From f50661aac44f59e7be2cb0abf9148c7a09e7f32c Mon Sep 17 00:00:00 2001
From: Vijay Menon <vsm@google.com>
Date: Tue, 14 Jul 2015 17:48:38 -0700
Subject: [PATCH] Add support for Enums

Fixes #248

R=jmesserly@google.com

Review URL: https://codereview.chromium.org/1224083017.
---
 .../lib/src/codegen/js_codegen.dart           | 53 ++++++++++++++++++-
 .../test/codegen/expect/fieldtest.js          | 19 +++++++
 pkg/dev_compiler/test/codegen/fieldtest.dart  |  4 ++
 3 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/pkg/dev_compiler/lib/src/codegen/js_codegen.dart b/pkg/dev_compiler/lib/src/codegen/js_codegen.dart
index 1eab31a1d0a5..3dfbe257d4fe 100644
--- a/pkg/dev_compiler/lib/src/codegen/js_codegen.dart
+++ b/pkg/dev_compiler/lib/src/codegen/js_codegen.dart
@@ -420,8 +420,57 @@ class JSCodegenVisitor extends GeneralizingAstVisitor {
   }
 
   @override
-  JS.Statement visitEnumDeclaration(EnumDeclaration node) =>
-      _unimplementedCall("Unimplemented enum: $node").toStatement();
+  JS.Statement visitEnumDeclaration(EnumDeclaration node) {
+    var element = node.element;
+    var type = element.type;
+    var name = js.string(type.name);
+    var id = new JS.Identifier(type.name);
+
+    // Generate a class per section 13 of the spec.
+    // TODO(vsm): Generate any accompanying metadata
+
+    // Create constructor and initialize index
+    var constructor =
+        new JS.Method(name, js.call('function(index) { this.index = index; }'));
+    var fields = new List<ConstFieldElementImpl>.from(
+        element.fields.where((f) => f.type == type));
+
+    // Create toString() method
+    var properties = new List<JS.Property>();
+    for (var i = 0; i < fields.length; ++i) {
+      properties.add(new JS.Property(
+          js.number(i), js.string('${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(
+        id, _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('#.# = dart.const(new #(#));', [
+        id,
+        fields[i].name,
+        id,
+        js.number(i)
+      ]));
+    }
+
+    // Create static values list
+    var values = new JS.ArrayInitializer(
+        fields.map((f) => js.call('#.#', [id, f.name])).toList());
+    result.add(js.statement('#.values = dart.const(dart.list(#, #));', [
+      id,
+      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),
diff --git a/pkg/dev_compiler/test/codegen/expect/fieldtest.js b/pkg/dev_compiler/test/codegen/expect/fieldtest.js
index b69e90dba298..f69baba971e9 100644
--- a/pkg/dev_compiler/test/codegen/expect/fieldtest.js
+++ b/pkg/dev_compiler/test/codegen/expect/fieldtest.js
@@ -92,12 +92,31 @@ dart_library.library('fieldtest', null, /* Imports */[
   StaticFieldOrder2.c = dart.notNull(StaticFieldOrder2.d) + 2;
   StaticFieldOrder2.b = dart.notNull(StaticFieldOrder2.c) + 3;
   StaticFieldOrder2.a = dart.notNull(StaticFieldOrder2.b) + 1;
+  class MyEnum extends core.Object {
+    MyEnum(index) {
+      this.index = index;
+    }
+    toString() {
+      return {
+        0: "MyEnum.Val1",
+        1: "MyEnum.Val2",
+        2: "MyEnum.Val3",
+        3: "MyEnum.Val4"
+      }[this.index];
+    }
+  };
+  MyEnum.Val1 = dart.const(new MyEnum(0));
+  MyEnum.Val2 = dart.const(new MyEnum(1));
+  MyEnum.Val3 = dart.const(new MyEnum(2));
+  MyEnum.Val4 = dart.const(new MyEnum(3));
+  MyEnum.values = dart.const(dart.list([MyEnum.Val1, MyEnum.Val2, MyEnum.Val3, MyEnum.Val4], MyEnum));
   function main() {
     let a = new A();
     foo(a);
     bar(a);
     core.print(baz(a));
     core.print(new (Generic$(core.String))().foo(' world'));
+    core.print(MyEnum.values);
   }
   dart.fn(main, dart.void, []);
   // Exports:
diff --git a/pkg/dev_compiler/test/codegen/fieldtest.dart b/pkg/dev_compiler/test/codegen/fieldtest.dart
index a6b140e72df5..b3a596ee61f4 100644
--- a/pkg/dev_compiler/test/codegen/fieldtest.dart
+++ b/pkg/dev_compiler/test/codegen/fieldtest.dart
@@ -64,6 +64,8 @@ class StaticFieldOrder2 {
   static const d = 4;
 }
 
+enum MyEnum { Val1, Val2, Val3, Val4 }
+
 void main() {
   var a = new A();
   foo(a);
@@ -71,4 +73,6 @@ void main() {
   print(baz(a));
 
   print(new Generic<String>().foo(' world'));
+
+  print(MyEnum.values);
 }