DesignPatternsPHP/Specification/Not.php

<?php
namespace DesignPatterns\Specification;

/**
 * A logical Not specification
 */
class Not extends AbstractSpecification
{

    protected $spec;

    /**
     * Creates a new specification wrapping another
     * 
     * @param SpecificationInterface $spec

     */
    public function __construct(SpecificationInterface $spec)
    {
        $this->spec = $spec;
    }

    /**
     * Returns the negated result of the wrapped specification
     * 
     * @param Item $item
     * 
     * @return bool
     */
    public function isSatisfiedBy(Item $item)
    {
        return !$this->spec->isSatisfiedBy($item);
    }
}