<!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 `/home/sangenya/.cargo/registry/src/github.com-1ecc6299db9ec823/deflate-0.7.20/src/chained_hash_table.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>chained_hash_table.rs - source</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled ><script id="default-settings"></script><script src="../../storage.js"></script><script src="../../crates.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../../favicon.svg">
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</pre><pre class="rust">
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">WINDOW_SIZE</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">32768</span>;
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">WINDOW_MASK</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="ident">WINDOW_SIZE</span> <span class="op">-</span> <span class="number">1</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">HASH_BYTES</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">3</span>;
<span class="kw">const</span> <span class="ident">HASH_SHIFT</span>: <span class="ident">u16</span> <span class="op">=</span> <span class="number">5</span>;
<span class="kw">const</span> <span class="ident">HASH_MASK</span>: <span class="ident">u16</span> <span class="op">=</span> <span class="ident">WINDOW_MASK</span> <span class="kw">as</span> <span class="ident">u16</span>;
<span class="doccomment">/// Helper struct to let us allocate both head and prev in the same block.</span>
<span class="kw">struct</span> <span class="ident">Tables</span> {
<span class="doccomment">/// Starts of hash chains (in prev)</span>
<span class="kw">pub</span> <span class="ident">head</span>: [<span class="ident">u16</span>; <span class="ident">WINDOW_SIZE</span>],
<span class="doccomment">/// Link to previous occurence of this hash value</span>
<span class="kw">pub</span> <span class="ident">prev</span>: [<span class="ident">u16</span>; <span class="ident">WINDOW_SIZE</span>],
}
<span class="kw">impl</span> <span class="ident">Default</span> <span class="kw">for</span> <span class="ident">Tables</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">default</span>() <span class="op">-</span><span class="op">></span> <span class="ident">Tables</span> {
<span class="ident">Tables</span> {
<span class="ident">head</span>: [<span class="number">0</span>;<span class="ident">WINDOW_SIZE</span>],
<span class="ident">prev</span>: [<span class="number">0</span>;<span class="ident">WINDOW_SIZE</span>],
}
}
}
<span class="kw">impl</span> <span class="ident">Tables</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">fill_prev</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">prev</span>.<span class="ident">copy_from_slice</span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">head</span>);
}
}
<span class="doccomment">/// Create and box the hash chains.</span>
<span class="kw">fn</span> <span class="ident">create_tables</span>() <span class="op">-</span><span class="op">></span> <span class="ident">Box</span><span class="op"><</span><span class="ident">Tables</span><span class="op">></span> {
<span class="comment">// Using default here is a trick to get around the lack of box syntax on stable rust.</span>
<span class="comment">//</span>
<span class="comment">// Box::new([0u16,n]) ends up creating an temporary array on the stack which is not optimised</span>
<span class="comment">// but using default, which simply calls `box value` internally allows us to get around this.</span>
<span class="comment">//</span>
<span class="comment">// We could use vec instead, but using a boxed array helps the compiler optimise</span>
<span class="comment">// away bounds checks as `n & WINDOW_MASK < WINDOW_SIZE` will always be true.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">t</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">Tables</span><span class="op">></span> <span class="op">=</span> <span class="ident">Box::default</span>();
<span class="kw">for</span> (<span class="ident">n</span>, <span class="ident">b</span>) <span class="kw">in</span> <span class="ident">t</span>.<span class="ident">head</span>.<span class="ident">iter_mut</span>().<span class="ident">enumerate</span>() {
<span class="kw-2">*</span><span class="ident">b</span> <span class="op">=</span> <span class="ident">n</span> <span class="kw">as</span> <span class="ident">u16</span>;
}
<span class="ident">t</span>.<span class="ident">fill_prev</span>();
<span class="ident">t</span>
}
<span class="doccomment">/// Returns a new hash value based on the previous value and the next byte</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">update_hash</span>(<span class="ident">current_hash</span>: <span class="ident">u16</span>, <span class="ident">to_insert</span>: <span class="ident">u8</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u16</span> {
<span class="ident">update_hash_conf</span>(<span class="ident">current_hash</span>, <span class="ident">to_insert</span>, <span class="ident">HASH_SHIFT</span>, <span class="ident">HASH_MASK</span>)
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">update_hash_conf</span>(<span class="ident">current_hash</span>: <span class="ident">u16</span>, <span class="ident">to_insert</span>: <span class="ident">u8</span>, <span class="ident">shift</span>: <span class="ident">u16</span>, <span class="ident">mask</span>: <span class="ident">u16</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u16</span> {
((<span class="ident">current_hash</span> <span class="op"><</span><span class="op"><</span> <span class="ident">shift</span>) <span class="op">^</span> (<span class="ident">to_insert</span> <span class="kw">as</span> <span class="ident">u16</span>)) <span class="op">&</span> <span class="ident">mask</span>
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">reset_array</span>(<span class="ident">arr</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u16</span>; <span class="ident">WINDOW_SIZE</span>]) {
<span class="kw">for</span> (<span class="ident">n</span>, <span class="ident">b</span>) <span class="kw">in</span> <span class="ident">arr</span>.<span class="ident">iter_mut</span>().<span class="ident">enumerate</span>() {
<span class="kw-2">*</span><span class="ident">b</span> <span class="op">=</span> <span class="ident">n</span> <span class="kw">as</span> <span class="ident">u16</span>;
}
}
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">ChainedHashTable</span> {
<span class="comment">// Current running hash value of the last 3 bytes</span>
<span class="ident">current_hash</span>: <span class="ident">u16</span>,
<span class="comment">// Hash chains.</span>
<span class="ident">c</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">Tables</span><span class="op">></span>,
<span class="comment">// Used for testing</span>
<span class="comment">// count: DebugCounter,</span>
}
<span class="kw">impl</span> <span class="ident">ChainedHashTable</span> {
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-</span><span class="op">></span> <span class="ident">ChainedHashTable</span> {
<span class="ident">ChainedHashTable</span> {
<span class="ident">current_hash</span>: <span class="number">0</span>,
<span class="ident">c</span>: <span class="ident">create_tables</span>(),
<span class="comment">//count: DebugCounter::default(),</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">from_starting_values</span>(<span class="ident">v1</span>: <span class="ident">u8</span>, <span class="ident">v2</span>: <span class="ident">u8</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ChainedHashTable</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">t</span> <span class="op">=</span> <span class="ident">ChainedHashTable::new</span>();
<span class="ident">t</span>.<span class="ident">current_hash</span> <span class="op">=</span> <span class="ident">update_hash</span>(<span class="ident">t</span>.<span class="ident">current_hash</span>, <span class="ident">v1</span>);
<span class="ident">t</span>.<span class="ident">current_hash</span> <span class="op">=</span> <span class="ident">update_hash</span>(<span class="ident">t</span>.<span class="ident">current_hash</span>, <span class="ident">v2</span>);
<span class="ident">t</span>
}
<span class="doccomment">/// Resets the hash value and hash chains</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="self">self</span>.<span class="ident">current_hash</span> <span class="op">=</span> <span class="number">0</span>;
<span class="ident">reset_array</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">c</span>.<span class="ident">head</span>);
{
<span class="kw">let</span> <span class="ident">h</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">c</span>.<span class="ident">head</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">c</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">c</span>.<span class="ident">prev</span>;
<span class="ident">c</span>[..].<span class="ident">copy_from_slice</span>(<span class="kw-2">&</span><span class="ident">h</span>[..]);
}
<span class="comment">/*if cfg!(debug_assertions) {
self.count.reset();
}*/</span>
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">add_initial_hash_values</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">v1</span>: <span class="ident">u8</span>, <span class="ident">v2</span>: <span class="ident">u8</span>) {
<span class="self">self</span>.<span class="ident">current_hash</span> <span class="op">=</span> <span class="ident">update_hash</span>(<span class="self">self</span>.<span class="ident">current_hash</span>, <span class="ident">v1</span>);
<span class="self">self</span>.<span class="ident">current_hash</span> <span class="op">=</span> <span class="ident">update_hash</span>(<span class="self">self</span>.<span class="ident">current_hash</span>, <span class="ident">v2</span>);
}
<span class="doccomment">/// Insert a byte into the hash table</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">add_hash_value</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">position</span>: <span class="ident">usize</span>, <span class="ident">value</span>: <span class="ident">u8</span>) {
<span class="comment">// Check that all bytes are input in order and at the correct positions.</span>
<span class="comment">// Disabled for now as it breaks when sync flushing.</span>
<span class="comment">/*debug_assert_eq!(
position & WINDOW_MASK,
self.count.get() as usize & WINDOW_MASK
);*/</span>
<span class="macro">debug_assert!</span>(
<span class="ident">position</span> <span class="op"><</span> <span class="ident">WINDOW_SIZE</span> <span class="op">*</span> <span class="number">2</span>,
<span class="string">"Position is larger than 2 * window size! {}"</span>,
<span class="ident">position</span>
);
<span class="comment">// Storing the hash in a temporary variable here makes the compiler avoid the</span>
<span class="comment">// bounds checks in this function.</span>
<span class="kw">let</span> <span class="ident">new_hash</span> <span class="op">=</span> <span class="ident">update_hash</span>(<span class="self">self</span>.<span class="ident">current_hash</span>, <span class="ident">value</span>);
<span class="self">self</span>.<span class="ident">add_with_hash</span>(<span class="ident">position</span>, <span class="ident">new_hash</span>);
<span class="comment">// Update the stored hash value with the new hash.</span>
<span class="self">self</span>.<span class="ident">current_hash</span> <span class="op">=</span> <span class="ident">new_hash</span>;
}
<span class="doccomment">/// Directly set the current hash value</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">set_hash</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">hash</span>: <span class="ident">u16</span>) {
<span class="self">self</span>.<span class="ident">current_hash</span> <span class="op">=</span> <span class="ident">hash</span>;
}
<span class="doccomment">/// Update the tables directly, providing the hash.</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">add_with_hash</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">position</span>: <span class="ident">usize</span>, <span class="ident">hash</span>: <span class="ident">u16</span>) {
<span class="comment">/*if cfg!(debug_assertions) {
self.count.add(1);
}*/</span>
<span class="self">self</span>.<span class="ident">c</span>.<span class="ident">prev</span>[<span class="ident">position</span> <span class="op">&</span> <span class="ident">WINDOW_MASK</span>] <span class="op">=</span> <span class="self">self</span>.<span class="ident">c</span>.<span class="ident">head</span>[<span class="ident">hash</span> <span class="kw">as</span> <span class="ident">usize</span>];
<span class="comment">// Ignoring any bits over 16 here is deliberate, as we only concern ourselves about</span>
<span class="comment">// where in the buffer (which is 64k bytes) we are referring to.</span>
<span class="self">self</span>.<span class="ident">c</span>.<span class="ident">head</span>[<span class="ident">hash</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">position</span> <span class="kw">as</span> <span class="ident">u16</span>;
}
<span class="comment">// Get the head of the hash chain for the current hash value</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">current_head</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u16</span> {
<span class="self">self</span>.<span class="ident">c</span>.<span class="ident">head</span>[<span class="self">self</span>.<span class="ident">current_hash</span> <span class="kw">as</span> <span class="ident">usize</span>]
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">current_hash</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u16</span> {
<span class="self">self</span>.<span class="ident">current_hash</span>
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">get_prev</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">bytes</span>: <span class="ident">usize</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u16</span> {
<span class="self">self</span>.<span class="ident">c</span>.<span class="ident">prev</span>[<span class="ident">bytes</span> <span class="op">&</span> <span class="ident">WINDOW_MASK</span>]
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">farthest_next</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">match_pos</span>: <span class="ident">usize</span>, <span class="ident">match_len</span>: <span class="ident">usize</span>) <span class="op">-</span><span class="op">></span> <span class="ident">usize</span> {
<span class="kw">let</span> <span class="ident">to_check</span> <span class="op">=</span> <span class="ident">match_len</span>.<span class="ident">saturating_sub</span>(<span class="number">2</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">n</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">smallest_prev</span> <span class="op">=</span>
<span class="self">self</span>.<span class="ident">get_prev</span>(<span class="ident">match_pos</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">smallest_pos</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">while</span> <span class="ident">n</span> <span class="op"><</span> <span class="ident">to_check</span> {
<span class="kw">let</span> <span class="ident">prev</span> <span class="op">=</span>
<span class="self">self</span>.<span class="ident">get_prev</span>(<span class="ident">match_pos</span> <span class="op">+</span> <span class="ident">n</span>);
<span class="kw">if</span> <span class="ident">prev</span> <span class="op"><</span> <span class="ident">smallest_prev</span> {
<span class="ident">smallest_prev</span> <span class="op">=</span> <span class="ident">prev</span>;
<span class="ident">smallest_pos</span> <span class="op">=</span> <span class="ident">n</span>;
}
<span class="ident">n</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>;
}
<span class="ident">smallest_pos</span>
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">slide_value</span>(<span class="ident">b</span>: <span class="ident">u16</span>, <span class="ident">pos</span>: <span class="ident">u16</span>, <span class="ident">bytes</span>: <span class="ident">u16</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u16</span> {
<span class="kw">if</span> <span class="ident">b</span> <span class="op">></span><span class="op">=</span> <span class="ident">bytes</span> {
<span class="ident">b</span> <span class="op">-</span> <span class="ident">bytes</span>
} <span class="kw">else</span> {
<span class="ident">pos</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">slide_table</span>(<span class="ident">table</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u16</span>; <span class="ident">WINDOW_SIZE</span>], <span class="ident">bytes</span>: <span class="ident">u16</span>) {
<span class="kw">for</span> (<span class="ident">n</span>, <span class="ident">b</span>) <span class="kw">in</span> <span class="ident">table</span>.<span class="ident">iter_mut</span>().<span class="ident">enumerate</span>() {
<span class="kw-2">*</span><span class="ident">b</span> <span class="op">=</span> <span class="ident">ChainedHashTable::slide_value</span>(<span class="kw-2">*</span><span class="ident">b</span>, <span class="ident">n</span> <span class="kw">as</span> <span class="ident">u16</span>, <span class="ident">bytes</span>);
}
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">slide</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">bytes</span>: <span class="ident">usize</span>) {
<span class="comment">/*if cfg!(debug_assertions) && bytes != WINDOW_SIZE {
// This should only happen in tests in this file.
self.count.reset();
}*/</span>
<span class="ident">ChainedHashTable::slide_table</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">c</span>.<span class="ident">head</span>, <span class="ident">bytes</span> <span class="kw">as</span> <span class="ident">u16</span>);
<span class="ident">ChainedHashTable::slide_table</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">c</span>.<span class="ident">prev</span>, <span class="ident">bytes</span> <span class="kw">as</span> <span class="ident">u16</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">filled_hash_table</span>(<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) <span class="op">-</span><span class="op">></span> <span class="ident">ChainedHashTable</span> {
<span class="macro">assert!</span>(<span class="ident">data</span>.<span class="ident">len</span>() <span class="op"><</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="number">2</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">hash_table</span> <span class="op">=</span> <span class="ident">ChainedHashTable::from_starting_values</span>(<span class="ident">data</span>[<span class="number">0</span>], <span class="ident">data</span>[<span class="number">1</span>]);
<span class="kw">for</span> (<span class="ident">n</span>, <span class="ident">b</span>) <span class="kw">in</span> <span class="ident">data</span>[<span class="number">2</span>..].<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="ident">hash_table</span>.<span class="ident">add_hash_value</span>(<span class="ident">n</span>, <span class="kw-2">*</span><span class="ident">b</span>);
}
<span class="ident">hash_table</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">filled_hash_table</span>, <span class="ident">ChainedHashTable</span>};
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">chained_hash</span>() {
<span class="kw">use</span> <span class="ident">std::str</span>;
<span class="kw">let</span> <span class="ident">test_string</span> <span class="op">=</span> <span class="string">"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do \
eiusmod tempor. rum. incididunt ut labore et dolore magna aliqua. Ut \
enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi \
ut aliquip ex ea commodo consequat. rum. Duis aute irure dolor in \
reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla \
pariatur. Excepteur sint occaecat cupidatat non proident, sunt in \
culpa qui officia deserunt mollit anim id est laborum."</span>;
<span class="kw">let</span> <span class="ident">test_data</span> <span class="op">=</span> <span class="ident">test_string</span>.<span class="ident">as_bytes</span>();
<span class="kw">let</span> <span class="ident">current_bytes</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">test_data</span>[<span class="ident">test_data</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="kw">super</span><span class="ident">::HASH_BYTES</span>..<span class="ident">test_data</span>.<span class="ident">len</span>()];
<span class="kw">let</span> <span class="ident">num_iters</span> <span class="op">=</span> <span class="ident">test_string</span>
.<span class="ident">matches</span>(<span class="ident">str::from_utf8</span>(<span class="ident">current_bytes</span>).<span class="ident">unwrap</span>())
.<span class="ident">count</span>();
<span class="kw">let</span> <span class="ident">hash_table</span> <span class="op">=</span> <span class="ident">filled_hash_table</span>(<span class="ident">test_data</span>);
<span class="comment">// Test that the positions in the chain are valid</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">prev_value</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">get_prev</span>(<span class="ident">hash_table</span>.<span class="ident">current_head</span>() <span class="kw">as</span> <span class="ident">usize</span>) <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">count</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">current</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">current_head</span>() <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">while</span> <span class="ident">current</span> <span class="op">!</span><span class="op">=</span> <span class="ident">prev_value</span> {
<span class="ident">count</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>;
<span class="ident">current</span> <span class="op">=</span> <span class="ident">prev_value</span>;
<span class="ident">prev_value</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">get_prev</span>(<span class="ident">prev_value</span>) <span class="kw">as</span> <span class="ident">usize</span>;
}
<span class="comment">// There should be at least as many occurences of the hash of the checked bytes as the</span>
<span class="comment">// numbers of occurences of the checked bytes themselves. As the hashes are not large enough</span>
<span class="comment">// to store 8 * 3 = 24 bits, there could be more with different input data.</span>
<span class="macro">assert!</span>(<span class="ident">count</span> <span class="op">></span><span class="op">=</span> <span class="ident">num_iters</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">table_unique</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">test_data</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
<span class="ident">test_data</span>.<span class="ident">extend</span>(<span class="number">0u8</span>..<span class="number">255</span>);
<span class="ident">test_data</span>.<span class="ident">extend</span>(<span class="number">255u8</span>..<span class="number">0</span>);
<span class="kw">let</span> <span class="ident">hash_table</span> <span class="op">=</span> <span class="ident">filled_hash_table</span>(<span class="kw-2">&</span><span class="ident">test_data</span>);
<span class="kw">let</span> <span class="ident">prev_pos</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">get_prev</span>(<span class="ident">hash_table</span>.<span class="ident">current_head</span>() <span class="kw">as</span> <span class="ident">usize</span>);
<span class="comment">// Since all sequences in the input are unique, there shouldn't be any previous values.</span>
<span class="macro">assert_eq!</span>(<span class="ident">prev_pos</span>, <span class="ident">hash_table</span>.<span class="ident">current_hash</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">table_slide</span>() {
<span class="kw">use</span> <span class="ident">std::fs::File</span>;
<span class="kw">use</span> <span class="ident">std::io::Read</span>;
<span class="kw">let</span> <span class="ident">window_size</span> <span class="op">=</span> <span class="kw">super</span><span class="ident">::WINDOW_SIZE</span>;
<span class="kw">let</span> <span class="ident">window_size16</span> <span class="op">=</span> <span class="kw">super</span><span class="ident">::WINDOW_SIZE</span> <span class="kw">as</span> <span class="ident">u16</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">input</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">f</span> <span class="op">=</span> <span class="ident">File::open</span>(<span class="string">"tests/pg11.txt"</span>).<span class="ident">unwrap</span>();
<span class="ident">f</span>.<span class="ident">read_to_end</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">input</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">hash_table</span> <span class="op">=</span> <span class="ident">filled_hash_table</span>(<span class="kw-2">&</span><span class="ident">input</span>[..<span class="ident">window_size</span> <span class="op">+</span> <span class="number">2</span>]);
<span class="kw">for</span> (<span class="ident">n</span>, <span class="ident">b</span>) <span class="kw">in</span> <span class="ident">input</span>[<span class="number">2</span>..<span class="ident">window_size</span> <span class="op">+</span> <span class="number">2</span>].<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="ident">hash_table</span>.<span class="ident">add_hash_value</span>(<span class="ident">n</span> <span class="op">+</span> <span class="ident">window_size</span>, <span class="kw-2">*</span><span class="ident">b</span>);
}
<span class="ident">hash_table</span>.<span class="ident">slide</span>(<span class="ident">window_size</span>);
{
<span class="kw">let</span> <span class="ident">max_head</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">c</span>.<span class="ident">head</span>.<span class="ident">iter</span>().<span class="ident">max</span>().<span class="ident">unwrap</span>();
<span class="comment">// After sliding there should be no hashes referring to values</span>
<span class="comment">// higher than the window size</span>
<span class="macro">assert!</span>(<span class="kw-2">*</span><span class="ident">max_head</span> <span class="op"><</span> <span class="ident">window_size16</span>);
<span class="macro">assert!</span>(<span class="kw-2">*</span><span class="ident">max_head</span> <span class="op">></span> <span class="number">0</span>);
<span class="kw">let</span> <span class="ident">pos</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">get_prev</span>(<span class="ident">hash_table</span>.<span class="ident">current_head</span>() <span class="kw">as</span> <span class="ident">usize</span>);
<span class="comment">// There should be a previous occurence since we inserted the data 3 times</span>
<span class="macro">assert!</span>(<span class="ident">pos</span> <span class="op"><</span> <span class="ident">window_size16</span>);
<span class="macro">assert!</span>(<span class="ident">pos</span> <span class="op">></span> <span class="number">0</span>);
}
<span class="kw">for</span> (<span class="ident">n</span>, <span class="ident">b</span>) <span class="kw">in</span> <span class="ident">input</span>[<span class="number">2</span>..(<span class="ident">window_size</span> <span class="op">/</span> <span class="number">2</span>)].<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="ident">hash_table</span>.<span class="ident">add_hash_value</span>(<span class="ident">n</span> <span class="op">+</span> <span class="ident">window_size</span>, <span class="kw-2">*</span><span class="ident">b</span>);
}
<span class="comment">// There should hashes referring to values in the upper part of the input window</span>
<span class="comment">// at this point</span>
<span class="kw">let</span> <span class="ident">max_prev</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">c</span>.<span class="ident">prev</span>.<span class="ident">iter</span>().<span class="ident">max</span>().<span class="ident">unwrap</span>();
<span class="macro">assert!</span>(<span class="kw-2">*</span><span class="ident">max_prev</span> <span class="op">></span> <span class="ident">window_size16</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">pos</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">current_head</span>();
<span class="comment">// There should be a previous occurence since we inserted the data 3 times</span>
<span class="macro">assert!</span>(<span class="ident">pos</span> <span class="op">></span> <span class="ident">window_size16</span>);
<span class="kw">let</span> <span class="ident">end_byte</span> <span class="op">=</span> <span class="ident">input</span>[(<span class="ident">window_size</span> <span class="op">/</span> <span class="number">2</span>) <span class="op">-</span> <span class="number">1</span> <span class="op">-</span> <span class="number">2</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iterations</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">while</span> <span class="ident">pos</span> <span class="op">></span> <span class="ident">window_size16</span> <span class="op">&&</span> <span class="ident">iterations</span> <span class="op"><</span> <span class="number">5000</span> {
<span class="macro">assert_eq!</span>(<span class="ident">input</span>[<span class="ident">pos</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">&</span> <span class="ident">window_size</span> <span class="op">-</span> <span class="number">1</span>], <span class="ident">end_byte</span>);
<span class="ident">pos</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">get_prev</span>(<span class="ident">pos</span> <span class="kw">as</span> <span class="ident">usize</span>);
<span class="ident">iterations</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>;
}
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="doccomment">/// Ensure that the initial hash values are correct.</span>
<span class="kw">fn</span> <span class="ident">initial_chains</span>() {
<span class="kw">let</span> <span class="ident">t</span> <span class="op">=</span> <span class="ident">ChainedHashTable::new</span>();
<span class="kw">for</span> (<span class="ident">n</span>, <span class="kw-2">&</span><span class="ident">b</span>) <span class="kw">in</span> <span class="ident">t</span>.<span class="ident">c</span>.<span class="ident">head</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="macro">assert_eq!</span>(<span class="ident">n</span>, <span class="ident">b</span> <span class="kw">as</span> <span class="ident">usize</span>);
}
<span class="kw">for</span> (<span class="ident">n</span>, <span class="kw-2">&</span><span class="ident">b</span>) <span class="kw">in</span> <span class="ident">t</span>.<span class="ident">c</span>.<span class="ident">prev</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="macro">assert_eq!</span>(<span class="ident">n</span>, <span class="ident">b</span> <span class="kw">as</span> <span class="ident">usize</span>);
}
}
}
</pre></div>
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