automatically explode visitors

src/babel/messages.js

@@ -26,7 +26,6 @@ export const MESSAGES = {
 
   traverseNeedsParent: "Must pass a scope and parentPath unless traversing a Program/File got a $1 node",
   traverseVerifyRootFunction: "You passed `traverse()` a function when it expected a visitor object, are you sure you didn't mean `{ enter: Function }`?",
-  traverseVerifyVisitorFunction: "You passed \`traverse()\` a visitor object with the key $1 that's a `Function` instead of `{ enter: Function }`. You need to normalise your visitor with `traverse.explode(visitor)`.",
   traverseVerifyVisitorProperty: "You passed `traverse()` a visitor object with the property $1 that has the invalid property $2",
   traverseVerifyNodeType: "You gave us a visitor for the node type $1 but it's not a valid type",
 

src/babel/transformation/modules/_default.js

@@ -5,7 +5,7 @@ import object from "../../helpers/object";
 import * as util from  "../../util";
 import * as t from "../../types";
 
-var remapVisitor = traverse.explode({
+var remapVisitor = {
   enter(node, parent, scope, formatter) {
     if (node._skipModulesRemap) {
       return this.skip();
@@ -63,7 +63,7 @@ var remapVisitor = traverse.explode({
 
     return t.sequenceExpression(nodes);
   }
-});
+};
 
 var importsVisitor = {
   ImportDeclaration: {
@@ -74,7 +74,7 @@ var importsVisitor = {
   }
 };
 
-var exportsVisitor = traverse.explode({
+var exportsVisitor = {
   ExportDeclaration: {
     enter(node, parent, scope, formatter) {
       formatter.hasLocalExports = true;
@@ -106,7 +106,7 @@ var exportsVisitor = traverse.explode({
       }
     }
   }
-});
+};
 
 export default class DefaultFormatter {
   constructor(file) {

src/babel/transformation/transformers/es6/classes.js

@@ -35,7 +35,7 @@ var collectPropertyReferencesVisitor = {
   }
 };
 
-var constructorVisitor = traverse.explode({
+var constructorVisitor = {
   ThisExpression: {
     enter(node, parent, scope, ref) {
       return ref;
@@ -49,9 +49,9 @@ var constructorVisitor = traverse.explode({
       }
     }
   }
-});
+};
 
-var verifyConstructorVisitor = traverse.explode({
+var verifyConstructorVisitor = {
   MethodDefinition: {
     enter() {
       this.skip();
@@ -96,7 +96,7 @@ var verifyConstructorVisitor = traverse.explode({
       }
     }
   }
-});
+};
 
 class ClassTransformer {
 

src/babel/transformation/transformers/es6/parameters.default.js

@@ -10,7 +10,7 @@ var hasDefaults = function (node) {
   return false;
 };
 
-var iifeVisitor = traverse.explode({
+var iifeVisitor = {
   ReferencedIdentifier(node, parent, scope, state) {
     if (!state.scope.hasOwnBinding(node.name)) return;
     if (state.scope.bindingIdentifierEquals(node.name, node)) return;
@@ -18,7 +18,7 @@ var iifeVisitor = traverse.explode({
     state.iife = true;
     this.stop();
   }
-});
+};
 
 exports.Function = function (node, parent, scope, file) {
   if (!hasDefaults(node)) return;

src/babel/transformation/transformers/es6/spec.block-scoping.js

@@ -1,7 +1,7 @@
 import traverse from "../../../traversal";
 import * as t from "../../../types";
 
-var visitor = traverse.explode({
+var visitor = {
   ReferencedIdentifier(node, parent, scope, state) {
     if (t.isFor(parent) && parent.left === node) return;
 
@@ -25,7 +25,7 @@ var visitor = traverse.explode({
       return t.logicalExpression("&&", assert, node);
     }
   }
-});
+};
 
 export var metadata = {
   optional: true,

src/babel/transformation/transformers/es6/tail-call.js

@@ -21,7 +21,7 @@ function returnBlock(expr) {
 }
 
 // looks for and replaces tail recursion calls
-var firstPass = traverse.explode({
+var firstPass = {
   enter(node, parent, scope, state) {
     if (t.isTryStatement(parent)) {
       if (node === parent.block) {
@@ -45,11 +45,11 @@ var firstPass = traverse.explode({
     this.skip();
     state.vars.push(node);
   }
-});
+};
 
 // hoists up function declarations, replaces `this` and `arguments` and marks
 // them as needed
-var secondPass = traverse.explode({
+var secondPass = {
   ThisExpression(node, parent, scope, state) {
     state.needsThis = true;
     return state.getThisId();
@@ -71,10 +71,10 @@ var secondPass = traverse.explode({
       return node;
     }
   }
-});
+};
 
 // optimizes recursion by removing `this` and `arguments` if they aren't used
-var thirdPass = traverse.explode({
+var thirdPass = {
   ExpressionStatement(node, parent, scope, state) {
     var expr = node.expression;
     if (!t.isAssignmentExpression(expr)) return;
@@ -87,7 +87,7 @@ var thirdPass = traverse.explode({
       });
     }
   }
-});
+};
 
 class TailCallTransformer {
   constructor(path, scope, file) {

src/babel/traversal/index.js

@@ -14,7 +14,9 @@ export default function traverse(parent, opts, scope, state, parentPath) {
   }
 
   if (!opts) opts = {};
+
   visitors.verify(opts);
+  visitors.explode(opts);
 
   // array of nodes
   if (Array.isArray(parent)) {

src/babel/traversal/visitors.js

@@ -4,6 +4,9 @@ import * as t from "../types";
 import esquery from "esquery";
 
 export function explode(visitor, mergeConflicts) {
+  if (visitor._exploded) return visitor;
+  visitor._exploded = true;
+
   // make sure there's no __esModule type since this is because we're using loose mode
   // and it sets __esModule to be enumerable on all modules :(
   delete visitor.__esModule;
@@ -86,15 +89,12 @@ export function verify(visitor) {
   for (var nodeType in visitor) {
     if (shouldIgnoreKey(nodeType)) continue;
 
-    if (t.TYPES.indexOf(nodeType) < 0) {
+    if (t.TYPES.indexOf(nodeType) < 0 && !virtualTypes[nodeType]) {
       throw new Error(messages.get("traverseVerifyNodeType", nodeType));
     }
 
     var visitors = visitor[nodeType];
-
-    if (typeof visitors === "function") {
-      throw new Error(messages.get("traverseVerifyVisitorFunction", nodeType));
-    } else if (typeof visitors === "object") {
+    if (typeof visitors === "object") {
       for (var visitorKey in visitors) {
         if (visitorKey === "enter" || visitorKey === "exit") continue;
         throw new Error(messages.get("traverseVerifyVisitorProperty", nodeType, visitorKey));