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<?php
/**
* Parses a reference to a CASE expression.
*/
namespace SqlParser\Components;
use SqlParser\Component;
use SqlParser\Parser;
use SqlParser\Token;
use SqlParser\TokensList;
/**
* Parses a reference to a CASE expression.
*
* @category Components
*
* @license https://www.gnu.org/licenses/gpl-2.0.txt GPL-2.0+
*/
class CaseExpression extends Component
{
/**
* The value to be compared.
*
* @var Expression
*/
public $value;
/**
* The conditions in WHEN clauses.
*
* @var array
*/
public $conditions;
/**
* The results matching with the WHEN clauses.
*
* @var array
*/
public $results;
/**
* The values to be compared against.
*
* @var array
*/
public $compare_values;
/**
* The result in ELSE section of expr.
*
* @var array
*/
public $else_result;
/**
* Constructor.
*/
public function __construct()
{
}
/**
* @param Parser $parser the parser that serves as context
* @param TokensList $list the list of tokens that are being parsed
*
* @return Expression
*/
public static function parse(Parser $parser, TokensList $list, array $options = array())
{
$ret = new self();
/**
* State of parser.
*
* @var int
*/
$state = 0;
/**
* Syntax type (type 0 or type 1).
*
* @var int
*/
$type = 0;
++$list->idx; // Skip 'CASE'
for (; $list->idx < $list->count; ++$list->idx) {
/**
* Token parsed at this moment.
*
* @var Token
*/
$token = $list->tokens[$list->idx];
// Skipping whitespaces and comments.
if (($token->type === Token::TYPE_WHITESPACE)
|| ($token->type === Token::TYPE_COMMENT)
) {
continue;
}
if ($state === 0) {
if ($token->type === Token::TYPE_KEYWORD
&& $token->value === 'WHEN'
) {
++$list->idx; // Skip 'WHEN'
$new_condition = Condition::parse($parser, $list);
$type = 1;
$state = 1;
$ret->conditions[] = $new_condition;
} elseif ($token->type === Token::TYPE_KEYWORD
&& $token->value === 'ELSE'
) {
++$list->idx; // Skip 'ELSE'
$ret->else_result = Expression::parse($parser, $list);
$state = 0; // last clause of CASE expression
} elseif ($token->type === Token::TYPE_KEYWORD
&& ($token->value === 'END'
|| $token->value === 'end')
) {
$state = 3; // end of CASE expression
++$list->idx;
break;
} elseif ($token->type === Token::TYPE_KEYWORD) {
$parser->error(__('Unexpected keyword.'), $token);
break;
} else {
$ret->value = Expression::parse($parser, $list);
$type = 0;
$state = 1;
}
} elseif ($state === 1) {
if ($type === 0) {
if ($token->type === Token::TYPE_KEYWORD
&& $token->value === 'WHEN'
) {
++$list->idx; // Skip 'WHEN'
$new_value = Expression::parse($parser, $list);
$state = 2;
$ret->compare_values[] = $new_value;
} elseif ($token->type === Token::TYPE_KEYWORD
&& $token->value === 'ELSE'
) {
++$list->idx; // Skip 'ELSE'
$ret->else_result = Expression::parse($parser, $list);
$state = 0; // last clause of CASE expression
} elseif ($token->type === Token::TYPE_KEYWORD
&& ($token->value === 'END'
|| $token->value === 'end')
) {
$state = 3; // end of CASE expression
++$list->idx;
break;
} elseif ($token->type === Token::TYPE_KEYWORD) {
$parser->error(__('Unexpected keyword.'), $token);
break;
}
} else {
if ($token->type === Token::TYPE_KEYWORD
&& $token->value === 'THEN'
) {
++$list->idx; // Skip 'THEN'
$new_result = Expression::parse($parser, $list);
$state = 0;
$ret->results[] = $new_result;
} elseif ($token->type === Token::TYPE_KEYWORD) {
$parser->error(__('Unexpected keyword.'), $token);
break;
}
}
} elseif ($state === 2) {
if ($type === 0) {
if ($token->type === Token::TYPE_KEYWORD
&& $token->value === 'THEN'
) {
++$list->idx; // Skip 'THEN'
$new_result = Expression::parse($parser, $list);
$ret->results[] = $new_result;
$state = 1;
} elseif ($token->type === Token::TYPE_KEYWORD) {
$parser->error(__('Unexpected keyword.'), $token);
break;
}
}
}
}
if ($state !== 3) {
$parser->error(
__('Unexpected end of CASE expression'),
$list->tokens[$list->idx - 1]
);
}
--$list->idx;
return $ret;
}
/**
* @param Expression $component the component to be built
* @param array $options parameters for building
*
* @return string
*/
public static function build($component, array $options = array())
{
$ret = 'CASE ';
if (isset($component->value)) {
// Syntax type 0
$ret .= $component->value . ' ';
for (
$i = 0;
$i < count($component->compare_values) && $i < count($component->results);
++$i
) {
$ret .= 'WHEN ' . $component->compare_values[$i] . ' ';
$ret .= 'THEN ' . $component->results[$i] . ' ';
}
} else {
// Syntax type 1
for (
$i = 0;
$i < count($component->conditions) && $i < count($component->results);
++$i
) {
$ret .= 'WHEN ' . Condition::build($component->conditions[$i]) . ' ';
$ret .= 'THEN ' . $component->results[$i] . ' ';
}
}
if (isset($component->else_result)) {
$ret .= 'ELSE ' . $component->else_result . ' ';
}
$ret .= 'END';
return $ret;
}
}
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