CacheBuilder.php

<?php
namespace Geek\Cache;
class CacheBuilder
{
	private $cache;
	private $memocache;
	private $tagsetfactory;

	public function __construct( Cache $cache, Cache $memocache, TagSetFactory $tagsetfactory, array $stack = null )
	{
		$this->cache = $cache;
		$this->memocache = $memocache;
		$this->tagsetfactory = $tagsetfactory;
		$this->stack = $stack ?: array( function() use( $cache ){ return $cache; } );
	}
	
	public function make()
	{
		$stack = $this->stack;
		$cache = $this->cache;

		while( $factory = array_shift( $stack ) )
			$cache = $factory( $cache );

		return $cache;
	}

	private function addToStack( callable $factory )
	{
		$stack = $this->stack;
		$stack[] = $factory;
		return new self( $this->cache, $this->memocache, $this->tagsetfactory, $stack );
	}

	public function memoize()
	{
		$memocache = $this->memocache;

		$factory = function( $cache ) use ( $memocache ){
			return new MemoizedCache( $cache, $memocache );
		};

		return $this->addToStack( $factory );
	}

	private function getSoftInvalidatableFactory( $policy )
	{
		return function( $cache ) use ( $policy ){
			if( $cache instanceof SoftInvalidatable )
				return new SoftInvalidatableCache( $cache, $policy, $cache );
			else
				return new SoftInvalidatableCache( $cache, $policy );
		};
	}

	public function addTags( array $tags )
	{
		$tagsetfactory = $this->tagsetfactory;
		$tagset        = $tagsetfactory->makeTagSet( $tags );
		$policy        = new TaggedFreshnessPolicy( $tagset );
		$factory       = $this->getSoftInvalidatableFactory( $policy );
		return $this->addToStack( $factory );
	}

	public function addGracePeriod( $gracePeriod = null )
	{
		$policy = new GracePeriodFreshnessPolicy( $gracePeriod );
		$factory = $this->getSoftInvalidatableFactory( $policy );
		return $this->addToStack( $factory );
	}
}