Specification Design Pattern

AndX.php

<?php

/**
 * class AndX
 * @author Vasil Dakov <[email protected]>
 */
class AndX extends CompositeSpecification
{
   /**
    * @var SpecificationInterface $left
    */
    private $left;
  
   /**
    * @var SpecificationInterface $right
    */
    private $right;
  
   /**
    * @param SpecificationInterface $left
    * @param SpecificationInterface $right
    */
    public function __construct(
       SpecificationInterface $left,
       SpecificationInterface $right
    ) {
        $this->left  = $left;
        $this->right = $right;
    }
  
   /**
    * @param mixed $value
    * @return bool
    */
    public function isSatisfiedBy($value) : bool
    {
        return $this->left->isSatisfiedBy($value) && $this->right->isSatisfiedBy($value);
    }
}

CompositeSpecification.php

<?php

/**
 * class CompositeSpecification
 * @author Vasil Dakov <[email protected]>
 */
abstract class CompositeSpecification implements CompositeSpecificationInterface
{
   /**
    * @param SpecificationInterface $specification
    * @return AndX
    */
    public function andX(SpecificationInterface $specification)
    {
        return new And($this, $specification);
    }
  
   /**
    * @param SpecificationInterface $specification
    * @return OrX
    */
    public function orX(SpecificationInterface $specification)
    {
        return new OrX($this, $specification);
    }
}

CompositeSpecificationInterface.php

<?php

/**
 * interface CompositeSpecificationInterface
 * @author Vasil Dakov <[email protected]>
 */
interface CompositeSpecificationInterface
{
   /**
    * @param SpecificationInterface $specification
    * @return AndX
    */
    public function andX(SpecificationInterface $specification);
  
   /**
    * @param SpecificationInterface $specification
    * @return OrX
    */
    public function orX(SpecificationInterface $specification);
  
}

OrX.php

<?php

/**
 * class OrX
 * @author Vasil Dakov <[email protected]>
 */
class OrX extends CompositeSpecification
{
   /**
    * @var SpecificationInterface $left
    */
    private $left;
  
   /**
    * @var SpecificationInterface $right
    */
    private $right;
  
   /**
    * @param SpecificationInterface $left
    * @param SpecificationInterface $right
    */
    public function __construct(SpecificationInterface $left, SpecificationInterface $right)
    {
        $this->left  = $left;
        $this->right = $right;
    }
  
   /**
    * @param mixed $value
    * @return bool
    */
    public function isSatisfiedBy($value) : bool
    {
        return $this->left->isSatisfiedBy($value) || $this->right->isSatisfiedBy($value);
    }
}

SpecificationInterface.php

<?php

/**
 * interface SpecificationInterface
 * @author Vasil Dakov <[email protected]>
 */
interface SpecificationInterface
{
   /**
    * @param mixed $value
    * @return bool
    */
    public function isSatisfiedBy($value) : bool;
}