Add global function to get block CSS selectors

lib/compat/wordpress-6.2/get-global-styles-and-settings.php

@@ -255,3 +255,138 @@ function _gutenberg_add_non_persistent_theme_json_cache_group() {
 	wp_cache_add_non_persistent_groups( 'theme_json' );
 }
 add_action( 'plugins_loaded', '_gutenberg_add_non_persistent_theme_json_cache_group' );
+
+if ( ! function_exists( 'wp_get_block_css_selector' ) ) {
+	/**
+	 * Determine the CSS selector for the block type and property provided,
+	 * returning it if available.
+	 *
+	 * @param WP_Block_Type $block_type The block's type.
+	 * @param string|array  $target     The desired selector's target, `root` or array path.
+	 * @param boolean       $fallback   Whether or not to fallback to broader selector.
+	 *
+	 * @return string|null CSS selector or `null` if no selector available.
+	 */
+	function wp_get_block_css_selector( $block_type, $target = 'root', $fallback = false ) {
+		if ( empty( $target ) ) {
+			return null;
+		}
+
+		$has_selectors = isset( $block_type->selectors ) && ! empty( $block_type->selectors );
+
+		// Duotone (No fallback selectors for Duotone).
+		if ( 'duotone' === $target ) {
+			// If selectors API in use, only use it's value or null.
+			if ( $has_selectors ) {
+				return _wp_array_get( $block_type->selectors, array( 'color', 'duotone' ), null );
+			}
+
+			// Selectors API, not available, check for old experimental selector.
+			return _wp_array_get( $block_type->supports, array( 'color', '__experimentalDuotone' ), null );
+		}
+
+		// Root Selector.
+
+		// Calculated before returning as it can be used as fallback for
+		// feature selectors later on.
+		$root_selector = null;
+
+		if ( $has_selectors && isset( $block_type->selectors['root'] ) ) {
+			// Prefer the selectors API if available.
+			$root_selector = $block_type->selectors['root'];
+		} elseif ( isset( $block_type->supports['__experimentalSelector'] ) && is_string( $block_type->supports['__experimentalSelector'] ) ) {
+			// Use the old experimental selector supports property if set.
+			$root_selector = $block_type->supports['__experimentalSelector'];
+		} else {
+			// If no root selector found, generate default block class selector.
+			$block_name    = str_replace( '/', '-', str_replace( 'core/', '', $block_type->name ) );
+			$root_selector = ".wp-block-{$block_name}";
+		}
+
+		// Return selector if it's the root target we are looking for.
+		if ( 'root' === $target ) {
+			return $root_selector;
+		}
+
+		// If target is not `root` or `duotone` we have a feature or subfeature
+		// as the target. If the target is a string convert to an array.
+		if ( is_string( $target ) ) {
+			$target = explode( '.', $target );
+		}
+
+		// Feature Selectors ( May fallback to root selector ).
+		if ( 1 === count( $target ) ) {
+			$fallback_selector = $fallback ? $root_selector : null;
+
+			// Prefer the selectors API if available.
+			if ( $has_selectors ) {
+				// Look for selector under `feature.root`.
+				$path             = array_merge( $target, array( 'root' ) );
+				$feature_selector = _wp_array_get( $block_type->selectors, $path, null );
+
+				if ( $feature_selector ) {
+					return $feature_selector;
+				}
+
+				// Check if feature selector set via shorthand.
+				$feature_selector = _wp_array_get( $block_type->selectors, $target, null );
+
+				return is_string( $feature_selector ) ? $feature_selector : $fallback_selector;
+			}
+
+			// Try getting old experimental supports selector value.
+			$path             = array_merge( $target, array( '__experimentalSelector' ) );
+			$feature_selector = _wp_array_get( $block_type->supports, $path, null );
+
+			// Nothing to work with, provide fallback or null.
+			if ( null === $feature_selector ) {
+				return $fallback_selector;
+			}
+
+			// Scope the feature selector by the block's root selector.
+			// TODO: Following is boilerplate from theme.json class. Is there a util?
+			$scopes    = explode( ',', $root_selector );
+			$selectors = explode( ',', $feature_selector );
+
+			$selectors_scoped = array();
+			foreach ( $scopes as $outer ) {
+				foreach ( $selectors as $inner ) {
+					$outer = trim( $outer );
+					$inner = trim( $inner );
+					if ( ! empty( $outer ) && ! empty( $inner ) ) {
+						$selectors_scoped[] = $outer . ' ' . $inner;
+					} elseif ( empty( $outer ) ) {
+						$selectors_scoped[] = $inner;
+					} elseif ( empty( $inner ) ) {
+						$selectors_scoped[] = $outer;
+					}
+				}
+			}
+
+			return implode( ', ', $selectors_scoped );
+		}
+
+		// Subfeature selector
+		// This may fallback either to parent feature or root selector.
+		$subfeature_selector = null;
+		// Use selectors API if available.
+		if ( $has_selectors ) {
+			$subfeature_selector = _wp_array_get( $block_type->selectors, $target, null );
+
+			// Only return if we have a subfeature selector.
+			if ( $subfeature_selector ) {
+				return $subfeature_selector;
+			}
+		}
+
+		// To this point we don't have a subfeature selector. If a fallback
+		// has been requested, remove subfeature from target path and return
+		// results of a call for the parent feature's selector.
+		if ( $fallback ) {
+			return wp_get_block_css_selector( $block_type, $target[0], $fallback );
+		}
+
+		// We tried...
+		return null;
+	}
+}