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<?php |
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/** |
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* @package s9e\RegexpBuilder |
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* @copyright Copyright (c) 2016 The s9e Authors |
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* @license http://www.opensource.org/licenses/mit-license.php The MIT License |
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*/ |
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namespace s9e\RegexpBuilder\Passes; |
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/** |
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* Replaces (?:axx|ayy) with a(?:xx|yy) |
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*/ |
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class MergePrefix extends AbstractPass |
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{ |
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/** |
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* {@inheritdoc} |
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*/ |
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protected function runPass(array $strings) |
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{ |
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$newStrings = []; |
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foreach ($this->getStringsByPrefix($strings) as $prefix => $strings) |
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{ |
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$newStrings[] = (isset($strings[1])) ? $this->mergeStrings($strings) : $strings[0]; |
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} |
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return $newStrings; |
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} |
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/** |
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* Get the number of leading elements common to all given strings |
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* |
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* @param array[] $strings |
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* @return integer |
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*/ |
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protected function getPrefixLength(array $strings) |
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{ |
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$len = 1; |
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$cnt = count($strings[0]); |
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while ($len < $cnt && $this->stringsMatch($strings, $len)) |
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{ |
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++$len; |
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} |
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return $len; |
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} |
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/** |
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* Return given strings grouped by their first element |
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* |
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* NOTE: assumes that this pass is run before the first element of any string could be replaced |
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* |
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* @param array[] $strings |
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* @return array[] |
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*/ |
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protected function getStringsByPrefix(array $strings) |
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{ |
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$byPrefix = []; |
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foreach ($strings as $string) |
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{ |
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$byPrefix[$string[0]][] = $string; |
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} |
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return $byPrefix; |
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} |
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/** |
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* Merge given strings into a new single string |
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* |
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* @param array[] $strings |
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* @return array |
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*/ |
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protected function mergeStrings(array $strings) |
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{ |
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$len = $this->getPrefixLength($strings); |
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$newString = array_slice($strings[0], 0, $len); |
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foreach ($strings as $string) |
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{ |
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$newString[$len][] = array_slice($string, $len); |
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} |
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return $newString; |
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} |
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/** |
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* Test whether all given strings' elements match at given position |
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* |
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* @param array[] $strings |
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* @param integer $pos |
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* @return bool |
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*/ |
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protected function stringsMatch(array $strings, $pos) |
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{ |
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$value = $strings[0][$pos]; |
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foreach ($strings as $string) |
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{ |
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if (!isset($string[$pos]) || $string[$pos] !== $value) |
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{ |
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return false; |
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} |
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} |
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return true; |
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} |
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} |
s9e /
RegexpBuilder
