| <!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/utf8-ranges-1.0.5/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.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="../../utf8_ranges/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="../../utf8_ranges/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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| <span id="522">522</span> |
| <span id="523">523</span> |
| <span id="524">524</span> |
| <span id="525">525</span> |
| <span id="526">526</span> |
| <span id="527">527</span> |
| <span id="528">528</span> |
| <span id="529">529</span> |
| <span id="530">530</span> |
| <span id="531">531</span> |
| <span id="532">532</span> |
| </pre><pre class="rust"><code><span class="doccomment">/*! |
| Crate `utf8-ranges` converts ranges of Unicode scalar values to equivalent |
| ranges of UTF-8 bytes. This is useful for constructing byte based automatons |
| that need to embed UTF-8 decoding. |
| |
| See the documentation on the `Utf8Sequences` iterator for more details and |
| an example. |
| |
| # Wait, what is this? |
| |
| This is simplest to explain with an example. Let's say you wanted to test |
| whether a particular byte sequence was a Cyrillic character. One possible |
| scalar value range is `[0400-04FF]`. The set of allowed bytes for this |
| range can be expressed as a sequence of byte ranges: |
| |
| ```ignore |
| [D0-D3][80-BF] |
| ``` |
| |
| This is simple enough: simply encode the boundaries, `0400` encodes to |
| `D0 80` and `04FF` encodes to `D3 BF`, and create ranges from each |
| corresponding pair of bytes: `D0` to `D3` and `80` to `BF`. |
| |
| However, what if you wanted to add the Cyrillic Supplementary characters to |
| your range? Your range might then become `[0400-052F]`. The same procedure |
| as above doesn't quite work because `052F` encodes to `D4 AF`. The byte ranges |
| you'd get from the previous transformation would be `[D0-D4][80-AF]`. However, |
| this isn't quite correct because this range doesn't capture many characters, |
| for example, `04FF` (because its last byte, `BF` isn't in the range `80-AF`). |
| |
| Instead, you need multiple sequences of byte ranges: |
| |
| ```ignore |
| [D0-D3][80-BF] # matches codepoints 0400-04FF |
| [D4][80-AF] # matches codepoints 0500-052F |
| ``` |
| |
| This gets even more complicated if you want bigger ranges, particularly if |
| they naively contain surrogate codepoints. For example, the sequence of byte |
| ranges for the basic multilingual plane (`[0000-FFFF]`) look like this: |
| |
| ```ignore |
| [0-7F] |
| [C2-DF][80-BF] |
| [E0][A0-BF][80-BF] |
| [E1-EC][80-BF][80-BF] |
| [ED][80-9F][80-BF] |
| [EE-EF][80-BF][80-BF] |
| ``` |
| |
| Note that the byte ranges above will *not* match any erroneous encoding of |
| UTF-8, including encodings of surrogate codepoints. |
| |
| And, of course, for all of Unicode (`[000000-10FFFF]`): |
| |
| ```ignore |
| [0-7F] |
| [C2-DF][80-BF] |
| [E0][A0-BF][80-BF] |
| [E1-EC][80-BF][80-BF] |
| [ED][80-9F][80-BF] |
| [EE-EF][80-BF][80-BF] |
| [F0][90-BF][80-BF][80-BF] |
| [F1-F3][80-BF][80-BF][80-BF] |
| [F4][80-8F][80-BF][80-BF] |
| ``` |
| |
| This crate automates the process of creating these byte ranges from ranges of |
| Unicode scalar values. |
| |
| # Why would I ever use this? |
| |
| You probably won't ever need this. In 99% of cases, you just decode the byte |
| sequence into a Unicode scalar value and compare scalar values directly. |
| However, this explicit decoding step isn't always possible. For example, the |
| construction of some finite state machines may benefit from converting ranges |
| of scalar values into UTF-8 decoder automata (e.g., for character classes in |
| regular expressions). |
| |
| # Lineage |
| |
| I got the idea and general implementation strategy from Russ Cox in his |
| [article on regexps](https://web.archive.org/web/20160404141123/https://swtch.com/~rsc/regexp/regexp3.html) and RE2. |
| Russ Cox got it from Ken Thompson's `grep` (no source, folk lore?). |
| I also got the idea from |
| [Lucene](https://github.com/apache/lucene-solr/blob/ae93f4e7ac6a3908046391de35d4f50a0d3c59ca/lucene/core/src/java/org/apache/lucene/util/automaton/UTF32ToUTF8.java), |
| which uses it for executing automata on their term index. |
| */ |
| |
| </span><span class="attribute">#![deny(missing_docs)] |
| |
| #[cfg(test)] |
| </span><span class="kw">extern crate </span>quickcheck; |
| |
| <span class="kw">use </span>std::char; |
| <span class="kw">use </span>std::fmt; |
| <span class="kw">use </span>std::slice; |
| |
| <span class="kw">use </span>char_utf8::encode_utf8; |
| |
| <span class="kw">const </span>MAX_UTF8_BYTES: usize = <span class="number">4</span>; |
| |
| <span class="kw">mod </span>char_utf8; |
| |
| <span class="doccomment">/// Utf8Sequence represents a sequence of byte ranges. |
| /// |
| /// To match a Utf8Sequence, a candidate byte sequence must match each |
| /// successive range. |
| /// |
| /// For example, if there are two ranges, `[C2-DF][80-BF]`, then the byte |
| /// sequence `\xDD\x61` would not match because `0x61 < 0x80`. |
| </span><span class="attribute">#[derive(Copy, Clone, Eq, PartialEq)] |
| </span><span class="kw">pub enum </span>Utf8Sequence { |
| <span class="doccomment">/// One byte range. |
| </span>One(Utf8Range), |
| <span class="doccomment">/// Two successive byte ranges. |
| </span>Two([Utf8Range; <span class="number">2</span>]), |
| <span class="doccomment">/// Three successive byte ranges. |
| </span>Three([Utf8Range; <span class="number">3</span>]), |
| <span class="doccomment">/// Four successive byte ranges. |
| </span>Four([Utf8Range; <span class="number">4</span>]), |
| } |
| |
| <span class="kw">impl </span>Utf8Sequence { |
| <span class="doccomment">/// Creates a new UTF-8 sequence from the encoded bytes of a scalar value |
| /// range. |
| /// |
| /// This assumes that `start` and `end` have the same length. |
| </span><span class="kw">fn </span>from_encoded_range(start: <span class="kw-2">&</span>[u8], end: <span class="kw-2">&</span>[u8]) -> <span class="self">Self </span>{ |
| <span class="macro">assert_eq!</span>(start.len(), end.len()); |
| <span class="kw">match </span>start.len() { |
| <span class="number">2 </span>=> Utf8Sequence::Two([ |
| Utf8Range::new(start[<span class="number">0</span>], end[<span class="number">0</span>]), |
| Utf8Range::new(start[<span class="number">1</span>], end[<span class="number">1</span>]), |
| ]), |
| <span class="number">3 </span>=> Utf8Sequence::Three([ |
| Utf8Range::new(start[<span class="number">0</span>], end[<span class="number">0</span>]), |
| Utf8Range::new(start[<span class="number">1</span>], end[<span class="number">1</span>]), |
| Utf8Range::new(start[<span class="number">2</span>], end[<span class="number">2</span>]), |
| ]), |
| <span class="number">4 </span>=> Utf8Sequence::Four([ |
| Utf8Range::new(start[<span class="number">0</span>], end[<span class="number">0</span>]), |
| Utf8Range::new(start[<span class="number">1</span>], end[<span class="number">1</span>]), |
| Utf8Range::new(start[<span class="number">2</span>], end[<span class="number">2</span>]), |
| Utf8Range::new(start[<span class="number">3</span>], end[<span class="number">3</span>]), |
| ]), |
| n => <span class="macro">unreachable!</span>(<span class="string">"invalid encoded length: {}"</span>, n), |
| } |
| } |
| |
| <span class="doccomment">/// Returns the underlying sequence of byte ranges as a slice. |
| </span><span class="kw">pub fn </span>as_slice(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>[Utf8Range] { |
| <span class="kw">use </span><span class="self">self</span>::Utf8Sequence::<span class="kw-2">*</span>; |
| <span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| One(<span class="kw-2">ref </span>r) => slice::from_ref(r), |
| Two(<span class="kw-2">ref </span>r) => <span class="kw-2">&</span>r[..], |
| Three(<span class="kw-2">ref </span>r) => <span class="kw-2">&</span>r[..], |
| Four(<span class="kw-2">ref </span>r) => <span class="kw-2">&</span>r[..], |
| } |
| } |
| |
| <span class="doccomment">/// Returns the number of byte ranges in this sequence. |
| /// |
| /// The length is guaranteed to be in the closed interval `[1, 4]`. |
| </span><span class="kw">pub fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.as_slice().len() |
| } |
| |
| <span class="doccomment">/// Returns true if and only if a prefix of `bytes` matches this sequence |
| /// of byte ranges. |
| </span><span class="kw">pub fn </span>matches(<span class="kw-2">&</span><span class="self">self</span>, bytes: <span class="kw-2">&</span>[u8]) -> bool { |
| <span class="kw">if </span>bytes.len() < <span class="self">self</span>.len() { |
| <span class="kw">return </span><span class="bool-val">false</span>; |
| } |
| <span class="kw">for </span>(<span class="kw-2">&</span>b, r) <span class="kw">in </span>bytes.iter().zip(<span class="self">self</span>) { |
| <span class="kw">if </span>!r.matches(b) { |
| <span class="kw">return </span><span class="bool-val">false</span>; |
| } |
| } |
| <span class="bool-val">true |
| </span>} |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> IntoIterator <span class="kw">for </span><span class="kw-2">&</span><span class="lifetime">'a </span>Utf8Sequence { |
| <span class="kw">type </span>IntoIter = slice::Iter<<span class="lifetime">'a</span>, Utf8Range>; |
| <span class="kw">type </span>Item = <span class="kw-2">&</span><span class="lifetime">'a </span>Utf8Range; |
| |
| <span class="kw">fn </span>into_iter(<span class="self">self</span>) -> <span class="self">Self</span>::IntoIter { |
| <span class="self">self</span>.as_slice().into_iter() |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Utf8Sequence { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter) -> fmt::Result { |
| <span class="kw">use </span><span class="self">self</span>::Utf8Sequence::<span class="kw-2">*</span>; |
| <span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| One(<span class="kw-2">ref </span>r) => <span class="macro">write!</span>(f, <span class="string">"{:?}"</span>, r), |
| Two(<span class="kw-2">ref </span>r) => <span class="macro">write!</span>(f, <span class="string">"{:?}{:?}"</span>, r[<span class="number">0</span>], r[<span class="number">1</span>]), |
| Three(<span class="kw-2">ref </span>r) => <span class="macro">write!</span>(f, <span class="string">"{:?}{:?}{:?}"</span>, r[<span class="number">0</span>], r[<span class="number">1</span>], r[<span class="number">2</span>]), |
| Four(<span class="kw-2">ref </span>r) => <span class="macro">write!</span>(f, <span class="string">"{:?}{:?}{:?}{:?}"</span>, |
| r[<span class="number">0</span>], r[<span class="number">1</span>], r[<span class="number">2</span>], r[<span class="number">3</span>]), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// A single inclusive range of UTF-8 bytes. |
| </span><span class="attribute">#[derive(Clone, Copy, PartialEq, Eq)] |
| </span><span class="kw">pub struct </span>Utf8Range { |
| <span class="doccomment">/// Start of byte range (inclusive). |
| </span><span class="kw">pub </span>start: u8, |
| <span class="doccomment">/// End of byte range (inclusive). |
| </span><span class="kw">pub </span>end: u8, |
| } |
| |
| <span class="kw">impl </span>Utf8Range { |
| <span class="kw">fn </span>new(start: u8, end: u8) -> <span class="self">Self </span>{ |
| Utf8Range { start: start, end: end } |
| } |
| |
| <span class="doccomment">/// Returns true if and only if the given byte is in this range. |
| </span><span class="kw">pub fn </span>matches(<span class="kw-2">&</span><span class="self">self</span>, b: u8) -> bool { |
| <span class="self">self</span>.start <= b && b <= <span class="self">self</span>.end |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Utf8Range { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter) -> fmt::Result { |
| <span class="kw">if </span><span class="self">self</span>.start == <span class="self">self</span>.end { |
| <span class="macro">write!</span>(f, <span class="string">"[{:X}]"</span>, <span class="self">self</span>.start) |
| } <span class="kw">else </span>{ |
| <span class="macro">write!</span>(f, <span class="string">"[{:X}-{:X}]"</span>, <span class="self">self</span>.start, <span class="self">self</span>.end) |
| } |
| } |
| } |
| |
| <span class="doccomment">/// An iterator over ranges of matching UTF-8 byte sequences. |
| /// |
| /// The iteration represents an alternation of comprehensive byte sequences |
| /// that match precisely the set of UTF-8 encoded scalar values. |
| /// |
| /// A byte sequence corresponds to one of the scalar values in the range given |
| /// if and only if it completely matches exactly one of the sequences of byte |
| /// ranges produced by this iterator. |
| /// |
| /// Each sequence of byte ranges matches a unique set of bytes. That is, no two |
| /// sequences will match the same bytes. |
| /// |
| /// # Example |
| /// |
| /// This shows how to match an arbitrary byte sequence against a range of |
| /// scalar values. |
| /// |
| /// ```rust |
| /// use utf8_ranges::{Utf8Sequences, Utf8Sequence}; |
| /// |
| /// fn matches(seqs: &[Utf8Sequence], bytes: &[u8]) -> bool { |
| /// for range in seqs { |
| /// if range.matches(bytes) { |
| /// return true; |
| /// } |
| /// } |
| /// false |
| /// } |
| /// |
| /// // Test the basic multilingual plane. |
| /// let seqs: Vec<_> = Utf8Sequences::new('\u{0}', '\u{FFFF}').collect(); |
| /// |
| /// // UTF-8 encoding of 'a'. |
| /// assert!(matches(&seqs, &[0x61])); |
| /// // UTF-8 encoding of '☃' (`\u{2603}`). |
| /// assert!(matches(&seqs, &[0xE2, 0x98, 0x83])); |
| /// // UTF-8 encoding of `\u{10348}` (outside the BMP). |
| /// assert!(!matches(&seqs, &[0xF0, 0x90, 0x8D, 0x88])); |
| /// // Tries to match against a UTF-8 encoding of a surrogate codepoint, |
| /// // which is invalid UTF-8, and therefore fails, despite the fact that |
| /// // the corresponding codepoint (0xD800) falls in the range given. |
| /// assert!(!matches(&seqs, &[0xED, 0xA0, 0x80])); |
| /// // And fails against plain old invalid UTF-8. |
| /// assert!(!matches(&seqs, &[0xFF, 0xFF])); |
| /// ``` |
| /// |
| /// If this example seems circuitous, that's because it is! It's meant to be |
| /// illustrative. In practice, you could just try to decode your byte sequence |
| /// and compare it with the scalar value range directly. However, this is not |
| /// always possible (for example, in a byte based automaton). |
| </span><span class="kw">pub struct </span>Utf8Sequences { |
| range_stack: Vec<ScalarRange>, |
| } |
| |
| <span class="kw">impl </span>Utf8Sequences { |
| <span class="doccomment">/// Create a new iterator over UTF-8 byte ranges for the scalar value range |
| /// given. |
| </span><span class="kw">pub fn </span>new(start: char, end: char) -> <span class="self">Self </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>it = Utf8Sequences { range_stack: <span class="macro">vec!</span>[] }; |
| it.push(start <span class="kw">as </span>u32, end <span class="kw">as </span>u32); |
| it |
| } |
| |
| <span class="doccomment">/// reset resets the scalar value range. |
| /// Any existing state is cleared, but resources may be reused. |
| /// |
| /// N.B. Benchmarks say that this method is dubious. |
| </span><span class="attribute">#[doc(hidden)] |
| </span><span class="kw">pub fn </span>reset(<span class="kw-2">&mut </span><span class="self">self</span>, start: char, end: char) { |
| <span class="self">self</span>.range_stack.clear(); |
| <span class="self">self</span>.push(start <span class="kw">as </span>u32, end <span class="kw">as </span>u32); |
| } |
| |
| <span class="kw">fn </span>push(<span class="kw-2">&mut </span><span class="self">self</span>, start: u32, end: u32) { |
| <span class="self">self</span>.range_stack.push(ScalarRange { start: start, end: end }); |
| } |
| } |
| |
| <span class="kw">struct </span>ScalarRange { |
| start: u32, |
| end: u32, |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>ScalarRange { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter) -> fmt::Result { |
| <span class="macro">write!</span>(f, <span class="string">"ScalarRange({:X}, {:X})"</span>, <span class="self">self</span>.start, <span class="self">self</span>.end) |
| } |
| } |
| |
| <span class="kw">impl </span>Iterator <span class="kw">for </span>Utf8Sequences { |
| <span class="kw">type </span>Item = Utf8Sequence; |
| |
| <span class="kw">fn </span>next(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="self">Self</span>::Item> { |
| <span class="lifetime">'TOP</span>: |
| <span class="kw">while let </span><span class="prelude-val">Some</span>(<span class="kw-2">mut </span>r) = <span class="self">self</span>.range_stack.pop() { |
| <span class="lifetime">'INNER</span>: |
| <span class="kw">loop </span>{ |
| <span class="kw">if let </span><span class="prelude-val">Some</span>((r1, r2)) = r.split() { |
| <span class="self">self</span>.push(r2.start, r2.end); |
| r.start = r1.start; |
| r.end = r1.end; |
| <span class="kw">continue </span><span class="lifetime">'INNER</span>; |
| } |
| <span class="kw">if </span>!r.is_valid() { |
| <span class="kw">continue </span><span class="lifetime">'TOP</span>; |
| } |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">1</span>..MAX_UTF8_BYTES { |
| <span class="kw">let </span>max = max_scalar_value(i); |
| <span class="kw">if </span>r.start <= max && max < r.end { |
| <span class="self">self</span>.push(max + <span class="number">1</span>, r.end); |
| r.end = max; |
| <span class="kw">continue </span><span class="lifetime">'INNER</span>; |
| } |
| } |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(ascii_range) = r.as_ascii() { |
| <span class="kw">return </span><span class="prelude-val">Some</span>(Utf8Sequence::One(ascii_range)); |
| } |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">1</span>..MAX_UTF8_BYTES { |
| <span class="kw">let </span>m = (<span class="number">1 </span><< (<span class="number">6 </span>* i)) - <span class="number">1</span>; |
| <span class="kw">if </span>(r.start & !m) != (r.end & !m) { |
| <span class="kw">if </span>(r.start & m) != <span class="number">0 </span>{ |
| <span class="self">self</span>.push((r.start | m) + <span class="number">1</span>, r.end); |
| r.end = r.start | m; |
| <span class="kw">continue </span><span class="lifetime">'INNER</span>; |
| } |
| <span class="kw">if </span>(r.end & m) != m { |
| <span class="self">self</span>.push(r.end & !m, r.end); |
| r.end = (r.end & !m) - <span class="number">1</span>; |
| <span class="kw">continue </span><span class="lifetime">'INNER</span>; |
| } |
| } |
| } |
| <span class="kw">let </span><span class="kw-2">mut </span>start = [<span class="number">0</span>; MAX_UTF8_BYTES]; |
| <span class="kw">let </span><span class="kw-2">mut </span>end = [<span class="number">0</span>; MAX_UTF8_BYTES]; |
| <span class="kw">let </span>n = r.encode(<span class="kw-2">&mut </span>start, <span class="kw-2">&mut </span>end); |
| <span class="kw">return </span><span class="prelude-val">Some</span>(Utf8Sequence::from_encoded_range( |
| <span class="kw-2">&</span>start[<span class="number">0</span>..n], <span class="kw-2">&</span>end[<span class="number">0</span>..n])); |
| } |
| } |
| <span class="prelude-val">None |
| </span>} |
| } |
| |
| <span class="kw">impl </span>ScalarRange { |
| <span class="doccomment">/// split splits this range if it overlaps with a surrogate codepoint. |
| /// |
| /// Either or both ranges may be invalid. |
| </span><span class="kw">fn </span>split(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><(ScalarRange, ScalarRange)> { |
| <span class="kw">if </span><span class="self">self</span>.start < <span class="number">0xE000 </span>&& <span class="self">self</span>.end > <span class="number">0xD7FF </span>{ |
| <span class="prelude-val">Some</span>((ScalarRange { |
| start: <span class="self">self</span>.start, |
| end: <span class="number">0xD7FF</span>, |
| }, ScalarRange { |
| start: <span class="number">0xE000</span>, |
| end: <span class="self">self</span>.end, |
| })) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">None |
| </span>} |
| } |
| |
| <span class="doccomment">/// is_valid returns true if and only if start <= end. |
| </span><span class="kw">fn </span>is_valid(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.start <= <span class="self">self</span>.end |
| } |
| |
| <span class="doccomment">/// as_ascii returns this range as a Utf8Range if and only if all scalar |
| /// values in this range can be encoded as a single byte. |
| </span><span class="kw">fn </span>as_ascii(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><Utf8Range> { |
| <span class="kw">if </span><span class="self">self</span>.is_ascii() { |
| <span class="prelude-val">Some</span>(Utf8Range::new(<span class="self">self</span>.start <span class="kw">as </span>u8, <span class="self">self</span>.end <span class="kw">as </span>u8)) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">None |
| </span>} |
| } |
| |
| <span class="doccomment">/// is_ascii returns true if the range is ASCII only (i.e., takes a single |
| /// byte to encode any scalar value). |
| </span><span class="kw">fn </span>is_ascii(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.is_valid() && <span class="self">self</span>.end <= <span class="number">0x7f |
| </span>} |
| |
| <span class="doccomment">/// encode writes the UTF-8 encoding of the start and end of this range |
| /// to the corresponding destination slices. |
| /// |
| /// The slices should have room for at least `MAX_UTF8_BYTES`. |
| </span><span class="kw">fn </span>encode(<span class="kw-2">&</span><span class="self">self</span>, start: <span class="kw-2">&mut </span>[u8], end: <span class="kw-2">&mut </span>[u8]) -> usize { |
| <span class="kw">let </span>cs = char::from_u32(<span class="self">self</span>.start).unwrap(); |
| <span class="kw">let </span>ce = char::from_u32(<span class="self">self</span>.end).unwrap(); |
| <span class="kw">let </span>n = encode_utf8(cs, start).unwrap(); |
| <span class="kw">let </span>m = encode_utf8(ce, end).unwrap(); |
| <span class="macro">assert_eq!</span>(n, m); |
| n |
| } |
| } |
| |
| <span class="kw">fn </span>max_scalar_value(nbytes: usize) -> u32 { |
| <span class="kw">match </span>nbytes { |
| <span class="number">1 </span>=> <span class="number">0x007F</span>, |
| <span class="number">2 </span>=> <span class="number">0x07FF</span>, |
| <span class="number">3 </span>=> <span class="number">0xFFFF</span>, |
| <span class="number">4 </span>=> <span class="number">0x10FFFF</span>, |
| <span class="kw">_ </span>=> <span class="macro">unreachable!</span>(<span class="string">"invalid UTF-8 byte sequence size"</span>), |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use </span>std::char; |
| |
| <span class="kw">use </span>quickcheck::{TestResult, quickcheck}; |
| |
| <span class="kw">use </span>{Utf8Range, Utf8Sequences}; |
| |
| <span class="kw">fn </span>rutf8(s: u8, e: u8) -> Utf8Range { |
| Utf8Range::new(s, e) |
| } |
| |
| <span class="kw">fn </span>never_accepts_surrogate_codepoints(start: char, end: char) { |
| <span class="kw">for </span>cp <span class="kw">in </span><span class="number">0xD800</span>..<span class="number">0xE000 </span>{ |
| <span class="kw">let </span>buf = encode_surrogate(cp); |
| <span class="kw">for </span>r <span class="kw">in </span>Utf8Sequences::new(start, end) { |
| <span class="kw">if </span>r.matches(<span class="kw-2">&</span>buf) { |
| <span class="macro">panic!</span>( |
| <span class="string">"Sequence ({:X}, {:X}) contains range {:?}, \ |
| which matches surrogate code point {:X} \ |
| with encoded bytes {:?}"</span>, |
| start <span class="kw">as </span>u32, end <span class="kw">as </span>u32, r, cp, buf, |
| ); |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>codepoints_no_surrogates() { |
| never_accepts_surrogate_codepoints(<span class="string">'\u{0}'</span>, <span class="string">'\u{FFFF}'</span>); |
| never_accepts_surrogate_codepoints(<span class="string">'\u{0}'</span>, <span class="string">'\u{10FFFF}'</span>); |
| never_accepts_surrogate_codepoints(<span class="string">'\u{0}'</span>, <span class="string">'\u{10FFFE}'</span>); |
| never_accepts_surrogate_codepoints(<span class="string">'\u{80}'</span>, <span class="string">'\u{10FFFF}'</span>); |
| never_accepts_surrogate_codepoints(<span class="string">'\u{D7FF}'</span>, <span class="string">'\u{E000}'</span>); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>single_codepoint_one_sequence() { |
| <span class="comment">// Tests that every range of scalar values that contains a single |
| // scalar value is recognized by one sequence of byte ranges. |
| </span><span class="kw">for </span>i <span class="kw">in </span><span class="number">0x0</span>..(<span class="number">0x10FFFF </span>+ <span class="number">1</span>) { |
| <span class="kw">let </span>c = <span class="kw">match </span>char::from_u32(i) { |
| <span class="prelude-val">None </span>=> <span class="kw">continue</span>, |
| <span class="prelude-val">Some</span>(c) => c, |
| }; |
| <span class="kw">let </span>seqs: Vec<<span class="kw">_</span>> = Utf8Sequences::new(c, c).collect(); |
| <span class="macro">assert_eq!</span>(seqs.len(), <span class="number">1</span>); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>qc_codepoints_no_surrogate() { |
| <span class="kw">fn </span>p(s: char, e: char) -> TestResult { |
| <span class="kw">if </span>s > e { |
| <span class="kw">return </span>TestResult::discard(); |
| } |
| never_accepts_surrogate_codepoints(s, e); |
| TestResult::passed() |
| } |
| quickcheck(p <span class="kw">as fn</span>(char, char) -> TestResult); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>bmp() { |
| <span class="kw">use </span>Utf8Sequence::<span class="kw-2">*</span>; |
| |
| <span class="kw">let </span>seqs = Utf8Sequences::new(<span class="string">'\u{0}'</span>, <span class="string">'\u{FFFF}'</span>) |
| .collect::<Vec<<span class="kw">_</span>>>(); |
| <span class="macro">assert_eq!</span>(seqs, <span class="macro">vec!</span>[ |
| One(rutf8(<span class="number">0x0</span>, <span class="number">0x7F</span>)), |
| Two([rutf8(<span class="number">0xC2</span>, <span class="number">0xDF</span>), rutf8(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| Three([rutf8(<span class="number">0xE0</span>, <span class="number">0xE0</span>), rutf8(<span class="number">0xA0</span>, <span class="number">0xBF</span>), rutf8(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| Three([rutf8(<span class="number">0xE1</span>, <span class="number">0xEC</span>), rutf8(<span class="number">0x80</span>, <span class="number">0xBF</span>), rutf8(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| Three([rutf8(<span class="number">0xED</span>, <span class="number">0xED</span>), rutf8(<span class="number">0x80</span>, <span class="number">0x9F</span>), rutf8(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| Three([rutf8(<span class="number">0xEE</span>, <span class="number">0xEF</span>), rutf8(<span class="number">0x80</span>, <span class="number">0xBF</span>), rutf8(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| ]); |
| } |
| |
| <span class="kw">fn </span>encode_surrogate(cp: u32) -> [u8; <span class="number">3</span>] { |
| <span class="kw">const </span>TAG_CONT: u8 = <span class="number">0b1000_0000</span>; |
| <span class="kw">const </span>TAG_THREE_B: u8 = <span class="number">0b1110_0000</span>; |
| |
| <span class="macro">assert!</span>(<span class="number">0xD800 </span><= cp && cp < <span class="number">0xE000</span>); |
| <span class="kw">let </span><span class="kw-2">mut </span>dst = [<span class="number">0</span>; <span class="number">3</span>]; |
| dst[<span class="number">0</span>] = (cp >> <span class="number">12 </span>& <span class="number">0x0F</span>) <span class="kw">as </span>u8 | TAG_THREE_B; |
| dst[<span class="number">1</span>] = (cp >> <span class="number">6 </span>& <span class="number">0x3F</span>) <span class="kw">as </span>u8 | TAG_CONT; |
| dst[<span class="number">2</span>] = (cp & <span class="number">0x3F</span>) <span class="kw">as </span>u8 | TAG_CONT; |
| dst |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="utf8_ranges" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
