| 1 |
<?php |
| 2 |
/** |
| 3 |
* Table of Contents block module for FrontBlocks. |
| 4 |
* |
| 5 |
* @package FrontBlocks |
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* @author Closemarketing |
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* @copyright 2026 Closemarketing |
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* @version 1.0 |
| 9 |
*/ |
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|
| 11 |
namespace FrontBlocks\Frontend; |
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|
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use WP_Block_Type_Registry; |
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|
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defined( 'ABSPATH' ) || exit; |
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|
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/** |
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* TableOfContents class. |
| 19 |
* |
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* Registers a dynamic "Table of Contents" block. Because the block usually |
| 21 |
* appears before the headings it needs to link to, it can't discover them |
| 22 |
* from within its own render_callback (sibling blocks haven't rendered |
| 23 |
* yet). Instead, render_callback() outputs a small placeholder carrying the |
| 24 |
* block's config, and a later the_content filter — running after do_blocks() |
| 25 |
* has rendered the whole post — scans the final HTML for headings, assigns |
| 26 |
* stable anchors, and replaces every placeholder with the real navigation |
| 27 |
* markup. |
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* |
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* @since 1.0.0 |
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*/ |
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class TableOfContents { |
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|
| 33 |
const BLOCK_NAME = 'frontblocks/table-of-contents'; |
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|
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/** |
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* Minimum heading level considered (h1 is reserved for the post title). |
| 37 |
*/ |
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const MIN_ALLOWED_LEVEL = 2; |
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|
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/** |
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* Maximum heading level considered. |
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*/ |
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const MAX_ALLOWED_LEVEL = 6; |
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|
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/** |
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* Constructor. |
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*/ |
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public function __construct() { |
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$this->init_hooks(); |
| 50 |
} |
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|
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/** |
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* Initialize hooks. |
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* |
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* @return void |
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*/ |
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private function init_hooks() { |
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add_action( 'init', array( $this, 'register_block' ) ); |
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add_filter( 'the_content', array( $this, 'inject_toc_into_content' ), 30 ); |
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add_action( 'template_redirect', array( $this, 'maybe_start_output_buffer' ) ); |
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add_action( 'enqueue_block_assets', array( $this, 'enqueue_block_style' ) ); |
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add_action( 'enqueue_block_editor_assets', array( $this, 'enqueue_block_editor_assets' ) ); |
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add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_frontend_assets' ) ); |
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} |
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|
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/** |
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* Enqueue the block's stylesheet on both the frontend and in the editor, |
| 68 |
* via `enqueue_block_assets` rather than `enqueue_block_editor_assets`. |
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* Since WordPress 5.9 the block canvas renders inside an iframe, and only |
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* styles registered through `enqueue_block_assets` are mirrored into that |
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* iframe — a style enqueued solely via `enqueue_block_editor_assets` only |
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* reaches the top-level admin document, never the iframed preview. That |
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* previously left the per-level indentation rules (`.frbl-toc__item-- |
| 74 |
* level-*`) missing from the editor preview even though the same classes |
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* and the same stylesheet made it to the published page. |
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* |
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* @return void |
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*/ |
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public function enqueue_block_style() { |
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wp_enqueue_style( |
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'frontblocks-toc-style', |
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FRBL_PLUGIN_URL . 'assets/table-of-contents/frontblocks-toc.css', |
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array(), |
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FRBL_VERSION |
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); |
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} |
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|
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/** |
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* Start a whole-page output buffer so a Table of Contents block placed |
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* directly in a block-theme Template (outside the Post Content block) is |
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* still filled in. `the_content` alone isn't enough there: only |
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* core/post-content runs that filter, so a TOC block rendered as a |
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* sibling of Post Content in the Template never receives it, and can't |
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* see the headings that live inside Post Content either since those are |
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* filtered in a separate, isolated pass. Buffering the entire page lets |
| 96 |
* the same placeholder/heading-discovery logic run once over the final, |
| 97 |
* fully assembled HTML. inject_toc_into_content() is idempotent and |
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* exits immediately when no placeholder is present, so this is a no-op |
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* for every request that doesn't use the block outside Post Content. |
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* |
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* @return void |
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*/ |
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public function maybe_start_output_buffer() { |
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if ( is_admin() || is_feed() || is_robots() || is_trackback() || wp_doing_ajax() || wp_doing_cron() ) { |
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return; |
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} |
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|
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if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) { |
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return; |
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} |
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|
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if ( defined( 'XMLRPC_REQUEST' ) && XMLRPC_REQUEST ) { |
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return; |
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} |
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|
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ob_start( array( $this, 'inject_toc_into_content' ) ); |
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} |
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|
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/** |
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* Register the Table of Contents block. |
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* |
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* @return void |
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*/ |
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public function register_block() { |
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if ( ! function_exists( 'register_block_type' ) ) { |
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return; |
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} |
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|
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$args = array( |
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'editor_script' => 'frontblocks-toc-option', |
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'render_callback' => array( $this, 'render_placeholder' ), |
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'attributes' => array( |
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'title' => array( |
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'type' => 'string', |
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'default' => __( 'Table of Contents', 'frontblocks' ), |
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), |
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'listStyle' => array( |
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'type' => 'string', |
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'default' => 'unordered', |
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), |
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'accentColor' => array( |
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'type' => 'string', |
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'default' => '', |
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), |
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'collapsible' => array( |
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'type' => 'boolean', |
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'default' => false, |
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), |
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'collapsedByDefault' => array( |
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'type' => 'boolean', |
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'default' => false, |
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), |
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'sticky' => array( |
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'type' => 'boolean', |
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'default' => false, |
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), |
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'minLevel' => array( |
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'type' => 'number', |
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'default' => 2, |
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), |
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'maxLevel' => array( |
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'type' => 'number', |
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'default' => 4, |
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), |
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), |
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); |
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|
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if ( ! WP_Block_Type_Registry::get_instance()->is_registered( self::BLOCK_NAME ) ) { |
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register_block_type( self::BLOCK_NAME, $args ); |
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} |
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} |
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|
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/** |
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* Render a placeholder carrying this instance's config. The real |
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* navigation markup is filled in later by inject_toc_into_content(), |
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* once every heading in the post has been rendered. |
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* |
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* @param array $attributes Block attributes. |
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* @return string |
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*/ |
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public function render_placeholder( $attributes ) { |
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$config = array( |
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'title' => isset( $attributes['title'] ) ? (string) $attributes['title'] : __( 'Table of Contents', 'frontblocks' ), |
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'listStyle' => $this->sanitize_list_style( $attributes['listStyle'] ?? 'unordered' ), |
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'accentColor' => isset( $attributes['accentColor'] ) ? sanitize_text_field( $attributes['accentColor'] ) : '', |
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'collapsible' => ! empty( $attributes['collapsible'] ), |
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'collapsedByDefault' => ! empty( $attributes['collapsedByDefault'] ), |
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'sticky' => ! empty( $attributes['sticky'] ), |
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'minLevel' => $this->clamp_level( $attributes['minLevel'] ?? 2 ), |
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'maxLevel' => $this->clamp_level( $attributes['maxLevel'] ?? 4 ), |
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); |
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|
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if ( $config['minLevel'] > $config['maxLevel'] ) { |
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list( $config['minLevel'], $config['maxLevel'] ) = array( $config['maxLevel'], $config['minLevel'] ); |
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} |
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|
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$id = wp_unique_id( 'frbl-toc-' ); |
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|
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return sprintf( |
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'<div class="frbl-toc-placeholder" data-frbl-toc-id="%1$s" data-frbl-toc-config="%2$s"></div>', |
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esc_attr( $id ), |
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esc_attr( wp_json_encode( $config ) ) |
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); |
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} |
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|
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/** |
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* Replace every Table of Contents placeholder in the final rendered |
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* content with real navigation markup, after assigning stable, unique |
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* anchors to every heading that doesn't already have one. |
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* |
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* Runs at priority 30 on `the_content` — after do_blocks() (priority 9) |
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* has rendered every block, including headings that come after this |
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* one in the post. |
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* |
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* @param string $content Fully rendered post content. |
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* @return string |
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*/ |
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public function inject_toc_into_content( $content ) { |
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if ( false === strpos( $content, 'frbl-toc-placeholder' ) ) { |
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return $content; |
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} |
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|
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$headings = array(); |
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$used_ids = array(); |
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|
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$content = $this->assign_heading_ids( $content, $headings, $used_ids ); |
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|
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return preg_replace_callback( |
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'/<div class="frbl-toc-placeholder" data-frbl-toc-id="([^"]*)" data-frbl-toc-config="([^"]*)"><\/div>/', |
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function ( $matches ) use ( $headings ) { |
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$config = json_decode( html_entity_decode( $matches[2], ENT_QUOTES ), true ); |
| 232 |
if ( ! is_array( $config ) ) { |
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return ''; |
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} |
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|
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return $this->build_toc_markup( $config, $headings ); |
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}, |
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$content |
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); |
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} |
| 241 |
|
| 242 |
/** |
| 243 |
* Find every heading in the content, assign a stable unique id (and a |
| 244 |
* tabindex, so keyboard navigation can focus it) to any heading that |
| 245 |
* doesn't already have one, and collect them for the TOC to link to. |
| 246 |
* Existing author-supplied ids are always preserved untouched. |
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* |
| 248 |
* @param string $content Rendered content. |
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* @param array $headings Populated by reference with { level, id, text }. |
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* @param array $used_ids Populated by reference with every id already in use. |
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* @return string Content with heading ids/tabindex added where missing. |
| 252 |
*/ |
| 253 |
private function assign_heading_ids( $content, array &$headings, array &$used_ids ) { |
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if ( preg_match_all( '/\bid=["\']([^"\']+)["\']/i', $content, $id_matches ) ) { |
| 255 |
foreach ( $id_matches[1] as $existing_id ) { |
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$used_ids[ $existing_id ] = true; |
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} |
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} |
| 259 |
|
| 260 |
return preg_replace_callback( |
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'/<h([1-6])((?:\s[^>]*)?)>(.*?)<\/h\1>/is', |
| 262 |
function ( $matches ) use ( &$headings, &$used_ids ) { |
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$level = (int) $matches[1]; |
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$attributes = $matches[2]; |
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$inner_html = $matches[3]; |
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$text = trim( wp_strip_all_tags( $inner_html ) ); |
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|
| 268 |
if ( '' === $text ) { |
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return $matches[0]; |
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} |
| 271 |
|
| 272 |
if ( preg_match( '/\bid=["\']([^"\']+)["\']/i', $attributes, $id_match ) ) { |
| 273 |
$id = $id_match[1]; |
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$used_ids[ $id ] = true; |
| 275 |
} else { |
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$id = $this->generate_unique_id( $text, $used_ids ); |
| 277 |
$used_ids[ $id ] = true; |
| 278 |
$attributes .= ' id="' . esc_attr( $id ) . '"'; |
| 279 |
} |
| 280 |
|
| 281 |
if ( ! preg_match( '/\btabindex=/i', $attributes ) ) { |
| 282 |
// data-frbl-toc-heading scopes the focus-visible style in |
| 283 |
// frontblocks-toc.css to only these headings, so adding |
| 284 |
// tabindex="-1" here doesn't affect focus styling on |
| 285 |
// unrelated tabindex="-1" elements elsewhere on the site. |
| 286 |
$attributes .= ' tabindex="-1" data-frbl-toc-heading="1"'; |
| 287 |
} |
| 288 |
|
| 289 |
$headings[] = array( |
| 290 |
'level' => $level, |
| 291 |
'id' => $id, |
| 292 |
'text' => $text, |
| 293 |
); |
| 294 |
|
| 295 |
return '<h' . $level . $attributes . '>' . $inner_html . '</h' . $level . '>'; |
| 296 |
}, |
| 297 |
$content |
| 298 |
); |
| 299 |
} |
| 300 |
|
| 301 |
/** |
| 302 |
* Generate a slug for a heading's text, disambiguating it from any id |
| 303 |
* already in use (including author-supplied ones) with a numeric suffix. |
| 304 |
* |
| 305 |
* @param string $text Heading text. |
| 306 |
* @param array $used_ids Ids already in use, keyed by id. |
| 307 |
* @return string |
| 308 |
*/ |
| 309 |
private function generate_unique_id( $text, array $used_ids ) { |
| 310 |
$base = sanitize_title( $text ); |
| 311 |
if ( '' === $base ) { |
| 312 |
$base = 'section'; |
| 313 |
} |
| 314 |
|
| 315 |
$id = $base; |
| 316 |
$suffix = 2; |
| 317 |
while ( isset( $used_ids[ $id ] ) ) { |
| 318 |
$id = $base . '-' . $suffix; |
| 319 |
++$suffix; |
| 320 |
} |
| 321 |
|
| 322 |
return $id; |
| 323 |
} |
| 324 |
|
| 325 |
/** |
| 326 |
* Build the final navigation markup for one Table of Contents instance. |
| 327 |
* |
| 328 |
* @param array $config Decoded block config. |
| 329 |
* @param array $headings All headings found in the content. |
| 330 |
* @return string |
| 331 |
*/ |
| 332 |
private function build_toc_markup( array $config, array $headings ) { |
| 333 |
$min_level = $this->clamp_level( $config['minLevel'] ?? 2 ); |
| 334 |
$max_level = $this->clamp_level( $config['maxLevel'] ?? 4 ); |
| 335 |
|
| 336 |
$entries = array_values( |
| 337 |
array_filter( |
| 338 |
$headings, |
| 339 |
function ( $heading ) use ( $min_level, $max_level ) { |
| 340 |
return $heading['level'] >= $min_level && $heading['level'] <= $max_level; |
| 341 |
} |
| 342 |
) |
| 343 |
); |
| 344 |
|
| 345 |
if ( empty( $entries ) ) { |
| 346 |
return ''; |
| 347 |
} |
| 348 |
|
| 349 |
$title = isset( $config['title'] ) && '' !== $config['title'] ? $config['title'] : __( 'Table of Contents', 'frontblocks' ); |
| 350 |
$list_style = $this->sanitize_list_style( $config['listStyle'] ?? 'unordered' ); |
| 351 |
$list_tag = 'ordered' === $list_style ? 'ol' : 'ul'; |
| 352 |
$sticky = ! empty( $config['sticky'] ); |
| 353 |
$collapsible = ! empty( $config['collapsible'] ); |
| 354 |
|
| 355 |
$list_items = ''; |
| 356 |
foreach ( $entries as $entry ) { |
| 357 |
$list_items .= sprintf( |
| 358 |
'<li class="frbl-toc__item frbl-toc__item--level-%1$d"><a class="frbl-toc__link" href="#%2$s">%3$s</a></li>', |
| 359 |
$entry['level'], |
| 360 |
esc_attr( $entry['id'] ), |
| 361 |
esc_html( $entry['text'] ) |
| 362 |
); |
| 363 |
} |
| 364 |
|
| 365 |
$list_html = sprintf( |
| 366 |
'<%1$s class="frbl-toc__list frbl-toc__list--%2$s">%3$s</%1$s>', |
| 367 |
$list_tag, |
| 368 |
esc_attr( $list_style ), |
| 369 |
$list_items |
| 370 |
); |
| 371 |
|
| 372 |
$wrapper_style = ''; |
| 373 |
if ( ! empty( $config['accentColor'] ) ) { |
| 374 |
$wrapper_style = ' style="--frbl-toc-accent: ' . esc_attr( $config['accentColor'] ) . ';"'; |
| 375 |
} |
| 376 |
|
| 377 |
$title_html = esc_html( $title ); |
| 378 |
|
| 379 |
if ( $collapsible ) { |
| 380 |
$open = empty( $config['collapsedByDefault'] ) ? ' open' : ''; |
| 381 |
|
| 382 |
return sprintf( |
| 383 |
'<details class="frbl-toc frbl-toc--collapsible%1$s"%2$s%3$s><summary class="frbl-toc__title">%4$s</summary><nav class="frbl-toc__nav" aria-label="%5$s">%6$s</nav></details>', |
| 384 |
$sticky ? ' frbl-toc--sticky' : '', |
| 385 |
$open, |
| 386 |
$wrapper_style, |
| 387 |
$title_html, |
| 388 |
esc_attr( $title ), |
| 389 |
$list_html |
| 390 |
); |
| 391 |
} |
| 392 |
|
| 393 |
return sprintf( |
| 394 |
'<nav class="frbl-toc%1$s" aria-label="%2$s"%3$s><p class="frbl-toc__title">%4$s</p>%5$s</nav>', |
| 395 |
$sticky ? ' frbl-toc--sticky' : '', |
| 396 |
esc_attr( $title ), |
| 397 |
$wrapper_style, |
| 398 |
$title_html, |
| 399 |
$list_html |
| 400 |
); |
| 401 |
} |
| 402 |
|
| 403 |
/** |
| 404 |
* Sanitize the listStyle attribute to one of the supported values. |
| 405 |
* |
| 406 |
* @param string $value Raw value. |
| 407 |
* @return string |
| 408 |
*/ |
| 409 |
private function sanitize_list_style( $value ) { |
| 410 |
return in_array( $value, array( 'unordered', 'ordered', 'plain' ), true ) ? $value : 'unordered'; |
| 411 |
} |
| 412 |
|
| 413 |
/** |
| 414 |
* Clamp a heading level to the supported h2-h6 range. |
| 415 |
* |
| 416 |
* @param mixed $value Raw value. |
| 417 |
* @return int |
| 418 |
*/ |
| 419 |
private function clamp_level( $value ) { |
| 420 |
return max( self::MIN_ALLOWED_LEVEL, min( self::MAX_ALLOWED_LEVEL, (int) $value ) ); |
| 421 |
} |
| 422 |
|
| 423 |
/** |
| 424 |
* Enqueue block editor assets. |
| 425 |
* |
| 426 |
* @return void |
| 427 |
*/ |
| 428 |
public function enqueue_block_editor_assets() { |
| 429 |
wp_enqueue_script( |
| 430 |
'frontblocks-toc-option', |
| 431 |
FRBL_PLUGIN_URL . 'assets/table-of-contents/frontblocks-toc-option.js', |
| 432 |
array( 'wp-blocks', 'wp-element', 'wp-components', 'wp-block-editor', 'wp-data', 'wp-i18n' ), |
| 433 |
FRBL_VERSION, |
| 434 |
true |
| 435 |
); |
| 436 |
|
| 437 |
wp_set_script_translations( 'frontblocks-toc-option', 'frontblocks' ); |
| 438 |
} |
| 439 |
|
| 440 |
/** |
| 441 |
* Enqueue frontend assets. |
| 442 |
* |
| 443 |
* Not gated behind has_block(): that only inspects the current post's |
| 444 |
* content, so it misses the block when it's placed directly in a |
| 445 |
* block-theme Template (outside the Post Content block) instead — the |
| 446 |
* same placement the whole-page output buffer in |
| 447 |
* maybe_start_output_buffer() exists to support. Both files are a few KB |
| 448 |
* combined, so loading them unconditionally on the frontend is a simpler |
| 449 |
* and more reliable trade-off than trying to detect every possible |
| 450 |
* placement up front. |
| 451 |
* |
| 452 |
* @return void |
| 453 |
*/ |
| 454 |
public function enqueue_frontend_assets() { |
| 455 |
wp_enqueue_script( |
| 456 |
'frontblocks-toc-frontend', |
| 457 |
FRBL_PLUGIN_URL . 'assets/table-of-contents/frontblocks-toc-frontend.js', |
| 458 |
array(), |
| 459 |
FRBL_VERSION, |
| 460 |
true |
| 461 |
); |
| 462 |
} |
| 463 |
} |
| 464 |
|
