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<?php
 namespace Fuse\Search\Bitap;
 
 function createPatternAlphabet(string $pattern): array
 {
 $mask = [];
 
 for ($i = 0, $len = mb_strlen($pattern); $i < $len; $i += 1) {
 $char = mb_substr($pattern, $i, 1);
 $mask[$char] = ($mask[$char] ?? 0) | (1 << $len - $i - 1);
 }
 
 return $mask;
 }
 
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