Draft YAML renderer.

index.js

@@ -3,6 +3,7 @@ var deserialize = require('mkast').deserialize
   , through = require('through3')
   , types = {
       markdown: './lib/render/markdown',
+      yaml: './lib/render/yaml',
       xml: 'commonmark/lib/xml',
       html: 'commonmark/lib/render/html'
     };

lib/render/yaml.js

@@ -0,0 +1,97 @@
+"use strict";
+
+var Renderer = require('commonmark/lib/render/renderer')
+  , Node = require('mkast').Node
+  , repeat = require('string-repeater');
+
+function YamlRendererer(options) {
+  options = options || {};
+  Renderer.call(this);
+  this.indent = '  ';
+}
+
+function properties(node, depth) {
+
+  var k, v;
+
+  for(k in node) {
+    v = node[k];
+    k = k.replace(/^_/, '');
+    if(k === 'type'
+        || k === 'firstChild'
+        || k === 'lastChild'
+        || k === 'next'
+        || k === 'prev'
+        || k === 'parent'
+        || v === undefined
+        || v === null
+        || typeof v === 'function') {
+      continue; 
+    }
+
+    this.out(repeat(this.indent, depth + 2));
+    if(k === 'literal' && ~v.indexOf('\n')) {
+      this.out(k + ': |' + v); 
+    }else{
+      this.out(k + ': ' + v); 
+    }
+    this.cr();
+  }
+}
+
+function render(ast) {
+  var walker = ast.walker()
+    , event
+    , entering
+    , node
+    , type
+    , depth
+    , p;
+
+  this.buffer = '';
+  this.lastOut = '\n';
+
+  while((event = walker.next())) {
+    entering = event.entering;
+    node = event.node;
+    type = node.type;
+    depth = 0;
+    p = node.parent;
+
+    while(p) {
+      depth++;
+      p = p.parent; 
+    }
+
+    if(Node.is(node, Node.DOCUMENT) && entering) {
+      this.out('---'); 
+      this.cr();
+    }
+
+    //console.error(depth);
+
+
+    this.out(repeat(this.indent, depth));
+    if(!Node.is(node, Node.DOCUMENT)) {
+      this.out('- '); 
+    }
+    this.out(type + ':');
+    this.cr();
+    this.properties(node, depth);
+
+    if(Node.is(node, Node.DOCUMENT) && !entering) {
+      this.out('---'); 
+      this.cr();
+    }
+
+  }
+
+  return this.buffer;
+}
+
+YamlRendererer.prototype = Object.create(Renderer.prototype);
+
+YamlRendererer.prototype.render = render;
+YamlRendererer.prototype.properties = properties;
+
+module.exports = YamlRendererer;