How to: get main plugin/theme file?

Question

There're the functions get_theme_data(); & get_plugin_data(); - which both use get_file_data(); that needs a specific file as $input.

I got a set of classes that may be used by a plugin or a theme, without a specific location. Everything works, but I don't know how i would determine what the main plugin or theme file is - I mean the one containing the comment header that holds the information (Version, Author, etc.) about the Theme/Plugin.

Answer 1

You can get theme's main file using following:

$theme_info_file = trailingslashit( get_template_directory() ) . 'style.css';

To get the plugin's main file you need to know the plugin name. And then you can use following function:

function get_plugin_file( $plugin_name ) {
    require_once( ABSPATH . '/wp-admin/includes/plugin.php' );
    $plugins = get_plugins();
    foreach( $plugins as $plugin_file => $plugin_info ) {
        if ( $plugin_info['Name'] == $plugin_name ) return $plugin_file;
    }
    return null;
}

For example to get the plugin main file for Akismet.

$akismet_plugin_file =  trailingslashit( WP_PLUGIN_DIR ) . get_plugin_file( 'Akismet' );

Answer 2

How do get the comment header data of a theme OR plugin...

... that holds a specific class.

The following shows how you can drop a class inside any plugin or theme and still be able to get any theme or plugin data from the comment header. This is useful for updating settings/db-options for example.

You don't know:

1. if it's a plugin, mu-plugin or a theme
2. and how deeply nested your container/root theme or plugin folder is.

Notes:

1. Works for mu-plugins too.
2. Might not work if an additional theme directory was registered later (thanks to @toscho for the hint).
3. Performance test for a theme shows 0.0042 sec. loading time on 1.000 runs.
4. The following functions are meant to reside in a class.

---

/**
 * Plugin root
 * @return Full Path to plugin folder
 */
public function set_root_path() 
{
    $_path = trailingslashit( str_replace( basename( __FILE__ ), "", plugin_basename( __FILE__ ) ) );

    // Allow overriding the location
    $_path = apply_filters( __CLASS__.'_root', $_path );

    return $this->_path = $_path;
}


/**
 * Gets the data of the base 'theme' / 'plugin' / 'wpmuplugin'
 * Performance: average loading time on a local (not vanilla) install for 1.000 runs: 0.0042 sec.
 * 
 * @param (mixed) $value
 * @return (array) $value | Theme/Plugin comment header data OR false on failure | default: 'Version'
 */
public function get_data( $value = 'Version' )
{
    // Class basename - String to Array
    $_path_data = explode( '/', $this->_path );
    // Get rid of the last element, as it's only a trailing slash
    array_pop( $_path_data );
    // reverse for faster processing
    krsort( $_path_data );

    // Themes basename
    $theme_roots = get_theme_roots();
    // In case some used register_theme_directory(); before
    // Might not work if an additional themes directory will be registered later
    // Thanks to @Thomas Scholz <http://toscho.de> for the hint
    if ( is_array( $theme_roots ) )
    {    
        foreach ( $_path_data as $_path_part )
        {
            foreach( $theme_roots as $root )
            {
                if ( in_array( $root, $_path_data ) )
                    $_theme_root = $root;
            }
        }
    }
    else 
    {
        // Get rid of the leading slash
        $_theme_root = str_replace( '/', '', $theme_roots );
    }

    // Plugins basename
    $_plugin_root = basename( WP_PLUGIN_DIR );


    # >>>> get file & load data
    $base_file = '';
    // Themes
    if ( in_array( $_theme_root, $_path_data ) )
    {
        foreach ( search_theme_directories() as $folder => $data )
        {
            foreach ( $_path_data as $_path_part )
            {
                if ( $_path_part == $folder )
                    $base_file = trailingslashit( $data['theme_root'] ).$data['theme_file'];
            }
        }

        $file_data = get_theme_data( $base_file );
    }
    // Plugins
    elseif( in_array( $_plugin_root, $_path_data ) )
    {
        $plugins = get_plugins();
        foreach ( $plugins as $plugin_file => $plugin_info )
        {
            $data   = explode( '/', $plugin_file );
            $file   = $data[1];
            foreach ( $_path_data as $_path_part )
            {
                if ( $_path_part !== $file )
                    $base_file = WP_CONTENT_DIR.$_type.'/'.$data[0].'/'.$data[1];
            }
        }

        $file_data = get_plugin_data( $base_file );
    }
    // WPMU Plugins
    else
    {
        // MU plugins basename - compatible for older MU too
        // Thanks (again) to @Thomas Scholz <http://toscho.de> for the hint that mu plugins really exists
        $mu_plugin_dir = ! version_compare( $GLOBALS['wp_version'], '3.0.0', '>=' ) ? MUPLUGINDIR : WPMU_PLUGIN_DIR;
        $_mu_plugin_root = basename( $mu_plugin_dir );

        if ( ! in_array( $_mu_plugin_root, $_path_data ) )
            return false;

        $mu_plugins = get_mu_plugins();
        foreach ( $mu_plugins as $mu_plugin_file => $mu_plugin_info )
        {
            $data   = explode( '/', $mu_plugin_file );
            $file   = $data[1];
            foreach ( $_path_data as $_path_part )
            {
                if ( $_path_part !== $file )
                    $base_file = WP_CONTENT_DIR.$_type.'/'.$data[0].'/'.$data[1];
            }
        }

        $file_data = get_plugin_data( $base_file );
    }
    # <<<< get file & load data


    // return
    if ( ! empty ( $file_data ) )
        return $file_data[ $value ];

    // return false to determine that we couldn't load the comment header data
    return false;
}

Usage Example:

echo $this->get_data( 'Author' ); // The Plugin or Theme Author
echo $this->get_data( 'Version' ); // The Plugin or Theme Version
echo $this->get_data( 'Name' ); // The Plugin or Theme Name