Add support for skipping headings

Related to syntax-tree/mdast-util-toc#61
Closes GH-24.

Reviewed-by: Christian Murphy <[email protected]>
Reviewed-by: Merlijn Vos <[email protected]>
Reviewed-by: Titus Wormer <[email protected]>

index.js

@@ -11,14 +11,16 @@ function toc(options) {
   var heading = settings.heading || defaultHeading
   var depth = settings.maxDepth || 6
   var tight = settings.tight
+  var skip = settings.skip
 
   return transformer
 
   function transformer(node) {
     var result = util(node, {
       heading: heading,
       maxDepth: depth,
-      tight: tight
+      tight: tight,
+      skip: skip
     })
 
     if (result.index === null || result.index === -1 || !result.map) {

readme.md

@@ -105,6 +105,12 @@ are included (those with three hashes, `###`).
 
 `boolean?`, default: `false` — Whether to compile list-items tightly.
 
+###### `options.skip`
+
+`string?` — Headings to skip, wrapped in `new RegExp('^(' + value + ')$', 'i')`.
+Any heading matching this expression will not be present in the table of
+contents.
+
 ## Related
 
 *   [`remark-slug`][slug]

test/fixtures/skip/config.json

@@ -0,0 +1,3 @@
+{
+  "skip": "example|notes?"
+}

test/fixtures/skip/input.md

@@ -0,0 +1,27 @@
+# Normal
+
+## Table of Contents
+
+## Alpha
+
+## Bravo
+
+### Example
+
+### Note
+
+## Charlie
+
+### Note
+
+## Delta
+
+### Examples
+
+## Echo
+
+### Notes
+
+## Foxtrot
+
+## Example

test/fixtures/skip/output.md

@@ -0,0 +1,41 @@
+# Normal
+
+## Table of Contents
+
+-   [Alpha](#alpha)
+
+-   [Bravo](#bravo)
+
+-   [Charlie](#charlie)
+
+-   [Delta](#delta)
+
+    -   [Examples](#examples)
+
+-   [Echo](#echo)
+
+-   [Foxtrot](#foxtrot)
+
+## Alpha
+
+## Bravo
+
+### Example
+
+### Note
+
+## Charlie
+
+### Note
+
+## Delta
+
+### Examples
+
+## Echo
+
+### Notes
+
+## Foxtrot
+
+## Example

test/index.js

@@ -1,8 +1,8 @@
 'use strict'
 
-var test = require('tape')
 var fs = require('fs')
 var path = require('path')
+var test = require('tape')
 var remark = require('remark')
 var negate = require('negate')
 var hidden = require('is-hidden')