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<?php |
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namespace KamranAhmed\Shorthand; |
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use Exception; |
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/** |
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* Class Shorthand |
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* |
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* @package KamranAhmed\Shorthand |
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*/ |
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class Shorthand |
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{ |
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/** |
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* @var array |
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*/ |
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private $words = []; |
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/** |
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* Shorthand constructor. |
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* |
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* @param array $words |
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*/ |
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public function __construct($words = []) |
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{ |
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$this->setWords($words); |
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} |
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/** |
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* @param mixed $words |
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* |
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* @return void |
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*/ |
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public function setWords($words) |
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{ |
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$this->words = !is_array($words) ? [$words] : $words; |
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} |
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/** |
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* @return array |
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* |
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* @throws \Exception |
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*/ |
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public function generate() |
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{ |
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if (empty($this->words)) { |
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throw new Exception('Word(s) are required to generate shorthands'); |
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} |
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// Sort them lexicographically, so that they're next to their nearest kin |
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$words = $this->sortWordsLexico($this->words); |
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$shorthands = []; |
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$previous = ''; |
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foreach ($words as $counter => $current) { |
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// Get the next word |
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$next = isset($words[$counter + 1]) ? $words[$counter + 1] : ""; |
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// Two matching words found, we cannot make any unique shorthands out of this one |
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if ($current === $next) { |
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continue; |
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} |
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// Get the index at which current word differs from the next and previous words |
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$diffPoint = $this->getDiffPoint($current, $next, $previous); |
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$previous = $current; |
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// End of the current word has already been reached, just put the whole word |
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// in the shorthands and continue as it means there was no difference |
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// between the current word and the next/previous words |
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if ($diffPoint === strlen($current)) { |
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$shorthands[$current] = $current; |
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continue; |
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} |
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// Generate the shorthands by creating substring from the diff point to the end |
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while ($diffPoint <= strlen($current)) { |
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$shorthand = substr($current, 0, $diffPoint); |
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$shorthands[$shorthand] = $current; |
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$diffPoint++; |
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} |
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} |
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return $shorthands; |
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} |
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/** |
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* Gets the point at which current word differs from the next and previous words |
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* |
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* @param string $current |
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* @param string $next |
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* @param string $previous |
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* |
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* @return int |
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*/ |
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protected function getDiffPoint($current, $next, $previous) |
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{ |
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$nextCharMatches = true; |
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$prevCharMatches = true; |
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$currentLength = strlen($current); |
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// Iterate through each character of the current word |
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// and find the point where it differs from the previous and next word |
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for ($diffPoint = 0; $diffPoint < $currentLength; $diffPoint++) { |
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$currChar = $current[$diffPoint]; |
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$nextChar = !empty($next[$diffPoint]) ? $next[$diffPoint] : ''; |
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$prevChar = !empty($previous[$diffPoint]) ? $previous[$diffPoint] : ''; |
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$nextCharMatches = $nextCharMatches && $currChar === $nextChar; |
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$prevCharMatches = $prevCharMatches && $currChar === $prevChar; |
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// If neither of the next and previous word characters match, |
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// we have found ourselves the point at which both the words differ |
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if (!$nextCharMatches && !$prevCharMatches) { |
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$diffPoint++; |
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break; |
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} |
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} |
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return $diffPoint; |
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} |
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/** |
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* Sorts the words lexicographically in order to bring the words closer to their kin |
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* |
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* @param array $words |
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* |
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* @return array |
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*/ |
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protected function sortWordsLexico($words) |
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{ |
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usort($words, function ($a, $b) { |
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if ($a === $b) { |
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return 0; |
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} |
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return $a > $b ? 1 : -1; |
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}); |
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return $words; |
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} |
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} |
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