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<?php |
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declare(strict_types=1); |
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namespace TinyID; |
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use BCMathExtended\BC; |
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use InvalidArgumentException; |
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class TinyID |
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{ |
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private array $dictionary; |
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private int $dictionaryLength; |
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public function __construct(string $dictionary) |
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{ |
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$dictionaryLength = mb_strlen($dictionary, 'UTF-8'); |
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if ($dictionaryLength <= 1) { |
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throw new InvalidArgumentException('dictionary too short'); |
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} |
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$this->dictionary = $this->stringSplit($dictionary); |
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$this->dictionaryLength = count(array_unique($this->dictionary)); |
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if ($dictionaryLength !== $this->dictionaryLength) { |
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throw new InvalidArgumentException('dictionary contains duplicated characters'); |
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} |
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} |
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private function stringSplit(string $value): array |
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{ |
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return (array)preg_split('//u', $value, -1, PREG_SPLIT_NO_EMPTY); |
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} |
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public function encode(string $value): string |
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{ |
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if (BC::COMPARE_RIGHT_GRATER === BC::comp($value, '0')) { |
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throw new InvalidArgumentException('cannot encode negative number'); |
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} |
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$encoded = ''; |
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do { |
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$encoded = $this->dictionary[BC::mod($value, (string)$this->dictionaryLength, 0)] . $encoded; |
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$value = BC::div($value, (string)$this->dictionaryLength, 0); |
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} while ($value); |
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return $encoded; |
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} |
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public function decode(string $value): string |
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{ |
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$charsToPosition = array_flip($this->dictionary); |
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$out = '0'; |
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foreach (array_reverse($this->stringSplit($value)) as $pos => $tmp) { |
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if (!isset($charsToPosition[$tmp])) { |
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throw new InvalidArgumentException('cannot decode string with characters not in dictionary'); |
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} |
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$out = BC::add($out, BC::mul((string)$charsToPosition[$tmp], BC::pow((string)$this->dictionaryLength, (string)$pos, 0), 0), 0); |
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} |
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return $out; |
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} |
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} |
krowinski /
tinyID
