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<?php
/**
* `ORDER BY` keyword parser.
*
* @package SqlParser
* @subpackage Components
*/
namespace SqlParser\Components;
use SqlParser\Component;
use SqlParser\Parser;
use SqlParser\Token;
use SqlParser\TokensList;
/**
* `ORDER BY` keyword parser.
*
* @category Keywords
* @package SqlParser
* @subpackage Components
* @author Dan Ungureanu <udan1107@gmail.com>
* @license http://opensource.org/licenses/GPL-2.0 GNU Public License
*/
class OrderKeyword extends Component
{
/**
* The expression that is used for ordering.
*
* @var Expression
*/
public $expr;
/**
* The order type.
*
* @var string
*/
public $type;
/**
* Constructor.
*
* @param Expression $expr The expression that we are sorting by.
* @param string $type The sorting type.
*/
public function __construct($expr = null, $type = 'ASC')
{
$this->expr = $expr;
$this->type = $type;
}
/**
* @param Parser $parser The parser that serves as context.
* @param TokensList $list The list of tokens that are being parsed.
* @param array $options Parameters for parsing.
*
* @return OrderKeyword[]
*/
public static function parse(Parser $parser, TokensList $list, array $options = array())
{
$ret = array();
$expr = new OrderKeyword();
/**
* The state of the parser.
*
* Below are the states of the parser.
*
* 0 --------------------[ expression ]-------------------> 1
*
* 1 ------------------------[ , ]------------------------> 0
* 1 -------------------[ ASC / DESC ]--------------------> 1
*
* @var int
*/
$state = 0;
for (; $list->idx < $list->count; ++$list->idx) {
/**
* Token parsed at this moment.
* @var Token $token
*/
$token = $list->tokens[$list->idx];
// End of statement.
if ($token->type === Token::TYPE_DELIMITER) {
break;
}
// Skipping whitespaces and comments.
if (($token->type === Token::TYPE_WHITESPACE) || ($token->type === Token::TYPE_COMMENT)) {
continue;
}
if ($state === 0) {
$expr->expr = Expression::parse($parser, $list);
$state = 1;
} elseif ($state === 1) {
if (($token->type === Token::TYPE_KEYWORD) && (($token->value === 'ASC') || ($token->value === 'DESC'))) {
$expr->type = $token->value;
} elseif (($token->type === Token::TYPE_OPERATOR) && ($token->value === ',')) {
if (!empty($expr->expr)) {
$ret[] = $expr;
}
$expr = new OrderKeyword();
$state = 0;
} else {
break;
}
}
}
// Last iteration was not processed.
if (!empty($expr->expr)) {
$ret[] = $expr;
}
--$list->idx;
return $ret;
}
/**
* @param OrderKeyword $component The component to be built.
*
* @return string
*/
public static function build($component)
{
if (is_array($component)) {
$ret = array();
foreach ($component as $c) {
$ret[] = static::build($c);
}
return implode(", ", $ret);
} else {
return Expression::build($component->expr) . ' ' . $component->type;
}
}
}
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