51 lines
1.2 KiB
PHP
51 lines
1.2 KiB
PHP
<?php
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// Base62.php
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// Created: 2022-01-28
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// Updated: 2023-07-21
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namespace Index\Serialisation;
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use Index\IO\Stream;
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/**
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* Provides a Base62 serialiser.
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*/
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final class Base62 {
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private const CHARS = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
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/**
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* Encodes an integer as a Base62 string.
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*
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* @param int $input Integer.
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* @return string Base64 string representing the integer.
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*/
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public static function encode(int $input): string {
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$output = '';
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for($i = floor(log10($input) / log10(62)); $i >= 0; --$i) {
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$index = (int)floor($input / (62 ** $i));
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$output .= substr(self::CHARS, $index, 1);
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$input -= $index * (62 ** $i);
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}
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return $output;
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}
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/**
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* Decodes a Base62 string back to an integer.
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*
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* @param Stream|string $input Input Base62 string.
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* @return int Integer.
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*/
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public static function decode(Stream|string $input): int {
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$input = (string)$input;
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$output = 0;
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$length = strlen($input) - 1;
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for($i = 0; $i <= $length; ++$i)
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$output += strpos(self::CHARS, $input[$i]) * (62 ** ($length - $i));
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return $output;
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}
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}
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