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<?php |
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namespace Caxy\HtmlDiff; |
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class LcsService |
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{ |
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/** |
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* @var null|callable |
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*/ |
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protected $comparator; |
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/** |
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* LcsService constructor. |
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* |
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* @param null|callable $comparator |
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*/ |
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public function __construct($comparator = null) |
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{ |
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if (null === $comparator) { |
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$comparator = function ($a, $b) { |
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return $a === $b; |
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}; |
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} |
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$this->comparator = $comparator; |
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} |
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/** |
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* @param array $a |
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* @param array $b |
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* |
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* @return array |
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*/ |
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public function longestCommonSubsequence(array $a, array $b) |
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{ |
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$c = array(); |
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$m = count($a); |
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$n = count($b); |
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$comparator = $this->comparator; |
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for ($i = 0; $i <= $m; $i++) { |
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$c[$i][0] = 0; |
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} |
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for ($j = 0; $j <= $n; $j++) { |
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$c[0][$j] = 0; |
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} |
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for ($i = 1; $i <= $m; $i++) { |
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for ($j = 1; $j <= $n; $j++) { |
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if ($comparator($a[$i - 1], $b[$j - 1])) { |
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$c[$i][$j] = 1 + (isset($c[$i - 1][$j - 1]) ? $c[$i - 1][$j - 1] : 0); |
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} else { |
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$c[$i][$j] = max( |
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isset($c[$i][$j - 1]) ? $c[$i][$j - 1] : 0, |
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isset($c[$i - 1][$j]) ? $c[$i - 1][$j] : 0 |
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); |
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} |
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} |
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} |
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$lcs = array_pad([], $m + 1, 0); |
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$this->compileMatches($c, $a, $b, $m, $n, $comparator, $lcs); |
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return $lcs; |
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} |
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protected function compileMatches($c, $a, $b, $i, $j, $comparator, &$matches) |
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{ |
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if ($i > 0 && $j > 0 && $comparator($a[$i - 1], $b[$j - 1])) { |
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$this->compileMatches($c, $a, $b, $i - 1, $j - 1, $comparator, $matches); |
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$matches[$i] = $j; |
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} elseif ($j > 0 && ($i === 0 || $c[$i][$j - 1] >= $c[$i - 1][$j])) { |
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$this->compileMatches($c, $a, $b, $i, $j - 1, $comparator, $matches); |
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} elseif ($i > 0 && ($j === 0 || $c[$i][$j - 1] < $c[$i - 1][$j])) { |
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$this->compileMatches($c, $a, $b, $i - 1, $j, $comparator, $matches); |
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} |
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} |
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} |
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caxy /
php-htmldiff
