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| </pre><pre class="rust"><code><span class="kw">use </span>std::io::{Write, Read, Error, ErrorKind}; |
| <span class="kw">use </span>std::io; |
| <span class="kw">use </span>std::fmt; |
| |
| <span class="kw">pub fn </span>write_char<W: Write>(writer: <span class="kw-2">&mut </span>W, c: char) -> io::Result<()> { |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = [<span class="number">0u8</span>;<span class="number">4</span>]; |
| <span class="kw">let </span>utf8 = encode_char_utf8(c, <span class="kw-2">&mut </span>buf); |
| writer.write_all(utf8) |
| } |
| |
| <span class="kw">fn </span>encode_char_utf8<<span class="lifetime">'a</span>>(c: char, buf: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>[u8]) -> <span class="kw-2">&</span><span class="lifetime">'a </span>[u8] { |
| <span class="kw">let </span>c = c <span class="kw">as </span>u32; |
| <span class="kw">if </span>c <= <span class="number">0x7f </span>{ |
| buf[<span class="number">0</span>] = c <span class="kw">as </span>u8; |
| <span class="kw-2">&</span>buf[..<span class="number">1</span>] |
| } <span class="kw">else if </span>c <= <span class="number">0x7ff </span>{ |
| buf[<span class="number">1</span>] = <span class="number">0b10000000 </span>| (c & <span class="number">0b00111111</span>) <span class="kw">as </span>u8; |
| buf[<span class="number">0</span>] = <span class="number">0b11000000 </span>| ((c >> <span class="number">6</span>) & <span class="number">0b00011111</span>) <span class="kw">as </span>u8; |
| <span class="kw-2">&</span>buf[..<span class="number">2</span>] |
| } <span class="kw">else if </span>c <= <span class="number">0xffff </span>{ |
| buf[<span class="number">2</span>] = <span class="number">0b10000000 </span>| (c & <span class="number">0b00111111</span>) <span class="kw">as </span>u8; |
| buf[<span class="number">1</span>] = <span class="number">0b10000000 </span>| ((c >> <span class="number">6</span>) & <span class="number">0b00111111</span>) <span class="kw">as </span>u8; |
| buf[<span class="number">0</span>] = <span class="number">0b11100000 </span>| ((c >> <span class="number">12</span>) & <span class="number">0b00001111</span>) <span class="kw">as </span>u8; |
| <span class="kw-2">&</span>buf[..<span class="number">3</span>] |
| } <span class="kw">else </span>{ |
| buf[<span class="number">3</span>] = <span class="number">0b10000000 </span>| (c & <span class="number">0b00111111</span>) <span class="kw">as </span>u8; |
| buf[<span class="number">2</span>] = <span class="number">0b10000000 </span>| ((c >> <span class="number">6</span>) & <span class="number">0b00111111</span>) <span class="kw">as </span>u8; |
| buf[<span class="number">1</span>] = <span class="number">0b10000000 </span>| ((c >> <span class="number">12</span>) & <span class="number">0b00111111</span>) <span class="kw">as </span>u8; |
| buf[<span class="number">0</span>] = <span class="number">0b11110000 </span>| ((c >> <span class="number">18</span>) & <span class="number">0b00000111</span>) <span class="kw">as </span>u8; |
| <span class="kw-2">&</span>buf[..<span class="number">4</span>] |
| } |
| } |
| |
| <span class="kw">fn </span>utf8_char_bytes(first: u8) -> usize { |
| <span class="kw">if </span>first & <span class="number">0b10000000 </span>== <span class="number">0 </span>{ |
| <span class="number">1 |
| </span>} <span class="kw">else if </span>first & <span class="number">0b11100000 </span>== <span class="number">0b11000000 </span>{ |
| <span class="number">2 |
| </span>} <span class="kw">else if </span>first & <span class="number">0b11110000 </span>== <span class="number">0b11100000 </span>{ |
| <span class="number">3 |
| </span>} <span class="kw">else if </span>first & <span class="number">0b11111000 </span>== <span class="number">0b11110000 </span>{ |
| <span class="number">4 |
| </span>} <span class="kw">else </span>{ |
| <span class="number">0 |
| </span>} |
| } |
| |
| |
| <span class="comment">// `Chars` code copied and modified from `std` |
| // The reason for doing this is that when using Chars from std, read_one_byte() isn't inlined. |
| // This is very painful when the backing Reader is just a Cursor over a byte array, |
| // and read_one_byte() should be much more than return buf[idx++] (+ check for end ofc.). |
| |
| </span><span class="kw">pub struct </span>Chars<R> { |
| inner: R |
| } |
| |
| <span class="kw">pub fn </span>chars<R: Read>(reader: R) -> Chars<R> { |
| Chars { inner: reader } |
| } |
| |
| <span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub enum </span>CharsError { |
| <span class="doccomment">/// Variant representing that the underlying stream was read successfully |
| /// but it did not contain valid utf8 data. |
| </span>NotUtf8, |
| |
| <span class="doccomment">/// Variant representing that an I/O error occurred. |
| </span>Other(Error), |
| } |
| |
| <span class="kw">impl</span><R: Read> Iterator <span class="kw">for </span>Chars<R> { |
| <span class="kw">type </span>Item = <span class="prelude-ty">Result</span><char, CharsError>; |
| |
| <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="prelude-ty">Result</span><char, CharsError>> { |
| <span class="kw">let </span>first_byte = <span class="kw">match </span>read_a_byte(<span class="kw-2">&mut </span><span class="self">self</span>.inner) { |
| <span class="prelude-val">None </span>=> <span class="kw">return </span><span class="prelude-val">None</span>, |
| <span class="prelude-val">Some</span>(<span class="prelude-val">Ok</span>(b)) => b, |
| <span class="prelude-val">Some</span>(<span class="prelude-val">Err</span>(e)) => <span class="kw">return </span><span class="prelude-val">Some</span>(<span class="prelude-val">Err</span>(CharsError::Other(e))), |
| }; |
| <span class="kw">let </span>width = utf8_char_bytes(first_byte); |
| <span class="kw">if </span>width == <span class="number">1 </span>{ <span class="kw">return </span><span class="prelude-val">Some</span>(<span class="prelude-val">Ok</span>(first_byte <span class="kw">as </span>char)) } |
| <span class="kw">if </span>width == <span class="number">0 </span>{ <span class="kw">return </span><span class="prelude-val">Some</span>(<span class="prelude-val">Err</span>(CharsError::NotUtf8)) } |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = [first_byte, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>]; |
| { |
| <span class="kw">let </span><span class="kw-2">mut </span>start = <span class="number">1</span>; |
| <span class="kw">while </span>start < width { |
| <span class="kw">match </span><span class="self">self</span>.inner.read(<span class="kw-2">&mut </span>buf[start..width]) { |
| <span class="prelude-val">Ok</span>(<span class="number">0</span>) => <span class="kw">return </span><span class="prelude-val">Some</span>(<span class="prelude-val">Err</span>(CharsError::NotUtf8)), |
| <span class="prelude-val">Ok</span>(n) => start += n, |
| <span class="prelude-val">Err</span>(<span class="kw-2">ref </span>e) <span class="kw">if </span>e.kind() == ErrorKind::Interrupted => <span class="kw">continue</span>, |
| <span class="prelude-val">Err</span>(e) => <span class="kw">return </span><span class="prelude-val">Some</span>(<span class="prelude-val">Err</span>(CharsError::Other(e))), |
| } |
| } |
| } |
| <span class="prelude-val">Some</span>(<span class="kw">match </span>::std::str::from_utf8(<span class="kw-2">&</span>buf[..width]).ok() { |
| <span class="prelude-val">Some</span>(s) => <span class="prelude-val">Ok</span>(s.chars().next().unwrap()), |
| <span class="prelude-val">None </span>=> <span class="prelude-val">Err</span>(CharsError::NotUtf8), |
| }) |
| } |
| } |
| |
| <span class="kw">fn </span>read_a_byte<R: Read>(reader: <span class="kw-2">&mut </span>R) -> <span class="prelude-ty">Option</span><io::Result<u8>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = [<span class="number">0</span>]; |
| <span class="kw">loop </span>{ |
| <span class="kw">return match </span>reader.read(<span class="kw-2">&mut </span>buf) { |
| <span class="prelude-val">Ok</span>(<span class="number">0</span>) => <span class="prelude-val">None</span>, |
| <span class="prelude-val">Ok</span>(..) => <span class="prelude-val">Some</span>(<span class="prelude-val">Ok</span>(buf[<span class="number">0</span>])), |
| <span class="prelude-val">Err</span>(<span class="kw-2">ref </span>e) <span class="kw">if </span>e.kind() == ErrorKind::Interrupted => <span class="kw">continue</span>, |
| <span class="prelude-val">Err</span>(e) => <span class="prelude-val">Some</span>(<span class="prelude-val">Err</span>(e)), |
| }; |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>CharsError { |
| <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">match </span><span class="kw-2">*</span><span class="self">self </span>{ |
| CharsError::NotUtf8 => { |
| <span class="string">"byte stream did not contain valid utf8"</span>.fmt(f) |
| } |
| CharsError::Other(<span class="kw-2">ref </span>e) => e.fmt(f), |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>test { |
| |
| <span class="kw">use </span><span class="kw">super</span>::encode_char_utf8; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_encode_char_utf8() { |
| do_test_encode_char_utf8(<span class="string">'$'</span>, <span class="kw-2">&</span>[<span class="number">0x24</span>]); |
| do_test_encode_char_utf8(<span class="string">'¢'</span>, <span class="kw-2">&</span>[<span class="number">0xc2</span>, <span class="number">0xa2</span>]); |
| do_test_encode_char_utf8(<span class="string">'€'</span>, <span class="kw-2">&</span>[<span class="number">0xe2</span>, <span class="number">0x82</span>, <span class="number">0xac</span>]); |
| do_test_encode_char_utf8(<span class="string">'\u{10348}'</span>, <span class="kw-2">&</span>[<span class="number">0xf0</span>, <span class="number">0x90</span>, <span class="number">0x8d</span>, <span class="number">0x88</span>]); |
| } |
| |
| <span class="kw">fn </span>do_test_encode_char_utf8(c: char, expected: <span class="kw-2">&</span>[u8]) { |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = [<span class="number">0u8</span>;<span class="number">4</span>]; |
| <span class="kw">let </span>utf8 = encode_char_utf8(c, <span class="kw-2">&mut </span>buf); |
| <span class="macro">assert_eq!</span>(utf8, expected); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="htmlescape" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
