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| </pre><pre class="rust "> |
| <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://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/trunk/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">#<span class="op">!</span>[<span class="ident">deny</span>(<span class="ident">missing_docs</span>)]</span> |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span> <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">quickcheck</span>; |
| |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">char</span>; |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>; |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">slice</span>; |
| |
| <span class="kw">use</span> <span class="ident">char_utf8</span>::<span class="ident">encode_utf8</span>; |
| |
| <span class="kw">const</span> <span class="ident">MAX_UTF8_BYTES</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">4</span>; |
| |
| <span class="kw">mod</span> <span class="ident">char_utf8</span>; |
| |
| <span class="doccomment">/// Utf8Sequence represents a sequence of byte ranges.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// To match a Utf8Sequence, a candidate byte sequence must match each</span> |
| <span class="doccomment">/// successive range.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// For example, if there are two ranges, `[C2-DF][80-BF]`, then the byte</span> |
| <span class="doccomment">/// sequence `\xDD\x61` would not match because `0x61 < 0x80`.</span> |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Copy</span>, <span class="ident">Clone</span>, <span class="ident">Eq</span>, <span class="ident">PartialEq</span>)]</span> |
| <span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">Utf8Sequence</span> { |
| <span class="doccomment">/// One byte range.</span> |
| <span class="ident">One</span>(<span class="ident">Utf8Range</span>), |
| <span class="doccomment">/// Two successive byte ranges.</span> |
| <span class="ident">Two</span>([<span class="ident">Utf8Range</span>; <span class="number">2</span>]), |
| <span class="doccomment">/// Three successive byte ranges.</span> |
| <span class="ident">Three</span>([<span class="ident">Utf8Range</span>; <span class="number">3</span>]), |
| <span class="doccomment">/// Four successive byte ranges.</span> |
| <span class="ident">Four</span>([<span class="ident">Utf8Range</span>; <span class="number">4</span>]), |
| } |
| |
| <span class="kw">impl</span> <span class="ident">Utf8Sequence</span> { |
| <span class="doccomment">/// Creates a new UTF-8 sequence from the encoded bytes of a scalar value</span> |
| <span class="doccomment">/// range.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// This assumes that `start` and `end` have the same length.</span> |
| <span class="kw">fn</span> <span class="ident">from_encoded_range</span>(<span class="ident">start</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>], <span class="ident">end</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) <span class="op">-></span> <span class="self">Self</span> { |
| <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">start</span>.<span class="ident">len</span>(), <span class="ident">end</span>.<span class="ident">len</span>()); |
| <span class="kw">match</span> <span class="ident">start</span>.<span class="ident">len</span>() { |
| <span class="number">2</span> <span class="op">=></span> <span class="ident">Utf8Sequence</span>::<span class="ident">Two</span>([ |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">0</span>], <span class="ident">end</span>[<span class="number">0</span>]), |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">1</span>], <span class="ident">end</span>[<span class="number">1</span>]), |
| ]), |
| <span class="number">3</span> <span class="op">=></span> <span class="ident">Utf8Sequence</span>::<span class="ident">Three</span>([ |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">0</span>], <span class="ident">end</span>[<span class="number">0</span>]), |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">1</span>], <span class="ident">end</span>[<span class="number">1</span>]), |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">2</span>], <span class="ident">end</span>[<span class="number">2</span>]), |
| ]), |
| <span class="number">4</span> <span class="op">=></span> <span class="ident">Utf8Sequence</span>::<span class="ident">Four</span>([ |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">0</span>], <span class="ident">end</span>[<span class="number">0</span>]), |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">1</span>], <span class="ident">end</span>[<span class="number">1</span>]), |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">2</span>], <span class="ident">end</span>[<span class="number">2</span>]), |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">start</span>[<span class="number">3</span>], <span class="ident">end</span>[<span class="number">3</span>]), |
| ]), |
| <span class="ident">n</span> <span class="op">=></span> <span class="macro">unreachable</span><span class="macro">!</span>(<span class="string">"invalid encoded length: {}"</span>, <span class="ident">n</span>), |
| } |
| } |
| |
| <span class="doccomment">/// Returns the underlying sequence of byte ranges as a slice.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">as_slice</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span>[<span class="ident">Utf8Range</span>] { |
| <span class="kw">use</span> <span class="self">self</span>::<span class="ident">Utf8Sequence</span>::<span class="kw-2">*</span>; |
| <span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> { |
| <span class="ident">One</span>(<span class="kw-2">ref</span> <span class="ident">r</span>) <span class="op">=></span> <span class="kw">unsafe</span> { <span class="ident">slice</span>::<span class="ident">from_raw_parts</span>(<span class="ident">r</span>, <span class="number">1</span>) }, |
| <span class="ident">Two</span>(<span class="kw-2">ref</span> <span class="ident">r</span>) <span class="op">=></span> <span class="kw-2">&</span><span class="ident">r</span>[..], |
| <span class="ident">Three</span>(<span class="kw-2">ref</span> <span class="ident">r</span>) <span class="op">=></span> <span class="kw-2">&</span><span class="ident">r</span>[..], |
| <span class="ident">Four</span>(<span class="kw-2">ref</span> <span class="ident">r</span>) <span class="op">=></span> <span class="kw-2">&</span><span class="ident">r</span>[..], |
| } |
| } |
| |
| <span class="doccomment">/// Returns the number of byte ranges in this sequence.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// The length is guaranteed to be in the closed interval `[1, 4]`.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> { |
| <span class="self">self</span>.<span class="ident">as_slice</span>().<span class="ident">len</span>() |
| } |
| |
| <span class="doccomment">/// Returns true if and only if a prefix of `bytes` matches this sequence</span> |
| <span class="doccomment">/// of byte ranges.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">matches</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">bytes</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) <span class="op">-></span> <span class="ident">bool</span> { |
| <span class="kw">if</span> <span class="ident">bytes</span>.<span class="ident">len</span>() <span class="op"><</span> <span class="self">self</span>.<span class="ident">len</span>() { |
| <span class="kw">return</span> <span class="bool-val">false</span>; |
| } |
| <span class="kw">for</span> (<span class="kw-2">&</span><span class="ident">b</span>, <span class="ident">r</span>) <span class="kw">in</span> <span class="ident">bytes</span>.<span class="ident">iter</span>().<span class="ident">zip</span>(<span class="self">self</span>) { |
| <span class="kw">if</span> <span class="op">!</span><span class="ident">r</span>.<span class="ident">matches</span>(<span class="ident">b</span>) { |
| <span class="kw">return</span> <span class="bool-val">false</span>; |
| } |
| } |
| <span class="bool-val">true</span> |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">IntoIterator</span> <span class="kw">for</span> <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Utf8Sequence</span> { |
| <span class="kw">type</span> <span class="ident">IntoIter</span> <span class="op">=</span> <span class="ident">slice</span>::<span class="ident">Iter</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">Utf8Range</span><span class="op">></span>; |
| <span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Utf8Range</span>; |
| |
| <span class="kw">fn</span> <span class="ident">into_iter</span>(<span class="self">self</span>) <span class="op">-></span> <span class="self">Self</span>::<span class="ident">IntoIter</span> { |
| <span class="self">self</span>.<span class="ident">as_slice</span>().<span class="ident">into_iter</span>() |
| } |
| } |
| |
| <span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Utf8Sequence</span> { |
| <span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> { |
| <span class="kw">use</span> <span class="self">self</span>::<span class="ident">Utf8Sequence</span>::<span class="kw-2">*</span>; |
| <span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> { |
| <span class="ident">One</span>(<span class="kw-2">ref</span> <span class="ident">r</span>) <span class="op">=></span> <span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"{:?}"</span>, <span class="ident">r</span>), |
| <span class="ident">Two</span>(<span class="kw-2">ref</span> <span class="ident">r</span>) <span class="op">=></span> <span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"{:?}{:?}"</span>, <span class="ident">r</span>[<span class="number">0</span>], <span class="ident">r</span>[<span class="number">1</span>]), |
| <span class="ident">Three</span>(<span class="kw-2">ref</span> <span class="ident">r</span>) <span class="op">=></span> <span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"{:?}{:?}{:?}"</span>, <span class="ident">r</span>[<span class="number">0</span>], <span class="ident">r</span>[<span class="number">1</span>], <span class="ident">r</span>[<span class="number">2</span>]), |
| <span class="ident">Four</span>(<span class="kw-2">ref</span> <span class="ident">r</span>) <span class="op">=></span> <span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"{:?}{:?}{:?}{:?}"</span>, |
| <span class="ident">r</span>[<span class="number">0</span>], <span class="ident">r</span>[<span class="number">1</span>], <span class="ident">r</span>[<span class="number">2</span>], <span class="ident">r</span>[<span class="number">3</span>]), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// A single inclusive range of UTF-8 bytes.</span> |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>)]</span> |
| <span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Utf8Range</span> { |
| <span class="doccomment">/// Start of byte range (inclusive).</span> |
| <span class="kw">pub</span> <span class="ident">start</span>: <span class="ident">u8</span>, |
| <span class="doccomment">/// End of byte range (inclusive).</span> |
| <span class="kw">pub</span> <span class="ident">end</span>: <span class="ident">u8</span>, |
| } |
| |
| <span class="kw">impl</span> <span class="ident">Utf8Range</span> { |
| <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">start</span>: <span class="ident">u8</span>, <span class="ident">end</span>: <span class="ident">u8</span>) <span class="op">-></span> <span class="self">Self</span> { |
| <span class="ident">Utf8Range</span> { <span class="ident">start</span>: <span class="ident">start</span>, <span class="ident">end</span>: <span class="ident">end</span> } |
| } |
| |
| <span class="doccomment">/// Returns true if and only if the given byte is in this range.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">matches</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">b</span>: <span class="ident">u8</span>) <span class="op">-></span> <span class="ident">bool</span> { |
| <span class="self">self</span>.<span class="ident">start</span> <span class="op"><=</span> <span class="ident">b</span> <span class="op">&&</span> <span class="ident">b</span> <span class="op"><=</span> <span class="self">self</span>.<span class="ident">end</span> |
| } |
| } |
| |
| <span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Utf8Range</span> { |
| <span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> { |
| <span class="kw">if</span> <span class="self">self</span>.<span class="ident">start</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">end</span> { |
| <span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"[{:X}]"</span>, <span class="self">self</span>.<span class="ident">start</span>) |
| } <span class="kw">else</span> { |
| <span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"[{:X}-{:X}]"</span>, <span class="self">self</span>.<span class="ident">start</span>, <span class="self">self</span>.<span class="ident">end</span>) |
| } |
| } |
| } |
| |
| <span class="doccomment">/// An iterator over ranges of matching UTF-8 byte sequences.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// The iteration represents an alternation of comprehensive byte sequences</span> |
| <span class="doccomment">/// that match precisely the set of UTF-8 encoded scalar values.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// A byte sequence corresponds to one of the scalar values in the range given</span> |
| <span class="doccomment">/// if and only if it completely matches exactly one of the sequences of byte</span> |
| <span class="doccomment">/// ranges produced by this iterator.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Each sequence of byte ranges matches a unique set of bytes. That is, no two</span> |
| <span class="doccomment">/// sequences will match the same bytes.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # Example</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// This shows how to match an arbitrary byte sequence against a range of</span> |
| <span class="doccomment">/// scalar values.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// ```rust</span> |
| <span class="doccomment">/// use utf8_ranges::{Utf8Sequences, Utf8Sequence};</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// fn matches(seqs: &[Utf8Sequence], bytes: &[u8]) -> bool {</span> |
| <span class="doccomment">/// for range in seqs {</span> |
| <span class="doccomment">/// if range.matches(bytes) {</span> |
| <span class="doccomment">/// return true;</span> |
| <span class="doccomment">/// }</span> |
| <span class="doccomment">/// }</span> |
| <span class="doccomment">/// false</span> |
| <span class="doccomment">/// }</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// // Test the basic multilingual plane.</span> |
| <span class="doccomment">/// let seqs: Vec<_> = Utf8Sequences::new('\u{0}', '\u{FFFF}').collect();</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// // UTF-8 encoding of 'a'.</span> |
| <span class="doccomment">/// assert!(matches(&seqs, &[0x61]));</span> |
| <span class="doccomment">/// // UTF-8 encoding of '☃' (`\u{2603}`).</span> |
| <span class="doccomment">/// assert!(matches(&seqs, &[0xE2, 0x98, 0x83]));</span> |
| <span class="doccomment">/// // UTF-8 encoding of `\u{10348}` (outside the BMP).</span> |
| <span class="doccomment">/// assert!(!matches(&seqs, &[0xF0, 0x90, 0x8D, 0x88]));</span> |
| <span class="doccomment">/// // Tries to match against a UTF-8 encoding of a surrogate codepoint,</span> |
| <span class="doccomment">/// // which is invalid UTF-8, and therefore fails, despite the fact that</span> |
| <span class="doccomment">/// // the corresponding codepoint (0xD800) falls in the range given.</span> |
| <span class="doccomment">/// assert!(!matches(&seqs, &[0xED, 0xA0, 0x80]));</span> |
| <span class="doccomment">/// // And fails against plain old invalid UTF-8.</span> |
| <span class="doccomment">/// assert!(!matches(&seqs, &[0xFF, 0xFF]));</span> |
| <span class="doccomment">/// ```</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// If this example seems circuitous, that's because it is! It's meant to be</span> |
| <span class="doccomment">/// illustrative. In practice, you could just try to decode your byte sequence</span> |
| <span class="doccomment">/// and compare it with the scalar value range directly. However, this is not</span> |
| <span class="doccomment">/// always possible (for example, in a byte based automaton).</span> |
| <span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Utf8Sequences</span> { |
| <span class="ident">range_stack</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">ScalarRange</span><span class="op">></span>, |
| } |
| |
| <span class="kw">impl</span> <span class="ident">Utf8Sequences</span> { |
| <span class="doccomment">/// Create a new iterator over UTF-8 byte ranges for the scalar value range</span> |
| <span class="doccomment">/// given.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">start</span>: <span class="ident">char</span>, <span class="ident">end</span>: <span class="ident">char</span>) <span class="op">-></span> <span class="self">Self</span> { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">it</span> <span class="op">=</span> <span class="ident">Utf8Sequences</span> { <span class="ident">range_stack</span>: <span class="macro">vec</span><span class="macro">!</span>[] }; |
| <span class="ident">it</span>.<span class="ident">push</span>(<span class="ident">start</span> <span class="kw">as</span> <span class="ident">u32</span>, <span class="ident">end</span> <span class="kw">as</span> <span class="ident">u32</span>); |
| <span class="ident">it</span> |
| } |
| |
| <span class="doccomment">/// reset resets the scalar value range.</span> |
| <span class="doccomment">/// Any existing state is cleared, but resources may be reused.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// N.B. Benchmarks say that this method is dubious.</span> |
| <span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">reset</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">start</span>: <span class="ident">char</span>, <span class="ident">end</span>: <span class="ident">char</span>) { |
| <span class="self">self</span>.<span class="ident">range_stack</span>.<span class="ident">clear</span>(); |
| <span class="self">self</span>.<span class="ident">push</span>(<span class="ident">start</span> <span class="kw">as</span> <span class="ident">u32</span>, <span class="ident">end</span> <span class="kw">as</span> <span class="ident">u32</span>); |
| } |
| |
| <span class="kw">fn</span> <span class="ident">push</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">start</span>: <span class="ident">u32</span>, <span class="ident">end</span>: <span class="ident">u32</span>) { |
| <span class="self">self</span>.<span class="ident">range_stack</span>.<span class="ident">push</span>(<span class="ident">ScalarRange</span> { <span class="ident">start</span>: <span class="ident">start</span>, <span class="ident">end</span>: <span class="ident">end</span> }); |
| } |
| } |
| |
| <span class="kw">struct</span> <span class="ident">ScalarRange</span> { |
| <span class="ident">start</span>: <span class="ident">u32</span>, |
| <span class="ident">end</span>: <span class="ident">u32</span>, |
| } |
| |
| <span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">ScalarRange</span> { |
| <span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> { |
| <span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"ScalarRange({:X}, {:X})"</span>, <span class="self">self</span>.<span class="ident">start</span>, <span class="self">self</span>.<span class="ident">end</span>) |
| } |
| } |
| |
| <span class="kw">impl</span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Utf8Sequences</span> { |
| <span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">Utf8Sequence</span>; |
| |
| <span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span> { |
| <span class="lifetime">'TOP</span>: |
| <span class="kw">while</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="kw-2">mut</span> <span class="ident">r</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">range_stack</span>.<span class="ident">pop</span>() { |
| <span class="lifetime">'INNER</span>: |
| <span class="kw">loop</span> { |
| <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>((<span class="ident">r1</span>, <span class="ident">r2</span>)) <span class="op">=</span> <span class="ident">r</span>.<span class="ident">split</span>() { |
| <span class="self">self</span>.<span class="ident">push</span>(<span class="ident">r2</span>.<span class="ident">start</span>, <span class="ident">r2</span>.<span class="ident">end</span>); |
| <span class="ident">r</span>.<span class="ident">start</span> <span class="op">=</span> <span class="ident">r1</span>.<span class="ident">start</span>; |
| <span class="ident">r</span>.<span class="ident">end</span> <span class="op">=</span> <span class="ident">r1</span>.<span class="ident">end</span>; |
| <span class="kw">continue</span> <span class="lifetime">'INNER</span>; |
| } |
| <span class="kw">if</span> <span class="op">!</span><span class="ident">r</span>.<span class="ident">is_valid</span>() { |
| <span class="kw">continue</span> <span class="lifetime">'TOP</span>; |
| } |
| <span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="number">1</span>..<span class="ident">MAX_UTF8_BYTES</span> { |
| <span class="kw">let</span> <span class="ident">max</span> <span class="op">=</span> <span class="ident">max_scalar_value</span>(<span class="ident">i</span>); |
| <span class="kw">if</span> <span class="ident">r</span>.<span class="ident">start</span> <span class="op"><=</span> <span class="ident">max</span> <span class="op">&&</span> <span class="ident">max</span> <span class="op"><</span> <span class="ident">r</span>.<span class="ident">end</span> { |
| <span class="self">self</span>.<span class="ident">push</span>(<span class="ident">max</span> <span class="op">+</span> <span class="number">1</span>, <span class="ident">r</span>.<span class="ident">end</span>); |
| <span class="ident">r</span>.<span class="ident">end</span> <span class="op">=</span> <span class="ident">max</span>; |
| <span class="kw">continue</span> <span class="lifetime">'INNER</span>; |
| } |
| } |
| <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">ascii_range</span>) <span class="op">=</span> <span class="ident">r</span>.<span class="ident">as_ascii</span>() { |
| <span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">Utf8Sequence</span>::<span class="ident">One</span>(<span class="ident">ascii_range</span>)); |
| } |
| <span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="number">1</span>..<span class="ident">MAX_UTF8_BYTES</span> { |
| <span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> (<span class="number">1</span> <span class="op"><<</span> (<span class="number">6</span> <span class="op">*</span> <span class="ident">i</span>)) <span class="op">-</span> <span class="number">1</span>; |
| <span class="kw">if</span> (<span class="ident">r</span>.<span class="ident">start</span> <span class="op">&</span> <span class="op">!</span><span class="ident">m</span>) <span class="op">!=</span> (<span class="ident">r</span>.<span class="ident">end</span> <span class="op">&</span> <span class="op">!</span><span class="ident">m</span>) { |
| <span class="kw">if</span> (<span class="ident">r</span>.<span class="ident">start</span> <span class="op">&</span> <span class="ident">m</span>) <span class="op">!=</span> <span class="number">0</span> { |
| <span class="self">self</span>.<span class="ident">push</span>((<span class="ident">r</span>.<span class="ident">start</span> <span class="op">|</span> <span class="ident">m</span>) <span class="op">+</span> <span class="number">1</span>, <span class="ident">r</span>.<span class="ident">end</span>); |
| <span class="ident">r</span>.<span class="ident">end</span> <span class="op">=</span> <span class="ident">r</span>.<span class="ident">start</span> <span class="op">|</span> <span class="ident">m</span>; |
| <span class="kw">continue</span> <span class="lifetime">'INNER</span>; |
| } |
| <span class="kw">if</span> (<span class="ident">r</span>.<span class="ident">end</span> <span class="op">&</span> <span class="ident">m</span>) <span class="op">!=</span> <span class="ident">m</span> { |
| <span class="self">self</span>.<span class="ident">push</span>(<span class="ident">r</span>.<span class="ident">end</span> <span class="op">&</span> <span class="op">!</span><span class="ident">m</span>, <span class="ident">r</span>.<span class="ident">end</span>); |
| <span class="ident">r</span>.<span class="ident">end</span> <span class="op">=</span> (<span class="ident">r</span>.<span class="ident">end</span> <span class="op">&</span> <span class="op">!</span><span class="ident">m</span>) <span class="op">-</span> <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> <span class="ident">start</span> <span class="op">=</span> [<span class="number">0</span>; <span class="ident">MAX_UTF8_BYTES</span>]; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">end</span> <span class="op">=</span> [<span class="number">0</span>; <span class="ident">MAX_UTF8_BYTES</span>]; |
| <span class="kw">let</span> <span class="ident">n</span> <span class="op">=</span> <span class="ident">r</span>.<span class="ident">encode</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">start</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">end</span>); |
| <span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">Utf8Sequence</span>::<span class="ident">from_encoded_range</span>( |
| <span class="kw-2">&</span><span class="ident">start</span>[<span class="number">0</span>..<span class="ident">n</span>], <span class="kw-2">&</span><span class="ident">end</span>[<span class="number">0</span>..<span class="ident">n</span>])); |
| } |
| } |
| <span class="prelude-val">None</span> |
| } |
| } |
| |
| <span class="kw">impl</span> <span class="ident">ScalarRange</span> { |
| <span class="doccomment">/// split splits this range if it overlaps with a surrogate codepoint.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Either or both ranges may be invalid.</span> |
| <span class="kw">fn</span> <span class="ident">split</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">ScalarRange</span>, <span class="ident">ScalarRange</span>)<span class="op">></span> { |
| <span class="kw">if</span> <span class="self">self</span>.<span class="ident">start</span> <span class="op"><</span> <span class="number">0xE000</span> <span class="op">&&</span> <span class="self">self</span>.<span class="ident">end</span> <span class="op">></span> <span class="number">0xD7FF</span> { |
| <span class="prelude-val">Some</span>((<span class="ident">ScalarRange</span> { |
| <span class="ident">start</span>: <span class="self">self</span>.<span class="ident">start</span>, |
| <span class="ident">end</span>: <span class="number">0xD7FF</span>, |
| }, <span class="ident">ScalarRange</span> { |
| <span class="ident">start</span>: <span class="number">0xE000</span>, |
| <span class="ident">end</span>: <span class="self">self</span>.<span class="ident">end</span>, |
| })) |
| } <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> <span class="ident">is_valid</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> { |
| <span class="self">self</span>.<span class="ident">start</span> <span class="op"><=</span> <span class="self">self</span>.<span class="ident">end</span> |
| } |
| |
| <span class="doccomment">/// as_ascii returns this range as a Utf8Range if and only if all scalar</span> |
| <span class="doccomment">/// values in this range can be encoded as a single byte.</span> |
| <span class="kw">fn</span> <span class="ident">as_ascii</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Utf8Range</span><span class="op">></span> { |
| <span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_ascii</span>() { |
| <span class="prelude-val">Some</span>(<span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="self">self</span>.<span class="ident">start</span> <span class="kw">as</span> <span class="ident">u8</span>, <span class="self">self</span>.<span class="ident">end</span> <span class="kw">as</span> <span class="ident">u8</span>)) |
| } <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</span> |
| <span class="doccomment">/// byte to encode any scalar value).</span> |
| <span class="kw">fn</span> <span class="ident">is_ascii</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> { |
| <span class="self">self</span>.<span class="ident">is_valid</span>() <span class="op">&&</span> <span class="self">self</span>.<span class="ident">end</span> <span class="op"><=</span> <span class="number">0x7f</span> |
| } |
| |
| <span class="doccomment">/// encode writes the UTF-8 encoding of the start and end of this range</span> |
| <span class="doccomment">/// to the corresponding destination slices.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// The slices should have room for at least `MAX_UTF8_BYTES`.</span> |
| <span class="kw">fn</span> <span class="ident">encode</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">start</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>], <span class="ident">end</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) <span class="op">-></span> <span class="ident">usize</span> { |
| <span class="kw">let</span> <span class="ident">cs</span> <span class="op">=</span> <span class="ident">char</span>::<span class="ident">from_u32</span>(<span class="self">self</span>.<span class="ident">start</span>).<span class="ident">unwrap</span>(); |
| <span class="kw">let</span> <span class="ident">ce</span> <span class="op">=</span> <span class="ident">char</span>::<span class="ident">from_u32</span>(<span class="self">self</span>.<span class="ident">end</span>).<span class="ident">unwrap</span>(); |
| <span class="kw">let</span> <span class="ident">n</span> <span class="op">=</span> <span class="ident">encode_utf8</span>(<span class="ident">cs</span>, <span class="ident">start</span>).<span class="ident">unwrap</span>(); |
| <span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">encode_utf8</span>(<span class="ident">ce</span>, <span class="ident">end</span>).<span class="ident">unwrap</span>(); |
| <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">n</span>, <span class="ident">m</span>); |
| <span class="ident">n</span> |
| } |
| } |
| |
| <span class="kw">fn</span> <span class="ident">max_scalar_value</span>(<span class="ident">nbytes</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="ident">u32</span> { |
| <span class="kw">match</span> <span class="ident">nbytes</span> { |
| <span class="number">1</span> <span class="op">=></span> <span class="number">0x007F</span>, |
| <span class="number">2</span> <span class="op">=></span> <span class="number">0x07FF</span>, |
| <span class="number">3</span> <span class="op">=></span> <span class="number">0xFFFF</span>, |
| <span class="number">4</span> <span class="op">=></span> <span class="number">0x10FFFF</span>, |
| _ <span class="op">=></span> <span class="macro">unreachable</span><span class="macro">!</span>(<span class="string">"invalid UTF-8 byte sequence size"</span>), |
| } |
| } |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span> |
| <span class="kw">mod</span> <span class="ident">tests</span> { |
| <span class="kw">use</span> <span class="ident">quickcheck</span>::{<span class="ident">TestResult</span>, <span class="ident">quickcheck</span>}; |
| |
| <span class="kw">use</span> <span class="ident">char_utf8</span>::<span class="ident">encode_utf8</span>; |
| <span class="kw">use</span> {<span class="ident">MAX_UTF8_BYTES</span>, <span class="ident">Utf8Range</span>, <span class="ident">Utf8Sequences</span>}; |
| |
| <span class="kw">fn</span> <span class="ident">rutf8</span>(<span class="ident">s</span>: <span class="ident">u8</span>, <span class="ident">e</span>: <span class="ident">u8</span>) <span class="op">-></span> <span class="ident">Utf8Range</span> { |
| <span class="ident">Utf8Range</span>::<span class="ident">new</span>(<span class="ident">s</span>, <span class="ident">e</span>) |
| } |
| |
| <span class="kw">fn</span> <span class="ident">never_accepts_surrogate_codepoints</span>(<span class="ident">start</span>: <span class="ident">char</span>, <span class="ident">end</span>: <span class="ident">char</span>) { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buf</span> <span class="op">=</span> [<span class="number">0</span>; <span class="ident">MAX_UTF8_BYTES</span>]; |
| <span class="kw">for</span> <span class="ident">cp</span> <span class="kw">in</span> <span class="number">0xD800</span>..<span class="number">0xE000</span> { |
| <span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="kw">unsafe</span> { ::<span class="ident">std</span>::<span class="ident">mem</span>::<span class="ident">transmute</span>(<span class="ident">cp</span>) }; |
| <span class="kw">let</span> <span class="ident">n</span> <span class="op">=</span> <span class="ident">encode_utf8</span>(<span class="ident">c</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buf</span>).<span class="ident">unwrap</span>(); |
| <span class="kw">for</span> <span class="ident">r</span> <span class="kw">in</span> <span class="ident">Utf8Sequences</span>::<span class="ident">new</span>(<span class="ident">start</span>, <span class="ident">end</span>) { |
| <span class="kw">if</span> <span class="ident">r</span>.<span class="ident">matches</span>(<span class="kw-2">&</span><span class="ident">buf</span>[<span class="number">0</span>..<span class="ident">n</span>]) { |
| <span class="macro">panic</span><span class="macro">!</span>(<span class="string">"Sequence ({:X}, {:X}) contains range {:?}, \ |
| which matches surrogate code point {:X} \ |
| with encoded bytes {:?}"</span>, |
| <span class="ident">start</span> <span class="kw">as</span> <span class="ident">u32</span>, <span class="ident">end</span> <span class="kw">as</span> <span class="ident">u32</span>, <span class="ident">r</span>, <span class="ident">cp</span>, <span class="kw-2">&</span><span class="ident">buf</span>[<span class="number">0</span>..<span class="ident">n</span>]); |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">codepoints_no_surrogates</span>() { |
| <span class="ident">never_accepts_surrogate_codepoints</span>(<span class="string">'\u{0}'</span>, <span class="string">'\u{FFFF}'</span>); |
| <span class="ident">never_accepts_surrogate_codepoints</span>(<span class="string">'\u{0}'</span>, <span class="string">'\u{10FFFF}'</span>); |
| <span class="ident">never_accepts_surrogate_codepoints</span>(<span class="string">'\u{0}'</span>, <span class="string">'\u{10FFFE}'</span>); |
| <span class="ident">never_accepts_surrogate_codepoints</span>(<span class="string">'\u{80}'</span>, <span class="string">'\u{10FFFF}'</span>); |
| <span class="ident">never_accepts_surrogate_codepoints</span>(<span class="string">'\u{D7FF}'</span>, <span class="string">'\u{E000}'</span>); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">qc_codepoints_no_surrogate</span>() { |
| <span class="kw">fn</span> <span class="ident">p</span>(<span class="ident">s</span>: <span class="ident">char</span>, <span class="ident">e</span>: <span class="ident">char</span>) <span class="op">-></span> <span class="ident">TestResult</span> { |
| <span class="kw">if</span> <span class="ident">s</span> <span class="op">></span> <span class="ident">e</span> { |
| <span class="kw">return</span> <span class="ident">TestResult</span>::<span class="ident">discard</span>(); |
| } |
| <span class="ident">never_accepts_surrogate_codepoints</span>(<span class="ident">s</span>, <span class="ident">e</span>); |
| <span class="ident">TestResult</span>::<span class="ident">passed</span>() |
| } |
| <span class="ident">quickcheck</span>(<span class="ident">p</span> <span class="kw">as</span> <span class="kw">fn</span>(<span class="ident">char</span>, <span class="ident">char</span>) <span class="op">-></span> <span class="ident">TestResult</span>); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">bmp</span>() { |
| <span class="kw">use</span> <span class="ident">Utf8Sequence</span>::<span class="kw-2">*</span>; |
| |
| <span class="kw">let</span> <span class="ident">seqs</span> <span class="op">=</span> <span class="ident">Utf8Sequences</span>::<span class="ident">new</span>(<span class="string">'\u{0}'</span>, <span class="string">'\u{FFFF}'</span>) |
| .<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span>_<span class="op">>></span>(); |
| <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">seqs</span>, <span class="macro">vec</span><span class="macro">!</span>[ |
| <span class="ident">One</span>(<span class="ident">rutf8</span>(<span class="number">0x0</span>, <span class="number">0x7F</span>)), |
| <span class="ident">Two</span>([<span class="ident">rutf8</span>(<span class="number">0xC2</span>, <span class="number">0xDF</span>), <span class="ident">rutf8</span>(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| <span class="ident">Three</span>([<span class="ident">rutf8</span>(<span class="number">0xE0</span>, <span class="number">0xE0</span>), <span class="ident">rutf8</span>(<span class="number">0xA0</span>, <span class="number">0xBF</span>), <span class="ident">rutf8</span>(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| <span class="ident">Three</span>([<span class="ident">rutf8</span>(<span class="number">0xE1</span>, <span class="number">0xEC</span>), <span class="ident">rutf8</span>(<span class="number">0x80</span>, <span class="number">0xBF</span>), <span class="ident">rutf8</span>(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| <span class="ident">Three</span>([<span class="ident">rutf8</span>(<span class="number">0xED</span>, <span class="number">0xED</span>), <span class="ident">rutf8</span>(<span class="number">0x80</span>, <span class="number">0x9F</span>), <span class="ident">rutf8</span>(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| <span class="ident">Three</span>([<span class="ident">rutf8</span>(<span class="number">0xEE</span>, <span class="number">0xEF</span>), <span class="ident">rutf8</span>(<span class="number">0x80</span>, <span class="number">0xBF</span>), <span class="ident">rutf8</span>(<span class="number">0x80</span>, <span class="number">0xBF</span>)]), |
| ]); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">scratch</span>() { |
| <span class="kw">for</span> <span class="ident">range</span> <span class="kw">in</span> <span class="ident">Utf8Sequences</span>::<span class="ident">new</span>(<span class="string">'\u{0}'</span>, <span class="string">'\u{FFFF}'</span>) { |
| <span class="macro">println</span><span class="macro">!</span>(<span class="string">"{:?}"</span>, <span class="ident">range</span>); |
| } |
| } |
| } |
| </pre> |
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