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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/regex-syntax-0.7.2/src/hir/interval.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>interval.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../regex_syntax/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../regex_syntax/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span>
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</pre><pre class="rust"><code><span class="kw">use </span>core::{char, cmp, fmt::Debug, slice};
<span class="kw">use </span>alloc::vec::Vec;
<span class="kw">use </span><span class="kw">crate</span>::unicode;
<span class="comment">// This module contains an *internal* implementation of interval sets.
//
// The primary invariant that interval sets guards is canonical ordering. That
// is, every interval set contains an ordered sequence of intervals where
// no two intervals are overlapping or adjacent. While this invariant is
// occasionally broken within the implementation, it should be impossible for
// callers to observe it.
//
// Since case folding (as implemented below) breaks that invariant, we roll
// that into this API even though it is a little out of place in an otherwise
// generic interval set. (Hence the reason why the `unicode` module is imported
// here.)
//
// Some of the implementation complexity here is a result of me wanting to
// preserve the sequential representation without using additional memory.
// In many cases, we do use linear extra memory, but it is at most 2x and it
// is amortized. If we relaxed the memory requirements, this implementation
// could become much simpler. The extra memory is honestly probably OK, but
// character classes (especially of the Unicode variety) can become quite
// large, and it would be nice to keep regex compilation snappy even in debug
// builds. (In the past, I have been careless with this area of code and it has
// caused slow regex compilations in debug mode, so this isn&#39;t entirely
// unwarranted.)
//
// Tests on this are relegated to the public API of HIR in src/hir.rs.
</span><span class="attribute">#[derive(Clone, Debug)]
</span><span class="kw">pub struct </span>IntervalSet&lt;I&gt; {
<span class="doccomment">/// A sorted set of non-overlapping ranges.
</span>ranges: Vec&lt;I&gt;,
<span class="doccomment">/// While not required at all for correctness, we keep track of whether an
/// interval set has been case folded or not. This helps us avoid doing
/// redundant work if, for example, a set has already been cased folded.
/// And note that whether a set is folded or not is preserved through
/// all of the pairwise set operations. That is, if both interval sets
/// have been case folded, then any of difference, union, intersection or
/// symmetric difference all produce a case folded set.
///
/// Note that when this is true, it *must* be the case that the set is case
/// folded. But when it&#39;s false, the set *may* be case folded. In other
/// words, we only set this to true when we know it to be case, but we&#39;re
/// okay with it being false if it would otherwise be costly to determine
/// whether it should be true. This means code cannot assume that a false
/// value necessarily indicates that the set is not case folded.
///
/// Bottom line: this is a performance optimization.
</span>folded: bool,
}
<span class="kw">impl</span>&lt;I: Interval&gt; Eq <span class="kw">for </span>IntervalSet&lt;I&gt; {}
<span class="comment">// We implement PartialEq manually so that we don&#39;t consider the set&#39;s internal
// &#39;folded&#39; property to be part of its identity. The &#39;folded&#39; property is
// strictly an optimization.
</span><span class="kw">impl</span>&lt;I: Interval&gt; PartialEq <span class="kw">for </span>IntervalSet&lt;I&gt; {
<span class="kw">fn </span>eq(<span class="kw-2">&amp;</span><span class="self">self</span>, other: <span class="kw-2">&amp;</span>IntervalSet&lt;I&gt;) -&gt; bool {
<span class="self">self</span>.ranges.eq(<span class="kw-2">&amp;</span>other.ranges)
}
}
<span class="kw">impl</span>&lt;I: Interval&gt; IntervalSet&lt;I&gt; {
<span class="doccomment">/// Create a new set from a sequence of intervals. Each interval is
/// specified as a pair of bounds, where both bounds are inclusive.
///
/// The given ranges do not need to be in any specific order, and ranges
/// may overlap.
</span><span class="kw">pub fn </span>new&lt;T: IntoIterator&lt;Item = I&gt;&gt;(intervals: T) -&gt; IntervalSet&lt;I&gt; {
<span class="kw">let </span>ranges: Vec&lt;I&gt; = intervals.into_iter().collect();
<span class="comment">// An empty set is case folded.
</span><span class="kw">let </span>folded = ranges.is_empty();
<span class="kw">let </span><span class="kw-2">mut </span>set = IntervalSet { ranges, folded };
set.canonicalize();
set
}
<span class="doccomment">/// Add a new interval to this set.
</span><span class="kw">pub fn </span>push(<span class="kw-2">&amp;mut </span><span class="self">self</span>, interval: I) {
<span class="comment">// TODO: This could be faster. e.g., Push the interval such that
// it preserves canonicalization.
</span><span class="self">self</span>.ranges.push(interval);
<span class="self">self</span>.canonicalize();
<span class="comment">// We don&#39;t know whether the new interval added here is considered
// case folded, so we conservatively assume that the entire set is
// no longer case folded if it was previously.
</span><span class="self">self</span>.folded = <span class="bool-val">false</span>;
}
<span class="doccomment">/// Return an iterator over all intervals in this set.
///
/// The iterator yields intervals in ascending order.
</span><span class="kw">pub fn </span>iter(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; IntervalSetIter&lt;<span class="lifetime">&#39;_</span>, I&gt; {
IntervalSetIter(<span class="self">self</span>.ranges.iter())
}
<span class="doccomment">/// Return an immutable slice of intervals in this set.
///
/// The sequence returned is in canonical ordering.
</span><span class="kw">pub fn </span>intervals(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>[I] {
<span class="kw-2">&amp;</span><span class="self">self</span>.ranges
}
<span class="doccomment">/// Expand this interval set such that it contains all case folded
/// characters. For example, if this class consists of the range `a-z`,
/// then applying case folding will result in the class containing both the
/// ranges `a-z` and `A-Z`.
///
/// This returns an error if the necessary case mapping data is not
/// available.
</span><span class="kw">pub fn </span>case_fold_simple(<span class="kw-2">&amp;mut </span><span class="self">self</span>) -&gt; <span class="prelude-ty">Result</span>&lt;(), unicode::CaseFoldError&gt; {
<span class="kw">if </span><span class="self">self</span>.folded {
<span class="kw">return </span><span class="prelude-val">Ok</span>(());
}
<span class="kw">let </span>len = <span class="self">self</span>.ranges.len();
<span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..len {
<span class="kw">let </span>range = <span class="self">self</span>.ranges[i];
<span class="kw">if let </span><span class="prelude-val">Err</span>(err) = range.case_fold_simple(<span class="kw-2">&amp;mut </span><span class="self">self</span>.ranges) {
<span class="self">self</span>.canonicalize();
<span class="kw">return </span><span class="prelude-val">Err</span>(err);
}
}
<span class="self">self</span>.canonicalize();
<span class="self">self</span>.folded = <span class="bool-val">true</span>;
<span class="prelude-val">Ok</span>(())
}
<span class="doccomment">/// Union this set with the given set, in place.
</span><span class="kw">pub fn </span>union(<span class="kw-2">&amp;mut </span><span class="self">self</span>, other: <span class="kw-2">&amp;</span>IntervalSet&lt;I&gt;) {
<span class="kw">if </span>other.ranges.is_empty() || <span class="self">self</span>.ranges == other.ranges {
<span class="kw">return</span>;
}
<span class="comment">// This could almost certainly be done more efficiently.
</span><span class="self">self</span>.ranges.extend(<span class="kw-2">&amp;</span>other.ranges);
<span class="self">self</span>.canonicalize();
<span class="self">self</span>.folded = <span class="self">self</span>.folded &amp;&amp; other.folded;
}
<span class="doccomment">/// Intersect this set with the given set, in place.
</span><span class="kw">pub fn </span>intersect(<span class="kw-2">&amp;mut </span><span class="self">self</span>, other: <span class="kw-2">&amp;</span>IntervalSet&lt;I&gt;) {
<span class="kw">if </span><span class="self">self</span>.ranges.is_empty() {
<span class="kw">return</span>;
}
<span class="kw">if </span>other.ranges.is_empty() {
<span class="self">self</span>.ranges.clear();
<span class="comment">// An empty set is case folded.
</span><span class="self">self</span>.folded = <span class="bool-val">true</span>;
<span class="kw">return</span>;
}
<span class="comment">// There should be a way to do this in-place with constant memory,
// but I couldn&#39;t figure out a simple way to do it. So just append
// the intersection to the end of this range, and then drain it before
// we&#39;re done.
</span><span class="kw">let </span>drain_end = <span class="self">self</span>.ranges.len();
<span class="kw">let </span><span class="kw-2">mut </span>ita = <span class="number">0</span>..drain_end;
<span class="kw">let </span><span class="kw-2">mut </span>itb = <span class="number">0</span>..other.ranges.len();
<span class="kw">let </span><span class="kw-2">mut </span>a = ita.next().unwrap();
<span class="kw">let </span><span class="kw-2">mut </span>b = itb.next().unwrap();
<span class="kw">loop </span>{
<span class="kw">if let </span><span class="prelude-val">Some</span>(ab) = <span class="self">self</span>.ranges[a].intersect(<span class="kw-2">&amp;</span>other.ranges[b]) {
<span class="self">self</span>.ranges.push(ab);
}
<span class="kw">let </span>(it, aorb) =
<span class="kw">if </span><span class="self">self</span>.ranges[a].upper() &lt; other.ranges[b].upper() {
(<span class="kw-2">&amp;mut </span>ita, <span class="kw-2">&amp;mut </span>a)
} <span class="kw">else </span>{
(<span class="kw-2">&amp;mut </span>itb, <span class="kw-2">&amp;mut </span>b)
};
<span class="kw">match </span>it.next() {
<span class="prelude-val">Some</span>(v) =&gt; <span class="kw-2">*</span>aorb = v,
<span class="prelude-val">None </span>=&gt; <span class="kw">break</span>,
}
}
<span class="self">self</span>.ranges.drain(..drain_end);
<span class="self">self</span>.folded = <span class="self">self</span>.folded &amp;&amp; other.folded;
}
<span class="doccomment">/// Subtract the given set from this set, in place.
</span><span class="kw">pub fn </span>difference(<span class="kw-2">&amp;mut </span><span class="self">self</span>, other: <span class="kw-2">&amp;</span>IntervalSet&lt;I&gt;) {
<span class="kw">if </span><span class="self">self</span>.ranges.is_empty() || other.ranges.is_empty() {
<span class="kw">return</span>;
}
<span class="comment">// This algorithm is (to me) surprisingly complex. A search of the
// interwebs indicate that this is a potentially interesting problem.
// Folks seem to suggest interval or segment trees, but I&#39;d like to
// avoid the overhead (both runtime and conceptual) of that.
//
// The following is basically my Shitty First Draft. Therefore, in
// order to grok it, you probably need to read each line carefully.
// Simplifications are most welcome!
//
// Remember, we can assume the canonical format invariant here, which
// says that all ranges are sorted, not overlapping and not adjacent in
// each class.
</span><span class="kw">let </span>drain_end = <span class="self">self</span>.ranges.len();
<span class="kw">let </span>(<span class="kw-2">mut </span>a, <span class="kw-2">mut </span>b) = (<span class="number">0</span>, <span class="number">0</span>);
<span class="lifetime">&#39;LOOP</span>: <span class="kw">while </span>a &lt; drain_end &amp;&amp; b &lt; other.ranges.len() {
<span class="comment">// Basically, the easy cases are when neither range overlaps with
// each other. If the `b` range is less than our current `a`
// range, then we can skip it and move on.
</span><span class="kw">if </span>other.ranges[b].upper() &lt; <span class="self">self</span>.ranges[a].lower() {
b += <span class="number">1</span>;
<span class="kw">continue</span>;
}
<span class="comment">// ... similarly for the `a` range. If it&#39;s less than the smallest
// `b` range, then we can add it as-is.
</span><span class="kw">if </span><span class="self">self</span>.ranges[a].upper() &lt; other.ranges[b].lower() {
<span class="kw">let </span>range = <span class="self">self</span>.ranges[a];
<span class="self">self</span>.ranges.push(range);
a += <span class="number">1</span>;
<span class="kw">continue</span>;
}
<span class="comment">// Otherwise, we have overlapping ranges.
</span><span class="macro">assert!</span>(!<span class="self">self</span>.ranges[a].is_intersection_empty(<span class="kw-2">&amp;</span>other.ranges[b]));
<span class="comment">// This part is tricky and was non-obvious to me without looking
// at explicit examples (see the tests). The trickiness stems from
// two things: 1) subtracting a range from another range could
// yield two ranges and 2) after subtracting a range, it&#39;s possible
// that future ranges can have an impact. The loop below advances
// the `b` ranges until they can&#39;t possible impact the current
// range.
//
// For example, if our `a` range is `a-t` and our next three `b`
// ranges are `a-c`, `g-i`, `r-t` and `x-z`, then we need to apply
// subtraction three times before moving on to the next `a` range.
</span><span class="kw">let </span><span class="kw-2">mut </span>range = <span class="self">self</span>.ranges[a];
<span class="kw">while </span>b &lt; other.ranges.len()
&amp;&amp; !range.is_intersection_empty(<span class="kw-2">&amp;</span>other.ranges[b])
{
<span class="kw">let </span>old_range = range;
range = <span class="kw">match </span>range.difference(<span class="kw-2">&amp;</span>other.ranges[b]) {
(<span class="prelude-val">None</span>, <span class="prelude-val">None</span>) =&gt; {
<span class="comment">// We lost the entire range, so move on to the next
// without adding this one.
</span>a += <span class="number">1</span>;
<span class="kw">continue </span><span class="lifetime">&#39;LOOP</span>;
}
(<span class="prelude-val">Some</span>(range1), <span class="prelude-val">None</span>) | (<span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(range1)) =&gt; range1,
(<span class="prelude-val">Some</span>(range1), <span class="prelude-val">Some</span>(range2)) =&gt; {
<span class="self">self</span>.ranges.push(range1);
range2
}
};
<span class="comment">// It&#39;s possible that the `b` range has more to contribute
// here. In particular, if it is greater than the original
// range, then it might impact the next `a` range *and* it
// has impacted the current `a` range as much as possible,
// so we can quit. We don&#39;t bump `b` so that the next `a`
// range can apply it.
</span><span class="kw">if </span>other.ranges[b].upper() &gt; old_range.upper() {
<span class="kw">break</span>;
}
<span class="comment">// Otherwise, the next `b` range might apply to the current
// `a` range.
</span>b += <span class="number">1</span>;
}
<span class="self">self</span>.ranges.push(range);
a += <span class="number">1</span>;
}
<span class="kw">while </span>a &lt; drain_end {
<span class="kw">let </span>range = <span class="self">self</span>.ranges[a];
<span class="self">self</span>.ranges.push(range);
a += <span class="number">1</span>;
}
<span class="self">self</span>.ranges.drain(..drain_end);
<span class="self">self</span>.folded = <span class="self">self</span>.folded &amp;&amp; other.folded;
}
<span class="doccomment">/// Compute the symmetric difference of the two sets, in place.
///
/// This computes the symmetric difference of two interval sets. This
/// removes all elements in this set that are also in the given set,
/// but also adds all elements from the given set that aren&#39;t in this
/// set. That is, the set will contain all elements in either set,
/// but will not contain any elements that are in both sets.
</span><span class="kw">pub fn </span>symmetric_difference(<span class="kw-2">&amp;mut </span><span class="self">self</span>, other: <span class="kw-2">&amp;</span>IntervalSet&lt;I&gt;) {
<span class="comment">// TODO(burntsushi): Fix this so that it amortizes allocation.
</span><span class="kw">let </span><span class="kw-2">mut </span>intersection = <span class="self">self</span>.clone();
intersection.intersect(other);
<span class="self">self</span>.union(other);
<span class="self">self</span>.difference(<span class="kw-2">&amp;</span>intersection);
}
<span class="doccomment">/// Negate this interval set.
///
/// For all `x` where `x` is any element, if `x` was in this set, then it
/// will not be in this set after negation.
</span><span class="kw">pub fn </span>negate(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<span class="kw">if </span><span class="self">self</span>.ranges.is_empty() {
<span class="kw">let </span>(min, max) = (I::Bound::min_value(), I::Bound::max_value());
<span class="self">self</span>.ranges.push(I::create(min, max));
<span class="comment">// The set containing everything must case folded.
</span><span class="self">self</span>.folded = <span class="bool-val">true</span>;
<span class="kw">return</span>;
}
<span class="comment">// There should be a way to do this in-place with constant memory,
// but I couldn&#39;t figure out a simple way to do it. So just append
// the negation to the end of this range, and then drain it before
// we&#39;re done.
</span><span class="kw">let </span>drain_end = <span class="self">self</span>.ranges.len();
<span class="comment">// We do checked arithmetic below because of the canonical ordering
// invariant.
</span><span class="kw">if </span><span class="self">self</span>.ranges[<span class="number">0</span>].lower() &gt; I::Bound::min_value() {
<span class="kw">let </span>upper = <span class="self">self</span>.ranges[<span class="number">0</span>].lower().decrement();
<span class="self">self</span>.ranges.push(I::create(I::Bound::min_value(), upper));
}
<span class="kw">for </span>i <span class="kw">in </span><span class="number">1</span>..drain_end {
<span class="kw">let </span>lower = <span class="self">self</span>.ranges[i - <span class="number">1</span>].upper().increment();
<span class="kw">let </span>upper = <span class="self">self</span>.ranges[i].lower().decrement();
<span class="self">self</span>.ranges.push(I::create(lower, upper));
}
<span class="kw">if </span><span class="self">self</span>.ranges[drain_end - <span class="number">1</span>].upper() &lt; I::Bound::max_value() {
<span class="kw">let </span>lower = <span class="self">self</span>.ranges[drain_end - <span class="number">1</span>].upper().increment();
<span class="self">self</span>.ranges.push(I::create(lower, I::Bound::max_value()));
}
<span class="self">self</span>.ranges.drain(..drain_end);
<span class="comment">// We don&#39;t need to update whether this set is folded or not, because
// it is conservatively preserved through negation. Namely, if a set
// is not folded, then it is possible that its negation is folded, for
// example, [^☃]. But we&#39;re fine with assuming that the set is not
// folded in that case. (`folded` permits false negatives but not false
// positives.)
//
// But what about when a set is folded, is its negation also
// necessarily folded? Yes. Because if a set is folded, then for every
// character in the set, it necessarily included its equivalence class
// of case folded characters. Negating it in turn means that all
// equivalence classes in the set are negated, and any equivalence
// class that was previously not in the set is now entirely in the set.
</span>}
<span class="doccomment">/// Converts this set into a canonical ordering.
</span><span class="kw">fn </span>canonicalize(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<span class="kw">if </span><span class="self">self</span>.is_canonical() {
<span class="kw">return</span>;
}
<span class="self">self</span>.ranges.sort();
<span class="macro">assert!</span>(!<span class="self">self</span>.ranges.is_empty());
<span class="comment">// Is there a way to do this in-place with constant memory? I couldn&#39;t
// figure out a way to do it. So just append the canonicalization to
// the end of this range, and then drain it before we&#39;re done.
</span><span class="kw">let </span>drain_end = <span class="self">self</span>.ranges.len();
<span class="kw">for </span>oldi <span class="kw">in </span><span class="number">0</span>..drain_end {
<span class="comment">// If we&#39;ve added at least one new range, then check if we can
// merge this range in the previously added range.
</span><span class="kw">if </span><span class="self">self</span>.ranges.len() &gt; drain_end {
<span class="kw">let </span>(last, rest) = <span class="self">self</span>.ranges.split_last_mut().unwrap();
<span class="kw">if let </span><span class="prelude-val">Some</span>(union) = last.union(<span class="kw-2">&amp;</span>rest[oldi]) {
<span class="kw-2">*</span>last = union;
<span class="kw">continue</span>;
}
}
<span class="kw">let </span>range = <span class="self">self</span>.ranges[oldi];
<span class="self">self</span>.ranges.push(range);
}
<span class="self">self</span>.ranges.drain(..drain_end);
}
<span class="doccomment">/// Returns true if and only if this class is in a canonical ordering.
</span><span class="kw">fn </span>is_canonical(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; bool {
<span class="kw">for </span>pair <span class="kw">in </span><span class="self">self</span>.ranges.windows(<span class="number">2</span>) {
<span class="kw">if </span>pair[<span class="number">0</span>] &gt;= pair[<span class="number">1</span>] {
<span class="kw">return </span><span class="bool-val">false</span>;
}
<span class="kw">if </span>pair[<span class="number">0</span>].is_contiguous(<span class="kw-2">&amp;</span>pair[<span class="number">1</span>]) {
<span class="kw">return </span><span class="bool-val">false</span>;
}
}
<span class="bool-val">true
</span>}
}
<span class="doccomment">/// An iterator over intervals.
</span><span class="attribute">#[derive(Debug)]
</span><span class="kw">pub struct </span>IntervalSetIter&lt;<span class="lifetime">&#39;a</span>, I&gt;(slice::Iter&lt;<span class="lifetime">&#39;a</span>, I&gt;);
<span class="kw">impl</span>&lt;<span class="lifetime">&#39;a</span>, I&gt; Iterator <span class="kw">for </span>IntervalSetIter&lt;<span class="lifetime">&#39;a</span>, I&gt; {
<span class="kw">type </span>Item = <span class="kw-2">&amp;</span><span class="lifetime">&#39;a </span>I;
<span class="kw">fn </span>next(<span class="kw-2">&amp;mut </span><span class="self">self</span>) -&gt; <span class="prelude-ty">Option</span>&lt;<span class="kw-2">&amp;</span><span class="lifetime">&#39;a </span>I&gt; {
<span class="self">self</span>.<span class="number">0</span>.next()
}
}
<span class="kw">pub trait </span>Interval:
Clone + Copy + Debug + Default + Eq + PartialEq + PartialOrd + Ord
{
<span class="kw">type </span>Bound: Bound;
<span class="kw">fn </span>lower(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="self">Self</span>::Bound;
<span class="kw">fn </span>upper(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="self">Self</span>::Bound;
<span class="kw">fn </span>set_lower(<span class="kw-2">&amp;mut </span><span class="self">self</span>, bound: <span class="self">Self</span>::Bound);
<span class="kw">fn </span>set_upper(<span class="kw-2">&amp;mut </span><span class="self">self</span>, bound: <span class="self">Self</span>::Bound);
<span class="kw">fn </span>case_fold_simple(
<span class="kw-2">&amp;</span><span class="self">self</span>,
intervals: <span class="kw-2">&amp;mut </span>Vec&lt;<span class="self">Self</span>&gt;,
) -&gt; <span class="prelude-ty">Result</span>&lt;(), unicode::CaseFoldError&gt;;
<span class="doccomment">/// Create a new interval.
</span><span class="kw">fn </span>create(lower: <span class="self">Self</span>::Bound, upper: <span class="self">Self</span>::Bound) -&gt; <span class="self">Self </span>{
<span class="kw">let </span><span class="kw-2">mut </span>int = <span class="self">Self</span>::default();
<span class="kw">if </span>lower &lt;= upper {
int.set_lower(lower);
int.set_upper(upper);
} <span class="kw">else </span>{
int.set_lower(upper);
int.set_upper(lower);
}
int
}
<span class="doccomment">/// Union the given overlapping range into this range.
///
/// If the two ranges aren&#39;t contiguous, then this returns `None`.
</span><span class="kw">fn </span>union(<span class="kw-2">&amp;</span><span class="self">self</span>, other: <span class="kw-2">&amp;</span><span class="self">Self</span>) -&gt; <span class="prelude-ty">Option</span>&lt;<span class="self">Self</span>&gt; {
<span class="kw">if </span>!<span class="self">self</span>.is_contiguous(other) {
<span class="kw">return </span><span class="prelude-val">None</span>;
}
<span class="kw">let </span>lower = cmp::min(<span class="self">self</span>.lower(), other.lower());
<span class="kw">let </span>upper = cmp::max(<span class="self">self</span>.upper(), other.upper());
<span class="prelude-val">Some</span>(<span class="self">Self</span>::create(lower, upper))
}
<span class="doccomment">/// Intersect this range with the given range and return the result.
///
/// If the intersection is empty, then this returns `None`.
</span><span class="kw">fn </span>intersect(<span class="kw-2">&amp;</span><span class="self">self</span>, other: <span class="kw-2">&amp;</span><span class="self">Self</span>) -&gt; <span class="prelude-ty">Option</span>&lt;<span class="self">Self</span>&gt; {
<span class="kw">let </span>lower = cmp::max(<span class="self">self</span>.lower(), other.lower());
<span class="kw">let </span>upper = cmp::min(<span class="self">self</span>.upper(), other.upper());
<span class="kw">if </span>lower &lt;= upper {
<span class="prelude-val">Some</span>(<span class="self">Self</span>::create(lower, upper))
} <span class="kw">else </span>{
<span class="prelude-val">None
</span>}
}
<span class="doccomment">/// Subtract the given range from this range and return the resulting
/// ranges.
///
/// If subtraction would result in an empty range, then no ranges are
/// returned.
</span><span class="kw">fn </span>difference(<span class="kw-2">&amp;</span><span class="self">self</span>, other: <span class="kw-2">&amp;</span><span class="self">Self</span>) -&gt; (<span class="prelude-ty">Option</span>&lt;<span class="self">Self</span>&gt;, <span class="prelude-ty">Option</span>&lt;<span class="self">Self</span>&gt;) {
<span class="kw">if </span><span class="self">self</span>.is_subset(other) {
<span class="kw">return </span>(<span class="prelude-val">None</span>, <span class="prelude-val">None</span>);
}
<span class="kw">if </span><span class="self">self</span>.is_intersection_empty(other) {
<span class="kw">return </span>(<span class="prelude-val">Some</span>(<span class="self">self</span>.clone()), <span class="prelude-val">None</span>);
}
<span class="kw">let </span>add_lower = other.lower() &gt; <span class="self">self</span>.lower();
<span class="kw">let </span>add_upper = other.upper() &lt; <span class="self">self</span>.upper();
<span class="comment">// We know this because !self.is_subset(other) and the ranges have
// a non-empty intersection.
</span><span class="macro">assert!</span>(add_lower || add_upper);
<span class="kw">let </span><span class="kw-2">mut </span>ret = (<span class="prelude-val">None</span>, <span class="prelude-val">None</span>);
<span class="kw">if </span>add_lower {
<span class="kw">let </span>upper = other.lower().decrement();
ret.<span class="number">0 </span>= <span class="prelude-val">Some</span>(<span class="self">Self</span>::create(<span class="self">self</span>.lower(), upper));
}
<span class="kw">if </span>add_upper {
<span class="kw">let </span>lower = other.upper().increment();
<span class="kw">let </span>range = <span class="self">Self</span>::create(lower, <span class="self">self</span>.upper());
<span class="kw">if </span>ret.<span class="number">0</span>.is_none() {
ret.<span class="number">0 </span>= <span class="prelude-val">Some</span>(range);
} <span class="kw">else </span>{
ret.<span class="number">1 </span>= <span class="prelude-val">Some</span>(range);
}
}
ret
}
<span class="doccomment">/// Compute the symmetric difference the given range from this range. This
/// returns the union of the two ranges minus its intersection.
</span><span class="kw">fn </span>symmetric_difference(
<span class="kw-2">&amp;</span><span class="self">self</span>,
other: <span class="kw-2">&amp;</span><span class="self">Self</span>,
) -&gt; (<span class="prelude-ty">Option</span>&lt;<span class="self">Self</span>&gt;, <span class="prelude-ty">Option</span>&lt;<span class="self">Self</span>&gt;) {
<span class="kw">let </span>union = <span class="kw">match </span><span class="self">self</span>.union(other) {
<span class="prelude-val">None </span>=&gt; <span class="kw">return </span>(<span class="prelude-val">Some</span>(<span class="self">self</span>.clone()), <span class="prelude-val">Some</span>(other.clone())),
<span class="prelude-val">Some</span>(union) =&gt; union,
};
<span class="kw">let </span>intersection = <span class="kw">match </span><span class="self">self</span>.intersect(other) {
<span class="prelude-val">None </span>=&gt; <span class="kw">return </span>(<span class="prelude-val">Some</span>(<span class="self">self</span>.clone()), <span class="prelude-val">Some</span>(other.clone())),
<span class="prelude-val">Some</span>(intersection) =&gt; intersection,
};
union.difference(<span class="kw-2">&amp;</span>intersection)
}
<span class="doccomment">/// Returns true if and only if the two ranges are contiguous. Two ranges
/// are contiguous if and only if the ranges are either overlapping or
/// adjacent.
</span><span class="kw">fn </span>is_contiguous(<span class="kw-2">&amp;</span><span class="self">self</span>, other: <span class="kw-2">&amp;</span><span class="self">Self</span>) -&gt; bool {
<span class="kw">let </span>lower1 = <span class="self">self</span>.lower().as_u32();
<span class="kw">let </span>upper1 = <span class="self">self</span>.upper().as_u32();
<span class="kw">let </span>lower2 = other.lower().as_u32();
<span class="kw">let </span>upper2 = other.upper().as_u32();
cmp::max(lower1, lower2) &lt;= cmp::min(upper1, upper2).saturating_add(<span class="number">1</span>)
}
<span class="doccomment">/// Returns true if and only if the intersection of this range and the
/// other range is empty.
</span><span class="kw">fn </span>is_intersection_empty(<span class="kw-2">&amp;</span><span class="self">self</span>, other: <span class="kw-2">&amp;</span><span class="self">Self</span>) -&gt; bool {
<span class="kw">let </span>(lower1, upper1) = (<span class="self">self</span>.lower(), <span class="self">self</span>.upper());
<span class="kw">let </span>(lower2, upper2) = (other.lower(), other.upper());
cmp::max(lower1, lower2) &gt; cmp::min(upper1, upper2)
}
<span class="doccomment">/// Returns true if and only if this range is a subset of the other range.
</span><span class="kw">fn </span>is_subset(<span class="kw-2">&amp;</span><span class="self">self</span>, other: <span class="kw-2">&amp;</span><span class="self">Self</span>) -&gt; bool {
<span class="kw">let </span>(lower1, upper1) = (<span class="self">self</span>.lower(), <span class="self">self</span>.upper());
<span class="kw">let </span>(lower2, upper2) = (other.lower(), other.upper());
(lower2 &lt;= lower1 &amp;&amp; lower1 &lt;= upper2)
&amp;&amp; (lower2 &lt;= upper1 &amp;&amp; upper1 &lt;= upper2)
}
}
<span class="kw">pub trait </span>Bound:
Copy + Clone + Debug + Eq + PartialEq + PartialOrd + Ord
{
<span class="kw">fn </span>min_value() -&gt; <span class="self">Self</span>;
<span class="kw">fn </span>max_value() -&gt; <span class="self">Self</span>;
<span class="kw">fn </span>as_u32(<span class="self">self</span>) -&gt; u32;
<span class="kw">fn </span>increment(<span class="self">self</span>) -&gt; <span class="self">Self</span>;
<span class="kw">fn </span>decrement(<span class="self">self</span>) -&gt; <span class="self">Self</span>;
}
<span class="kw">impl </span>Bound <span class="kw">for </span>u8 {
<span class="kw">fn </span>min_value() -&gt; <span class="self">Self </span>{
u8::MIN
}
<span class="kw">fn </span>max_value() -&gt; <span class="self">Self </span>{
u8::MAX
}
<span class="kw">fn </span>as_u32(<span class="self">self</span>) -&gt; u32 {
u32::from(<span class="self">self</span>)
}
<span class="kw">fn </span>increment(<span class="self">self</span>) -&gt; <span class="self">Self </span>{
<span class="self">self</span>.checked_add(<span class="number">1</span>).unwrap()
}
<span class="kw">fn </span>decrement(<span class="self">self</span>) -&gt; <span class="self">Self </span>{
<span class="self">self</span>.checked_sub(<span class="number">1</span>).unwrap()
}
}
<span class="kw">impl </span>Bound <span class="kw">for </span>char {
<span class="kw">fn </span>min_value() -&gt; <span class="self">Self </span>{
<span class="string">&#39;\x00&#39;
</span>}
<span class="kw">fn </span>max_value() -&gt; <span class="self">Self </span>{
<span class="string">&#39;\u{10FFFF}&#39;
</span>}
<span class="kw">fn </span>as_u32(<span class="self">self</span>) -&gt; u32 {
u32::from(<span class="self">self</span>)
}
<span class="kw">fn </span>increment(<span class="self">self</span>) -&gt; <span class="self">Self </span>{
<span class="kw">match </span><span class="self">self </span>{
<span class="string">&#39;\u{D7FF}&#39; </span>=&gt; <span class="string">&#39;\u{E000}&#39;</span>,
c =&gt; char::from_u32(u32::from(c).checked_add(<span class="number">1</span>).unwrap()).unwrap(),
}
}
<span class="kw">fn </span>decrement(<span class="self">self</span>) -&gt; <span class="self">Self </span>{
<span class="kw">match </span><span class="self">self </span>{
<span class="string">&#39;\u{E000}&#39; </span>=&gt; <span class="string">&#39;\u{D7FF}&#39;</span>,
c =&gt; char::from_u32(u32::from(c).checked_sub(<span class="number">1</span>).unwrap()).unwrap(),
}
}
}
<span class="comment">// Tests for interval sets are written in src/hir.rs against the public API.
</span></code></pre></div>
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