maxbuttons / assets / libraries / scssphp / src / SourceMap / Base64VLQEncoder.php

Base64VLQEncoder.php in MaxButtons – Create buttons 7.13.3, at assets/libraries/scssphp/src/SourceMap/Base64VLQEncoder.php

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1	<?php
2	/**
3	* SCSSPHP
4	*
5	* @copyright 2012-2018 Leaf Corcoran
6	*
7	* @license http://opensource.org/licenses/MIT MIT
8	*
9	* @link http://leafo.github.io/scssphp
10	*/
11
12	namespace Leafo\ScssPhp\SourceMap;
13
14	/**
15	* Base64 VLQ Encoder
16	*
17	* {@internal Derivative of oyejorge/less.php's lib/SourceMap/Base64VLQ.php, relicensed with permission. }}
18	*
19	* @author Josh Schmidt <oyejorge@gmail.com>
20	* @author Nicolas FRANÇOIS <nicolas.francois@frog-labs.com>
21	*/
22	class Base64VLQEncoder
23	{
24	/**
25	* Shift
26	*
27	* @var integer
28	*/
29	private $shift = 5;
30
31	/**
32	* Mask
33	*
34	* @var integer
35	*/
36	private $mask = 0x1F; // == (1 << shift) == 0b00011111
37
38	/**
39	* Continuation bit
40	*
41	* @var integer
42	*/
43	private $continuationBit = 0x20; // == (mask - 1 ) == 0b00100000
44
45	/**
46	* Char to integer map
47	*
48	* @var array
49	*/
50	private $charToIntMap = array(
51	'A' => 0, 'B' => 1, 'C' => 2, 'D' => 3, 'E' => 4, 'F' => 5, 'G' => 6, 'H' => 7,
52	'I' => 8, 'J' => 9, 'K' => 10, 'L' => 11, 'M' => 12, 'N' => 13, 'O' => 14, 'P' => 15,
53	'Q' => 16, 'R' => 17, 'S' => 18, 'T' => 19, 'U' => 20, 'V' => 21, 'W' => 22, 'X' => 23,
54	'Y' => 24, 'Z' => 25, 'a' => 26, 'b' => 27, 'c' => 28, 'd' => 29, 'e' => 30, 'f' => 31,
55	'g' => 32, 'h' => 33, 'i' => 34, 'j' => 35, 'k' => 36, 'l' => 37, 'm' => 38, 'n' => 39,
56	'o' => 40, 'p' => 41, 'q' => 42, 'r' => 43, 's' => 44, 't' => 45, 'u' => 46, 'v' => 47,
57	'w' => 48, 'x' => 49, 'y' => 50, 'z' => 51, 0 => 52, 1 => 53, 2 => 54, 3 => 55,
58	4 => 56, 5 => 57, 6 => 58, 7 => 59, 8 => 60, 9 => 61, '+' => 62, '/' => 63,
59	);
60
61	/**
62	* Integer to char map
63	*
64	* @var array
65	*/
66	private $intToCharMap = array(
67	0 => 'A', 1 => 'B', 2 => 'C', 3 => 'D', 4 => 'E', 5 => 'F', 6 => 'G', 7 => 'H',
68	8 => 'I', 9 => 'J', 10 => 'K', 11 => 'L', 12 => 'M', 13 => 'N', 14 => 'O', 15 => 'P',
69	16 => 'Q', 17 => 'R', 18 => 'S', 19 => 'T', 20 => 'U', 21 => 'V', 22 => 'W', 23 => 'X',
70	24 => 'Y', 25 => 'Z', 26 => 'a', 27 => 'b', 28 => 'c', 29 => 'd', 30 => 'e', 31 => 'f',
71	32 => 'g', 33 => 'h', 34 => 'i', 35 => 'j', 36 => 'k', 37 => 'l', 38 => 'm', 39 => 'n',
72	40 => 'o', 41 => 'p', 42 => 'q', 43 => 'r', 44 => 's', 45 => 't', 46 => 'u', 47 => 'v',
73	48 => 'w', 49 => 'x', 50 => 'y', 51 => 'z', 52 => '0', 53 => '1', 54 => '2', 55 => '3',
74	56 => '4', 57 => '5', 58 => '6', 59 => '7', 60 => '8', 61 => '9', 62 => '+', 63 => '/',
75	);
76
77	/**
78	* Constructor
79	*/
80	public function __construct()
81	{
82	// I leave it here for future reference
83	// foreach (str_split('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/') as $i => $char)
84	// {
85	// $this->charToIntMap[$char] = $i;
86	// $this->intToCharMap[$i] = $char;
87	// }
88	}
89
90	/**
91	* Convert from a two-complement value to a value where the sign bit is
92	* is placed in the least significant bit. For example, as decimals:
93	* 1 becomes 2 (10 binary), -1 becomes 3 (11 binary)
94	* 2 becomes 4 (100 binary), -2 becomes 5 (101 binary)
95	* We generate the value for 32 bit machines, hence -2147483648 becomes 1, not 4294967297,
96	* even on a 64 bit machine.
97	*
98	* @param string $aValue
99	*/
100	public function toVLQSigned($aValue)
101	{
102	return 0xffffffff & ($aValue < 0 ? ((-$aValue) << 1) + 1 : ($aValue << 1) + 0);
103	}
104
105	/**
106	* Convert to a two-complement value from a value where the sign bit is
107	* is placed in the least significant bit. For example, as decimals:
108	* 2 (10 binary) becomes 1, 3 (11 binary) becomes -1
109	* 4 (100 binary) becomes 2, 5 (101 binary) becomes -2
110	* We assume that the value was generated with a 32 bit machine in mind.
111	* Hence
112	* 1 becomes -2147483648
113	* even on a 64 bit machine.
114	*
115	* @param integer $aValue
116	*/
117	public function fromVLQSigned($aValue)
118	{
119	return $aValue & 1 ? $this->zeroFill(~$aValue + 2, 1) \| (-1 - 0x7fffffff) : $this->zeroFill($aValue, 1);
120	}
121
122	/**
123	* Return the base 64 VLQ encoded value.
124	*
125	* @param string $aValue The value to encode
126	*
127	* @return string The encoded value
128	*/
129	public function encode($aValue)
130	{
131	$encoded = '';
132	$vlq = $this->toVLQSigned($aValue);
133
134	do {
135	$digit = $vlq & $this->mask;
136	$vlq = $this->zeroFill($vlq, $this->shift);
137
138	if ($vlq > 0) {
139	$digit \|= $this->continuationBit;
140	}
141
142	$encoded .= $this->base64Encode($digit);
143	} while ($vlq > 0);
144
145	return $encoded;
146	}
147
148	/**
149	* Return the value decoded from base 64 VLQ.
150	*
151	* @param string $encoded The encoded value to decode
152	*
153	* @return integer The decoded value
154	*/
155	public function decode($encoded)
156	{
157	$vlq = 0;
158	$i = 0;
159
160	do {
161	$digit = $this->base64Decode($encoded[$i]);
162	$vlq \|= ($digit & $this->mask) << ($i * $this->shift);
163	$i++;
164	} while ($digit & $this->continuationBit);
165
166	return $this->fromVLQSigned($vlq);
167	}
168
169	/**
170	* Right shift with zero fill.
171	*
172	* @param integer $a number to shift
173	* @param integer $b number of bits to shift
174	*
175	* @return integer
176	*/
177	public function zeroFill($a, $b)
178	{
179	$bmin = $b - 1;
180	return ($a >= 0) ? ($a >> $b) : ($a >> $b) & (PHP_INT_MAX >> ($bmin));
181	}
182
183	/**
184	* Encode single 6-bit digit as base64.
185	*
186	* @param integer $number
187	*
188	* @return string
189	*
190	* @throws \Exception If the number is invalid
191	*/
192	public function base64Encode($number)
193	{
194	if ($number < 0 \|\| $number > 63) {
195	throw new \Exception(sprintf('Invalid number "%s" given. Must be between 0 and 63.', $number));
196	}
197
198	return $this->intToCharMap[$number];
199	}
200
201	/**
202	* Decode single 6-bit digit from base64
203	*
204	* @param string $char
205	*
206	* @return integer
207	*
208	* @throws \Exception If the number is invalid
209	*/
210	public function base64Decode($char)
211	{
212	if (! array_key_exists($char, $this->charToIntMap)) {
213	throw new \Exception(sprintf('Invalid base 64 digit "%s" given.', $char));
214	}
215
216	return $this->charToIntMap[$char];
217	}
218	}
219