ToC block: use static markup and only support core Heading and Page B…

…reak blocks.

lib/blocks.php

@@ -40,7 +40,7 @@ function gutenberg_reregister_core_block_types() {
 				'social-links',
 				'spacer',
 				'table',
-				// 'table-of-contents',
+				'table-of-contents',
 				'text-columns',
 				'verse',
 				'video',
@@ -92,7 +92,7 @@ function gutenberg_reregister_core_block_types() {
 				'site-logo.php'                 => 'core/site-logo',
 				'site-tagline.php'              => 'core/site-tagline',
 				'site-title.php'                => 'core/site-title',
-				// 'table-of-contents.php'         => 'core/table-of-contents',
+				'table-of-contents.php'         => 'core/table-of-contents',
 				'template-part.php'             => 'core/template-part',
 				'term-description.php'          => 'core/term-description',
 			),

packages/block-library/src/index.js

@@ -55,7 +55,7 @@ import * as separator from './separator';
 import * as shortcode from './shortcode';
 import * as spacer from './spacer';
 import * as table from './table';
-// import * as tableOfContents from './table-of-contents';
+import * as tableOfContents from './table-of-contents';
 import * as textColumns from './text-columns';
 import * as verse from './verse';
 import * as video from './video';
@@ -166,7 +166,7 @@ export const __experimentalGetCoreBlocks = () => [
 	socialLink,
 	spacer,
 	table,
-	// tableOfContents,
+	tableOfContents,
 	tagCloud,
 	textColumns,
 	verse,

packages/block-library/src/table-of-contents/block.json

@@ -3,13 +3,19 @@
 	"name": "core/table-of-contents",
 	"category": "layout",
 	"attributes": {
+		"headings": {
+			"type": "array",
+			"items": {
+				"type": "object"
+			}
+		},
 		"onlyIncludeCurrentPage": {
 			"type": "boolean",
 			"default": false
 		}
 	},
-	"usesContext": [ "postId" ],
 	"supports": {
 		"html": false
-	}
+	},
+	"example": {}
 }

packages/block-library/src/table-of-contents/edit.js

@@ -23,20 +23,32 @@ import {
 } from '@wordpress/components';
 import { useDispatch, useSelect } from '@wordpress/data';
 import { store as editorStore } from '@wordpress/editor';
-import { renderToString, useEffect, useState } from '@wordpress/element';
+import { renderToString, useState } from '@wordpress/element';
 import { __ } from '@wordpress/i18n';
+import { addQueryArgs, removeQueryArgs } from '@wordpress/url';
 
 /**
  * Internal dependencies
  */
+import icon from './icon';
 import TableOfContentsList from './list';
-import { getHeadingsFromContent, linearToNestedHeadingList } from './utils';
+import { linearToNestedHeadingList } from './utils';
+
+/**
+ * @typedef HeadingData
+ *
+ * @property {string} content The plain text content of the heading.
+ * @property {number} level   The heading level.
+ * @property {string} link    Link to the heading.
+ */
 
 /**
  * Table of Contents block edit component.
  *
  * @param {Object}                       props            The props.
  * @param {Object}                       props.attributes The block attributes.
+ * @param {HeadingData[]}                props.attributes.headings
+ * A list of data for each heading in the post.
  * @param {boolean}                      props.attributes.onlyIncludeCurrentPage
  * Whether to only include headings from the current page (if the post is
  * paginated).
@@ -46,94 +58,112 @@ import { getHeadingsFromContent, linearToNestedHeadingList } from './utils';
  * @return {WPComponent} The component.
  */
 export default function TableOfContentsEdit( {
-	attributes: { onlyIncludeCurrentPage },
+	attributes: { headings = [], onlyIncludeCurrentPage },
 	clientId,
 	setAttributes,
 } ) {
 	const blockProps = useBlockProps();
 
-	// Local state; not saved to block attributes. The saved block is dynamic and uses PHP to generate its content.
-	const [ headings, setHeadings ] = useState( [] );
 	const [ headingTree, setHeadingTree ] = useState( [] );
 
-	const { listBlockExists, postContent } = useSelect(
-		( select ) => ( {
-			listBlockExists: !! select( blocksStore ).getBlockType(
-				'core/list'
-			),
-			postContent: select( editorStore ).getEditedPostContent(),
-		} ),
+	const listBlockExists = useSelect(
+		( select ) => !! select( blocksStore ).getBlockType( 'core/list' ),
 		[]
 	);
 
+	const {
+		// __unstableMarkNextChangeAsNotPersistent,
+		replaceBlocks,
+	} = useDispatch( blockEditorStore );
+
 	// The page this block would be part of on the front-end. For performance
 	// reasons, this is only calculated when onlyIncludeCurrentPage is true.
-	const pageIndex = useSelect(
+	useSelect(
 		( select ) => {
-			if ( ! onlyIncludeCurrentPage ) {
-				return null;
-			}
-
 			const {
 				getBlockAttributes,
 				getBlockIndex,
 				getBlockName,
 				getBlockOrder,
+				getGlobalBlockCount,
 			} = select( blockEditorStore );
+			const { getPermalink } = select( editorStore );
+
+			const isPaginated = getGlobalBlockCount( 'core/nextpage' ) !== 0;
 
 			const blockIndex = getBlockIndex( clientId );
 			const blockOrder = getBlockOrder();
 
-			// Calculate which page the block will appear in on the front-end by
-			// counting how many <!--nextpage--> tags precede it.
-			// Unfortunately, this implementation only accounts for Page Break and
-			// Classic blocks, so if there are any <!--nextpage--> tags in any
-			// other block, they won't be counted. This will result in the table
-			// of contents showing headings from the wrong page if
-			// onlyIncludeCurrentPage === true. Thankfully, this issue only
-			// affects the editor implementation.
-			let page = 1;
-			for ( let i = 0; i < blockIndex; i++ ) {
-				const blockName = getBlockName( blockOrder[ i ] );
-				if ( blockName === 'core/nextpage' ) {
-					page++;
-				} else if ( blockName === 'core/freeform' ) {
-					// Count the page breaks inside the Classic block.
-					const pageBreaks = getBlockAttributes(
-						blockOrder[ i ]
-					).content?.match( /<!--nextpage-->/g );
-
-					if ( pageBreaks !== null && pageBreaks !== undefined ) {
-						page += pageBreaks.length;
-					}
-				}
-			}
+			const latestHeadings = [];
 
-			return page;
-		},
-		[ clientId, onlyIncludeCurrentPage ]
-	);
+			// The page (of a paginated post) the Table of Contents block will be
+			// part of.
+			let tocPage = 1;
 
-	useEffect( () => {
-		let latestHeadings;
+			// The page (of a paginated post) a heading will be part of.
+			let headingPage = 1;
 
-		if ( onlyIncludeCurrentPage ) {
-			const pagesOfContent = postContent.split( '<!--nextpage-->' );
+			// Link to post including pagination query if necessary.
+			const permalink = getPermalink();
 
-			latestHeadings = getHeadingsFromContent(
-				pagesOfContent[ pageIndex - 1 ]
-			);
-		} else {
-			latestHeadings = getHeadingsFromContent( postContent );
-		}
+			let headingPageLink = isPaginated
+				? addQueryArgs( permalink, { page: headingPage } )
+				: permalink;
 
-		if ( ! isEqual( headings, latestHeadings ) ) {
-			setHeadings( latestHeadings );
-			setHeadingTree( linearToNestedHeadingList( latestHeadings ) );
-		}
-	}, [ pageIndex, postContent, onlyIncludeCurrentPage ] );
+			for ( const [ i, blockClientId ] of blockOrder.entries() ) {
+				const blockName = getBlockName( blockClientId );
+				if ( blockName === 'core/nextpage' ) {
+					headingPage++;
+					headingPageLink = addQueryArgs(
+						removeQueryArgs( permalink, [ 'page' ] ),
+						{ page: headingPage }
+					);
+					if ( i < blockIndex ) {
+						tocPage++;
+					}
+				} else if ( blockName === 'core/heading' ) {
+					// If we're only including headings from the current page (of a
+					// paginated post), then exit the loop if we've reached headings
+					// on the pages after the one with the Table of Contents block.
+					if ( onlyIncludeCurrentPage && headingPage > tocPage ) {
+						break;
+					}
+					// If we're including all headings or we've reached headings on
+					// the same page as the Table of Contents block, add them to the
+					// list.
+					if ( ! onlyIncludeCurrentPage || headingPage === tocPage ) {
+						const headingAttributes = getBlockAttributes(
+							blockClientId
+						);
+
+						const hasAnchor =
+							typeof headingAttributes.anchor === 'string' &&
+							headingAttributes.anchor !== '';
+
+						latestHeadings.push( {
+							content: headingAttributes.content,
+							level: headingAttributes.level,
+							link: hasAnchor
+								? `${ headingPageLink }#${ headingAttributes.anchor }`
+								: null,
+							// page: headingPage,
+						} );
+					}
+				}
+			}
 
-	const { replaceBlocks } = useDispatch( blockEditorStore );
+			if ( ! isEqual( headings, latestHeadings ) ) {
+				// __unstableMarkNextChangeAsNotPersistent();
+				setAttributes( { headings: latestHeadings } );
+				setHeadingTree( linearToNestedHeadingList( latestHeadings ) );
+			}
+		}
+		// ,[
+		// 	clientId,
+		// 	onlyIncludeCurrentPage,
+		// 	// __unstableMarkNextChangeAsNotPersistent,
+		// ]
+	);
 
 	const toolbarControls = listBlockExists && (
 		<BlockControls>
@@ -189,7 +219,7 @@ export default function TableOfContentsEdit( {
 			<>
 				<div { ...blockProps }>
 					<Placeholder
-						icon={ <BlockIcon icon="list-view" /> }
+						icon={ <BlockIcon icon={ icon } /> }
 						label="Table of Contents"
 						instructions={ __(
 							'Start adding Heading blocks to create a table of contents. Headings with HTML anchors will be linked here.'

packages/block-library/src/table-of-contents/index.js

@@ -9,6 +9,7 @@ import { __ } from '@wordpress/i18n';
 import metadata from './block.json';
 import edit from './edit';
 import icon from './icon';
+import save from './save';
 
 const { name } = metadata;
 
@@ -22,4 +23,5 @@ export const settings = {
 	icon,
 	keywords: [ __( 'document outline' ), __( 'summary' ) ],
 	edit,
+	save,
 };