261 lines
11 KiB
C++
261 lines
11 KiB
C++
// 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 max_matches 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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#include "../Utils/ASCIIFolding.hpp"
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// Public interface
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namespace fts {
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using char_type = wchar_t;
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using pos_type = uint16_t;
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static constexpr pos_type stopper = pos_type(-1);
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static constexpr int max_matches = 255;
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static bool fuzzy_match(char_type const * pattern, char_type const * str, int & outScore);
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static bool fuzzy_match(char_type const * pattern, char_type const * str, int & outScore, pos_type * matches);
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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_type * pattern, const char_type * str, int & outScore, const char_type * const strBegin,
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pos_type const * srcMatches, pos_type * newMatches, int nextMatch,
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int recursionCount, const int recursionLimit);
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static void copy_matches(pos_type * dst, pos_type const* src);
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}
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// Public interface
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static bool fuzzy_match(char_type const * pattern, char_type const * str, int & outScore) {
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pos_type matches[max_matches + 1]; // with the room for the stopper
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matches[0] = stopper;
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return fuzzy_match(pattern, str, outScore, matches);
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}
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static bool fuzzy_match(char_type const * pattern, char_type const * str, int & outScore, pos_type * matches) {
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int recursionCount = 0;
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static constexpr int recursionLimit = 10;
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return fuzzy_internal::fuzzy_match_recursive(pattern, str, outScore, str, nullptr, matches, 0, recursionCount, recursionLimit);
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}
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// Private implementation
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static bool fuzzy_internal::fuzzy_match_recursive(
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// Pattern to match over str.
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const char_type * pattern,
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// Text to match the pattern over.
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const char_type * str,
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// Score of the pattern matching str. Output variable.
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int & outScore,
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// The very start of str, for calculating indices of matches and for calculating matches from the start of the input string.
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const char_type * const strBegin,
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// Matches when entering this function.
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pos_type const * srcMatches,
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// Output matches.
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pos_type * matches,
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// Number of matched characters stored in srcMatches when entering this function, also tracking the successive matches.
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int nextMatch,
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// Recursion count is input / output to track the maximum depth reached.
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// Was given by reference &recursionCount, see discussion in https://github.com/forrestthewoods/lib_fts/issues/21
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// int & recursionCount,
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int recursionCount,
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const int recursionLimit)
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{
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// Count recursions
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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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pos_type bestRecursiveMatches[max_matches + 1]; // with the room for the stopper
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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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int num_matched = std::tolower(*pattern) == std::tolower(*str) ? 1 : 0;
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bool folded_match = false;
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if (! num_matched) {
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char tmp[4];
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char *end = Slic3r::fold_to_ascii(*str, tmp);
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char *c = tmp;
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for (const wchar_t* d = pattern; c != end && *d != 0 && wchar_t(std::tolower(*c)) == std::tolower(*d); ++c, ++d);
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if (c == end) {
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folded_match = true;
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num_matched = end - tmp;
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}
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}
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// Found match
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if (num_matched) {
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// Supplied matches buffer was too short
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if (nextMatch + num_matched > max_matches)
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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, sizeof(pos_type) * (nextMatch + 1)); // including the stopper
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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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pos_type recursiveMatches[max_matches + 1]; // with the room for the stopper
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int recursiveScore;
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if (fuzzy_match_recursive(pattern, str + 1, recursiveScore, strBegin, matches, recursiveMatches, nextMatch, recursionCount, recursionLimit)) {
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// Pick best recursive score
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if (!recursiveMatch || recursiveScore > bestRecursiveScore) {
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copy_matches(bestRecursiveMatches, recursiveMatches);
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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++] = (pos_type)(str - strBegin);
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// Write a stopper sign.
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matches[nextMatch] = stopper;
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// Advance pattern by the number of matched characters (could be more if ASCII folding triggers in).
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pattern += num_matched;
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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';
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// Calculate score
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if (matched) {
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static constexpr int sequential_bonus = 15; // bonus for adjacent matches
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static constexpr int separator_bonus = 30; // bonus if match occurs after a separator
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static constexpr int camel_bonus = 30; // bonus if match is uppercase and prev is lower
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static constexpr int first_letter_bonus = 15; // bonus if the first letter is matched
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static constexpr int leading_letter_penalty = -5; // penalty applied for every letter in str before the first match
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static constexpr int max_leading_letter_penalty = -15; // maximum penalty for leading letters
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static constexpr 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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// Start of the first group that contains matches[0].
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const char_type *group_start = strBegin + matches[0];
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for (const char_type *c = group_start; c >= strBegin && *c != ':'; -- c)
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if (*c != ' ' && *c != '\t')
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group_start = c;
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// Apply leading letter penalty or bonus.
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outScore += matches[0] == int(group_start - strBegin) ?
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first_letter_bonus :
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std::max((matches[0] - int(group_start - strBegin)) * leading_letter_penalty, max_leading_letter_penalty);
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// Apply unmatched letters after the end penalty
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// outScore += (int(str - group_start) - matches[nextMatch-1] + 1) * unmatched_letter_penalty;
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// Apply unmatched penalty
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outScore += (int(str - group_start) - nextMatch) * unmatched_letter_penalty;
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// Apply ordering bonuses
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int sequential_state = sequential_bonus;
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for (int i = 0; i < nextMatch; ++i) {
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pos_type currIdx = matches[i];
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// Check for bonuses based on neighbor character value
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if (currIdx > 0) {
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if (i > 0 && currIdx == matches[i - 1] + 1) {
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// Sequential
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outScore += sequential_state;
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// Exponential grow of the sequential bonus.
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sequential_state = std::min(5 * sequential_bonus, sequential_state + sequential_state / 3);
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} else {
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// Reset the sequential bonus exponential grow.
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sequential_state = sequential_bonus;
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}
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char_type prev = strBegin[currIdx - 1];
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/*
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// Camel case
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if (std::islower(prev) && std::isupper(strBegin[currIdx]))
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outScore += camel_bonus;
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*/
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// Separator
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if (prev == '_' || prev == ' ')
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outScore += separator_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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copy_matches(matches, bestRecursiveMatches);
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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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// Copy matches up to a stopper.
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static void fuzzy_internal::copy_matches(pos_type * dst, pos_type const* src)
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{
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while (*src != stopper)
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*dst++ = *src++;
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*dst = stopper;
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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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