Update for remark 13

* Update to a micromark parser, defer work to
  <https://github.com/micromark/micromark-extension-frontmatter>,
  <https://github.com/syntax-tree/mdast-util-frontmatter>
* Frontmatter must now start on the first line
  Previously, delaying with blank lines first worked.
  That behavior does not match how GitHub parses YAML, and is thus removed.

index.js

@@ -1,62 +1,19 @@
 'use strict'
 
-var matters = require('./lib/matters')
-var parse = require('./lib/parse')
-var compile = require('./lib/compile')
+var syntax = require('micromark-extension-frontmatter')
+var fromMarkdown = require('mdast-util-frontmatter/from-markdown')
+var toMarkdown = require('mdast-util-frontmatter/to-markdown')
 
 module.exports = frontmatter
 
 function frontmatter(options) {
-  var parser = this.Parser
-  var compiler = this.Compiler
-  var config = matters(options || ['yaml'])
-
-  if (isRemarkParser(parser)) {
-    attachParser(parser, config)
-  }
-
-  if (isRemarkCompiler(compiler)) {
-    attachCompiler(compiler, config)
-  }
-}
-
-function attachParser(parser, matters) {
-  var proto = parser.prototype
-  var tokenizers = wrap(parse, matters)
-  var names = []
-  var key
-
-  for (key in tokenizers) {
-    names.push(key)
+  var data = this.data()
+  add('micromarkExtensions', syntax(options))
+  add('fromMarkdownExtensions', fromMarkdown(options))
+  add('toMarkdownExtensions', toMarkdown(options))
+  function add(field, value) {
+    /* istanbul ignore if - other extensions. */
+    if (data[field]) data[field].push(value)
+    else data[field] = [value]
   }
-
-  proto.blockMethods = names.concat(proto.blockMethods)
-  proto.blockTokenizers = Object.assign({}, tokenizers, proto.blockTokenizers)
-}
-
-function attachCompiler(compiler, matters) {
-  var proto = compiler.prototype
-  proto.visitors = Object.assign({}, wrap(compile, matters), proto.visitors)
-}
-
-function wrap(func, matters) {
-  var result = {}
-  var length = matters.length
-  var index = -1
-  var tuple
-
-  while (++index < length) {
-    tuple = func(matters[index])
-    result[tuple[0]] = tuple[1]
-  }
-
-  return result
-}
-
-function isRemarkParser(parser) {
-  return Boolean(parser && parser.prototype && parser.prototype.blockTokenizers)
-}
-
-function isRemarkCompiler(compiler) {
-  return Boolean(compiler && compiler.prototype && compiler.prototype.visitors)
 }

package.json

@@ -28,12 +28,12 @@
   ],
   "files": [
     "index.js",
-    "lib",
     "types/index.d.ts"
   ],
   "types": "types/index.d.ts",
   "dependencies": {
-    "fault": "^1.0.1"
+    "mdast-util-frontmatter": "^0.2.0",
+    "micromark-extension-frontmatter": "^0.2.0"
   },
   "devDependencies": {
     "browserify": "^16.0.0",
@@ -42,7 +42,7 @@
     "not": "^0.1.0",
     "nyc": "^15.0.0",
     "prettier": "^2.0.0",
-    "remark": "^12.0.0",
+    "remark": "^13.0.0-alpha.1",
     "remark-cli": "^8.0.0",
     "remark-preset-wooorm": "^7.0.0",
     "tape": "^5.0.0",