1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
<?php
/**
* Implementation for UTF-8 strings.
*
* The subscript operator in PHP, when used with string will return a byte
* and not a character. Because in UTF-8 strings a character may occupy more
* than one byte, the subscript operator may return an invalid character.
*
* Because the lexer relies on the subscript operator this class had to be
* implemented.
*/
declare(strict_types=1);
namespace PhpMyAdmin\SqlParser;
use ArrayAccess;
use Exception;
/**
* Implements array-like access for UTF-8 strings.
*
* In this library, this class should be used to parse UTF-8 queries.
*/
class UtfString implements ArrayAccess
{
/**
* The raw, multi-byte string.
*
* @var string
*/
public $str = '';
/**
* The index of current byte.
*
* For ASCII strings, the byte index is equal to the character index.
*
* @var int
*/
public $byteIdx = 0;
/**
* The index of current character.
*
* For non-ASCII strings, some characters occupy more than one byte and
* the character index will have a lower value than the byte index.
*
* @var int
*/
public $charIdx = 0;
/**
* The length of the string (in bytes).
*
* @var int
*/
public $byteLen = 0;
/**
* The length of the string (in characters).
*
* @var int
*/
public $charLen = 0;
/**
* @param string $str the string
*/
public function __construct($str)
{
$this->str = $str;
$this->byteIdx = 0;
$this->charIdx = 0;
$this->byteLen = mb_strlen($str, '8bit');
if (! mb_check_encoding($str, 'UTF-8')) {
$this->charLen = 0;
} else {
$this->charLen = mb_strlen($str, 'UTF-8');
}
}
/**
* Checks if the given offset exists.
*
* @param int $offset the offset to be checked
*
* @return bool
*/
public function offsetExists($offset)
{
return ($offset >= 0) && ($offset < $this->charLen);
}
/**
* Gets the character at given offset.
*
* @param int $offset the offset to be returned
*
* @return string|null
*/
public function offsetGet($offset)
{
if (($offset < 0) || ($offset >= $this->charLen)) {
return null;
}
$delta = $offset - $this->charIdx;
if ($delta > 0) {
// Fast forwarding.
while ($delta-- > 0) {
$this->byteIdx += static::getCharLength($this->str[$this->byteIdx]);
++$this->charIdx;
}
} elseif ($delta < 0) {
// Rewinding.
while ($delta++ < 0) {
do {
$byte = ord($this->str[--$this->byteIdx]);
} while (($byte >= 128) && ($byte < 192));
--$this->charIdx;
}
}
$bytesCount = static::getCharLength($this->str[$this->byteIdx]);
$ret = '';
for ($i = 0; $bytesCount-- > 0; ++$i) {
$ret .= $this->str[$this->byteIdx + $i];
}
return $ret;
}
/**
* Sets the value of a character.
*
* @param int $offset the offset to be set
* @param string $value the value to be set
*
* @throws Exception not implemented.
*/
public function offsetSet($offset, $value)
{
throw new Exception('Not implemented.');
}
/**
* Unsets an index.
*
* @param int $offset the value to be unset
*
* @throws Exception not implemented.
*/
public function offsetUnset($offset)
{
throw new Exception('Not implemented.');
}
/**
* Gets the length of an UTF-8 character.
*
* According to RFC 3629, a UTF-8 character can have at most 4 bytes.
* However, this implementation supports UTF-8 characters containing up to 6
* bytes.
*
* @see https://tools.ietf.org/html/rfc3629
*
* @param string $byte the byte to be analyzed
*
* @return int
*/
public static function getCharLength($byte)
{
$byte = ord($byte);
if ($byte < 128) {
return 1;
} elseif ($byte < 224) {
return 2;
} elseif ($byte < 240) {
return 3;
} elseif ($byte < 248) {
return 4;
} elseif ($byte < 252) {
return 5; // unofficial
}
return 6; // unofficial
}
/**
* Returns the length in characters of the string.
*
* @return int
*/
public function length()
{
return $this->charLen;
}
/**
* Returns the contained string.
*
* @return string
*/
public function __toString()
{
return $this->str;
}
}
|
