diff --git a/wp-admin/includes/post.php b/wp-admin/includes/post.php
index 8db2a77dd3..039f223270 100644
--- a/wp-admin/includes/post.php
+++ b/wp-admin/includes/post.php
@@ -2023,3 +2023,146 @@ function taxonomy_meta_box_sanitize_cb_input( $taxonomy, $terms ) {
 
 	return $clean_terms;
 }
+
+/**
+ * Return whether the post can be edited in the block editor.
+ *
+ * @since 5.0.0
+ *
+ * @param int|WP_Post $post Post ID or WP_Post object.
+ * @return bool Whether the post can be edited in the block editor.
+ */
+function use_block_editor_for_post( $post ) {
+	$post = get_post( $post );
+
+	if ( ! $post ) {
+		return false;
+	}
+
+	$use_block_editor = use_block_editor_for_post_type( $post->post_type );
+
+	/**
+	 * Filter whether a post is able to be edited in the block editor.
+	 *
+	 * @since 5.0.0
+	 *
+	 * @param bool    $use_block_editor Whether the post can be edited or not.
+	 * @param WP_Post $post             The post being checked.
+	 */
+	return apply_filters( 'use_block_editor_for_post', $use_block_editor, $post );
+}
+
+/**
+ * Return whether a post type is compatible with the block editor.
+ *
+ * The block editor depends on the REST API, and if the post type is not shown in the
+ * REST API, then it won't work with the block editor.
+ *
+ * @since 5.0.0
+ *
+ * @param string $post_type The post type.
+ * @return bool Whether the post type can be edited with the block editor.
+ */
+function use_block_editor_for_post_type( $post_type ) {
+	if ( ! post_type_exists( $post_type ) ) {
+		return false;
+	}
+
+	if ( ! post_type_supports( $post_type, 'editor' ) ) {
+		return false;
+	}
+
+	$post_type_object = get_post_type_object( $post_type );
+	if ( $post_type_object && ! $post_type_object->show_in_rest ) {
+		return false;
+	}
+
+	/**
+	 * Filter whether a post is able to be edited in the block editor.
+	 *
+	 * @since 5.0.0
+	 *
+	 * @param bool   $use_block_editor  Whether the post type can be edited or not. Default true.
+	 * @param string $post_type         The post type being checked.
+	 */
+	return apply_filters( 'use_block_editor_for_post_type', true, $post_type );
+}
+
+/**
+ * Returns all the block categories that will be shown in the block editor.
+ *
+ * @since 5.0.0
+ *
+ * @param WP_Post $post Post object.
+ * @return array Array of block categories.
+ */
+function get_block_categories( $post ) {
+	$default_categories = array(
+		array(
+			'slug'  => 'common',
+			'title' => __( 'Common Blocks', 'gutenberg' ),
+		),
+		array(
+			'slug'  => 'formatting',
+			'title' => __( 'Formatting', 'gutenberg' ),
+		),
+		array(
+			'slug'  => 'layout',
+			'title' => __( 'Layout Elements', 'gutenberg' ),
+		),
+		array(
+			'slug'  => 'widgets',
+			'title' => __( 'Widgets', 'gutenberg' ),
+		),
+		array(
+			'slug'  => 'embed',
+			'title' => __( 'Embeds', 'gutenberg' ),
+		),
+		array(
+			'slug'  => 'reusable',
+			'title' => __( 'Reusable Blocks', 'gutenberg' ),
+		),
+	);
+
+	/**
+	 * Filter the default array of block categories.
+	 *
+	 * @since 5.0.0
+	 *
+	 * @param array   $default_categories Array of block categories.
+	 * @param WP_Post $post               Post being loaded.
+	 */
+	return apply_filters( 'block_categories', $default_categories, $post );
+}
+
+/**
+ * Prepares server-registered blocks for the block editor.
+ *
+ * Returns an associative array of registered block data keyed by block name. Data includes properties
+ * of a block relevant for client registration.
+ *
+ * @since 5.0.0
+ *
+ * @return array An associative array of registered block data.
+ */
+function get_block_editor_server_block_settings() {
+	$block_registry = WP_Block_Type_Registry::get_instance();
+	$blocks         = array();
+	$keys_to_pick   = array( 'title', 'description', 'icon', 'category', 'keywords', 'supports', 'attributes' );
+
+	foreach ( $block_registry->get_all_registered() as $block_name => $block_type ) {
+		foreach ( $keys_to_pick as $key ) {
+			if ( ! isset( $block_type->{ $key } ) ) {
+				continue;
+			}
+
+			if ( ! isset( $blocks[ $block_name ] ) ) {
+				$blocks[ $block_name ] = array();
+			}
+
+			$blocks[ $block_name ][ $key ] = $block_type->{ $key };
+		}
+	}
+
+	return $blocks;
+}
diff --git a/wp-includes/version.php b/wp-includes/version.php
index e68e7514e5..5f0cd56ce3 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.1-alpha-44121';
+$wp_version = '5.1-alpha-44122';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.