wp_get_global_stylesheet()

wp_get_global_stylesheet( array $types = array() ): string

function wp_get_global_stylesheet( $types = array() ) {
	/*
	 * Ignore cache when the development mode is set to 'theme', so it doesn't interfere with the theme
	 * developer's workflow.
	 */
	$can_use_cached = empty( $types ) && ! wp_is_development_mode( 'theme' );

	/*
	 * By using the 'theme_json' group, this data is marked to be non-persistent across requests.
	 * @see `wp_cache_add_non_persistent_groups()`.
	 *
	 * The rationale for this is to make sure derived data from theme.json
	 * is always fresh from the potential modifications done via hooks
	 * that can use dynamic data (modify the stylesheet depending on some option,
	 * settings depending on user permissions, etc.).
	 * See some of the existing hooks to modify theme.json behavior:
	 * @see https://make.wordpress.org/core/2022/10/10/filters-for-theme-json-data/
	 *
	 * A different alternative considered was to invalidate the cache upon certain
	 * events such as options add/update/delete, user meta, etc.
	 * It was judged not enough, hence this approach.
	 * @see https://github.com/WordPress/gutenberg/pull/45372
	 */
	$cache_group = 'theme_json';
	$cache_key   = 'wp_get_global_stylesheet';
	if ( $can_use_cached ) {
		$cached = wp_cache_get( $cache_key, $cache_group );
		if ( $cached ) {
			return $cached;
		}
	}

	$tree = WP_Theme_JSON_Resolver::resolve_theme_file_uris( WP_Theme_JSON_Resolver::get_merged_data() );

	if ( empty( $types ) ) {
		$types = array( 'variables', 'styles', 'presets' );
	}

	/*
	 * Enable base layout styles only mode for classic themes without theme.json.
	 * This skips alignment styles that target .wp-site-blocks which is only used by block themes.
	 */
	$options = array();
	if ( ! wp_is_block_theme() && ! wp_theme_has_theme_json() ) {
		$options['base_layout_styles'] = true;
	}

	/*
	 * If variables are part of the stylesheet, then add them.
	 * This is so themes without a theme.json still work as before 5.9:
	 * they can override the default presets.
	 * See https://core.trac.wordpress.org/ticket/54782
	 */
	$styles_variables = '';
	if ( in_array( 'variables', $types, true ) ) {
		/*
		 * Only use the default, theme, and custom origins. Why?
		 * Because styles for `blocks` origin are added at a later phase
		 * (i.e. in the render cycle). Here, only the ones in use are rendered.
		 * @see wp_add_global_styles_for_blocks
		 */
		$origins          = array( 'default', 'theme', 'custom' );
		$styles_variables = $tree->get_stylesheet( array( 'variables' ), $origins, $options );
		$types            = array_diff( $types, array( 'variables' ) );
	}

	/*
	 * For the remaining types (presets, styles), we do consider origins:
	 *
	 * - themes without theme.json: only the classes for the presets defined by core
	 * - themes with theme.json: the presets and styles classes, both from core and the theme
	 */
	$styles_rest = '';
	if ( ! empty( $types ) ) {
		/*
		 * Only use the default, theme, and custom origins. Why?
		 * Because styles for `blocks` origin are added at a later phase
		 * (i.e. in the render cycle). Here, only the ones in use are rendered.
		 * @see wp_add_global_styles_for_blocks
		 */
		$origins     = array( 'default', 'theme', 'custom' );
		$styles_rest = $tree->get_stylesheet( $types, $origins, $options );
	}

	$stylesheet = $styles_variables . $styles_rest;
	if ( $can_use_cached ) {
		wp_cache_set( $cache_key, $stylesheet, $cache_group );
	}

	return $stylesheet;
}