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<?php |
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namespace Fisharebest\Algorithm; |
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/** |
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* @author Greg Roach <[email protected]> |
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* @copyright (c) 2021 Greg Roach <[email protected]> |
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* @license GPL-3.0+ |
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* |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation, either version 3 of the License, or |
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* (at your option) any later version. |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* You should have received a copy of the GNU General Public License |
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* along with this program. If not, see <https://www.gnu.org/licenses>. |
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*/ |
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/** |
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* Class MyersDiff - find the shortest edit sequence to transform one string into another. |
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* |
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* Based on "An O(ND) Difference Algorithm and Its Variations" by Eugene W Myers. |
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* |
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* http://www.xmailserver.org/diff2.pdf |
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* http://www.codeproject.com/Articles/42279/Investigating-Myers-diff-algorithm-Part-of |
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*/ |
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class MyersDiff |
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{ |
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/** Instruction to delete a token which only appears in the first sequence */ |
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const DELETE = -1; |
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/** Instruction to keep a token which is common to both sequences */ |
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const KEEP = 0; |
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/** Instruction to insert a token which only appears in the last sequence */ |
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const INSERT = 1; |
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/** |
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* Backtrack through the intermediate results to extract the "snakes" that |
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* are visited on the chosen "D-path". |
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* |
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* @param string[] $v_save Intermediate results |
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* @param int $x End position |
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* @param int $y End position |
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* |
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* @return list<array{int, int}> |
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*/ |
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private function extractSnakes(array $v_save, $x, $y) |
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{ |
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$snakes = array(); |
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for ($d = count($v_save) - 1; $x >= 0 && $y >= 0; $d--) { |
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array_unshift($snakes, array($x, $y)); |
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$v = $v_save[$d]; |
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$k = $x - $y; |
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if ($k === -$d || $k !== $d && $v[$k - 1] < $v[$k + 1]) { |
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$k_prev = $k + 1; |
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} else { |
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$k_prev = $k - 1; |
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} |
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$x = $v[$k_prev]; |
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$y = $x - $k_prev; |
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} |
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return $snakes; |
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} |
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/** |
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* Convert a list of "snakes" into a set of insert/keep/delete instructions. |
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* |
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* @template T |
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* |
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* @param list<array{int, int}> $snakes Common subsequences |
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* @param list<T> $a First sequence |
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* @param list<T> $b Second sequence |
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* |
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* @return list<array{T, -1|0|1}> - pairs of token and edit (-1 for delete, 0 for keep, +1 for insert) |
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*/ |
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private function formatSolution(array $snakes, array $a, array $b) |
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{ |
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$solution = array(); |
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$x = 0; |
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$y = 0; |
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foreach ($snakes as $snake) { |
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// Horizontals |
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while ($snake[0] - $snake[1] > $x - $y) { |
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$solution[] = array($a[$x], self::DELETE); |
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$x++; |
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} |
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// Verticals |
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while ($snake[0] - $snake[1] < $x - $y) { |
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$solution[] = array($b[$y], self::INSERT); |
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$y++; |
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} |
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// Diagonals |
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while ($x < $snake[0]) { |
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$solution[] = array($a[$x], self::KEEP); |
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$x++; |
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$y++; |
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} |
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} |
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return $solution; |
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} |
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/** |
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* Calculate the shortest edit sequence to convert $x into $y. |
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* |
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* @template T |
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* |
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* @param list<T> $a - List of values to compare. |
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* @param list<T> $b - List of values to compare. |
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* @param (callable(T, T): bool)|null $compare - comparison function for tokens, or NULL to use === comparison. |
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* |
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* @return list<array{T, -1|0|1}> - pairs of token and edit (-1 for delete, 0 for keep, +1 for insert) |
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*/ |
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public function calculate(array $a, array $b, $compare = null) |
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{ |
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if ($compare === null) { |
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$compare = function ($x, $y) { |
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return $x === $y; |
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}; |
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} |
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// The algorithm uses array keys numbered from zero. |
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$n = count($a); |
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$m = count($b); |
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$a = array_values($a); |
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$b = array_values($b); |
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$max = $m + $n; |
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// Keep a copy of $v after each iteration of $d. |
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$v_save = array(); |
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// Find the shortest "D-path". |
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$v = array(1 => 0); |
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for ($d = 0; $d <= $max; $d++) { |
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// Examine all possible "K-lines" for this "D-path". |
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for ($k = -$d; $k <= $d; $k += 2) { |
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if ($k === -$d || $k !== $d && $v[$k - 1] < $v[$k + 1]) { |
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// Move down. |
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$x = $v[$k + 1]; |
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} else { |
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// Move right. |
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$x = $v[$k - 1] + 1; |
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} |
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// Derive Y from X. |
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$y = $x - $k; |
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// Follow the diagonal. |
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while ($x < $n && $y < $m && $compare($a[$x], $b[$y])) { |
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$x++; |
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$y++; |
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} |
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// Just store X, as we can calculate Y (from X + K). |
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$v[$k] = $x; |
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$v_save[$d] = $v; |
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// Solution found? |
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if ($x === $n && $y === $m) { |
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break 2; |
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} |
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} |
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} |
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// Extract the solution by back-tracking through the saved results. |
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$snakes = $this->extractSnakes($v_save, $n, $m); |
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// Format the snakes as a set of instructions. |
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return $this->formatSolution($snakes, $a, $b); |
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} |
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} |
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fisharebest /
algorithm
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The issue could also be caused by a filter entry in the build configuration. If the path has been excluded in your configuration, e.g.
excluded_paths: ["lib/*"], you can move it to the dependency path list as follows:For further information see https://scrutinizer-ci.com/docs/tools/php/php-scrutinizer/#list-dependency-paths