[es7] implement |do| expressions proposal

src/ast.h

Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index af6ecb8d10647d27faf9d01f5dc37928b30b77aa..fd7ca9ece823adb39a08bd538593c4f2fd8bdd89 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -90,7 +90,8 @@ namespace internal {
   V(SuperPropertyReference)     \
   V(SuperCallReference)         \
   V(CaseClause)                 \
-  V(EmptyParentheses)
+  V(EmptyParentheses)           \
+  V(DoExpression)
 
 #define AST_NODE_LIST(V)                        \
   DECLARATION_NODE_LIST(V)                      \
@@ -2690,6 +2691,42 @@ class NativeFunctionLiteral final : public Expression {
 };
 
 
+class DoExpression final : public Expression {
+ public:
+  DECLARE_NODE_TYPE(DoExpression)
+
+  Scope* scope() { return scope_; }

[rossberg, 2015/10/12 13:52:39]

Why not just have a DoExpression carry a Block, instead of its own scope and
statements? That seems natural, and probably allows a bit more code reuse.
(TryStatement does the same, for example.)

[caitp (gmail), 2015/10/12 18:22:59]

Done

+  ZoneList<Statement*>* statements() { return statements_; }
+
+  static int num_ids() { return parent_num_ids() + 1; }
+  BailoutId EntryId() const { return BailoutId(local_id(0)); }
+  BailoutId ExitId() const { return BailoutId(local_id(1)); }
+  BailoutId DeclsId() const { return BailoutId(local_id(2)); }
+
+  VariableProxy* result() { return result_; }
+
+ protected:
+  DoExpression(Zone* zone, Scope* scope, ZoneList<Statement*>* statements,
+               VariableProxy* result, int pos)
+      : Expression(zone, pos),
+        scope_(scope),
+        statements_(statements),
+        result_(result) {
+    DCHECK_NOT_NULL(scope_);
+    DCHECK_NOT_NULL(statements_);
+    DCHECK_NOT_NULL(result_);
+  }
+  static int parent_num_ids() { return Expression::num_ids(); }
+
+ private:
+  int local_id(int n) const { return base_id() + parent_num_ids() + n; }
+
+  Scope* scope_;
+  ZoneList<Statement*>* statements_;
+  VariableProxy* result_;
+};
+
+
 class ThisFunction final : public Expression {
  public:
   DECLARE_NODE_TYPE(ThisFunction)
@@ -3558,6 +3595,15 @@ class AstNodeFactory final BASE_EMBEDDED {
         NativeFunctionLiteral(parser_zone_, name, extension, pos);
   }
 
+  DoExpression* NewDoExpression(Scope* scope, ZoneList<Statement*>* statements,
+                                int pos, int end_pos) {
+    Variable* result_var =
+        NewTemporaryVar(scope, ast_value_factory()->dot_result_string());
+    VariableProxy* result = NewVariableProxy(result_var, end_pos, end_pos);
+    return new (parser_zone_)
+        DoExpression(parser_zone_, scope, statements, result, pos);
+  }
+
   ThisFunction* NewThisFunction(int pos) {
     return new (local_zone_) ThisFunction(local_zone_, pos);
   }
@@ -3610,6 +3656,8 @@ class AstNodeFactory final BASE_EMBEDDED {
   // the parser-level zone.
   Zone* parser_zone_;
   AstValueFactory* ast_value_factory_;
+
+  Variable* NewTemporaryVar(Scope* scope, const AstRawString* name);
 };