Class fields, part 1 (parsing and infrastructure)

src/ast/ast.h

Index: src/ast/ast.h
diff --git a/src/ast/ast.h b/src/ast/ast.h
index 4885379c9a60f3f0bbdb04fee9dddde2f455a1ed..007ad5d26d2c0405d8bd3e2c8b6809efc435f051 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -2623,6 +2623,15 @@ class FunctionLiteral final : public Expression {
   int yield_count() { return yield_count_; }
   void set_yield_count(int yield_count) { yield_count_ = yield_count; }
 
+  bool requires_class_field_init() { return requires_class_field_init_; }
+  void set_requires_class_field_init(bool requires_class_field_init) {
+    requires_class_field_init_ = requires_class_field_init;
+  }
+  bool is_class_field_initializer() { return is_class_field_initializer_; }
+  void set_is_class_field_initializer(bool is_class_field_initializer) {
+    is_class_field_initializer_ = is_class_field_initializer;
+  }
+
  private:
   friend class AstNodeFactory;
 
@@ -2645,7 +2654,9 @@ class FunctionLiteral final : public Expression {
         scope_(scope),
         body_(body),
         raw_inferred_name_(ast_value_factory->empty_string()),
-        ast_properties_(zone) {
+        ast_properties_(zone),
+        requires_class_field_init_(false),
+        is_class_field_initializer_(false) {
     bitfield_ =
         FunctionTypeBits::encode(function_type) | Pretenure::encode(false) |
         HasDuplicateParameters::encode(has_duplicate_parameters ==
@@ -2682,13 +2693,16 @@ class FunctionLiteral final : public Expression {
   const AstString* raw_inferred_name_;
   Handle<String> inferred_name_;
   AstProperties ast_properties_;
+
+  bool requires_class_field_init_;   // TODO(bakkot) this should be a bitfield
+  bool is_class_field_initializer_;  // TODO(bakkot) this should be a bitfield

[Dan Ehrenberg, 2016/09/06 23:55:59]

As we discussed offline, it'd be nice to find these bits in FunctionKind before
submitting, especially given all the ongoing work in reducing the memory that
parser structures take.

[bakkot, 2016/09/07 19:30:12]

I ended up just expanding the bitfield in FunctionLiterals, which (after some
past reorganization of Expressions) doesn't use any more space, as far as I can
tell.

 };
 
 // Property is used for passing information
 // about a class literal's properties from the parser to the code generator.
 class ClassLiteralProperty final : public LiteralProperty {
  public:
-  enum Kind : uint8_t { METHOD, GETTER, SETTER };
+  enum Kind : uint8_t { METHOD, GETTER, SETTER, FIELD };
 
   Kind kind() const { return kind_; }
 
@@ -2717,6 +2731,13 @@ class ClassLiteral final : public Expression {
   int start_position() const { return position(); }
   int end_position() const { return end_position_; }
 
+  VariableProxy* static_initializer_proxy() const {
+    return static_initializer_proxy_;
+  }
+  void set_static_initializer_proxy(VariableProxy* proxy) {
+    static_initializer_proxy_ = proxy;
+  }
+
   BailoutId CreateLiteralId() const { return BailoutId(local_id(0)); }
   BailoutId PrototypeId() { return BailoutId(local_id(1)); }
 
@@ -2751,7 +2772,8 @@ class ClassLiteral final : public Expression {
         class_variable_proxy_(class_variable_proxy),
         extends_(extends),
         constructor_(constructor),
-        properties_(properties) {}
+        properties_(properties),
+        static_initializer_proxy_(nullptr) {}
 
   static int parent_num_ids() { return Expression::num_ids(); }
   int local_id(int n) const { return base_id() + parent_num_ids() + n; }
@@ -2763,6 +2785,7 @@ class ClassLiteral final : public Expression {
   Expression* extends_;
   FunctionLiteral* constructor_;
   ZoneList<Property*>* properties_;
+  VariableProxy* static_initializer_proxy_;  // TODO(bakkot) initialize inline

[Dan Ehrenberg, 2016/09/06 23:55:59]

What do you mean by this TODO?

[bakkot, 2016/09/07 19:30:12]

Sorry, that's stale. I was originally going to have static_initializer_proxy_ be
initialized to its final value in the constructor, but decided against it.

 };