| <!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 `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/levenshtein_automata-0.2.1/src/parametric_dfa.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>parametric_dfa.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../levenshtein_automata/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../levenshtein_automata/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">super</span>::alphabet::Alphabet; |
| <span class="kw">use </span><span class="kw">super</span>::dfa::{Utf8DFABuilder, DFA}; |
| <span class="kw">use </span><span class="kw">super</span>::levenshtein_nfa::Distance; |
| <span class="kw">use </span><span class="kw">super</span>::levenshtein_nfa::{LevenshteinNFA, MultiState}; |
| <span class="kw">use </span><span class="kw">super</span>::Index; |
| |
| <span class="attribute">#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)] |
| </span><span class="kw">pub struct </span>ParametricState { |
| shape_id: u32, |
| offset: u32, |
| } |
| |
| <span class="kw">impl </span>ParametricState { |
| <span class="kw">fn </span>empty() -> ParametricState { |
| ParametricState { |
| shape_id: <span class="number">0u32</span>, |
| offset: <span class="number">0u32</span>, |
| } |
| } |
| <span class="kw">fn </span>is_dead_end(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.shape_id == <span class="number">0 |
| </span>} |
| } |
| |
| <span class="attribute">#[derive(Clone, Copy)] |
| </span><span class="kw">pub struct </span>Transition { |
| dest_shape_id: u32, |
| delta_offset: u32, |
| } |
| |
| <span class="kw">impl </span>Transition { |
| <span class="kw">fn </span>apply(<span class="kw-2">&</span><span class="self">self</span>, state: ParametricState) -> ParametricState { |
| ParametricState { |
| shape_id: <span class="self">self</span>.dest_shape_id, |
| offset: <span class="kw">if </span><span class="self">self</span>.dest_shape_id == <span class="number">0 </span>{ |
| <span class="number">0 </span><span class="comment">//< We don't need any offset if we are in the dead state. |
| // This ensures we have only one dead state. |
| </span>} <span class="kw">else </span>{ |
| state.offset + <span class="self">self</span>.delta_offset |
| }, |
| } |
| } |
| } |
| |
| <span class="kw">struct </span>ParametricStateIndex { |
| state_index: Vec<<span class="prelude-ty">Option</span><u32>>, |
| state_queue: Vec<ParametricState>, |
| num_offsets: usize, |
| } |
| |
| <span class="kw">impl </span>ParametricStateIndex { |
| <span class="kw">fn </span>new(query_len: usize, num_param_states: usize) -> ParametricStateIndex { |
| <span class="kw">let </span>num_offsets = query_len + <span class="number">1</span>; |
| <span class="kw">let </span>max_num_states = num_param_states * num_offsets; |
| ParametricStateIndex { |
| state_index: <span class="macro">vec!</span>[<span class="prelude-val">None</span>; max_num_states], |
| state_queue: Vec::with_capacity(<span class="number">100</span>), |
| num_offsets: num_offsets, |
| } |
| } |
| |
| <span class="kw">fn </span>num_states(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.state_queue.len() |
| } |
| |
| <span class="kw">fn </span>max_num_states(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.state_index.len() |
| } |
| |
| <span class="kw">fn </span>get_or_allocate(<span class="kw-2">&mut </span><span class="self">self</span>, parametric_state: ParametricState) -> u32 { |
| <span class="kw">let </span>bucket = (parametric_state.shape_id <span class="kw">as </span>usize) * <span class="self">self</span>.num_offsets |
| + parametric_state.offset <span class="kw">as </span>usize; |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(state_id) = <span class="self">self</span>.state_index[bucket] { |
| <span class="kw">return </span>state_id; |
| } |
| <span class="kw">let </span>new_state = <span class="self">self</span>.state_queue.len() <span class="kw">as </span>u32; |
| <span class="self">self</span>.state_queue.push(parametric_state); |
| <span class="self">self</span>.state_index[bucket] = <span class="prelude-val">Some</span>(new_state); |
| new_state |
| } |
| |
| <span class="kw">fn </span>get(<span class="kw-2">&</span><span class="self">self</span>, state_id: u32) -> ParametricState { |
| <span class="self">self</span>.state_queue[state_id <span class="kw">as </span>usize] |
| } |
| } |
| |
| <span class="kw">pub struct </span>ParametricDFA { |
| distance: Vec<u8>, |
| transitions: Vec<Transition>, |
| max_distance: u8, |
| transition_stride: usize, |
| diameter: usize, |
| } |
| |
| <span class="kw">impl </span>ParametricDFA { |
| <span class="kw">pub fn </span>initial_state() -> ParametricState { |
| ParametricState { |
| shape_id: <span class="number">1</span>, |
| offset: <span class="number">0</span>, |
| } |
| } |
| |
| <span class="comment">// Returns true iff whatever characters come afterward, we will never reach |
| // a shorter distance |
| </span><span class="kw">fn </span>is_prefix_sink(<span class="kw-2">&</span><span class="self">self</span>, state: ParametricState, query_len: usize) -> bool { |
| <span class="kw">if </span>state.is_dead_end() { |
| <span class="kw">return </span><span class="bool-val">true</span>; |
| } |
| <span class="kw">let </span>remaining_offset: usize = query_len - state.offset <span class="kw">as </span>usize; |
| <span class="kw">if </span>remaining_offset < <span class="self">self</span>.diameter { |
| <span class="kw">let </span>state_distances = <span class="kw-2">&</span><span class="self">self</span>.distance[(<span class="self">self</span>.diameter * state.shape_id <span class="kw">as </span>usize)..]; |
| <span class="kw">let </span>prefix_distance = state_distances[remaining_offset]; |
| <span class="kw">if </span>prefix_distance > <span class="self">self</span>.max_distance { |
| <span class="kw">return </span><span class="bool-val">false</span>; |
| } |
| <span class="kw">for </span>potential_distance <span class="kw">in </span>state_distances[..remaining_offset].iter().cloned() { |
| <span class="kw">if </span>potential_distance < prefix_distance { |
| <span class="kw">return </span><span class="bool-val">false</span>; |
| } |
| } |
| <span class="bool-val">true |
| </span>} <span class="kw">else </span>{ |
| <span class="bool-val">false |
| </span>} |
| } |
| |
| <span class="doccomment">/// Builds a [DFA] for the given query. If `prefix` is set to `true`, the resulting |
| /// DFA will match whenever the `query` is a prefix of the input being processed. |
| </span><span class="kw">pub fn </span>build_dfa(<span class="kw-2">&</span><span class="self">self</span>, query: <span class="kw-2">&</span>str, prefix: bool) -> DFA { |
| <span class="self">self</span>.build_custom_dfa(query, prefix, <span class="bool-val">false</span>) |
| } |
| |
| <span class="doccomment">/// Builds a [DFA] for the given query. If `prefix` is set to `true`, the resulting |
| /// DFA will match whenever the `query` is a prefix of the input being processed. |
| /// If `use_applied_distance` is set to `true`, the distance being reported isn't the |
| /// "absolute distance" for the query but rather the distance (number of edits) which |
| /// have been applied so far. |
| </span><span class="kw">pub fn </span>build_custom_dfa(<span class="kw-2">&</span><span class="self">self</span>, query: <span class="kw-2">&</span>str, prefix: bool, use_applied_distance: bool) -> DFA { |
| <span class="kw">let </span>query_chars: Vec<char> = query.chars().collect(); |
| <span class="kw">let </span>query_len = query_chars.len(); |
| <span class="kw">let </span>alphabet = Alphabet::for_query_chars(<span class="kw-2">&</span>query_chars); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>parametric_state_index = ParametricStateIndex::new(query_len, <span class="self">self</span>.num_states()); |
| <span class="kw">let </span>max_num_states = parametric_state_index.max_num_states(); |
| |
| <span class="kw">let </span>dead_end_state_id = parametric_state_index.get_or_allocate(ParametricState::empty()); |
| <span class="macro">assert_eq!</span>(dead_end_state_id, <span class="number">0</span>); |
| <span class="kw">let </span>initial_state_id = |
| parametric_state_index.get_or_allocate(ParametricDFA::initial_state()); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>dfa_builder = Utf8DFABuilder::with_max_num_states(max_num_states); |
| <span class="kw">let </span>mask = (<span class="number">1 </span><< <span class="self">self</span>.diameter) - <span class="number">1</span>; |
| |
| <span class="kw">for </span>state_id <span class="kw">in </span><span class="number">0u32</span>.. { |
| <span class="kw">if </span>state_id == parametric_state_index.num_states() <span class="kw">as </span>u32 { |
| <span class="kw">break</span>; |
| } |
| <span class="kw">let </span>state = parametric_state_index.get(state_id); |
| <span class="kw">let </span>distance = <span class="kw">if </span>use_applied_distance { |
| <span class="self">self</span>.applied_distance(state) |
| } <span class="kw">else </span>{ |
| <span class="self">self</span>.distance(state, query_len) |
| }; |
| |
| <span class="kw">if </span>prefix && <span class="self">self</span>.is_prefix_sink(state, query_len) { |
| dfa_builder.add_state(state_id, distance, state_id); |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span>default_successor = <span class="self">self</span>.transition(state, <span class="number">0u32</span>).apply(state); |
| <span class="kw">let </span>default_successor_id = |
| parametric_state_index.get_or_allocate(default_successor); |
| <span class="kw">let </span><span class="kw-2">mut </span>state_builder = |
| dfa_builder.add_state(state_id, distance, default_successor_id); |
| <span class="kw">for </span><span class="kw-2">&</span>(<span class="kw-2">ref </span>chr, <span class="kw-2">ref </span>characteristic_vec) <span class="kw">in </span>alphabet.iter() { |
| <span class="kw">let </span>chi = characteristic_vec.shift_and_mask(state.offset <span class="kw">as </span>usize, mask); |
| <span class="kw">let </span>dest_state: ParametricState = <span class="self">self</span>.transition(state, chi).apply(state); |
| <span class="kw">let </span>dest_state_id = parametric_state_index.get_or_allocate(dest_state); |
| state_builder.add_transition(<span class="kw-2">*</span>chr, dest_state_id); |
| } |
| } |
| } |
| |
| dfa_builder.set_initial_state(initial_state_id); |
| dfa_builder.build() |
| } |
| |
| <span class="kw">pub fn </span>num_states(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.transitions.len() / <span class="self">self</span>.transition_stride |
| } |
| |
| <span class="comment">// only for debug |
| </span><span class="attribute">#[cfg(test)] |
| </span><span class="kw">pub fn </span>compute_distance(<span class="kw-2">&</span><span class="self">self</span>, left: <span class="kw-2">&</span>str, right: <span class="kw-2">&</span>str) -> Distance { |
| <span class="kw">use </span><span class="kw">super</span>::levenshtein_nfa::compute_characteristic_vector; |
| <span class="kw">use </span>std::cmp; |
| <span class="kw">let </span><span class="kw-2">mut </span>state = <span class="self">Self</span>::initial_state(); |
| <span class="kw">let </span>left_chars: Vec<char> = left.chars().collect(); |
| <span class="kw">for </span>chr <span class="kw">in </span>right.chars() { |
| <span class="kw">let </span>start = state.offset <span class="kw">as </span>usize; |
| <span class="kw">let </span>stop = cmp::min(start + <span class="self">self</span>.diameter, left_chars.len()); |
| <span class="kw">let </span>chi = compute_characteristic_vector(<span class="kw-2">&</span>left_chars[start..stop], chr) <span class="kw">as </span>u32; |
| state = <span class="self">self</span>.transition(state, chi).apply(state); |
| <span class="kw">if </span>state.is_dead_end() { |
| <span class="kw">return </span>Distance::AtLeast(<span class="self">self</span>.max_distance + <span class="number">1u8</span>); |
| } |
| } |
| <span class="self">self</span>.distance(state, left.len()) |
| } |
| |
| <span class="kw">pub fn </span>distance(<span class="kw-2">&</span><span class="self">self</span>, state: ParametricState, query_len: usize) -> Distance { |
| <span class="kw">let </span>remaining_offset: usize = query_len - state.offset <span class="kw">as </span>usize; |
| <span class="kw">if </span>state.is_dead_end() || remaining_offset >= <span class="self">self</span>.diameter { |
| Distance::AtLeast(<span class="self">self</span>.max_distance + <span class="number">1u8</span>) |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span>d = <span class="self">self</span>.distance[(<span class="self">self</span>.diameter * state.shape_id <span class="kw">as </span>usize) + remaining_offset]; |
| <span class="kw">if </span>d > <span class="self">self</span>.max_distance { |
| Distance::AtLeast(d) |
| } <span class="kw">else </span>{ |
| Distance::Exact(d) |
| } |
| } |
| } |
| |
| <span class="kw">pub fn </span>applied_distance(<span class="kw-2">&</span><span class="self">self</span>, state: ParametricState) -> Distance { |
| <span class="kw">let </span>d = <span class="self">self</span>.distance[<span class="self">self</span>.diameter * state.shape_id <span class="kw">as </span>usize]; |
| <span class="kw">if </span>d > <span class="self">self</span>.max_distance { |
| Distance::AtLeast(d) |
| } <span class="kw">else </span>{ |
| Distance::Exact(d) |
| } |
| } |
| |
| <span class="kw">pub fn </span>transition(<span class="kw-2">&</span><span class="self">self</span>, state: ParametricState, chi: u32) -> Transition { |
| <span class="macro">assert!</span>((chi <span class="kw">as </span>usize) < <span class="self">self</span>.transition_stride); |
| <span class="self">self</span>.transitions[<span class="self">self</span>.transition_stride * state.shape_id <span class="kw">as </span>usize + chi <span class="kw">as </span>usize] |
| } |
| |
| <span class="kw">pub fn </span>from_nfa(nfa: <span class="kw-2">&</span>LevenshteinNFA) -> ParametricDFA { |
| <span class="kw">let </span><span class="kw-2">mut </span>index: Index<MultiState> = Index::new(); |
| index.get_or_allocate(<span class="kw-2">&</span>MultiState::empty()); |
| <span class="kw">let </span>initial_state = nfa.initial_states(); |
| index.get_or_allocate(<span class="kw-2">&</span>initial_state); |
| |
| <span class="kw">let </span>max_distance = nfa.max_distance(); |
| <span class="kw">let </span>multistate_diameter = nfa.multistate_diameter(); |
| <span class="kw">let </span><span class="kw-2">mut </span>transitions: Vec<Transition> = <span class="macro">vec!</span>[]; |
| |
| <span class="kw">let </span>num_chi = <span class="number">1 </span><< multistate_diameter; |
| <span class="kw">let </span>chi_values: Vec<u64> = (<span class="number">0</span>..num_chi).collect(); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>dest_multistate = MultiState::empty(); |
| |
| <span class="kw">for </span>state_id <span class="kw">in </span><span class="number">0</span>.. { |
| <span class="kw">if </span>state_id == index.len() { |
| <span class="kw">break</span>; |
| } |
| <span class="kw">for </span><span class="kw-2">&</span>chi <span class="kw">in </span><span class="kw-2">&</span>chi_values { |
| { |
| <span class="kw">let </span>multistate: <span class="kw-2">&</span>MultiState = index.get_from_id(state_id); |
| nfa.transition(multistate, <span class="kw-2">&mut </span>dest_multistate, chi); |
| } |
| <span class="kw">let </span>translation = dest_multistate.normalize(); |
| <span class="kw">let </span>dest_id = index.get_or_allocate(<span class="kw-2">&</span>dest_multistate); |
| transitions.push(Transition { |
| dest_shape_id: dest_id, |
| delta_offset: translation, |
| }); |
| } |
| } |
| |
| <span class="kw">let </span>num_states = index.len(); |
| <span class="kw">let </span>multistate_diameter = multistate_diameter <span class="kw">as </span>usize; |
| <span class="kw">let </span><span class="kw-2">mut </span>distance: Vec<u8> = Vec::with_capacity(multistate_diameter * num_states <span class="kw">as </span>usize); |
| |
| <span class="kw">for </span>state_id <span class="kw">in </span><span class="number">0</span>..num_states { |
| <span class="kw">let </span>multistate = index.get_from_id(state_id); |
| <span class="kw">for </span>offset <span class="kw">in </span><span class="number">0</span>..multistate_diameter { |
| <span class="kw">let </span>dist = nfa.multistate_distance(multistate, offset <span class="kw">as </span>u32).to_u8(); |
| distance.push(dist); |
| } |
| } |
| |
| ParametricDFA { |
| transition_stride: num_chi <span class="kw">as </span>usize, |
| distance, |
| max_distance, |
| transitions, |
| diameter: multistate_diameter <span class="kw">as </span>usize, |
| } |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="levenshtein_automata" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
