Add support for phrasing content

Previously, only the textual content of headings was used to generate the entries in the Table of Contents. This lead to a bug (or feature?) where HTML in headings made entries in the TOC appear with literal HTML.

mdast has a concept of static phrasing content, which includes all the things that can appear in links. Instead of using just the textual content of a heading, this commit introduces a new behaviour where any static phrasing content, such as HTML, inline code, and emphasis, are copied over into the Table of Contents. Interactive phrasing content (links, link references) are handled by replacing them with their children.

See: <https://github.com/syntax-tree/mdast#staticphrasingcontent>

Closes GH-56.
Closes GH-57.
Closes GH-58.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>
Reviewed-by: Jonathan Haines <jonno.haines@gmail.com>

lib/contents.js

@@ -1,12 +1,14 @@
 'use strict'
 
+var extend = require('extend')
+
 module.exports = contents
 
 var LIST = 'list'
 var LIST_ITEM = 'listItem'
 var PARAGRAPH = 'paragraph'
 var LINK = 'link'
-var TEXT = 'text'
+var LINK_REFERENCE = 'linkReference'
 
 // Transform a list of heading objects to a markdown list.
 function contents(map, tight) {
@@ -42,16 +44,16 @@ function contents(map, tight) {
   return table
 }
 
-// Insert a `node` into a `parent`.
-function insert(node, parent, tight) {
+// Insert an entry into `parent`.
+function insert(entry, parent, tight) {
   var children = parent.children
   var length = children.length
   var last = children[length - 1]
   var isLoose = false
   var index
   var item
 
-  if (node.depth === 1) {
+  if (entry.depth === 1) {
     item = listItem()
 
     item.children.push({
@@ -60,30 +62,30 @@ function insert(node, parent, tight) {
         {
           type: LINK,
           title: null,
-          url: '#' + node.id,
-          children: [{type: TEXT, value: node.value}]
+          url: '#' + entry.id,
+          children: all(entry.children)
         }
       ]
     })
 
     children.push(item)
   } else if (last && last.type === LIST_ITEM) {
-    insert(node, last, tight)
+    insert(entry, last, tight)
   } else if (last && last.type === LIST) {
-    node.depth--
+    entry.depth--
 
-    insert(node, last, tight)
+    insert(entry, last, tight)
   } else if (parent.type === LIST) {
     item = listItem()
 
-    insert(node, item, tight)
+    insert(entry, item, tight)
 
     children.push(item)
   } else {
     item = list()
-    node.depth--
+    entry.depth--
 
-    insert(node, item, tight)
+    insert(entry, item, tight)
 
     children.push(item)
   }
@@ -129,6 +131,39 @@ function insert(node, parent, tight) {
   }
 }
 
+function all(children) {
+  var result = []
+  var length = children.length
+  var index = -1
+
+  while (++index < length) {
+    result = result.concat(one(children[index]))
+  }
+
+  return result
+}
+
+function one(node) {
+  var copy
+
+  if (node.type === LINK || node.type === LINK_REFERENCE) {
+    return all(node.children)
+  }
+
+  copy = extend({}, node)
+
+  delete copy.children
+  delete copy.position
+
+  copy = extend(true, {}, copy)
+
+  if (node.children) {
+    copy.children = all(node.children)
+  }
+
+  return copy
+}
+
 // Create a list.
 function list() {
   return {type: LIST, ordered: false, spread: false, children: []}

lib/search.js

@@ -63,7 +63,11 @@ function search(root, expression, settings) {
     }
 
     if (!lookingForToc && value && child.depth <= maxDepth) {
-      map.push({depth: child.depth, value: value, id: slugs.slug(id || value)})
+      map.push({
+        depth: child.depth,
+        children: child.children,
+        id: slugs.slug(id || value)
+      })
     }
   }
 }

package.json

@@ -20,6 +20,7 @@
     "index.js"
   ],
   "dependencies": {
+    "extend": "^3.0.2",
     "github-slugger": "^1.2.1",
     "mdast-util-to-string": "^1.0.5",
     "unist-util-is": "^2.1.2",
@@ -32,10 +33,12 @@
     "remark": "^10.0.0",
     "remark-attr": "^0.8.0",
     "remark-cli": "^6.0.0",
+    "remark-parse": "^6.0.3",
     "remark-preset-wooorm": "^4.0.0",
     "remark-usage": "^6.1.3",
     "tape": "^4.10.1",
     "tinyify": "^2.5.0",
+    "unified": "^7.1.0",
     "unist-builder": "^1.0.3",
     "xo": "^0.24.0"
   },

test/fixtures/normal-attr/config.json

@@ -0,0 +1,3 @@
+{
+  "useRemarkAttr": true
+}

test/fixtures/phrasing-content/config.json

@@ -0,0 +1,5 @@
+{
+  "remarkParseOptions": {
+    "footnotes": true
+  }
+}

test/fixtures/phrasing-content/input.md

@@ -0,0 +1,29 @@
+# Text
+
+# *Emphasis*
+
+# **Importance**
+
+# ~~Strikethrough~~
+
+# <i>HTML<i>
+
+# `inline.code()`
+
+# [^a footnote]
+
+# footnote reference [^1]
+
+# ![image](image.png)
+
+# ![image reference][image]
+
+# [link](example.com)
+
+# ![link reference][link]
+
+[^1]: footnote reference
+
+[image]: image.png
+
+[link]: example.com