1: <?php
  2: /**
  3:  * CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
  4:  * Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
  5:  *
  6:  * Licensed under The MIT License
  7:  * For full copyright and license information, please see the LICENSE.txt
  8:  * Redistributions of files must retain the above copyright notice.
  9:  *
 10:  * @copyright     Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 11:  * @link          https://cakephp.org CakePHP(tm) Project
 12:  * @since         3.0.0
 13:  * @license       https://opensource.org/licenses/mit-license.php MIT License
 14:  */
 15: namespace Cake\Database\Expression;
 16: 
 17: use Cake\Database\ExpressionInterface;
 18: use Cake\Database\ValueBinder;
 19: 
 20: /**
 21:  * An expression object that represents an expression with only a single operand.
 22:  */
 23: class UnaryExpression implements ExpressionInterface
 24: {
 25:     /**
 26:      * Indicates that the operation is in pre-order
 27:      *
 28:      */
 29:     const PREFIX = 0;
 30: 
 31:     /**
 32:      * Indicates that the operation is in post-order
 33:      *
 34:      */
 35:     const POSTFIX = 1;
 36: 
 37:     /**
 38:      * The operator this unary expression represents
 39:      *
 40:      * @var string
 41:      */
 42:     protected $_operator;
 43: 
 44:     /**
 45:      * Holds the value which the unary expression operates
 46:      *
 47:      * @var mixed
 48:      */
 49:     protected $_value;
 50: 
 51:     /**
 52:      * Where to place the operator
 53:      *
 54:      * @var int
 55:      */
 56:     protected $_mode;
 57: 
 58:     /**
 59:      * Constructor
 60:      *
 61:      * @param string $operator The operator to used for the expression
 62:      * @param mixed $value the value to use as the operand for the expression
 63:      * @param int $mode either UnaryExpression::PREFIX or UnaryExpression::POSTFIX
 64:      */
 65:     public function __construct($operator, $value, $mode = self::PREFIX)
 66:     {
 67:         $this->_operator = $operator;
 68:         $this->_value = $value;
 69:         $this->_mode = $mode;
 70:     }
 71: 
 72:     /**
 73:      * Converts the expression to its string representation
 74:      *
 75:      * @param \Cake\Database\ValueBinder $generator Placeholder generator object
 76:      * @return string
 77:      */
 78:     public function sql(ValueBinder $generator)
 79:     {
 80:         $operand = $this->_value;
 81:         if ($operand instanceof ExpressionInterface) {
 82:             $operand = $operand->sql($generator);
 83:         }
 84: 
 85:         if ($this->_mode === self::POSTFIX) {
 86:             return '(' . $operand . ') ' . $this->_operator;
 87:         }
 88: 
 89:         return $this->_operator . ' (' . $operand . ')';
 90:     }
 91: 
 92:     /**
 93:      * {@inheritDoc}
 94:      *
 95:      */
 96:     public function traverse(callable $callable)
 97:     {
 98:         if ($this->_value instanceof ExpressionInterface) {
 99:             $callable($this->_value);
100:             $this->_value->traverse($callable);
101:         }
102:     }
103: 
104:     /**
105:      * Perform a deep clone of the inner expression.
106:      *
107:      * @return void
108:      */
109:     public function __clone()
110:     {
111:         if ($this->_value instanceof ExpressionInterface) {
112:             $this->_value = clone $this->_value;
113:         }
114:     }
115: }
116: