Add support for extensions

Author: wooorm

lib/handle/index.js

@@ -0,0 +1,20 @@
+exports.blockquote = require('./blockquote')
+exports.break = require('./break')
+exports.code = require('./code')
+exports.definition = require('./definition')
+exports.emphasis = require('./emphasis')
+exports.hardBreak = require('./break')
+exports.heading = require('./heading')
+exports.html = require('./html')
+exports.image = require('./image')
+exports.imageReference = require('./image-reference')
+exports.inlineCode = require('./inline-code')
+exports.link = require('./link')
+exports.linkReference = require('./link-reference')
+exports.list = require('./list')
+exports.listItem = require('./list-item')
+exports.paragraph = require('./paragraph')
+exports.root = require('./root')
+exports.strong = require('./strong')
+exports.text = require('./text')
+exports.thematicBreak = require('./thematic-break')

lib/index.js

@@ -1,69 +1,27 @@
 module.exports = toMarkdown
 
 var zwitch = require('zwitch')
-var blockquote = require('./handle/blockquote')
-var code = require('./handle/code')
-var definition = require('./handle/definition')
-var emphasis = require('./handle/emphasis')
-var hardBreak = require('./handle/break')
-var heading = require('./handle/heading')
-var html = require('./handle/html')
-var image = require('./handle/image')
-var imageReference = require('./handle/image-reference')
-var inlineCode = require('./handle/inline-code')
-var link = require('./handle/link')
-var linkReference = require('./handle/link-reference')
-var list = require('./handle/list')
-var listItem = require('./handle/list-item')
-var paragraph = require('./handle/paragraph')
-var root = require('./handle/root')
-var strong = require('./handle/strong')
-var text = require('./handle/text')
-var thematicBreak = require('./handle/thematic-break')
-var unsafe = require('./unsafe')
+var defaultHandlers = require('./handle')
+var defaultUnsafePatterns = require('./unsafe')
 
 // To do (extension)
 // - GFM: `tableCellPadding`, `tablePipeAlign`, `stringLength`.
-// - Frontmatter: `yaml`, `toml`.
 // - Footnotes: `footnote`, `footnoteDefinition`, `footnoteReference`.
 function toMarkdown(tree, options) {
   var settings = options || {}
+  var extensions = configure(settings)
   var stack = []
   var handle = zwitch('type', {
     invalid: invalid,
     unknown: unknown,
-    handlers: Object.assign(
-      {
-        blockquote: blockquote,
-        break: hardBreak,
-        code: code,
-        definition: definition,
-        emphasis: emphasis,
-        heading: heading,
-        html: html,
-        image: image,
-        imageReference: imageReference,
-        inlineCode: inlineCode,
-        link: link,
-        linkReference: linkReference,
-        list: list,
-        listItem: listItem,
-        paragraph: paragraph,
-        root: root,
-        strong: strong,
-        text: text,
-        thematicBreak: thematicBreak
-      },
-      settings.handlers
-    )
+    handlers: extensions.handlers
   })
-
   var context = {
     handle: handle,
     stack: stack,
     enter: enter,
     options: settings,
-    unsafePatterns: unsafe.concat(settings.unsafe || [])
+    unsafePatterns: extensions.unsafe
   }
 
   return handle(tree, null, context, {before: '\n', after: '\n'})
@@ -85,3 +43,22 @@ function invalid(value) {
 function unknown(node) {
   throw new Error('Cannot handle unknown node `' + node.type + '`')
 }
+
+function configure(settings) {
+  var unsafe = defaultUnsafePatterns
+  var handlers = Object.assign({}, defaultHandlers)
+  var extensions = [
+    {unsafe: settings.unsafe, handlers: settings.handlers}
+  ].concat(settings.extensions || [])
+  var length = extensions.length
+  var index = -1
+  var extension
+
+  while (++index < length) {
+    extension = extensions[index]
+    unsafe = unsafe.concat(extension.unsafe || [])
+    handlers = Object.assign(handlers, extension.handlers || {})
+  }
+
+  return {unsafe: unsafe, handlers: handlers}
+}

readme.md

@@ -133,16 +133,21 @@ they’re empty.
 
 Marker to use to serialize strong (`'*'` or `'_'`, default: `'*'`).
 
-##### Escape options
+##### Extension options
+
+###### `options.extensions`
+
+List of extensions (`Array.<ToMarkdownExtension>`).
+Each `ToMarkdownExtension` is an object with optional `unsafe` and `handlers`
+keys, mapping to the values which can also be passed in directly, documented
+below.
 
 ###### `options.unsafe`
 
 List of patterns to escape.
 Useful for syntax extensions.
 Take a look at [`lib/unsafe.js`][unsafe] for examples.
 
-##### Extensions or overwrites options
-
 ###### `options.handlers`
 
 Object mapping node types to custom handlers.