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UtfString.php
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<?php
declare(strict_types=1);
namespace PhpMyAdmin\SqlParser;
use ArrayAccess;
use Exception;
use Stringable;
use function mb_check_encoding;
use function mb_strlen;
use function ord;
/**
* 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.
*
* Implements array-like access for UTF-8 strings.
*
* In this library, this class should be used to parse UTF-8 queries.
*
* @implements ArrayAccess<int, string>
*/
class UtfString implements ArrayAccess, Stringable
{
/**
* 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 $charLen = 0;
/**
* A map of ASCII binary values to their ASCII code
* This is to improve performance and avoid calling ord($byte)
*
* Source: https://www.freecodecamp.org/news/ascii-table-hex-to-ascii-value-character-code-chart-2/
*
* @var array<int|string,int>
*/
protected static $asciiMap = [
"\0" => 0, // (00000000) NUL Null
"\t" => 9, // (00001001) HT Horizontal Tab
"\n" => 10, // (00001010) LF Newline / Line Feed
"\v" => 11, // (00001011) VT Vertical Tab
"\f" => 12, // (00001100) FF Form Feed
"\r" => 13, // (00001101) CR Carriage Return
' ' => 32, // (00100000) SP Space
'!' => 33, // (00100001) ! Exclamation mark
'"' => 34, // (00100010) " Double quote
'#' => 35, // (00100011) # Number
'$' => 36, // (00100100) $ Dollar
'%' => 37, // (00100101) % Percent
'&' => 38, // (00100110) & Ampersand
'\'' => 39, // (00100111) ' Single quote
'(' => 40, // (00101000) ( Left parenthesis
')' => 41, // (00101001) ) Right parenthesis
'*' => 42, // (00101010) * Asterisk
'+' => 43, // (00101011) + Plus
',' => 44, // (00101100) , Comma
'-' => 45, // (00101101) - Minus
'.' => 46, // (00101110) . Period
'/' => 47, // (00101111) / Slash
'0' => 48, // (00110000) 0 Zero
'1' => 49, // (00110001) 1 One
'2' => 50, // (00110010) 2 Two
'3' => 51, // (00110011) 3 Three
'4' => 52, // (00110100) 4 Four
'5' => 53, // (00110101) 5 Five
'6' => 54, // (00110110) 6 Six
'7' => 55, // (00110111) 7 Seven
'8' => 56, // (00111000) 8 Eight
'9' => 57, // (00111001) 9 Nine
':' => 58, // (00111010) : Colon
';' => 59, // (00111011) ; Semicolon
'<' => 60, // (00111100) < Less than
'=' => 61, // (00111101) = Equal sign
'>' => 62, // (00111110) > Greater than
'?' => 63, // (00111111) ? Question mark
'@' => 64, // (01000000) @ At sign
'A' => 65, // (01000001) A Uppercase A
'B' => 66, // (01000010) B Uppercase B
'C' => 67, // (01000011) C Uppercase C
'D' => 68, // (01000100) D Uppercase D
'E' => 69, // (01000101) E Uppercase E
'F' => 70, // (01000110) F Uppercase F
'G' => 71, // (01000111) G Uppercase G
'H' => 72, // (01001000) H Uppercase H
'I' => 73, // (01001001) I Uppercase I
'J' => 74, // (01001010) J Uppercase J
'K' => 75, // (01001011) K Uppercase K
'L' => 76, // (01001100) L Uppercase L
'M' => 77, // (01001101) M Uppercase M
'N' => 78, // (01001110) N Uppercase N
'O' => 79, // (01001111) O Uppercase O
'P' => 80, // (01010000) P Uppercase P
'Q' => 81, // (01010001) Q Uppercase Q
'R' => 82, // (01010010) R Uppercase R
'S' => 83, // (01010011) S Uppercase S
'T' => 84, // (01010100) T Uppercase T
'U' => 85, // (01010101) U Uppercase U
'V' => 86, // (01010110) V Uppercase V
'W' => 87, // (01010111) W Uppercase W
'X' => 88, // (01011000) X Uppercase X
'Y' => 89, // (01011001) Y Uppercase Y
'Z' => 90, // (01011010) Z Uppercase Z
'[' => 91, // (01011011) [ Left square bracket
'\\' => 92, // (01011100) \ backslash
']' => 93, // (01011101) ] Right square bracket
'^' => 94, // (01011110) ^ Caret / circumflex
'_' => 95, // (01011111) _ Underscore
'`' => 96, // (01100000) ` Grave / accent
'a' => 97, // (01100001) a Lowercase a
'b' => 98, // (01100010) b Lowercase b
'c' => 99, // (01100011) c Lowercase c
'd' => 100, // (01100100) d Lowercase d
'e' => 101, // (01100101) e Lowercase e
'f' => 102, // (01100110) f Lowercase
'g' => 103, // (01100111) g Lowercase g
'h' => 104, // (01101000) h Lowercase h
'i' => 105, // (01101001) i Lowercase i
'j' => 106, // (01101010) j Lowercase j
'k' => 107, // (01101011) k Lowercase k
'l' => 108, // (01101100) l Lowercase l
'm' => 109, // (01101101) m Lowercase m
'n' => 110, // (01101110) n Lowercase n
'o' => 111, // (01101111) o Lowercase o
'p' => 112, // (01110000) p Lowercase p
'q' => 113, // (01110001) q Lowercase q
'r' => 114, // (01110010) r Lowercase r
's' => 115, // (01110011) s Lowercase s
't' => 116, // (01110100) t Lowercase t
'u' => 117, // (01110101) u Lowercase u
'v' => 118, // (01110110) v Lowercase v
'w' => 119, // (01110111) w Lowercase w
'x' => 120, // (01111000) x Lowercase x
'y' => 121, // (01111001) y Lowercase y
'z' => 122, // (01111010) z Lowercase z
'{' => 123, // (01111011) { Left curly bracket
'|' => 124, // (01111100) | Vertical bar
'}' => 125, // (01111101) } Right curly bracket
'~' => 126, // (01111110) ~ Tilde
"\x7f" => 127, // (01111111) DEL Delete
];
/**
* @param string $str the string
*/
public function __construct($str)
{
$this->str = $str;
$this->byteLen = mb_strlen($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 $offset the offset to be checked
*/
#[\ReturnTypeWillChange]
public function offsetExists($offset): bool
{
return ($offset >= 0) && ($offset < $this->charLen);
}
/**
* Gets the character at given offset.
*
* @param int $offset the offset to be returned
*
* @return string|null
*/
#[\ReturnTypeWillChange]
public function offsetGet($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 $value the value to be set
*
* @return void
*
* @throws Exception not implemented.
*/
#[\ReturnTypeWillChange]
public function offsetSet($offset, $value)
{
throw new Exception('Not implemented.');
}
/**
* Unsets an index.
*
* @param int $offset the value to be unset
*
* @return void
*
* @throws Exception not implemented.
*/
#[\ReturnTypeWillChange]
public function offsetUnset($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 $byte the byte to be analyzed
*/
public static function getCharLength($byte): int
{
// Use the default ASCII map as queries are mostly ASCII chars
// ord($byte) has a performance cost
if (! isset(static::$asciiMap[$byte])) {
// Complete the cache with missing items
static::$asciiMap[$byte] = ord($byte);
}
$byte = static::$asciiMap[$byte];
if ($byte < 128) {
return 1;
}
if ($byte < 224) {
return 2;
}
if ($byte < 240) {
return 3;
}
if ($byte < 248) {
return 4;
}
if ($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;
}
}