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596c806fa4
- yeah that - also Index::getTags for getting all tags in index now
221 lines
No EOL
8.5 KiB
C++
Vendored
221 lines
No EOL
8.5 KiB
C++
Vendored
// LICENSE
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//
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// This software is dual-licensed to the public domain and under the following
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// license: you are granted a perpetual, irrevocable license to copy, modify,
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// publish, and distribute this file as you see fit.
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//
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// VERSION
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// 0.2.0 (2017-02-18) Scored matches perform exhaustive search for best score
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// 0.1.0 (2016-03-28) Initial release
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//
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// AUTHOR
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// Forrest Smith
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//
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// NOTES
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// Compiling
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// You MUST add '#define FTS_FUZZY_MATCH_IMPLEMENTATION' before including this header in ONE source file to create implementation.
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//
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// fuzzy_match_simple(...)
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// Returns true if each character in pattern is found sequentially within str
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//
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// fuzzy_match(...)
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// Returns true if pattern is found AND calculates a score.
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// Performs exhaustive search via recursion to find all possible matches and match with highest score.
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// Scores values have no intrinsic meaning. Possible score range is not normalized and varies with pattern.
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// Recursion is limited internally (default=10) to prevent degenerate cases (pattern="aaaaaa" str="aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
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// Uses uint8_t for match indices. Therefore patterns are limited to 256 characters.
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// Score system should be tuned for YOUR use case. Words, sentences, file names, or method names all prefer different tuning.
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#ifndef FTS_FUZZY_MATCH_H
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#define FTS_FUZZY_MATCH_H
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#include <cstdint> // uint8_t
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#include <ctype.h> // ::tolower, ::toupper
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#include <cstring> // memcpy
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#include <cstdio>
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// Public interface
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namespace fts {
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static bool fuzzy_match_simple(char const * pattern, char const * str);
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static bool fuzzy_match(char const * pattern, char const * str, int & outScore);
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static bool fuzzy_match(char const * pattern, char const * str, int & outScore, uint8_t * matches, int maxMatches);
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}
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#ifdef FTS_FUZZY_MATCH_IMPLEMENTATION
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namespace fts {
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// Forward declarations for "private" implementation
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namespace fuzzy_internal {
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static bool fuzzy_match_recursive(const char * pattern, const char * str, int & outScore, const char * strBegin,
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uint8_t const * srcMatches, uint8_t * newMatches, int maxMatches, int nextMatch,
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int & recursionCount, int recursionLimit);
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}
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// Public interface
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static bool fuzzy_match_simple(char const * pattern, char const * str) {
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while (*pattern != '\0' && *str != '\0') {
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if (tolower(*pattern) == tolower(*str))
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++pattern;
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++str;
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}
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return *pattern == '\0' ? true : false;
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}
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static bool fuzzy_match(char const * pattern, char const * str, int & outScore) {
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uint8_t matches[256];
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return fuzzy_match(pattern, str, outScore, matches, sizeof(matches));
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}
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static bool fuzzy_match(char const * pattern, char const * str, int & outScore, uint8_t * matches, int maxMatches) {
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int recursionCount = 0;
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int recursionLimit = 10;
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return fuzzy_internal::fuzzy_match_recursive(pattern, str, outScore, str, nullptr, matches, maxMatches, 0, recursionCount, recursionLimit);
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}
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// Private implementation
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static bool fuzzy_internal::fuzzy_match_recursive(const char * pattern, const char * str, int & outScore,
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const char * strBegin, uint8_t const * srcMatches, uint8_t * matches, int maxMatches,
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int nextMatch, int & recursionCount, int recursionLimit)
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{
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// Count recursions
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++recursionCount;
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if (recursionCount >= recursionLimit)
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return false;
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// Detect end of strings
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if (*pattern == '\0' || *str == '\0')
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return false;
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// Recursion params
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bool recursiveMatch = false;
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uint8_t bestRecursiveMatches[256];
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int bestRecursiveScore = 0;
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// Loop through pattern and str looking for a match
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bool first_match = true;
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while (*pattern != '\0' && *str != '\0') {
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// Found match
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if (tolower(*pattern) == tolower(*str)) {
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// Supplied matches buffer was too short
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if (nextMatch >= maxMatches)
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return false;
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// "Copy-on-Write" srcMatches into matches
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if (first_match && srcMatches) {
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memcpy(matches, srcMatches, nextMatch);
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first_match = false;
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}
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// Recursive call that "skips" this match
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uint8_t recursiveMatches[256];
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int recursiveScore;
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if (fuzzy_match_recursive(pattern, str + 1, recursiveScore, strBegin, matches, recursiveMatches, sizeof(recursiveMatches), nextMatch, recursionCount, recursionLimit)) {
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// Pick best recursive score
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if (!recursiveMatch || recursiveScore > bestRecursiveScore) {
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memcpy(bestRecursiveMatches, recursiveMatches, 256);
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bestRecursiveScore = recursiveScore;
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}
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recursiveMatch = true;
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}
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// Advance
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matches[nextMatch++] = (uint8_t)(str - strBegin);
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++pattern;
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}
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++str;
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}
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// Determine if full pattern was matched
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bool matched = *pattern == '\0' ? true : false;
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// Calculate score
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if (matched) {
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const int sequential_bonus = 15; // bonus for adjacent matches
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const int separator_bonus = 30; // bonus if match occurs after a separator
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const int camel_bonus = 30; // bonus if match is uppercase and prev is lower
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const int first_letter_bonus = 15; // bonus if the first letter is matched
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const int leading_letter_penalty = -5; // penalty applied for every letter in str before the first match
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const int max_leading_letter_penalty = -15; // maximum penalty for leading letters
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const int unmatched_letter_penalty = -1; // penalty for every letter that doesn't matter
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// Iterate str to end
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while (*str != '\0')
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++str;
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// Initialize score
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outScore = 100;
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// Apply leading letter penalty
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int penalty = leading_letter_penalty * matches[0];
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if (penalty < max_leading_letter_penalty)
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penalty = max_leading_letter_penalty;
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outScore += penalty;
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// Apply unmatched penalty
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int unmatched = (int)(str - strBegin) - nextMatch;
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outScore += unmatched_letter_penalty * unmatched;
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// Apply ordering bonuses
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for (int i = 0; i < nextMatch; ++i) {
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uint8_t currIdx = matches[i];
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if (i > 0) {
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uint8_t prevIdx = matches[i - 1];
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// Sequential
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if (currIdx == (prevIdx + 1))
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outScore += sequential_bonus;
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}
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// Check for bonuses based on neighbor character value
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if (currIdx > 0) {
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// Camel case
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char neighbor = strBegin[currIdx - 1];
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char curr = strBegin[currIdx];
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if (::islower(neighbor) && ::isupper(curr))
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outScore += camel_bonus;
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// Separator
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bool neighborSeparator = neighbor == '_' || neighbor == ' ';
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if (neighborSeparator)
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outScore += separator_bonus;
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}
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else {
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// First letter
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outScore += first_letter_bonus;
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}
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}
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}
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// Return best result
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if (recursiveMatch && (!matched || bestRecursiveScore > outScore)) {
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// Recursive score is better than "this"
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memcpy(matches, bestRecursiveMatches, maxMatches);
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outScore = bestRecursiveScore;
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return true;
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}
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else if (matched) {
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// "this" score is better than recursive
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return true;
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}
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else {
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// no match
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return false;
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}
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}
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} // namespace fts
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#endif // FTS_FUZZY_MATCH_IMPLEMENTATION
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#endif // FTS_FUZZY_MATCH_H
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