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</pre><pre class="rust">
<span class="kw">use</span> <span class="ident">std::cmp</span>;
<span class="kw">use</span> <span class="ident">chained_hash_table::WINDOW_SIZE</span>;
<span class="kw">use</span> <span class="ident">huffman_table</span>;
<span class="kw">const</span> <span class="ident">MAX_MATCH</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="ident">huffman_table::MAX_MATCH</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="doccomment">/// The maximum size of the buffer.</span>
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">BUFFER_SIZE</span>: <span class="ident">usize</span> <span class="op">=</span> (<span class="ident">WINDOW_SIZE</span> <span class="op">*</span> <span class="number">2</span>) <span class="op">+</span> <span class="ident">MAX_MATCH</span>;
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">InputBuffer</span> {
<span class="ident">buffer</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span>,
}
<span class="kw">impl</span> <span class="ident">InputBuffer</span> {
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>(<span class="ident">data</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u8</span>]) <span class="op">-</span><span class="op">></span> (<span class="ident">InputBuffer</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span>[<span class="ident">u8</span>]<span class="op">></span>) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">InputBuffer::empty</span>();
<span class="kw">let</span> <span class="ident">rem</span> <span class="op">=</span> <span class="ident">b</span>.<span class="ident">add_data</span>(<span class="ident">data</span>);
(<span class="ident">b</span>, <span class="ident">rem</span>)
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">empty</span>() <span class="op">-</span><span class="op">></span> <span class="ident">InputBuffer</span> {
<span class="ident">InputBuffer</span> {
<span class="ident">buffer</span>: <span class="ident">Vec::with_capacity</span>(<span class="ident">BUFFER_SIZE</span>),
}
}
<span class="doccomment">/// Add data to the buffer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns a slice of the data that was not added (including the lookahead if any).</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">add_data</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">data</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u8</span>]) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u8</span>]<span class="op">></span> {
<span class="macro">debug_assert!</span>(<span class="self">self</span>.<span class="ident">current_end</span>() <span class="op"><</span><span class="op">=</span> <span class="ident">BUFFER_SIZE</span>);
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">current_end</span>() <span class="op">+</span> <span class="ident">data</span>.<span class="ident">len</span>() <span class="op">></span> <span class="ident">BUFFER_SIZE</span> {
<span class="comment">// Add data and return how much was left.</span>
<span class="kw">let</span> <span class="ident">consumed</span> <span class="op">=</span> {
<span class="kw">let</span> <span class="ident">space_left</span> <span class="op">=</span> <span class="ident">BUFFER_SIZE</span> <span class="op">-</span> <span class="self">self</span>.<span class="ident">buffer</span>.<span class="ident">len</span>();
<span class="self">self</span>.<span class="ident">buffer</span>.<span class="ident">extend_from_slice</span>(<span class="kw-2">&</span><span class="ident">data</span>[..<span class="ident">space_left</span>]);
<span class="ident">space_left</span>
};
<span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="ident">data</span>[<span class="ident">consumed</span>..])
} <span class="kw">else</span> {
<span class="comment">// There's space for all of the data.</span>
<span class="self">self</span>.<span class="ident">buffer</span>.<span class="ident">extend_from_slice</span>(<span class="ident">data</span>);
<span class="prelude-val">None</span>
}
}
<span class="doccomment">/// Get the current amount of data in the buffer.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">current_end</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">buffer</span>.<span class="ident">len</span>()
}
<span class="doccomment">/// Slide the input window and add new data.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns a slice containing the data that did not fit, or None if all data was consumed.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">slide</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">data</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u8</span>]) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u8</span>]<span class="op">></span> {
<span class="comment">// This should only be used when the buffer is full</span>
<span class="macro">assert!</span>(<span class="self">self</span>.<span class="ident">buffer</span>.<span class="ident">len</span>() <span class="op">></span> <span class="ident">WINDOW_SIZE</span> <span class="op">*</span> <span class="number">2</span>);
<span class="comment">// Do this in a closure to to end the borrow of buffer.</span>
<span class="kw">let</span> (<span class="ident">final_len</span>, <span class="ident">upper_len</span>, <span class="ident">end</span>) <span class="op">=</span> {
<span class="comment">// Split into lower window and upper window + lookahead</span>
<span class="kw">let</span> (<span class="ident">lower</span>, <span class="ident">upper</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">buffer</span>.<span class="ident">split_at_mut</span>(<span class="ident">WINDOW_SIZE</span>);
<span class="comment">// Copy the upper window to the lower window</span>
<span class="ident">lower</span>.<span class="ident">copy_from_slice</span>(<span class="kw-2">&</span><span class="ident">upper</span>[..<span class="ident">WINDOW_SIZE</span>]);
<span class="kw">let</span> <span class="ident">lookahead_len</span> <span class="op">=</span> {
<span class="comment">// Copy the lookahead to the start of the upper window</span>
<span class="kw">let</span> (<span class="ident">upper_2</span>, <span class="ident">lookahead</span>) <span class="op">=</span> <span class="ident">upper</span>.<span class="ident">split_at_mut</span>(<span class="ident">WINDOW_SIZE</span>);
<span class="kw">let</span> <span class="ident">lookahead_len</span> <span class="op">=</span> <span class="ident">lookahead</span>.<span class="ident">len</span>();
<span class="macro">debug_assert!</span>(<span class="ident">lookahead_len</span> <span class="op"><</span><span class="op">=</span> <span class="ident">MAX_MATCH</span>);
<span class="ident">upper_2</span>[..<span class="ident">lookahead_len</span>].<span class="ident">copy_from_slice</span>(<span class="ident">lookahead</span>);
<span class="ident">lookahead_len</span>
};
<span class="comment">// Length of the upper window minus the lookahead bytes</span>
<span class="kw">let</span> <span class="ident">upper_len</span> <span class="op">=</span> <span class="ident">upper</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="ident">lookahead_len</span>;
<span class="kw">let</span> <span class="ident">end</span> <span class="op">=</span> <span class="ident">cmp::min</span>(<span class="ident">data</span>.<span class="ident">len</span>(), <span class="ident">upper_len</span>);
<span class="ident">upper</span>[<span class="ident">lookahead_len</span>..<span class="ident">lookahead_len</span> <span class="op">+</span> <span class="ident">end</span>].<span class="ident">copy_from_slice</span>(<span class="kw-2">&</span><span class="ident">data</span>[..<span class="ident">end</span>]);
<span class="comment">// Remove unused data if any.</span>
(<span class="ident">lower</span>.<span class="ident">len</span>() <span class="op">+</span> <span class="ident">lookahead_len</span> <span class="op">+</span> <span class="ident">end</span>, <span class="ident">upper_len</span>, <span class="ident">end</span>)
};
<span class="comment">// Remove unused space.</span>
<span class="self">self</span>.<span class="ident">buffer</span>.<span class="ident">truncate</span>(<span class="ident">final_len</span>);
<span class="kw">if</span> <span class="ident">data</span>.<span class="ident">len</span>() <span class="op">></span> <span class="ident">upper_len</span> {
<span class="comment">// Return a slice of the data that was not added</span>
<span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="ident">data</span>[<span class="ident">end</span>..])
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
<span class="doccomment">/// Get a mutable slice of the used part of the buffer.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">get_buffer</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>] {
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">buffer</span>
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">mod</span> <span class="ident">test</span> {
<span class="kw">use</span> <span class="kw">super</span><span class="ident">::MAX_MATCH</span>;
<span class="kw">use</span> <span class="ident">chained_hash_table::WINDOW_SIZE</span>;
<span class="kw">use</span> <span class="kw">super</span>::<span class="kw-2">*</span>;
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">buffer_add_full</span>() {
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> [<span class="number">10u8</span>; <span class="ident">BUFFER_SIZE</span> <span class="op">+</span> <span class="number">10</span>];
<span class="kw">let</span> (<span class="kw-2">mut</span> <span class="ident">buf</span>, <span class="ident">extra</span>) <span class="op">=</span> <span class="ident">InputBuffer::new</span>(<span class="kw-2">&</span><span class="ident">data</span>[..]);
<span class="macro">assert!</span>(<span class="ident">extra</span>.<span class="ident">unwrap</span>() <span class="op">=</span><span class="op">=</span> <span class="kw-2">&</span>[<span class="number">10</span>; <span class="number">10</span>]);
<span class="kw">let</span> <span class="ident">to_add</span> <span class="op">=</span> [<span class="number">2</span>, <span class="number">5</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">not_added</span> <span class="op">=</span> <span class="ident">buf</span>.<span class="ident">add_data</span>(<span class="kw-2">&</span><span class="ident">to_add</span>);
<span class="macro">assert_eq!</span>(<span class="ident">not_added</span>.<span class="ident">unwrap</span>(), <span class="ident">to_add</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">buffer_add_not_full</span>() {
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> [<span class="number">10u8</span>; <span class="ident">BUFFER_SIZE</span> <span class="op">-</span> <span class="number">5</span>];
<span class="kw">let</span> (<span class="kw-2">mut</span> <span class="ident">buf</span>, <span class="ident">extra</span>) <span class="op">=</span> <span class="ident">InputBuffer::new</span>(<span class="kw-2">&</span><span class="ident">data</span>[..]);
<span class="macro">assert_eq!</span>(<span class="ident">buf</span>.<span class="ident">current_end</span>(), <span class="ident">data</span>.<span class="ident">len</span>());
<span class="macro">assert_eq!</span>(<span class="ident">extra</span>, <span class="prelude-val">None</span>);
<span class="kw">let</span> <span class="ident">to_add</span> <span class="op">=</span> [<span class="number">2</span>, <span class="number">5</span>, <span class="number">3</span>];
{
<span class="kw">let</span> <span class="ident">not_added</span> <span class="op">=</span> <span class="ident">buf</span>.<span class="ident">add_data</span>(<span class="kw-2">&</span><span class="ident">to_add</span>);
<span class="macro">assert!</span>(<span class="ident">not_added</span>.<span class="ident">is_none</span>());
}
<span class="kw">let</span> <span class="ident">not_added</span> <span class="op">=</span> <span class="ident">buf</span>.<span class="ident">add_data</span>(<span class="kw-2">&</span><span class="ident">to_add</span>);
<span class="macro">assert_eq!</span>(<span class="ident">not_added</span>.<span class="ident">unwrap</span>()[<span class="number">0</span>], <span class="number">3</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">slide</span>() {
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> [<span class="number">10u8</span>; <span class="ident">BUFFER_SIZE</span>];
<span class="kw">let</span> (<span class="kw-2">mut</span> <span class="ident">buf</span>, <span class="ident">extra</span>) <span class="op">=</span> <span class="ident">InputBuffer::new</span>(<span class="kw-2">&</span><span class="ident">data</span>[..]);
<span class="macro">assert_eq!</span>(<span class="ident">extra</span>, <span class="prelude-val">None</span>);
<span class="kw">let</span> <span class="ident">to_add</span> <span class="op">=</span> [<span class="number">5</span>; <span class="number">5</span>];
<span class="kw">let</span> <span class="ident">rem</span> <span class="op">=</span> <span class="ident">buf</span>.<span class="ident">slide</span>(<span class="kw-2">&</span><span class="ident">to_add</span>);
<span class="macro">assert!</span>(<span class="ident">rem</span>.<span class="ident">is_none</span>());
{
<span class="kw">let</span> <span class="ident">slice</span> <span class="op">=</span> <span class="ident">buf</span>.<span class="ident">get_buffer</span>();
<span class="macro">assert!</span>(<span class="ident">slice</span>[..<span class="ident">WINDOW_SIZE</span> <span class="op">+</span> <span class="ident">MAX_MATCH</span>] <span class="op">=</span><span class="op">=</span> <span class="ident">data</span>[<span class="ident">WINDOW_SIZE</span>..]);
<span class="macro">assert_eq!</span>(
<span class="ident">slice</span>[<span class="ident">WINDOW_SIZE</span> <span class="op">+</span> <span class="ident">MAX_MATCH</span>..<span class="ident">WINDOW_SIZE</span> <span class="op">+</span> <span class="ident">MAX_MATCH</span> <span class="op">+</span> <span class="number">5</span>],
<span class="ident">to_add</span>
);
}
<span class="macro">assert_eq!</span>(<span class="ident">buf</span>.<span class="ident">current_end</span>(), <span class="ident">WINDOW_SIZE</span> <span class="op">+</span> <span class="ident">MAX_MATCH</span> <span class="op">+</span> <span class="ident">to_add</span>.<span class="ident">len</span>());
}
}
</pre></div>
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