diff options
Diffstat (limited to 'vendor/sebastian/diff/src/TimeEfficientLongestCommonSubsequenceCalculator.php')
-rw-r--r-- | vendor/sebastian/diff/src/TimeEfficientLongestCommonSubsequenceCalculator.php | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/vendor/sebastian/diff/src/TimeEfficientLongestCommonSubsequenceCalculator.php b/vendor/sebastian/diff/src/TimeEfficientLongestCommonSubsequenceCalculator.php new file mode 100644 index 000000000..fd19cac76 --- /dev/null +++ b/vendor/sebastian/diff/src/TimeEfficientLongestCommonSubsequenceCalculator.php @@ -0,0 +1,70 @@ +<?php declare(strict_types=1); +/* + * This file is part of sebastian/diff. + * + * (c) Sebastian Bergmann <[email protected]> + * + * 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); + } +} |