feat(transpiler): allow @const annotation on class

Closes angular#148

Author: Tommy Odom

tools/transpiler/spec/classes_spec.js

@@ -21,6 +21,9 @@ class SubFoo extends Foo {
  }
 }
 
+@CONST
+class ConstClass {}
+
 class Const {
  @CONST
  constructor(a:number) {
@@ -62,6 +65,11 @@ export function main() {
  expect(subConst.b).toBe(2);
  });
 
+ it('@CONST on class without constructor should generate const constructor', function () {
+ var constClass = new ConstClass();
+ expect(constClass).not.toBe(null);
+ });
+
  describe('inheritance', function() {
  it('should support super call', function () {
  var subFoo = new SubFoo(1, 2);

tools/transpiler/src/codegeneration/ClassTransformer.js

@@ -19,6 +19,8 @@ import {propName} from 'traceur/src/staticsemantics/PropName';
 import {
  BinaryExpression,
  BindingIdentifier,
+ FormalParameterList,
+ FunctionBody,
  IdentifierExpression
 } from 'traceur/src/syntax/trees/ParseTrees';
 
@@ -48,15 +50,16 @@ export class ClassTransformer extends ParseTreeTransformer {
  var argumentTypesMap = {};
  var fields = [];
  var isConst;
+ var hasConstructor = false;
  var that = this;
 
  tree.elements.forEach(function(elementTree, index) {
  if (elementTree.type === PROPERTY_METHOD_ASSIGNMENT &&
  !elementTree.isStatic &&
  propName(elementTree) === CONSTRUCTOR) {
 
- isConst = elementTree.annotations.some((annotation) =>
-  annotation.name.identifierToken.value === 'CONST');
+ hasConstructor = true;
+ isConst = elementTree.annotations.some(that._isConstAnnotation);
 
  // Store constructor argument types,
  // so that we can use them to set the types of simple-assigned fields.
@@ -124,6 +127,26 @@ export class ClassTransformer extends ParseTreeTransformer {
  }
  });
 
+ // If no constructor exists then look to see if we should create a const constructor
+ // when the class is annotated with @CONST.
+ if (!hasConstructor) {
+ let constClassAnnotation = this._extractConstAnnotation(tree);
+ if (constClassAnnotation !== null) {
+ tree.elements = [(new PropertyConstructorAssignment(
+ constClassAnnotation.location,
+ false,
+ null,
+ tree.name,
+ new FormalParameterList(constClassAnnotation.location, []),
+ null,
+ [constClassAnnotation],
+ new FunctionBody(constClassAnnotation.location, []),
+ true,
+ []
+ ))].concat(tree.elements);
+ }
+ }
+
  // Add the field definitions to the beginning of the class.
  tree.elements = fields.concat(tree.elements);
 
@@ -183,4 +206,32 @@ export class ClassTransformer extends ParseTreeTransformer {
  body.statements = statements;
  return superCall;
  }
+
+ /**
+ * Extract the @CONST annotation from the class annotations.
+ * When found the annotation is removed from the class annotations and returned.
+ */
+ _extractConstAnnotation(tree) {
+ var annotations = [];
+ var constAnnotation = null;
+ var that = this;
+
+ tree.annotations.forEach((annotation) => {
+ if (that._isConstAnnotation(annotation)) {
+ constAnnotation = annotation;
+ } else {
+ annotations.push(annotation);
+ }
+ });
+
+ tree.annotations = annotations;
+ return constAnnotation;
+ }
+ /**
+ * Returns true if the annotation is @CONST
+ */
+ _isConstAnnotation(annotation) {
+ return annotation.name.identifierToken.value === 'CONST';
+ }
+
 }