WP Theme Asset Versioning

gistfile1.aw

<?php
/**
* Plugin Name: Theme Asset Versioning
*/

/**
 * Returns a versioned file name based on the last modified file date
 * 
 * @param string $fileUrl Pointing to the file as would have been from the html
 * @return string a versioned filename
 */
function getAssetVersionNumber($wordpressFileUrl)
{
	$fileUrl = stripWordpressVersioning($wordpressFileUrl);

	$fullPath = urlToFullPath($fileUrl);

    $fileInfo = new SplFileInfo($fullPath);
    
    if (!$fileInfo->isFile()) {
        return $wordpressFileUrl;
    }
    
    $modTime = $fileInfo->getMTime();
    
    $extension = $fileInfo->getExtension();
    if (! $extension) {
        return $wordpressFileUrl;
    }
    
    $versionedFilename = $fileInfo->getPath() . DIRECTORY_SEPARATOR . $fileInfo->getBasename('.'.$extension) . ".{$modTime}." . $extension;
    
    return fullPathToUrl($versionedFilename);
}
add_filter('style_loader_src', 'getAssetVersionNumber');

function stripWordpressVersioning($url)
{
	$url = preg_replace('/.css\?.*/', '.css', $url);
	$url = preg_replace('/.js\?.*/', '.js', $url);
	return $url;
}

function urlToFullPath($url)
{
	$path = str_replace(get_template_directory_uri(), get_template_directory(), $url);
	return $path;
}

function fullPathToUrl($path) {
	$url = str_replace(get_template_directory(), get_template_directory_uri(), $path);
	return $url;
}