Subversion-Projekte lars-tiefland.laravel_shop

<?php declare(strict_types=1);

/*

 * This file is part of sebastian/diff.

 *

 * (c) Sebastian Bergmann <sebastian@phpunit.de>

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */

namespace SebastianBergmann\Diff;

use function array_reverse;

use function count;

use function max;

use SplFixedArray;

final class TimeEfficientLongestCommonSubsequenceCalculator implements LongestCommonSubsequenceCalculator

{

    /**

     * {@inheritdoc}

     */

    public function calculate(array $from, array $to): array

    {

        $common     = [];

        $fromLength = count($from);

        $toLength   = count($to);

        $width      = $fromLength + 1;

        $matrix     = new SplFixedArray($width * ($toLength + 1));

        for ($i = 0; $i <= $fromLength; ++$i) {

            $matrix[$i] = 0;

        }

        for ($j = 0; $j <= $toLength; ++$j) {

            $matrix[$j * $width] = 0;

        }

        for ($i = 1; $i <= $fromLength; ++$i) {

            for ($j = 1; $j <= $toLength; ++$j) {

                $o          = ($j * $width) + $i;

                $matrix[$o] = max(

                    $matrix[$o - 1],

                    $matrix[$o - $width],

                    $from[$i - 1] === $to[$j - 1] ? $matrix[$o - $width - 1] + 1 : 0

                );

            }

        }

        $i = $fromLength;

        $j = $toLength;

        while ($i > 0 && $j > 0) {

            if ($from[$i - 1] === $to[$j - 1]) {

                $common[] = $from[$i - 1];

                --$i;

                --$j;

            } else {

                $o = ($j * $width) + $i;

                if ($matrix[$o - $width] > $matrix[$o - 1]) {

                    --$j;

                } else {

                    --$i;

                }

            }

        }

        return array_reverse($common);

    }

}