<?php
namespace Illuminate\View\Engines;
use Closure;
use InvalidArgumentException;
class EngineResolver
{// engineResolver
/**
* The array of engine resolvers.
*
* @var array
*/
protected $resolvers = [];// The array of engine resolvers.
/**
* The resolved engine instances.
*
* @var array
*/
protected $resolved = [];// The resolved engine instances.
/**
* Register a new engine resolver.
*
* The engine string typically corresponds to a file extension.
*
* @param string $engine
* @param \Closure $resolver
* @return void
*/
public function register($engine, Closure $resolver)
{
unset($this->resolved[$engine]);// first to unset it
$this->resolvers[$engine] = $resolver;// set it
}// Register a new engine resolver.
// change the new register
/**
* Resolver an engine instance by name.
*
* @param string $engine
* @return \Illuminate\View\Engines\EngineInterface
* @throws \InvalidArgumentException
*/
public function resolve($engine)
{// resolver an engine instance by name.
if (isset($this->resolved[$engine])) {
return $this->resolved[$engine];
}// isset resolved
if (isset($this->resolvers[$engine])) {
return $this->resolved[$engine] = call_user_func($this->resolvers[$engine]);
}// isset resolvers
// call_user_func has been used
throw new InvalidArgumentException("Engine $engine not found.");
}// throw new exception
}