Add support for Enums

lib/src/codegen/js_codegen.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dev_compiler.src.codegen.js_codegen;
 
 import 'dart:collection' show HashSet, HashMap, SplayTreeSet;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/src/generated/ast.dart' hide ConstantEvaluator;
@@ skipping 402 matching lines @@
           'dart.registerExtension(dart.global.#, #);', [
         _propertyName(jsPeerName),
         classElem.name
       ]);
       return _statement([result, copyMembers]);
     }
     return result;
   }
 
   @override
-  JS.Statement visitEnumDeclaration(EnumDeclaration node) =>
-      _unimplementedCall("Unimplemented enum: $node").toStatement();
+  JS.Statement visitEnumDeclaration(EnumDeclaration node) {
+    var element = node.element;
+    var type = element.type;
+    var name = js.string(type.name);
+
+    // Generate a class per section 13 of the spec.
+    // TODO(vsm): Generate any accompanying metadata
+
+    // Create constructor and initialize index
+    var constructor =
+        new JS.Method(name, js.call('function(index) { this.index = index; }'));
+    var fields = new List<ConstFieldElementImpl>.from(
+        element.fields.where((f) => f.type == type));
+
+    // Create toString() method
+    var properties = new List<JS.Property>();
+    for (var i = 0; i < fields.length; ++i) {
+      properties.add(new JS.Property(
+          js.number(i), js.string('${type.name}.${fields[i].name}')));
+    }
+    var nameMap = new JS.ObjectInitializer(properties, multiline: true);
+    var toStringF = new JS.Method(js.string('toString'),
+        js.call('function () { return #[this.index]; }', nameMap));
+
+    // Create enum class
+    var classExpr = new JS.ClassExpression(new JS.Identifier(type.name),
+        _classHeritage(element), [constructor, toStringF]);
+    var result = [js.statement('#', classExpr)];
+
+    // Create static fields for each enum value
+    for (var i = 0; i < fields.length; ++i) {
+      result.add(js.statement(
+          '${type.name}.${fields[i].name} = dart.const(new ${type.name}($i));'));

[Jennifer Messerly, 2015/07/14 23:57:02]

long line ... I think long strings confuse dartfmt ... BUT, this should probably
be rewritten to use js_ast's interpolation, otherwise it defeats the caching
mechanism. So like this:

result.add(js.statement('#.# = dart.const(new #(#));', [type.name,
js.string(fields[i].name), type.name, i]));

(if we had tagged templates in Dart, like JS does, we wouldn't need these
tricks, FWIW)

[vsm, 2015/07/15 00:34:03]

Done.

+    }
+
+    // Create static values list
+    var values = new JS.ArrayInitializer(
+        fields.map((f) => js.call('${type.name}.${f.name}')).toList());

[Jennifer Messerly, 2015/07/14 23:57:02]

here too: js.call('#.#', type.name, js.string(f.name))

(I'm not 100% sure js.string is needed for second arg ... I forgot if it will
implicitly convert a String to a string literal in the JS AST)

[vsm, 2015/07/15 00:34:03]

Done.

+    result.add(js.statement(
+        '${type.name}.values = dart.const(dart.list(#, #));', [

[Jennifer Messerly, 2015/07/14 23:57:02]

here too. Use #

[vsm, 2015/07/15 00:34:03]

Done.

+      values,
+      _emitTypeName(type)
+    ]));
+
+    return _statement(result);
+  }
 
   /// Given a class element and body, complete the class declaration.
   /// This handles generic type parameters, laziness (in library-cycle cases),
   /// and ensuring dependencies are loaded first.
   JS.Statement _finishClassDef(ParameterizedType type, JS.Statement body) {
     var name = type.name;
     var genericName = '$name\$';
 
     JS.Statement genericDef = null;
     if (type.typeParameters.isNotEmpty) {
@@ skipping 2388 matching lines @@
 
 class _JsThisFinder extends JS.BaseVisitor {
   bool found = false;
   visitThis(JS.This node) {
     found = true;
   }
   visitNode(JS.Node node) {
     if (!found) super.visitNode(node);
   }
 }