diff options
Diffstat (limited to 'lib/less.php/SourceMap/Base64VLQ.php')
| -rw-r--r-- | lib/less.php/SourceMap/Base64VLQ.php | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/lib/less.php/SourceMap/Base64VLQ.php b/lib/less.php/SourceMap/Base64VLQ.php new file mode 100644 index 0000000..f5b200c --- /dev/null +++ b/lib/less.php/SourceMap/Base64VLQ.php @@ -0,0 +1,187 @@ +<?php + +/** + * Encode / Decode Base64 VLQ. + * + * @package Less + * @subpackage SourceMap + */ +class Less_SourceMap_Base64VLQ { + + /** + * Shift + * + * @var integer + */ + private $shift = 5; + + /** + * Mask + * + * @var integer + */ + private $mask = 0x1F; // == (1 << shift) == 0b00011111 + + /** + * Continuation bit + * + * @var integer + */ + private $continuationBit = 0x20; // == (mask - 1 ) == 0b00100000 + + /** + * Char to integer map + * + * @var array + */ + private $charToIntMap = array( + 'A' => 0, 'B' => 1, 'C' => 2, 'D' => 3, 'E' => 4, 'F' => 5, 'G' => 6, + 'H' => 7,'I' => 8, 'J' => 9, 'K' => 10, 'L' => 11, 'M' => 12, 'N' => 13, + 'O' => 14, 'P' => 15, 'Q' => 16, 'R' => 17, 'S' => 18, 'T' => 19, 'U' => 20, + 'V' => 21, 'W' => 22, 'X' => 23, 'Y' => 24, 'Z' => 25, 'a' => 26, 'b' => 27, + 'c' => 28, 'd' => 29, 'e' => 30, 'f' => 31, 'g' => 32, 'h' => 33, 'i' => 34, + 'j' => 35, 'k' => 36, 'l' => 37, 'm' => 38, 'n' => 39, 'o' => 40, 'p' => 41, + 'q' => 42, 'r' => 43, 's' => 44, 't' => 45, 'u' => 46, 'v' => 47, 'w' => 48, + 'x' => 49, 'y' => 50, 'z' => 51, 0 => 52, 1 => 53, 2 => 54, 3 => 55, 4 => 56, + 5 => 57, 6 => 58, 7 => 59, 8 => 60, 9 => 61, '+' => 62, '/' => 63, + ); + + /** + * Integer to char map + * + * @var array + */ + private $intToCharMap = array( + 0 => 'A', 1 => 'B', 2 => 'C', 3 => 'D', 4 => 'E', 5 => 'F', 6 => 'G', + 7 => 'H', 8 => 'I', 9 => 'J', 10 => 'K', 11 => 'L', 12 => 'M', 13 => 'N', + 14 => 'O', 15 => 'P', 16 => 'Q', 17 => 'R', 18 => 'S', 19 => 'T', 20 => 'U', + 21 => 'V', 22 => 'W', 23 => 'X', 24 => 'Y', 25 => 'Z', 26 => 'a', 27 => 'b', + 28 => 'c', 29 => 'd', 30 => 'e', 31 => 'f', 32 => 'g', 33 => 'h', 34 => 'i', + 35 => 'j', 36 => 'k', 37 => 'l', 38 => 'm', 39 => 'n', 40 => 'o', 41 => 'p', + 42 => 'q', 43 => 'r', 44 => 's', 45 => 't', 46 => 'u', 47 => 'v', 48 => 'w', + 49 => 'x', 50 => 'y', 51 => 'z', 52 => '0', 53 => '1', 54 => '2', 55 => '3', + 56 => '4', 57 => '5', 58 => '6', 59 => '7', 60 => '8', 61 => '9', 62 => '+', + 63 => '/', + ); + + /** + * Constructor + */ + public function __construct(){ + // I leave it here for future reference + // foreach(str_split('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/') as $i => $char) + // { + // $this->charToIntMap[$char] = $i; + // $this->intToCharMap[$i] = $char; + // } + } + + /** + * Convert from a two-complement value to a value where the sign bit is + * is placed in the least significant bit. For example, as decimals: + * 1 becomes 2 (10 binary), -1 becomes 3 (11 binary) + * 2 becomes 4 (100 binary), -2 becomes 5 (101 binary) + * We generate the value for 32 bit machines, hence -2147483648 becomes 1, not 4294967297, + * even on a 64 bit machine. + * @param string $aValue + */ + public function toVLQSigned($aValue){ + return 0xffffffff & ($aValue < 0 ? ((-$aValue) << 1) + 1 : ($aValue << 1) + 0); + } + + /** + * Convert to a two-complement value from a value where the sign bit is + * is placed in the least significant bit. For example, as decimals: + * 2 (10 binary) becomes 1, 3 (11 binary) becomes -1 + * 4 (100 binary) becomes 2, 5 (101 binary) becomes -2 + * We assume that the value was generated with a 32 bit machine in mind. + * Hence + * 1 becomes -2147483648 + * even on a 64 bit machine. + * @param integer $aValue + */ + public function fromVLQSigned($aValue){ + return $aValue & 1 ? $this->zeroFill(~$aValue + 2, 1) | (-1 - 0x7fffffff) : $this->zeroFill($aValue, 1); + } + + /** + * Return the base 64 VLQ encoded value. + * + * @param string $aValue The value to encode + * @return string The encoded value + */ + public function encode($aValue){ + $encoded = ''; + $vlq = $this->toVLQSigned($aValue); + do + { + $digit = $vlq & $this->mask; + $vlq = $this->zeroFill($vlq, $this->shift); + if($vlq > 0){ + $digit |= $this->continuationBit; + } + $encoded .= $this->base64Encode($digit); + } while($vlq > 0); + + return $encoded; + } + + /** + * Return the value decoded from base 64 VLQ. + * + * @param string $encoded The encoded value to decode + * @return integer The decoded value + */ + public function decode($encoded){ + $vlq = 0; + $i = 0; + do + { + $digit = $this->base64Decode($encoded[$i]); + $vlq |= ($digit & $this->mask) << ($i * $this->shift); + $i++; + } while($digit & $this->continuationBit); + + return $this->fromVLQSigned($vlq); + } + + /** + * Right shift with zero fill. + * + * @param integer $a number to shift + * @param integer $b number of bits to shift + * @return integer + */ + public function zeroFill($a, $b){ + return ($a >= 0) ? ($a >> $b) : ($a >> $b) & (PHP_INT_MAX >> ($b - 1)); + } + + /** + * Encode single 6-bit digit as base64. + * + * @param integer $number + * @return string + * @throws Exception If the number is invalid + */ + public function base64Encode($number){ + if($number < 0 || $number > 63){ + throw new Exception(sprintf('Invalid number "%s" given. Must be between 0 and 63.', $number)); + } + return $this->intToCharMap[$number]; + } + + /** + * Decode single 6-bit digit from base64 + * + * @param string $char + * @return number + * @throws Exception If the number is invalid + */ + public function base64Decode($char){ + if(!array_key_exists($char, $this->charToIntMap)){ + throw new Exception(sprintf('Invalid base 64 digit "%s" given.', $char)); + } + return $this->charToIntMap[$char]; + } + +} |