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<?php |
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declare(strict_types = 1); |
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namespace byrokrat\banking\Rewriter; |
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/** |
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* Generate permutations for a set of values |
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*/ |
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class Permutator |
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{ |
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/** |
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* @param array<mixed> $set |
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* @return \Generator & iterable<array> |
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*/ |
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142 |
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public static function getPermutations(array $set): \Generator |
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{ |
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142 |
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foreach (self::getPowerSet($set) as $subset) { |
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142 |
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foreach (self::generateFixedLengthPermutations($subset) as $perm) { |
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142 |
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yield $perm; |
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} |
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} |
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59 |
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} |
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/** |
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* @param array<mixed> $set |
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* @return array<array> |
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*/ |
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142 |
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private static function getPowerSet(array $set): array |
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{ |
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142 |
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$results = [[]]; |
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142 |
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foreach ($set as $element) { |
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142 |
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foreach ($results as $combination) { |
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142 |
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$subset = array_merge([$element], $combination); |
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$results[] = $subset; |
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} |
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} |
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142 |
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usort( |
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142 |
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$results, |
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function (array $left, array $right): int { |
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142 |
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return count($left) <=> count($right); |
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142 |
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} |
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); |
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return array_filter($results); |
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} |
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/** |
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* @param array<mixed> $set |
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* @param array<array> $permutations |
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* @return \Generator & iterable<array> |
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*/ |
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142 |
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private static function generateFixedLengthPermutations(array $set, array $permutations = []): \Generator |
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{ |
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142 |
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if (empty($set)) { |
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yield $permutations; |
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} else { |
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142 |
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for ($i = count($set)-1; $i>=0; $i--) { |
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$newSet = $set; |
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$newPermutations = $permutations; |
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list($foo) = array_splice($newSet, $i, 1); |
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array_unshift($newPermutations, $foo); |
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yield from self::generateFixedLengthPermutations($newSet, $newPermutations); |
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} |
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} |
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142 |
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} |
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} |
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byrokrat /
banking
