Creates the generator XML or Comment for RSS, ATOM, etc.

Returns the correct generator type for the requested output format. Allows
for a plugin to filter generators on an individual basis using the
{@see ‘get_the_generator_$type’} filter.

function get_the_generator( $type = '' ) {
	if ( empty( $type ) ) {

		$current_filter = current_filter();
		if ( empty( $current_filter ) ) {
			return;
		}

		switch ( $current_filter ) {
			case 'rss2_head':
			case 'commentsrss2_head':
				$type = 'rss2';
				break;
			case 'rss_head':
			case 'opml_head':
				$type = 'comment';
				break;
			case 'rdf_header':
				$type = 'rdf';
				break;
			case 'atom_head':
			case 'comments_atom_head':
			case 'app_head':
				$type = 'atom';
				break;
		}
	}

	switch ( $type ) {
		case 'html':
			$gen = '';
			break;
		case 'xhtml':
			$gen = '';
			break;
		case 'atom':
			$gen = 'WordPress';
			break;
		case 'rss2':
			$gen = '' . sanitize_url( 'https://wordpress.org/?v=' . get_bloginfo_rss( 'version' ) ) . '';
			break;
		case 'rdf':
			$gen = '';
			break;
		case 'comment':
			$gen = '';
			break;
		case 'export':
			$gen = '';
			break;
	}

	/**
	 * Filters the HTML for the retrieved generator type.
	 *
	 * The dynamic portion of the hook name, `$type`, refers to the generator type.
	 *
	 * Possible hook names include:
	 *
	 *  - `get_the_generator_atom`
	 *  - `get_the_generator_comment`
	 *  - `get_the_generator_export`
	 *  - `get_the_generator_html`
	 *  - `get_the_generator_rdf`
	 *  - `get_the_generator_rss2`
	 *  - `get_the_generator_xhtml`
	 *
	 * @since 2.5.0
	 *
	 * @param string $gen  The HTML markup output to wp_head().
	 * @param string $type The type of generator. Accepts 'html', 'xhtml', 'atom',
	 *                     'rss2', 'rdf', 'comment', 'export'.
	 */
	return apply_filters( "get_the_generator_{$type}", $gen, $type );
}