<?php
/**
* CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
* Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
*
* Licensed under The MIT License
* For full copyright and license information, please see the LICENSE.txt
* Redistributions of files must retain the above copyright notice.
*
* @copyright Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
* @link https://cakephp.org CakePHP(tm) Project
* @since 3.0.0
* @license https://opensource.org/licenses/mit-license.php MIT License
*/
namespace Cake\Database\Expression;
use Cake\Database\ExpressionInterface;
use Cake\Database\ValueBinder;
/**
* An expression object that represents an expression with only a single operand.
*/
class UnaryExpression implements ExpressionInterface
{
/**
* Indicates that the operation is in pre-order
*
* @var int
*/
const PREFIX = 0;
/**
* Indicates that the operation is in post-order
*
* @var int
*/
const POSTFIX = 1;
/**
* The operator this unary expression represents
*
* @var string
*/
protected $_operator;
/**
* Holds the value which the unary expression operates
*
* @var mixed
*/
protected $_value;
/**
* Where to place the operator
*
* @var int
*/
protected $_mode;
/**
* Constructor
*
* @param string $operator The operator to used for the expression
* @param mixed $value the value to use as the operand for the expression
* @param int $mode either UnaryExpression::PREFIX or UnaryExpression::POSTFIX
*/
public function __construct($operator, $value, $mode = self::PREFIX)
{
$this->_operator = $operator;
$this->_value = $value;
$this->_mode = $mode;
}
/**
* Converts the expression to its string representation
*
* @param \Cake\Database\ValueBinder $generator Placeholder generator object
* @return string
*/
public function sql(ValueBinder $generator)
{
$operand = $this->_value;
if ($operand instanceof ExpressionInterface) {
$operand = $operand->sql($generator);
}
if ($this->_mode === self::POSTFIX) {
return '(' . $operand . ') ' . $this->_operator;
}
return $this->_operator . ' (' . $operand . ')';
}
/**
* {@inheritDoc}
*
*/
public function traverse(callable $visitor)
{
if ($this->_value instanceof ExpressionInterface) {
$visitor($this->_value);
$this->_value->traverse($visitor);
}
}
/**
* Perform a deep clone of the inner expression.
*
* @return void
*/
public function __clone()
{
if ($this->_value instanceof ExpressionInterface) {
$this->_value = clone $this->_value;
}
}
}