annotate vendor/sebastian/diff/src/TimeEfficientLongestCommonSubsequenceCalculator.php @ 19:fa3358dc1485 tip

Add ndrum files
author Chris Cannam
date Wed, 28 Aug 2019 13:14:47 +0100
parents 1fec387a4317
children
rev   line source
Chris@14 1 <?php declare(strict_types=1);
Chris@14 2 /*
Chris@14 3 * This file is part of sebastian/diff.
Chris@14 4 *
Chris@14 5 * (c) Sebastian Bergmann <sebastian@phpunit.de>
Chris@14 6 *
Chris@14 7 * For the full copyright and license information, please view the LICENSE
Chris@14 8 * file that was distributed with this source code.
Chris@14 9 */
Chris@14 10
Chris@14 11 namespace SebastianBergmann\Diff;
Chris@14 12
Chris@14 13 final class TimeEfficientLongestCommonSubsequenceCalculator implements LongestCommonSubsequenceCalculator
Chris@14 14 {
Chris@14 15 /**
Chris@14 16 * {@inheritdoc}
Chris@14 17 */
Chris@14 18 public function calculate(array $from, array $to): array
Chris@14 19 {
Chris@14 20 $common = [];
Chris@14 21 $fromLength = \count($from);
Chris@14 22 $toLength = \count($to);
Chris@14 23 $width = $fromLength + 1;
Chris@14 24 $matrix = new \SplFixedArray($width * ($toLength + 1));
Chris@14 25
Chris@14 26 for ($i = 0; $i <= $fromLength; ++$i) {
Chris@14 27 $matrix[$i] = 0;
Chris@14 28 }
Chris@14 29
Chris@14 30 for ($j = 0; $j <= $toLength; ++$j) {
Chris@14 31 $matrix[$j * $width] = 0;
Chris@14 32 }
Chris@14 33
Chris@14 34 for ($i = 1; $i <= $fromLength; ++$i) {
Chris@14 35 for ($j = 1; $j <= $toLength; ++$j) {
Chris@14 36 $o = ($j * $width) + $i;
Chris@14 37 $matrix[$o] = \max(
Chris@14 38 $matrix[$o - 1],
Chris@14 39 $matrix[$o - $width],
Chris@14 40 $from[$i - 1] === $to[$j - 1] ? $matrix[$o - $width - 1] + 1 : 0
Chris@14 41 );
Chris@14 42 }
Chris@14 43 }
Chris@14 44
Chris@14 45 $i = $fromLength;
Chris@14 46 $j = $toLength;
Chris@14 47
Chris@14 48 while ($i > 0 && $j > 0) {
Chris@14 49 if ($from[$i - 1] === $to[$j - 1]) {
Chris@14 50 $common[] = $from[$i - 1];
Chris@14 51 --$i;
Chris@14 52 --$j;
Chris@14 53 } else {
Chris@14 54 $o = ($j * $width) + $i;
Chris@14 55
Chris@14 56 if ($matrix[$o - $width] > $matrix[$o - 1]) {
Chris@14 57 --$j;
Chris@14 58 } else {
Chris@14 59 --$i;
Chris@14 60 }
Chris@14 61 }
Chris@14 62 }
Chris@14 63
Chris@14 64 return \array_reverse($common);
Chris@14 65 }
Chris@14 66 }