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</pre><pre class="rust"><code><span class="kw">mod </span>table;
<span class="kw">use </span><span class="self">self</span>::table::{DECODE_TABLE, ENCODE_TABLE};
<span class="kw">use </span><span class="kw">crate</span>::hpack::DecoderError;
<span class="kw">use </span>bytes::{BufMut, BytesMut};
<span class="comment">// Constructed in the generated `table.rs` file
</span><span class="kw">struct </span>Decoder {
state: usize,
maybe_eos: bool,
}
<span class="comment">// These flags must match the ones in genhuff.rs
</span><span class="kw">const </span>MAYBE_EOS: u8 = <span class="number">1</span>;
<span class="kw">const </span>DECODED: u8 = <span class="number">2</span>;
<span class="kw">const </span>ERROR: u8 = <span class="number">4</span>;
<span class="kw">pub fn </span>decode(src: <span class="kw-2">&amp;</span>[u8], buf: <span class="kw-2">&amp;mut </span>BytesMut) -&gt; <span class="prelude-ty">Result</span>&lt;BytesMut, DecoderError&gt; {
<span class="kw">let </span><span class="kw-2">mut </span>decoder = Decoder::new();
<span class="comment">// Max compression ratio is &gt;= 0.5
</span>buf.reserve(src.len() &lt;&lt; <span class="number">1</span>);
<span class="kw">for </span>b <span class="kw">in </span>src {
<span class="kw">if let </span><span class="prelude-val">Some</span>(b) = decoder.decode4(b &gt;&gt; <span class="number">4</span>)<span class="question-mark">? </span>{
buf.put_u8(b);
}
<span class="kw">if let </span><span class="prelude-val">Some</span>(b) = decoder.decode4(b &amp; <span class="number">0xf</span>)<span class="question-mark">? </span>{
buf.put_u8(b);
}
}
<span class="kw">if </span>!decoder.is_final() {
<span class="kw">return </span><span class="prelude-val">Err</span>(DecoderError::InvalidHuffmanCode);
}
<span class="prelude-val">Ok</span>(buf.split())
}
<span class="kw">pub fn </span>encode(src: <span class="kw-2">&amp;</span>[u8], dst: <span class="kw-2">&amp;mut </span>BytesMut) {
<span class="kw">let </span><span class="kw-2">mut </span>bits: u64 = <span class="number">0</span>;
<span class="kw">let </span><span class="kw-2">mut </span>bits_left = <span class="number">40</span>;
<span class="kw">for </span><span class="kw-2">&amp;</span>b <span class="kw">in </span>src {
<span class="kw">let </span>(nbits, code) = ENCODE_TABLE[b <span class="kw">as </span>usize];
bits |= code &lt;&lt; (bits_left - nbits);
bits_left -= nbits;
<span class="kw">while </span>bits_left &lt;= <span class="number">32 </span>{
dst.put_u8((bits &gt;&gt; <span class="number">32</span>) <span class="kw">as </span>u8);
bits &lt;&lt;= <span class="number">8</span>;
bits_left += <span class="number">8</span>;
}
}
<span class="kw">if </span>bits_left != <span class="number">40 </span>{
<span class="comment">// This writes the EOS token
</span>bits |= (<span class="number">1 </span>&lt;&lt; bits_left) - <span class="number">1</span>;
dst.put_u8((bits &gt;&gt; <span class="number">32</span>) <span class="kw">as </span>u8);
}
}
<span class="kw">impl </span>Decoder {
<span class="kw">fn </span>new() -&gt; Decoder {
Decoder {
state: <span class="number">0</span>,
maybe_eos: <span class="bool-val">false</span>,
}
}
<span class="comment">// Decodes 4 bits
</span><span class="kw">fn </span>decode4(<span class="kw-2">&amp;mut </span><span class="self">self</span>, input: u8) -&gt; <span class="prelude-ty">Result</span>&lt;<span class="prelude-ty">Option</span>&lt;u8&gt;, DecoderError&gt; {
<span class="comment">// (next-state, byte, flags)
</span><span class="kw">let </span>(next, byte, flags) = DECODE_TABLE[<span class="self">self</span>.state][input <span class="kw">as </span>usize];
<span class="kw">if </span>flags &amp; ERROR == ERROR {
<span class="comment">// Data followed the EOS marker
</span><span class="kw">return </span><span class="prelude-val">Err</span>(DecoderError::InvalidHuffmanCode);
}
<span class="kw">let </span><span class="kw-2">mut </span>ret = <span class="prelude-val">None</span>;
<span class="kw">if </span>flags &amp; DECODED == DECODED {
ret = <span class="prelude-val">Some</span>(byte);
}
<span class="self">self</span>.state = next;
<span class="self">self</span>.maybe_eos = flags &amp; MAYBE_EOS == MAYBE_EOS;
<span class="prelude-val">Ok</span>(ret)
}
<span class="kw">fn </span>is_final(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; bool {
<span class="self">self</span>.state == <span class="number">0 </span>|| <span class="self">self</span>.maybe_eos
}
}
<span class="attribute">#[cfg(test)]
</span><span class="kw">mod </span>test {
<span class="kw">use super</span>::<span class="kw-2">*</span>;
<span class="kw">fn </span>decode(src: <span class="kw-2">&amp;</span>[u8]) -&gt; <span class="prelude-ty">Result</span>&lt;BytesMut, DecoderError&gt; {
<span class="kw">let </span><span class="kw-2">mut </span>buf = BytesMut::new();
<span class="kw">super</span>::decode(src, <span class="kw-2">&amp;mut </span>buf)
}
<span class="attribute">#[test]
</span><span class="kw">fn </span>decode_single_byte() {
<span class="macro">assert_eq!</span>(<span class="string">&quot;o&quot;</span>, decode(<span class="kw-2">&amp;</span>[<span class="number">0b00111111</span>]).unwrap());
<span class="macro">assert_eq!</span>(<span class="string">&quot;0&quot;</span>, decode(<span class="kw-2">&amp;</span>[<span class="number">7</span>]).unwrap());
<span class="macro">assert_eq!</span>(<span class="string">&quot;A&quot;</span>, decode(<span class="kw-2">&amp;</span>[(<span class="number">0x21 </span>&lt;&lt; <span class="number">2</span>) + <span class="number">3</span>]).unwrap());
}
<span class="attribute">#[test]
</span><span class="kw">fn </span>single_char_multi_byte() {
<span class="macro">assert_eq!</span>(<span class="string">&quot;#&quot;</span>, decode(<span class="kw-2">&amp;</span>[<span class="number">255</span>, <span class="number">160 </span>+ <span class="number">15</span>]).unwrap());
<span class="macro">assert_eq!</span>(<span class="string">&quot;$&quot;</span>, decode(<span class="kw-2">&amp;</span>[<span class="number">255</span>, <span class="number">200 </span>+ <span class="number">7</span>]).unwrap());
<span class="macro">assert_eq!</span>(<span class="string">&quot;\x0a&quot;</span>, decode(<span class="kw-2">&amp;</span>[<span class="number">255</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">240 </span>+ <span class="number">3</span>]).unwrap());
}
<span class="attribute">#[test]
</span><span class="kw">fn </span>multi_char() {
<span class="macro">assert_eq!</span>(<span class="string">&quot;!0&quot;</span>, decode(<span class="kw-2">&amp;</span>[<span class="number">254</span>, <span class="number">1</span>]).unwrap());
<span class="macro">assert_eq!</span>(<span class="string">&quot; !&quot;</span>, decode(<span class="kw-2">&amp;</span>[<span class="number">0b01010011</span>, <span class="number">0b11111000</span>]).unwrap());
}
<span class="attribute">#[test]
</span><span class="kw">fn </span>encode_single_byte() {
<span class="kw">let </span><span class="kw-2">mut </span>dst = BytesMut::with_capacity(<span class="number">1</span>);
encode(<span class="string">b&quot;o&quot;</span>, <span class="kw-2">&amp;mut </span>dst);
<span class="macro">assert_eq!</span>(<span class="kw-2">&amp;</span>dst[..], <span class="kw-2">&amp;</span>[<span class="number">0b00111111</span>]);
dst.clear();
encode(<span class="string">b&quot;0&quot;</span>, <span class="kw-2">&amp;mut </span>dst);
<span class="macro">assert_eq!</span>(<span class="kw-2">&amp;</span>dst[..], <span class="kw-2">&amp;</span>[<span class="number">7</span>]);
dst.clear();
encode(<span class="string">b&quot;A&quot;</span>, <span class="kw-2">&amp;mut </span>dst);
<span class="macro">assert_eq!</span>(<span class="kw-2">&amp;</span>dst[..], <span class="kw-2">&amp;</span>[(<span class="number">0x21 </span>&lt;&lt; <span class="number">2</span>) + <span class="number">3</span>]);
}
<span class="attribute">#[test]
</span><span class="kw">fn </span>encode_decode_str() {
<span class="kw">const </span>DATA: <span class="kw-2">&amp;</span>[<span class="kw-2">&amp;</span>str] = <span class="kw-2">&amp;</span>[
<span class="string">&quot;hello world&quot;</span>,
<span class="string">&quot;:method&quot;</span>,
<span class="string">&quot;:scheme&quot;</span>,
<span class="string">&quot;:authority&quot;</span>,
<span class="string">&quot;yahoo.co.jp&quot;</span>,
<span class="string">&quot;GET&quot;</span>,
<span class="string">&quot;http&quot;</span>,
<span class="string">&quot;:path&quot;</span>,
<span class="string">&quot;/images/top/sp2/cmn/logo-ns-130528.png&quot;</span>,
<span class="string">&quot;example.com&quot;</span>,
<span class="string">&quot;hpack-test&quot;</span>,
<span class="string">&quot;xxxxxxx1&quot;</span>,
<span class="string">&quot;Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:16.0) Gecko/20100101 Firefox/16.0&quot;</span>,
<span class="string">&quot;accept&quot;</span>,
<span class="string">&quot;Accept&quot;</span>,
<span class="string">&quot;text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8&quot;</span>,
<span class="string">&quot;cookie&quot;</span>,
<span class="string">&quot;B=76j09a189a6h4&amp;b=3&amp;s=0b&quot;</span>,
<span class="string">&quot;TE&quot;</span>,
<span class="string">&quot;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi non bibendum libero. \
Etiam ultrices lorem ut.&quot;</span>,
];
<span class="kw">for </span>s <span class="kw">in </span>DATA {
<span class="kw">let </span><span class="kw-2">mut </span>dst = BytesMut::with_capacity(s.len());
encode(s.as_bytes(), <span class="kw-2">&amp;mut </span>dst);
<span class="kw">let </span>decoded = decode(<span class="kw-2">&amp;</span>dst).unwrap();
<span class="macro">assert_eq!</span>(<span class="kw-2">&amp;</span>decoded[..], s.as_bytes());
}
}
<span class="attribute">#[test]
</span><span class="kw">fn </span>encode_decode_u8() {
<span class="kw">const </span>DATA: <span class="kw-2">&amp;</span>[<span class="kw-2">&amp;</span>[u8]] = <span class="kw-2">&amp;</span>[<span class="string">b&quot;\0&quot;</span>, <span class="string">b&quot;\0\0\0&quot;</span>, <span class="string">b&quot;\0\x01\x02\x03\x04\x05&quot;</span>, <span class="string">b&quot;\xFF\xF8&quot;</span>];
<span class="kw">for </span>s <span class="kw">in </span>DATA {
<span class="kw">let </span><span class="kw-2">mut </span>dst = BytesMut::with_capacity(s.len());
encode(s, <span class="kw-2">&amp;mut </span>dst);
<span class="kw">let </span>decoded = decode(<span class="kw-2">&amp;</span>dst).unwrap();
<span class="macro">assert_eq!</span>(<span class="kw-2">&amp;</span>decoded[..], <span class="kw-2">&amp;</span>s[..]);
}
}
}
</code></pre></div>
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