wp_get_block_css_selector

确定所提供区块类型和属性的 CSS 选择器，如果可用，则返回该选择器。

function wp_get_block_css_selector( $block_type, $target = 'root', $fallback = false ) {
	if ( empty( $target ) ) {
		return null;
	}

	$has_selectors = ! empty( $block_type->selectors );

	// 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'] ) ) {
		// Use 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` 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( current( $target ), 'root' );
			$feature_selector = _wp_array_get( $block_type->selectors, $path, null );

			if ( $feature_selector ) {
				return $feature_selector;
			}

			// Check if feature selector is 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( current( $target ), '__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.
		return WP_Theme_JSON::scope_selector( $root_selector, $feature_selector );
	}

	// 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 );
	}

	return null;
}