better categorisation of transformers

lib/6to5/transformation/transform.js

@@ -3,6 +3,7 @@
 module.exports = transform;
 
 var Transformer = require("./transformer");
+var object      = require("../helpers/object");
 var File        = require("../file");
 var util        = require("../util");
 var _           = require("lodash");
@@ -24,7 +25,7 @@ transform.fromAst = function (ast, code, opts) {
 transform._ensureTransformerNames = function (type, keys) {
   for (var i = 0; i < keys.length; i++) {
     var key = keys[i];
-    if (!_.has(transform.transformers, key)) {
+    if (!transform.transformers[key]) {
       throw new ReferenceError(
         "Unknown transformer " + key + " specified in " + type + " - " +
         "transformer key names have been changed in 3.0.0 see " +
@@ -35,7 +36,7 @@ transform._ensureTransformerNames = function (type, keys) {
   }
 };
 
-transform.transformers = {};
+transform.transformers = object();
 
 transform.moduleFormatters = {
   common: require("./modules/common"),
@@ -46,18 +47,20 @@ transform.moduleFormatters = {
 };
 
 _.each({
-  "spec.noForInOfAssignment":           require("./transformers/spec/no-for-in-of-assignment"),
-  "spec.setters":                       require("./transformers/spec/setters"),
+  useStrict:                            require("./transformers/other/use-strict"),
+
+  "validation.undeclaredVariableCheck": require("./transformers/validation/undeclared-variable-check"),
+  "validation.noForInOfAssignment":     require("./transformers/validation/no-for-in-of-assignment"),
+  "validation.setters":                 require("./transformers/validation/setters"),
   "spec.blockScopedFunctions":          require("./transformers/spec/block-scoped-functions"),
-  "spec.illegalTopLevelThis":           require("./transformers/spec/illegal-top-level-this"),
 
   "playground.malletOperator":          require("./transformers/playground/mallet-operator"),
   "playground.methodBinding":           require("./transformers/playground/method-binding"),
   "playground.memoizationOperator":     require("./transformers/playground/memoization-operator"),
   "playground.objectGetterMemoization": require("./transformers/playground/object-getter-memoization"),
 
-  "optional.asyncToGenerator":        require("./transformers/optional/async-to-generator"),
-  "optional.bluebirdCoroutines":      require("./transformers/optional/bluebird-coroutines"),
+  "misc.asyncToGenerator":   require("./transformers/misc/async-to-generator"),
+  "misc.bluebirdCoroutines": require("./transformers/misc/bluebird-coroutines"),
 
   react:                              require("./transformers/other/react"),
 
@@ -96,9 +99,8 @@ _.each({
   "es6.blockScoping":                 require("./transformers/es6/block-scoping"),
 
   // needs to be after `es6.blockScoping` due to needing `letReferences` set on blocks
-  "optional.blockScopingTDZ":         require("./transformers/optional/block-scoping-tdz"),
+  "es6.blockScopingTDZ":              require("./transformers/es6/block-scoping-tdz"),
 
-  // needs to before `forOf` because otherwise regenerator wont be able to explode them
   // needs to be after block scoping since regenerator doesn't support it
   regenerator:                        require("./transformers/other/regenerator"),
 
@@ -110,25 +112,22 @@ _.each({
   // needs to be after `regenerator` due to needing `regeneratorRuntime` references
   // needs to be after `es6.forOf` due to needing `Symbol.iterator` references
   // needs to be before `es6.modules` due to dynamic imports
-  "optional.selfContained":           require("./transformers/optional/self-contained"),
+  "misc.selfContained":               require("./transformers/misc/self-contained"),
 
   _blockHoist:                        require("./transformers/_block-hoist"),
 
-  "optional.protoToAssign":           require("./transformers/optional/proto-to-assign"),
+  "spec.protoToAssign":               require("./transformers/spec/proto-to-assign"),
 
   _declarations:                      require("./transformers/_declarations"),
 
-  useStrict:                          require("./transformers/other/use-strict"),
-
   _aliasFunctions:                    require("./transformers/_alias-functions"),
   _moduleFormatter:                   require("./transformers/_module-formatter"),
 
-  "optional.typeofSymbol":            require("./transformers/optional/typeof-symbol"),
-  "optional.undefinedToVoid":         require("./transformers/optional/undefined-to-void"),
-  "optional.undeclaredVariableCheck": require("./transformers/optional/undeclared-variable-check"),
+  "spec.typeofSymbol":    require("./transformers/spec/typeof-symbol"),
+  "spec.undefinedToVoid": require("./transformers/spec/undefined-to-void"),
 
-  "spec.propertyLiterals":            require("./transformers/spec/property-literals"),
-  "spec.memberExpressionLiterals":    require("./transformers/spec/member-expression-literals")
+  "minification.propertyLiterals":         require("./transformers/minification/property-literals"),
+  "minification.memberExpressionLiterals": require("./transformers/minification/member-expression-literals")
 }, function (transformer, key) {
   transform.transformers[key] = new Transformer(key, transformer);
 });

lib/6to5/transformation/transformers/minification/member-expression-literals.js

@@ -5,10 +5,11 @@ var t = require("../../../types");
 exports.MemberExpression = function (node) {
   var prop = node.property;
   if (node.computed && t.isLiteral(prop) && t.isValidIdentifier(prop.value)) {
-    // computed literal that is a valid identifier
+    // foo["bar"] => foo.bar
     node.property = t.identifier(prop.value);
     node.computed = false;
   } else if (!node.computed && t.isIdentifier(prop) && !t.isValidIdentifier(prop.name)) {
+    // foo.default -> foo["default"]
     node.property = t.literal(prop.name);
     node.computed = true;
   }

lib/6to5/transformation/transformers/minification/property-literals.js

@@ -5,11 +5,11 @@ var t = require("../../../types");
 exports.Property = function (node) {
   var key = node.key;
   if (t.isLiteral(key) && t.isValidIdentifier(key.value)) {
-    // property key is a literal but a valid identifier
+    // "foo": "bar" -> foo: "bar"
     node.key = t.identifier(key.value);
     node.computed = false;
   } else if (!node.computed && t.isIdentifier(key) && !t.isValidIdentifier(key.name)) {
-    // property key is a keyword
+    // default: "bar" -> "default": "bar"
     node.key = t.literal(key.name);
   }
 };

lib/6to5/transformation/transformers/optional/block-scoping-tdz.js

@@ -1,48 +0,0 @@
-var traverse = require("../../../traverse");
-var t        = require("../../../types");
-
-var visitor = {
-  enter: function (node, parent, scope, context, state) {
-    if (!t.isReferencedIdentifier(node, parent)) return;
-
-    var declared = state.letRefs[node.name];
-    if (!declared) return;
-
-    // declared node is different in this scope
-    if (scope.get(node.name, true) !== declared) return;
-
-    var declaredLoc  = declared.loc;
-    var referenceLoc = node.loc;
-
-    if (!declaredLoc || !referenceLoc) return;
-
-    // does this reference appear on a line before the declaration?
-    var before = referenceLoc.start.line < declaredLoc.start.line;
-
-    if (referenceLoc.start.line === declaredLoc.start.line) {
-      // this reference appears on the same line
-      // check it appears before the declaration
-      before = referenceLoc.start.col < declaredLoc.start.col;
-    }
-
-    if (before) {
-      throw state.file.errorWithNode(node, "Temporal dead zone - accessing a variable before it's initialized");
-    }
-  }
-};
-
-exports.optional = true;
-
-exports.Loop =
-exports.Program =
-exports.BlockStatement = function (node, parent, scope, context, file) {
-  var letRefs = node._letReferences;
-  if (!letRefs) return;
-
-  var state = {
-    letRefs: letRefs,
-    file:    file
-  };
-
-  traverse(node, visitor, scope, state);
-};

lib/6to5/transformation/transformers/other/react.js

@@ -7,7 +7,6 @@
 
 var esutils = require("esutils");
 var t       = require("../../../types");
-var _       = require("lodash");
 
 exports.JSXIdentifier = function (node) {
   if (esutils.keyword.isIdentifierName(node.name)) {
@@ -148,7 +147,7 @@ exports.JSXElement = {
     for (var i = 0; i < node.children.length; i++) {
       var child = node.children[i];
 
-      if (t.isLiteral(child) && _.isString(child.value)) {
+      if (t.isLiteral(child) && typeof child.value === "string") {
         cleanJSXElementLiteralChild(child, callExpr.arguments);
         continue;
       } else if (t.isJSXEmptyExpression(child)) {

lib/6to5/transformation/transformers/other/use-strict.js

@@ -10,3 +10,12 @@ exports.ast = {
     }
   }
 };
+
+exports.FunctionDeclaration =
+exports.FunctionExpression = function (node, parent, scope, context) {
+  context.skip();
+};
+
+exports.ThisExpression = function (node, parent, scope, context, file) {
+  throw file.errorWithNode(node, "Top level `this` is not allowed", ReferenceError);
+};

lib/6to5/transformation/transformers/spec/illegal-top-level-this.js

@@ -1,8 +0,0 @@
-exports.FunctionDeclaration =
-exports.FunctionExpression = function (node, parent, scope, context) {
-  context.skip();
-};
-
-exports.ThisExpression = function (node, parent, scope, context, file) {
-  throw file.errorWithNode(node, "Top level `this` is not allowed", ReferenceError);
-};

test/fixtures/transformation/misc-async-to-generator/options.json

@@ -0,0 +1,4 @@
+{
+  "noCheckAst": true,
+  "optional": ["misc.asyncToGenerator"]
+}

test/fixtures/transformation/misc-bluebird-coroutines/options.json

@@ -0,0 +1,4 @@
+{
+  "optional": ["misc.bluebirdCoroutines"],
+  "noCheckAst": true
+}

test/fixtures/transformation/misc-self-contained/options.json

@@ -0,0 +1,4 @@
+{
+  "optional": ["misc.selfContained"],
+  "experimental": true
+}

test/fixtures/transformation/optional-async-to-generator/options.json

@@ -1,4 +0,0 @@
-{
-  "noCheckAst": true,
-  "optional": ["asyncToGenerator"]
-}

test/fixtures/transformation/optional-bluebird-coroutines/options.json

@@ -1,4 +0,0 @@
-{
-  "optional": ["bluebirdCoroutines"],
-  "noCheckAst": true
-}

test/fixtures/transformation/optional-proto-to-assign/options.json

@@ -1,3 +0,0 @@
-{
-  "optional": ["protoToAssign"]
-}

test/fixtures/transformation/optional-self-contained/options.json

@@ -1,4 +0,0 @@
-{
-  "optional": ["selfContained"],
-  "experimental": true
-}

test/fixtures/transformation/optional-typeof-symbol/options.json

@@ -1,3 +0,0 @@
-{
-  "optional": ["typeofSymbol"]
-}

test/fixtures/transformation/optional-undeclared-variable-check/options.json

@@ -1,3 +0,0 @@
-{
-  "optional": ["undeclaredVariableCheck"]
-}

test/fixtures/transformation/optional-undefined-to-void/options.json

@@ -1,3 +0,0 @@
-{
-  "optional": ["undefinedToVoid"]
-}

test/fixtures/transformation/spec-proto-to-assign/options.json

@@ -0,0 +1,3 @@
+{
+  "optional": ["spec.protoToAssign"]
+}

test/fixtures/transformation/spec-typeof-symbol/options.json

@@ -0,0 +1,3 @@
+{
+  "optional": ["spec.typeofSymbol"]
+}

test/fixtures/transformation/spec-undefined-to-void/options.json

@@ -0,0 +1,3 @@
+{
+  "optional": ["spec.undefinedToVoid"]
+}

test/fixtures/transformation/use-strict/illegal-this-root-call/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Top level `this` is not allowed"
+}

test/fixtures/transformation/use-strict/illegal-this-root-declaration/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Top level `this` is not allowed"
+}

test/fixtures/transformation/use-strict/illegal-this-root-reference/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Top level `this` is not allowed"
+}

test/fixtures/transformation/validation-undeclared-variable-check/options.json

@@ -0,0 +1,3 @@
+{
+  "optional": ["validation.undeclaredVariableCheck"]
+}