--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/class-wp-block-supports.php	Wed Sep 21 18:19:35 2022 +0200
@@ -0,0 +1,215 @@
+<?php
+/**
+ * Block support flags.
+ *
+ * @package WordPress
+ *
+ * @since 5.6.0
+ */
+
+/**
+ * Class encapsulating and implementing Block Supports.
+ *
+ * @since 5.6.0
+ *
+ * @access private
+ */
+class WP_Block_Supports {
+
+	/**
+	 * Config.
+	 *
+	 * @since 5.6.0
+	 * @var array
+	 */
+	private $block_supports = array();
+
+	/**
+	 * Tracks the current block to be rendered.
+	 *
+	 * @since 5.6.0
+	 * @var array
+	 */
+	public static $block_to_render = null;
+
+	/**
+	 * Container for the main instance of the class.
+	 *
+	 * @since 5.6.0
+	 * @var WP_Block_Supports|null
+	 */
+	private static $instance = null;
+
+	/**
+	 * Utility method to retrieve the main instance of the class.
+	 *
+	 * The instance will be created if it does not exist yet.
+	 *
+	 * @since 5.6.0
+	 *
+	 * @return WP_Block_Supports The main instance.
+	 */
+	public static function get_instance() {
+		if ( null === self::$instance ) {
+			self::$instance = new self();
+		}
+
+		return self::$instance;
+	}
+
+	/**
+	 * Initializes the block supports. It registes the block supports block attributes.
+	 *
+	 * @since 5.6.0
+	 */
+	public static function init() {
+		$instance = self::get_instance();
+		$instance->register_attributes();
+	}
+
+	/**
+	 * Registers a block support.
+	 *
+	 * @since 5.6.0
+	 *
+	 * @param string $block_support_name Block support name.
+	 * @param array  $block_support_config Array containing the properties of the block support.
+	 */
+	public function register( $block_support_name, $block_support_config ) {
+		$this->block_supports[ $block_support_name ] = array_merge(
+			$block_support_config,
+			array( 'name' => $block_support_name )
+		);
+	}
+
+	/**
+	 * Generates an array of HTML attributes, such as classes, by applying to
+	 * the given block all of the features that the block supports.
+	 *
+	 * @since 5.6.0
+	 *
+	 * @return array Array of HTML attributes.
+	 */
+	public function apply_block_supports() {
+		$block_attributes = self::$block_to_render['attrs'];
+		$block_type       = WP_Block_Type_Registry::get_instance()->get_registered(
+			self::$block_to_render['blockName']
+		);
+
+		// If no render_callback, assume styles have been previously handled.
+		if ( ! $block_type || empty( $block_type ) ) {
+			return array();
+		}
+
+		$output = array();
+		foreach ( $this->block_supports as $block_support_config ) {
+			if ( ! isset( $block_support_config['apply'] ) ) {
+				continue;
+			}
+
+			$new_attributes = call_user_func(
+				$block_support_config['apply'],
+				$block_type,
+				$block_attributes
+			);
+
+			if ( ! empty( $new_attributes ) ) {
+				foreach ( $new_attributes as $attribute_name => $attribute_value ) {
+					if ( empty( $output[ $attribute_name ] ) ) {
+						$output[ $attribute_name ] = $attribute_value;
+					} else {
+						$output[ $attribute_name ] .= " $attribute_value";
+					}
+				}
+			}
+		}
+
+		return $output;
+	}
+
+	/**
+	 * Registers the block attributes required by the different block supports.
+	 *
+	 * @since 5.6.0
+	 */
+	private function register_attributes() {
+		$block_registry         = WP_Block_Type_Registry::get_instance();
+		$registered_block_types = $block_registry->get_all_registered();
+		foreach ( $registered_block_types as $block_type ) {
+			if ( ! property_exists( $block_type, 'supports' ) ) {
+				continue;
+			}
+			if ( ! $block_type->attributes ) {
+				$block_type->attributes = array();
+			}
+
+			foreach ( $this->block_supports as $block_support_config ) {
+				if ( ! isset( $block_support_config['register_attribute'] ) ) {
+					continue;
+				}
+
+				call_user_func(
+					$block_support_config['register_attribute'],
+					$block_type
+				);
+			}
+		}
+	}
+}
+
+/**
+ * Generates a string of attributes by applying to the current block being
+ * rendered all of the features that the block supports.
+ *
+ * @since 5.6.0
+ *
+ * @param array $extra_attributes Optional. Extra attributes to render on the block wrapper.
+ *
+ * @return string String of HTML classes.
+ */
+function get_block_wrapper_attributes( $extra_attributes = array() ) {
+	$new_attributes = WP_Block_Supports::get_instance()->apply_block_supports();
+
+	if ( empty( $new_attributes ) && empty( $extra_attributes ) ) {
+		return '';
+	}
+
+	// This is hardcoded on purpose.
+	// We only support a fixed list of attributes.
+	$attributes_to_merge = array( 'style', 'class' );
+	$attributes          = array();
+	foreach ( $attributes_to_merge as $attribute_name ) {
+		if ( empty( $new_attributes[ $attribute_name ] ) && empty( $extra_attributes[ $attribute_name ] ) ) {
+			continue;
+		}
+
+		if ( empty( $new_attributes[ $attribute_name ] ) ) {
+			$attributes[ $attribute_name ] = $extra_attributes[ $attribute_name ];
+			continue;
+		}
+
+		if ( empty( $extra_attributes[ $attribute_name ] ) ) {
+			$attributes[ $attribute_name ] = $new_attributes[ $attribute_name ];
+			continue;
+		}
+
+		$attributes[ $attribute_name ] = $extra_attributes[ $attribute_name ] . ' ' . $new_attributes[ $attribute_name ];
+	}
+
+	foreach ( $extra_attributes as $attribute_name => $value ) {
+		if ( ! in_array( $attribute_name, $attributes_to_merge, true ) ) {
+			$attributes[ $attribute_name ] = $value;
+		}
+	}
+
+	if ( empty( $attributes ) ) {
+		return '';
+	}
+
+	$normalized_attributes = array();
+	foreach ( $attributes as $key => $value ) {
+		$normalized_attributes[] = $key . '="' . esc_attr( $value ) . '"';
+	}
+
+	return implode( ' ', $normalized_attributes );
+}