laravel/laravel/blade.php

<?php namespace Laravel; use FilesystemIterator as fIterator; use Closure;

class Blade {

	/**
	 * All of the compiler functions used by Blade.
	 *
	 * @var array
	 */
	protected static $compilers = array(
		'extensions',
		'layouts',
		'comments',
		'echos',
		'forelse',
		'empty',
		'endforelse',
		'structure_openings',
		'structure_closings',
		'else',
		'unless',
		'endunless',
		'includes',
		'render_each',
		'render',
		'yields',
		'yield_sections',
		'section_start',
		'section_end',
	);

	/**
	 * An array of user defined compilers.
	 *
	 * @var array
	 */
	protected static $extensions = array();

	/**
	 * Register the Blade view engine with Laravel.
	 *
	 * @return void
	 */
	public static function sharpen()
	{
		Event::listen(View::engine, function($view)
		{
			// The Blade view engine should only handle the rendering of views which
			// end with the Blade extension. If the given view does not, we will
			// return false so the View can be rendered as normal.
			if ( ! str_contains($view->path, BLADE_EXT))
			{
				return;
			}

			$compiled = Blade::compiled($view->path);

			// If the view doesn't exist or has been modified since the last time it
			// was compiled, we will recompile the view into pure PHP from it's
			// Blade representation, writing it to cached storage.
			if ( ! file_exists($compiled) or Blade::expired($view->view, $view->path))
			{
				file_put_contents($compiled, Blade::compile($view));
			}

			$view->path = $compiled;

			// Once the view has been compiled, we can simply set the path to the
			// compiled view on the view instance and call the typical "get"
			// method on the view to evaluate the compiled PHP view.
			return $view->get();
		});
	}

	/**
	 * Register a custom Blade compiler.
	 *
	 * <code>
	 * 		Blade::extend(function($view)
	 *		{
	 * 			return str_replace('foo', 'bar', $view);
	 * 		});
	 * </code>
	 *
	 * @param  Closure  $compiler
	 * @return void
	 */
	public static function extend(Closure $compiler)
	{
		static::$extensions[] = $compiler;
	}

	/**
	 * Determine if a view is "expired" and needs to be re-compiled.
	 *
	 * @param  string  $view
	 * @param  string  $path
	 * @param  string  $compiled
	 * @return bool
	 */
	public static function expired($view, $path)
	{
		return filemtime($path) > filemtime(static::compiled($path));
	}

	/**
	 * Compiles the specified file containing Blade pseudo-code into valid PHP.
	 *
	 * @param  string  $path
	 * @return string
	 */
	public static function compile($view)
	{
		return static::compile_string(file_get_contents($view->path), $view);
	}

	/**
	 * Compiles the given string containing Blade pseudo-code into valid PHP.
	 *
	 * @param  string  $value
	 * @param  View    $view
	 * @return string
	 */
	public static function compile_string($value, $view = null)
	{
		foreach (static::$compilers as $compiler)
		{
			$method = "compile_{$compiler}";

			$value = static::$method($value, $view);
		}

		return $value;
	}

	/**
	 * Rewrites Blade "@layout" expressions into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_layouts($value)
	{
		// If the Blade template is not using "layouts", we'll just return it
		// unchanged since there is nothing to do with layouts and we will
		// just let the other Blade compilers handle the rest.
		if ( ! starts_with($value, '@layout'))
		{
			return $value;
		}

		// First we'll get the layout from the top of the template and remove it.
		// Then it is replaced with @include and attached to the end.
		// By convention it must be located on the first line of the template contents.
		preg_replace_callback(
			'/^@layout(\s*?\(.+?\))(\r?\n)?/',
			function($matches) use (&$value)
			{
				$value = substr( $value, strlen( $matches[0] ) ).CRLF.'@include'.$matches[1];
			},
			$value
		);

		return $value;
	}

	/**
	 * Extract a variable value out of a Blade expression.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function extract($value, $expression)
	{
		if ( preg_match("/@layout\s*?\(\s*?'(.+?)'\s*?\)/", $value, $matches))
		{
			return trim( $matches[1] );
		}
	}

	/**
	 * Rewrites Blade comments into PHP comments.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_comments($value)
	{
		$value = preg_replace('/\{\{--(.+?)(--\}\})?\n/', "<?php // $1 ?>", $value);

		return preg_replace('/\{\{--((.|\s)*?)--\}\}/', "<?php /* $1 */ ?>\n", $value);
	}

	/**
	 * Rewrites Blade echo statements into PHP echo statements.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_echos($value)
	{
		return preg_replace('/\{\{(.+?)\}\}/', '<?php echo $1; ?>', $value);
	}

	/**
	 * Rewrites Blade "for else" statements into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_forelse($value)
	{
		preg_match_all('/@forelse\s*?\(\s*?\$(.+?)\s*?as\s*?\$(.+?)\s*?\)/', $value, $matches, PREG_SET_ORDER );
		
		if ( count($matches) < 1 ) return $value;

		foreach ($matches as $forelse)
		{
			// Once we have extracted the variable being looped against, we can add
			// an if statement to the start of the loop that checks if the count
			// of the variable being looped against is greater than zero.
			$replace = '<?php if (count($'.$forelse[1].') > 0): foreach ($'.$forelse[1].' as $'.$forelse[2].'): ?>';

			// Finally, once we have the check prepended to the loop we'll replace
			// all instances of this forelse syntax in the view content of the
			// view being compiled to Blade syntax with real PHP syntax.
			$value = str_replace($forelse[0], $replace, $value);
		}

		return $value;
	}

	/**
	 * Rewrites Blade "empty" statements into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_empty($value)
	{
		return str_replace('@empty', '<?php endforeach; else: ?>', $value);
	}

	/**
	 * Rewrites Blade "forelse" endings into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_endforelse($value)
	{
		return str_replace('@endforelse', '<?php endif; ?>', $value);
	}

	/**
	 * Rewrites Blade structure openings into PHP structure openings.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_structure_openings($value)
	{
		$pattern = '/@(if|elseif|foreach|for|while)\s*?(\(.+?\))/';

		return preg_replace($pattern, '<?php $1$2: ?>', $value);
	}

	/**
	 * Rewrites Blade structure closings into PHP structure closings.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_structure_closings($value)
	{
		$pattern = '/@(endif|endforeach|endfor|endwhile|break)/';

		return preg_replace($pattern, '<?php $1; ?>', $value);
	}

	/**
	 * Rewrites Blade else statements into PHP else statements.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_else($value)
	{
		return str_replace( '@else', '<?php else: ?>', $value);
	}

	/**
	 * Rewrites Blade "unless" statements into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_unless($value)
	{
		$pattern = static::matcher('unless');

		return preg_replace($pattern, '<?php if( ! ($1)): ?>', $value);
	}

	/**
	 * Rewrites Blade "unless" endings into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_endunless($value)
	{
		return str_replace('@endunless', '<?php endif; ?>', $value);
	}

	/**
	 * Rewrites Blade @include statements into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_includes($value)
	{
		$pattern = static::matcher('include');

		return preg_replace($pattern, '<?php echo view$1->with(get_defined_vars())->render(); ?>', $value);
	}

	/**
	 * Rewrites Blade @render statements into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_render($value)
	{
		$pattern = static::matcher('render');

		return preg_replace($pattern, '<?php echo render$1; ?>', $value);
	}

	/**
	 * Rewrites Blade @render_each statements into valid PHP.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_render_each($value)
	{
		$pattern = static::matcher('render_each');

		return preg_replace($pattern, '<?php echo render_each$1; ?>', $value);
	}

	/**
	 * Rewrites Blade @yield statements into Section statements.
	 *
	 * The Blade @yield statement is a shortcut to the Section::yield method.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_yields($value)
	{
		$pattern = static::matcher('yield');

		return preg_replace($pattern, '<?php echo \\Laravel\\Section::yield$1; ?>', $value);
	}

	/**
	 * Rewrites Blade yield section statements into valid PHP.
	 *
	 * @return string
	 */
	protected static function compile_yield_sections($value)
	{
		return str_replace('@yield_section', '<?php echo \\Laravel\\Section::yield_section(); ?>', $value);
	}

	/**
	 * Rewrites Blade @section statements into Section statements.
	 *
	 * The Blade @section statement is a shortcut to the Section::start method.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_section_start($value)
	{
		$pattern = static::matcher('section');

		return preg_replace($pattern, '<?php \\Laravel\\Section::start$1; ?>', $value);
	}

	/**
	 * Rewrites Blade @endsection statements into Section statements.
	 *
	 * The Blade @endsection statement is a shortcut to the Section::stop method.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_section_end($value)
	{
		return str_replace('@endsection', '<?php \\Laravel\\Section::stop(); ?>', $value);
	}

	/**
	 * Execute user defined compilers.
	 *
	 * @param  string  $value
	 * @return string
	 */
	protected static function compile_extensions($value)
	{
		foreach (static::$extensions as $compiler)
		{
			$value = $compiler($value);
		}

		return $value;
	}	

	/**
	 * Get the regular expression for a generic Blade function.
	 *
	 * @param  string  $function
	 * @return string
	 */
	public static function matcher($function)
	{
		return '/@'.$function.'\s*?(\(.+?\))/';
	}

	/**
	 * Get the fully qualified path for a compiled view.
	 *
	 * @param  string  $view
	 * @return string
	 */
	public static function compiled($path)
	{
		return path('storage').'views/'.md5($path);
	}

}