Expose visitors in code

This is working towards a simple API. This is taken from how we end up
using jstransform in React and internally. We build up these lists and
expose some APIs to get them. We can tweak this (it might make sense to
expose the keys of tranformVisitors).

src/visitors/index.js

@@ -0,0 +1,124 @@
+/*global exports:true*/
+
+'use strict';
+
+var es3ReservedWords = require('./es3/reserved-words');
+var es6ArrowFunctions = require('./es6/arrow-function');
+var es6CallSpread = require('./es6/call-spread');
+var es6Classes = require('./es6/class');
+var es6Destructuring = require('./es6/destructuring');
+var es6ObjectConciseMethod = require('./es6/object-concise-method');
+var es6ObjectShortNotation = require('./es6/object-short-notation');
+var es6RestParameters = require('./es6/rest-param');
+var es6Templates = require('./es6/template-string');
+var es7SpreadProperty = require('./es7/spread-property');
+var react = require('./react/react');
+var reactDisplayName = require('./react/reactDisplayName');
+
+/**
+ * Map from transformName => orderedListOfVisitors.
+ */
+var transformVisitors = {
+  'es6-arrow-functions': es6ArrowFunctions.visitorList,
+  'es6-classes': es6Classes.visitorList,
+  'es6-destructuring': es6Destructuring.visitorList,
+  'es6-object-concise-method': es6ObjectConciseMethod.visitorList,
+  'es6-object-short-notation': es6ObjectShortNotation.visitorList,
+  'es6-rest-params': es6RestParameters.visitorList,
+  'es6-templates': es6Templates.visitorList,
+  'es6-call-spread': es6CallSpread.visitorList,
+  'es7-spread-property': es7SpreadProperty.visitorList,
+  'react': react.visitorList
+  'react-display-name': reactDisplayName.visitorList,
+  'reserved-words': es3ReservedWords.visitorList,
+  'flow': flow
+};
+
+var transformSets = {
+  'harmony': [
+    'es6-arrow-functions',
+    'es6-object-concise-method',
+    'es6-object-short-notation',
+    'es6-classes',
+    'es6-rest-params',
+    'es6-templates',
+    'es6-destructuring',
+    'es6-call-spread',
+    'es7-spread-property'
+  ],
+  'es3': [
+    'reserved-words'
+  ],
+  'react': [
+    'react',
+    'react-display-name'
+  ]
+};
+
+/**
+ * Specifies the order in which each transform should run.
+ */
+var transformRunOrder = [
+  'reserved-words',
+  'es6-arrow-functions',
+  'es6-object-concise-method',
+  'es6-object-short-notation',
+  'es6-classes',
+  'es6-rest-params',
+  'es6-templates',
+  'es6-destructuring',
+  'es6-call-spread',
+  'es7-spread-property',
+  'react',
+  'react-display-name'
+];
+
+/**
+ * Given a list of transform names, return the ordered list of visitors to be
+ * passed to the transform() function.
+ *
+ * @param {array?} excludes
+ * @return {array}
+ */
+function getAllVisitors(excludes) {
+  var ret = [];
+  for (var i = 0, il = transformRunOrder.length; i < il; i++) {
+    if (!excludes || excludes.indexOf(transformRunOrder[i]) === -1) {
+      ret = ret.concat(transformVisitors[transformRunOrder[i]]);
+    }
+  }
+  return ret;
+}
+
+/**
+ * Given a list of visitor set names, return the ordered list of visitors to be
+ * passed to jstransform.
+ *
+ * @param {array}
+ * @return {array}
+ */
+function getVisitorsBySet(sets) {
+  var visitorsToInclude = sets.reduce(function(visitors, set) {
+    if (!transformSets.hasOwnProperty(set)) {
+      throw new Error('Unknown visitor set: ' + set);
+    }
+    transformSets[set].forEach(function(visitor) {
+      visitors[visitor] = true;
+    });
+    return visitors;
+  }, {});
+
+  var visitorList = [];
+  for (var i = 0; i < transformRunOrder.length; i++) {
+    if (visitorsToInclude.hasOwnProperty(transformRunOrder[i])) {
+      visitorList = visitorList.concat(transformVisitors[transformRunOrder[i]]);
+    }
+  }
+
+  return visitorList;
+}
+
+exports.getVisitorsBySet = getVisitorsBySet;
+exports.getAllVisitors = getAllVisitors;
+exports.transformVisitors = transformVisitors;
+