Inital commit

common/trie.cpp

@@ -0,0 +1,123 @@
+#include "trie.h"
+
+#include "unicode.h"
+
+#include <deque>
+
+common_trie::match_result common_trie::check_at(std::string_view sv, size_t start_pos) const {
+    size_t current = 0; // Start at root
+    size_t pos = start_pos;
+
+    // LOG_DBG("%s: checking at pos %zu, sv='%s'\n", __func__, start_pos, std::string(sv).c_str());
+
+    while (pos < sv.size()) {
+        auto result = common_parse_utf8_codepoint(sv, pos);
+        if (result.status != utf8_parse_result::SUCCESS) {
+            break;
+        }
+
+        auto it = nodes[current].children.find(result.codepoint);
+        if (it == nodes[current].children.end()) {
+            // Can't continue matching
+            return match_result{match_result::NO_MATCH};
+        }
+
+        current = it->second;
+        pos += result.bytes_consumed;
+
+        // Check if we've matched a complete word
+        if (nodes[current].pattern >= 0) {
+            return match_result{match_result::COMPLETE_MATCH};
+        }
+    }
+
+    // Reached end of input while still in the trie (not at root)
+    if (current != 0) {
+        // We're in the middle of a potential match
+        return match_result{match_result::PARTIAL_MATCH};
+    }
+
+    // Reached end at root (no match)
+    return match_result{match_result::NO_MATCH};
+}
+
+int32_t common_trie::insert(const std::string & word) {
+    std::vector<uint32_t> symbols;
+    size_t pos = 0;
+    while (pos < word.length()) {
+        auto result = common_parse_utf8_codepoint(word, pos);
+        if (result.status != utf8_parse_result::SUCCESS) {
+            break;
+        }
+
+        symbols.push_back(result.codepoint);
+        pos += result.bytes_consumed;
+    }
+    return insert(symbols);
+}
+
+int32_t common_trie::insert(const std::vector<uint32_t> & symbols) {
+    size_t current = 0;
+    for (uint32_t ch : symbols) {
+        auto it = nodes[current].children.find(ch);
+        if (it == nodes[current].children.end()) {
+            size_t child = create_node();
+            nodes[current].children[ch] = child;
+            current = child;
+        } else {
+            current = it->second;
+        }
+    }
+    if (nodes[current].pattern < 0) {
+        nodes[current].pattern = n_patterns++;
+    }
+    return nodes[current].pattern;
+}
+
+common_aho_corasick::common_aho_corasick(common_trie trie) : t(std::move(trie)) {
+    const auto & nodes = t.nodes;
+    const size_t n = nodes.size();
+
+    fail.assign(n, 0);
+    order.reserve(n);
+
+    std::deque<size_t> queue{ 0 };
+    while (!queue.empty()) {
+        size_t u = queue.front();
+        queue.pop_front();
+        order.push_back(u);
+        for (const auto & [ch, v] : nodes[u].children) {
+            if (u != 0) {
+                size_t f = fail[u];
+                while (f && nodes[f].children.find(ch) == nodes[f].children.end()) {
+                    f = fail[f];
+                }
+                auto it = nodes[f].children.find(ch);
+                fail[v] = (it != nodes[f].children.end() && it->second != v) ? it->second : 0;
+            }
+            queue.push_back(v);
+        }
+    }
+
+    // fail[u] points to a strictly shorter suffix, so the first pattern found on
+    // the fail chain (including u itself) is the longest pattern ending at u
+    match.assign(n, -1);
+    for (size_t u : order) {
+        match[u] = nodes[u].pattern >= 0 ? nodes[u].pattern : (u != 0 ? match[fail[u]] : -1);
+    }
+
+    for (const auto & node : nodes) {
+        for (const auto & [ch, v] : node.children) {
+            alphabet.insert(ch);
+        }
+    }
+}
+
+size_t common_aho_corasick::next(size_t state, uint32_t ch) const {
+    const auto & nodes = t.nodes;
+    while (state && nodes[state].children.find(ch) == nodes[state].children.end()) {
+        state = fail[state];
+    }
+    auto it = nodes[state].children.find(ch);
+    return it != nodes[state].children.end() ? it->second : 0;
+}