PHP port of https://github.com/joshaven/string_score

StringHelper.php

<?php
/**
 * Made by Erik Terwan
 * erik@erikterwan.com
 * https://erikterwan.com
 *
 * All rights reserved
 *
 * Created on 2019-03-26
 */

class StringHelper {
    /**
     * Score a string match
     * @param string $string
     * @param string $word
     * @param null|float $fuzziness
     * @return float|int
     */
    static function score($string, $word, $fuzziness = null) {
        // If the string is equal to the word, perfect match.
        if ($string == $word) { return 1; }

        // If it's not a perfect match and is empty return 0
        if ($word == "") { return 0; }

        $runningScore = 0;
        $charScore = 0;
        $finalScore = 0;
        $lString = strtolower($string);
        $strLength = strlen($string);

        $lWord = strtolower($word);
        $wordLength = strlen($word);

        $idxOf = null;
        $startAt = 0;
        $fuzzies = 1;

        $fuzzyFactor = null;

        // Cache fuzzyFactor for speed increase
        if ($fuzziness) { $fuzzyFactor = 1 - $fuzziness; }

        // Walk through word and add up scores.
        // Code duplication occurs to prevent checking fuzziness inside for loop
        if ($fuzziness) {
            for ($i = 0; $i < $wordLength; $i+=1) {
                $idxOf = strpos($lString, $lWord[$i], $startAt);

                if ($idxOf === false) {
                    $fuzzies += $fuzzyFactor;
                } else {
                    if ($startAt === $idxOf) {
                        // Consecutive letter & start-of-string Bonus
                        $charScore = 0.7;
                    } else {
                        $charScore = 0.1;

                        // Acronym Bonus
                        // Weighing Logic: Typing the first character of an acronym is as if you
                        // preceded it with two perfect character matches.
                        if ($string[$idxOf - 1] === ' ') {
                            $charScore += 0.8;
                        }
                    }

                    // Same case bonus.
                    if ($string[$idxOf] === $word[$i]) { $charScore += 0.1; }

                    // Update scores and startAt position for next round of indexOf
                    $runningScore += $charScore;
                    $startAt = $idxOf + 1;
                }
            }
        } else {
            for ($i = 0; $i < $wordLength; $i+=1) {
                $idxOf = strpos($lString, $lWord[$i], $startAt);

                if ($idxOf === false) { return 0; }

                if ($startAt === $idxOf) {
                    $charScore = 0.7;
                } else {
                    $charScore = 0.1;

                    if ($string[$idxOf - 1] === ' ') { $charScore += 0.8; }
                }

                if ($string[$idxOf] === $word[$i]) { $charScore += 0.1; }
                $runningScore += $charScore;
                $startAt = $idxOf + 1;
            }
        }

        // Reduce penalty for longer strings.
        $finalScore = 0.5 * ($runningScore / $strLength + $runningScore / $wordLength) / $fuzzies;

        if (($lWord[0] === $lString[0]) && ($finalScore < 0.85)) {
            $finalScore += 0.15;
        }

        return $finalScore;
    }
}