Joshua Morey | 2013-09-27

Reinventing The Wheel

I haven't posted about development for months, but I have been getting some work done. My current project is a new templating engine that I am preliminarily calling templ@te. I finalized the first draft of the template language recently and just got around to implementing a parser/evaluator in PHP.

So, why on earth would I create another templating language? There are plenty of options out there like Twig, Smarty, Jinja2, Cheetah, Genshi, Django, Mako, Myghty, ctemplate, and many more. The short answer, as with most of my projects, is that I work on whatever grabs my interest. The long answer is that while I like many of the templating languages out there (my favorites being Twig, Smarty, Django, and Jinja2), I wanted something that combined the most useful capabilities of those languages in a more elegant and compact notation with a focus on the particular style of data binding that I want. I have met this goal so far, but it will take some time for me to be sure that the language can be extended to all the uses that I will have for it. Beyond that, I have no idea yet whether this language will be general-purpose enough to compete with the other options that are available.

The performance of my first revision is reasonable, considering that I wrote it in PHP. I designed it to provide a good mix of flexibility and performance, so it beats most other templating engines, but not by much. In lieu of a full feature list (since I am still adding functionality), I will just provide an example to demonstrate the syntax. Here is a basic template with variables, in-line template definitions, includes, and binding blocks.


			

				
				
{@TemplateBase}
<!DOCTYPE html>
<html>
<head>
	<title>{$title}</title>
</head>
<body>
	<div id="header">
		{@Header}
			<h1><a href="{$root-url}">jacere.net</a></h1>
			{@Navigation}
				<div id="nav">
					<ul>
						{?nav-list}
							<li><a href="{$url}">{$text}</a></li>
						{/?}
					</ul>
				</div>
			{/@}
		{/@}
	</div>
​
	<div id="content">
		{$content}
	</div>
	<div id="sidebar">
		{#Sidebar}
	</div>
</body>
</html>
{/@}

Here is an example of inheriting this base template to show a list of posts.


			

				
				
{@Posts}
	{^TemplateBase}
	{.content}
		{?list}
			{#PostSection}
		{/?}
	{/.}
{/@}
​
{@PostSection}
<div class="article">
	<div class="title">
		<small>Posted by: <strong>{$author}</strong> | {$date}</small>
		<h2><a href="{$url}">{$title}</a></h2>
	</div>
	<div class="post">
		<div class="entry">
			{$content}
		</div>
		<div class="postinfo">
			Posted in
			<ul class="taglist">
				{?categories}
					<li><a href="{$url}">{$name}</a></li>
				{/?}
			</ul>
		</div>
	</div>
</div>
{/@}

The block closing syntax that I am using is mostly for style reasons. The following closing formats are parsed identically.


			

				
				
{/}
{/@}
{/name}

Similarly, the parser accepts alternate delimiters, so the individual brace format can be replaced as desired (e.g. {$var} could be <$var> or {{$var}}).

As for using the template, right now I am simply binding to nested PHP arrays. I have not yet decided where I want to go from here.


			

				
				
$context = [
	'Posts' => [
		'title'	=> 'templ@te',
		'list'	 => [
			[
				'author'  => 'Joshua Morey',
				'date'	=> '2013-03-14',
				'url'	 => '/2013/03/satr-development-finalized/',
				'title'   => 'SATR Development Finalized',
				'content' => '<p>I finally found some time...</p>',
				'categories' => [
					['url' => '/category/c/', 'name' => 'C#'],
					['url' => '/category/cloudae/', 'name' => 'CloudAE'],
					['url' => '/category/lidar/', 'name' => 'LiDAR'],
				],
			],
			[
				'author'  => 'Joshua Morey',
				'date'	=> '2011-12-23',
				'url'	 => '/2011/12/tile-stitching/',
				'title'   => 'Tile Stitching',
				'content' => '<p>I have completed...</p>',
				'categories' => [
					['url' => '/category/cloudae/', 'name' => 'CloudAE'],
				],
			],
		]
	],
	'Header' => [
		'root-url' => '/template/parse.php',
	],
	'Navigation' => [
		'nav-list' => [
			['url' => '/about', 'text' => 'Contact'],
			['url' => '/contact', 'text' => 'About'],
		],
	],
];
​
$output = TemplateManager::Evaluate('Posts', $context);

There are many things I plan to add/improve, such as filters (e.g. escaping), compacted syntax combinations, more versatile named bindings, and improved caching performance. Eventually, I will also choose a name for the project, since "templ@te" isn't very web-friendly.

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