124 lines
3.7 KiB
C++
124 lines
3.7 KiB
C++
#include "trie.h"
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#include "unicode.h"
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#include <deque>
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common_trie::match_result common_trie::check_at(std::string_view sv, size_t start_pos) const {
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size_t current = 0; // Start at root
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size_t pos = start_pos;
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// LOG_DBG("%s: checking at pos %zu, sv='%s'\n", __func__, start_pos, std::string(sv).c_str());
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while (pos < sv.size()) {
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auto result = common_parse_utf8_codepoint(sv, pos);
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if (result.status != utf8_parse_result::SUCCESS) {
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break;
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}
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auto it = nodes[current].children.find(result.codepoint);
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if (it == nodes[current].children.end()) {
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// Can't continue matching
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return match_result{match_result::NO_MATCH};
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}
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current = it->second;
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pos += result.bytes_consumed;
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// Check if we've matched a complete word
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if (nodes[current].pattern >= 0) {
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return match_result{match_result::COMPLETE_MATCH};
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}
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}
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// Reached end of input while still in the trie (not at root)
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if (current != 0) {
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// We're in the middle of a potential match
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return match_result{match_result::PARTIAL_MATCH};
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}
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// Reached end at root (no match)
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return match_result{match_result::NO_MATCH};
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}
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int32_t common_trie::insert(const std::string & word) {
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std::vector<uint32_t> symbols;
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size_t pos = 0;
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while (pos < word.length()) {
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auto result = common_parse_utf8_codepoint(word, pos);
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if (result.status != utf8_parse_result::SUCCESS) {
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break;
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}
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symbols.push_back(result.codepoint);
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pos += result.bytes_consumed;
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}
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return insert(symbols);
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}
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int32_t common_trie::insert(const std::vector<uint32_t> & symbols) {
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size_t current = 0;
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for (uint32_t ch : symbols) {
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auto it = nodes[current].children.find(ch);
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if (it == nodes[current].children.end()) {
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size_t child = create_node();
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nodes[current].children[ch] = child;
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current = child;
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} else {
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current = it->second;
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}
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}
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if (nodes[current].pattern < 0) {
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nodes[current].pattern = n_patterns++;
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}
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return nodes[current].pattern;
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}
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common_aho_corasick::common_aho_corasick(common_trie trie) : t(std::move(trie)) {
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const auto & nodes = t.nodes;
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const size_t n = nodes.size();
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fail.assign(n, 0);
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order.reserve(n);
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std::deque<size_t> queue{ 0 };
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while (!queue.empty()) {
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size_t u = queue.front();
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queue.pop_front();
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order.push_back(u);
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for (const auto & [ch, v] : nodes[u].children) {
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if (u != 0) {
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size_t f = fail[u];
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while (f && nodes[f].children.find(ch) == nodes[f].children.end()) {
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f = fail[f];
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}
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auto it = nodes[f].children.find(ch);
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fail[v] = (it != nodes[f].children.end() && it->second != v) ? it->second : 0;
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}
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queue.push_back(v);
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}
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}
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// fail[u] points to a strictly shorter suffix, so the first pattern found on
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// the fail chain (including u itself) is the longest pattern ending at u
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match.assign(n, -1);
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for (size_t u : order) {
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match[u] = nodes[u].pattern >= 0 ? nodes[u].pattern : (u != 0 ? match[fail[u]] : -1);
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}
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for (const auto & node : nodes) {
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for (const auto & [ch, v] : node.children) {
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alphabet.insert(ch);
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}
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}
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}
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size_t common_aho_corasick::next(size_t state, uint32_t ch) const {
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const auto & nodes = t.nodes;
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while (state && nodes[state].children.find(ch) == nodes[state].children.end()) {
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state = fail[state];
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}
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auto it = nodes[state].children.find(ch);
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return it != nodes[state].children.end() ? it->second : 0;
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}
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