the current cursor position. Only a part of</span>
<span class="doccomment">/// the string need be supplied. If the chunk is incomplete, then this</span>
<span class="doccomment">/// method might return `GraphemeIncomplete::PreContext` or</span>
<span class="doccomment">/// `GraphemeIncomplete::NextChunk`. In the former case, the caller should</span>
<span class="doccomment">/// call `provide_context` with the requested chunk, then retry. In the</span>
<span class="doccomment">/// latter case, the caller should provide the chunk following the one</span>
<span class="doccomment">/// given, then retry.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// See `is_boundary` for expectations on the provided chunk.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::GraphemeCursor;</span>
<span class="doccomment">/// let flags = &quot;\u{1F1F7}\u{1F1F8}\u{1F1EE}\u{1F1F4}&quot;;</span>
<span class="doccomment">/// let mut cursor = GraphemeCursor::new(4, flags.len(), false);</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(flags, 0), Ok(Some(8)));</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(flags, 0), Ok(Some(16)));</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(flags, 0), Ok(None));</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// And an example that uses partial strings:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::{GraphemeCursor, GraphemeIncomplete};</span>
<span class="doccomment">/// let s = &quot;abcd&quot;;</span>
<span class="doccomment">/// let mut cursor = GraphemeCursor::new(0, s.len(), false);</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(&amp;s[..2], 0), Ok(Some(1)));</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(&amp;s[..2], 0), Err(GraphemeIncomplete::NextChunk));</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(&amp;s[2..4], 2), Ok(Some(2)));</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(&amp;s[2..4], 2), Ok(Some(3)));</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(&amp;s[2..4], 2), Ok(Some(4)));</span>
<span class="doccomment">/// assert_eq!(cursor.next_boundary(&amp;s[2..4], 2), Ok(None));</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">next_boundary</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">chunk</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>, <span class="ident">chunk_start</span>: <span class="ident">usize</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span>, <span class="ident">GraphemeIncomplete</span><span class="op">&gt;</span> {
<span class="kw">use</span> <span class="ident">tables</span>::<span class="ident">grapheme</span> <span class="kw">as</span> <span class="ident">gr</span>;
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">len</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="prelude-val">None</span>);
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">chunk</span>[<span class="self">self</span>.<span class="ident">offset</span> <span class="op">-</span> <span class="ident">chunk_start</span>..].<span class="ident">chars</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ch</span> <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>();
<span class="kw">loop</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">resuming</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">cat_after</span>.<span class="ident">is_none</span>() {
<span class="self">self</span>.<span class="ident">cat_after</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>));
}
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">offset</span> <span class="op">+=</span> <span class="ident">ch</span>.<span class="ident">len_utf8</span>();
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">GraphemeState</span>::<span class="ident">Unknown</span>;
<span class="self">self</span>.<span class="ident">cat_before</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">cat_after</span>.<span class="ident">take</span>();
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">cat_before</span>.<span class="ident">is_none</span>() {
<span class="self">self</span>.<span class="ident">cat_before</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>));
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">cat_before</span>.<span class="ident">unwrap</span>() <span class="op">==</span> <span class="ident">GraphemeCat</span>::<span class="ident">GC_Regional_Indicator</span> {
<span class="self">self</span>.<span class="ident">ris_count</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">ris_count</span>.<span class="ident">map</span>(<span class="op">|</span><span class="ident">c</span><span class="op">|</span> <span class="ident">c</span> <span class="op">+</span> <span class="number">1</span>);
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">ris_count</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="number">0</span>);
}
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">next_ch</span>) <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">next</span>() {
<span class="ident">ch</span> <span class="op">=</span> <span class="ident">next_ch</span>;
<span class="self">self</span>.<span class="ident">cat_after</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>));
} <span class="kw">else</span> <span class="kw">if</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">len</span> {
<span class="self">self</span>.<span class="ident">decide</span>(<span class="bool-val">true</span>);
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">GraphemeIncomplete</span>::<span class="ident">NextChunk</span>);
}
}
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_boundary</span>(<span class="ident">chunk</span>, <span class="ident">chunk_start</span>)<span class="question-mark">?</span> {
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">offset</span>));
}
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
}
<span class="doccomment">/// Find the previous boundary after the current cursor position. Only a part</span>
<span class="doccomment">/// of the string need be supplied. If the chunk is incomplete, then this</span>
<span class="doccomment">/// method might return `GraphemeIncomplete::PreContext` or</span>
<span class="doccomment">/// `GraphemeIncomplete::PrevChunk`. In the former case, the caller should</span>
<span class="doccomment">/// call `provide_context` with the requested chunk, then retry. In the</span>
<span class="doccomment">/// latter case, the caller should provide the chunk preceding the one</span>
<span class="doccomment">/// given, then retry.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// See `is_boundary` for expectations on the provided chunk.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::GraphemeCursor;</span>
<span class="doccomment">/// let flags = &quot;\u{1F1F7}\u{1F1F8}\u{1F1EE}\u{1F1F4}&quot;;</span>
<span class="doccomment">/// let mut cursor = GraphemeCursor::new(12, flags.len(), false);</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(flags, 0), Ok(Some(8)));</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(flags, 0), Ok(Some(0)));</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(flags, 0), Ok(None));</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// And an example that uses partial strings (note the exact return is not</span>
<span class="doccomment">/// guaranteed, and may be `PrevChunk` or `PreContext` arbitrarily):</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// # use unicode_segmentation::{GraphemeCursor, GraphemeIncomplete};</span>
<span class="doccomment">/// let s = &quot;abcd&quot;;</span>
<span class="doccomment">/// let mut cursor = GraphemeCursor::new(4, s.len(), false);</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(&amp;s[2..4], 2), Ok(Some(3)));</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(&amp;s[2..4], 2), Err(GraphemeIncomplete::PrevChunk));</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(&amp;s[0..2], 0), Ok(Some(2)));</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(&amp;s[0..2], 0), Ok(Some(1)));</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(&amp;s[0..2], 0), Ok(Some(0)));</span>
<span class="doccomment">/// assert_eq!(cursor.prev_boundary(&amp;s[0..2], 0), Ok(None));</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">prev_boundary</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">chunk</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>, <span class="ident">chunk_start</span>: <span class="ident">usize</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">usize</span><span class="op">&gt;</span>, <span class="ident">GraphemeIncomplete</span><span class="op">&gt;</span> {
<span class="kw">use</span> <span class="ident">tables</span>::<span class="ident">grapheme</span> <span class="kw">as</span> <span class="ident">gr</span>;
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">==</span> <span class="number">0</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="prelude-val">None</span>);
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">chunk</span>[..<span class="self">self</span>.<span class="ident">offset</span> <span class="op">-</span> <span class="ident">chunk_start</span>].<span class="ident">chars</span>().<span class="ident">rev</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ch</span> <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>();
<span class="kw">loop</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">==</span> <span class="ident">chunk_start</span> {
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">GraphemeIncomplete</span>::<span class="ident">PrevChunk</span>);
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">resuming</span> {
<span class="self">self</span>.<span class="ident">cat_before</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>));
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">offset</span> <span class="op">-=</span> <span class="ident">ch</span>.<span class="ident">len_utf8</span>();
<span class="self">self</span>.<span class="ident">cat_after</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">cat_before</span>.<span class="ident">take</span>();
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">GraphemeState</span>::<span class="ident">Unknown</span>;
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">ris_count</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">ris_count</span> {
<span class="self">self</span>.<span class="ident">ris_count</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">ris_count</span> <span class="op">&gt;</span> <span class="number">0</span> { <span class="prelude-val">Some</span>(<span class="ident">ris_count</span> <span class="op">-</span> <span class="number">1</span>) } <span class="kw">else</span> { <span class="prelude-val">None</span> };
}
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">prev_ch</span>) <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">next</span>() {
<span class="ident">ch</span> <span class="op">=</span> <span class="ident">prev_ch</span>;
<span class="self">self</span>.<span class="ident">cat_before</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">gr</span>::<span class="ident">grapheme_category</span>(<span class="ident">ch</span>));
} <span class="kw">else</span> <span class="kw">if</span> <span class="self">self</span>.<span class="ident">offset</span> <span class="op">==</span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">decide</span>(<span class="bool-val">true</span>);
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">GraphemeIncomplete</span>::<span class="ident">PrevChunk</span>);
}
}
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_boundary</span>(<span class="ident">chunk</span>, <span class="ident">chunk_start</span>)<span class="question-mark">?</span> {
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">offset</span>));
}
<span class="self">self</span>.<span class="ident">resuming</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
}
}
</pre>
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