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109 lines
3.0 KiB
PHP
109 lines
3.0 KiB
PHP
<?php
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namespace Base\Tool;
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class Base62
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{
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const ENCODES = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/';
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private static function getCharArray($string)
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{
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$list = [];
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$length = strlen($string);
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for ($i = 0; $i < $length; $i++) {
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$list[] = $string[$i];
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}
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return $list;
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}
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private static function getIndexChars($string) {
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$length = strlen($string);
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$chars = [];
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for($i = 0; $i < 256; $i++) {
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$chars[] = 0;
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}
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for($i = 0; $i < $length; $i++) {
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$chars[$string[$i]] = $i ;
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}
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return $chars;
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}
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public static function getSpecialChar($char, $default = null)
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{
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if ($default == null) {
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$default = $char;
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}
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return $char == 'i' ? "ia" : ($char == '+' ? "ib" : ($char == '/' ? "ic" : $default));
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}
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public static function encode($string)
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{
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$encodes = self::getCharArray(self::ENCODES);
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$bytes = self::stringToBytes($string);
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$pos = 0;
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$val = 0;
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$result = [];
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for ($i = 0; $i < count($bytes); $i++) {
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$val = ($val << 8) | ($bytes[$i] & 0xFF);
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$pos += 8;
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while ($pos > 5) {
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$char = $encodes[$val >> ($pos -= 6)];
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$encodeChar = self::getSpecialChar($char);
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$result[] = $encodeChar;
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$val &= ((1 << $pos) - 1);
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}
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}
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if ($pos > 0) {
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$char = $encodes[$val << (6 - $pos)];
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$result[] = self::getSpecialChar($char);
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}
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return implode('', $result);
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}
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public static function decode($string)
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{
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$decodes = self::getIndexChars(self::ENCODES);
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$chars = self::getCharArray($string);
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$pos = 0;
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$val = 0;
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$bytes = [];
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for ($i = 0; $i < count($chars); $i++) {
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$char = $chars[$i];
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if ($char == 'i') {
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$char = $chars[++$i];
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$char =
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$char == 'a' ? 'i' :
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($char == 'b' ? '+' :
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($char == 'c' ? '/' : $chars[--$i]));
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}
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$val = ($val << 6) | $decodes[$char];
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$pos += 6;
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while ($pos > 7) {
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$bytes[] = $val >> ($pos -= 8);
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$val &= ((1 << $pos) - 1);
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}
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}
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return self::bytesToString($bytes);
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}
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private static function bytesToString($bytes) {
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$string = '';
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foreach($bytes as $byte) {
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$string .= chr($byte);
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}
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return $string;
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}
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private static function stringToBytes($string) {
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$length = strlen($string);
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$bytes = array();
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for($i = 0; $i < $length; $i++) {
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if(ord($string[$i]) >= 128){
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$byte = ord($string[$i]) - 256;
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}else{
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$byte = ord($string[$i]);
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}
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$bytes[] = $byte ;
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}
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return $bytes;
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}
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} |