Private fields

src/parsing/parser-base.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
@@ skipping 180 matching lines @@
         allow_lazy_(false),
         allow_natives_(false),
         allow_tailcalls_(false),
         allow_harmony_restrictive_declarations_(false),
         allow_harmony_do_expressions_(false),
         allow_harmony_for_in_(false),
         allow_harmony_function_sent_(false),
         allow_harmony_async_await_(false),
         allow_harmony_restrictive_generators_(false),
         allow_harmony_trailing_commas_(false),
-        allow_harmony_class_fields_(false) {}
+        allow_harmony_class_fields_(false),
+        allow_harmony_private_class_fields_(false) {}
 
 #define ALLOW_ACCESSORS(name)                           \
   bool allow_##name() const { return allow_##name##_; } \
   void set_allow_##name(bool allow) { allow_##name##_ = allow; }
 
   ALLOW_ACCESSORS(lazy);
   ALLOW_ACCESSORS(natives);
   ALLOW_ACCESSORS(tailcalls);
   ALLOW_ACCESSORS(harmony_restrictive_declarations);
   ALLOW_ACCESSORS(harmony_do_expressions);
   ALLOW_ACCESSORS(harmony_for_in);
   ALLOW_ACCESSORS(harmony_function_sent);
   ALLOW_ACCESSORS(harmony_async_await);
   ALLOW_ACCESSORS(harmony_restrictive_generators);
   ALLOW_ACCESSORS(harmony_trailing_commas);
   ALLOW_ACCESSORS(harmony_class_fields);
+  ALLOW_ACCESSORS(harmony_private_class_fields);
 
 #undef ALLOW_ACCESSORS
 
   uintptr_t stack_limit() const { return stack_limit_; }
 
   void set_stack_limit(uintptr_t stack_limit) { stack_limit_ = stack_limit; }
 
   Zone* zone() const { return zone_; }
 
  protected:
@@ skipping 870 matching lines @@
     kNotSet
   };
 
   bool SetPropertyKindFromToken(Token::Value token, PropertyKind* kind);
   ExpressionT ParsePropertyName(IdentifierT* name, PropertyKind* kind,
                                 bool* is_generator, bool* is_get, bool* is_set,
                                 bool* is_async, bool* is_computed_name,
                                 bool* ok);
   ExpressionT ParseObjectLiteral(bool* ok);
   ClassLiteralPropertyT ParseClassPropertyDefinition(
-      ClassLiteralChecker* checker, bool has_extends, bool* is_computed_name,
-      bool* has_seen_constructor, bool* ok);
+      ClassLiteralChecker* checker, bool has_extends, IdentifierT* private_name,
+      bool* is_computed_name, bool* has_seen_constructor, bool* ok);
   FunctionLiteralT ParseClassFieldForInitializer(bool has_initializer,
                                                  bool* ok);
   ObjectLiteralPropertyT ParseObjectPropertyDefinition(
       ObjectLiteralChecker* checker, bool* is_computed_name, bool* ok);
   ExpressionListT ParseArguments(Scanner::Location* first_spread_pos,
                                  bool maybe_arrow, bool* ok);
   ExpressionListT ParseArguments(Scanner::Location* first_spread_pos,
                                  bool* ok) {
     return ParseArguments(first_spread_pos, false, ok);
   }
@@ skipping 214 matching lines @@
   bool allow_natives_;
   bool allow_tailcalls_;
   bool allow_harmony_restrictive_declarations_;
   bool allow_harmony_do_expressions_;
   bool allow_harmony_for_in_;
   bool allow_harmony_function_sent_;
   bool allow_harmony_async_await_;
   bool allow_harmony_restrictive_generators_;
   bool allow_harmony_trailing_commas_;
   bool allow_harmony_class_fields_;
+  bool allow_harmony_private_class_fields_;
 
   friend class DiscardableZoneScope;
 };
 
 template <typename Impl>
 ParserBase<Impl>::FunctionState::FunctionState(
     FunctionState** function_state_stack, ScopeState** scope_stack,
     Scope* scope, FunctionKind kind)
     : ScopeState(scope_stack, scope),
       next_materialized_literal_index_(0),
@@ skipping 244 matching lines @@
   //   Number
   //   String
   //   ArrayLiteral
   //   ObjectLiteral
   //   RegExpLiteral
   //   ClassLiteral
   //   '(' Expression ')'
   //   TemplateLiteral
   //   do Block
   //   AsyncFunctionExpression
+  //   PrivateName
 
   int beg_pos = peek_position();
   switch (peek()) {
     case Token::THIS: {
       BindingPatternUnexpectedToken();
       Consume(Token::THIS);
       return impl()->ThisExpression(beg_pos);
     }
 
     case Token::NULL_LITERAL:
@@ skipping 103 matching lines @@
       }
       break;
 
     case Token::DO:
       if (allow_harmony_do_expressions()) {
         BindingPatternUnexpectedToken();
         return impl()->ParseDoExpression(ok);
       }
       break;
 
+    case Token::HASH:
+      if (allow_harmony_private_class_fields()) {
+        BindingPatternUnexpectedToken();

[Dan Ehrenberg, 2016/09/10 04:30:28]

This check makes sense, and reminds me: When you write parser tests, be sure to
have a test that verifies that you can have a private field as part of an
assignment pattern.

[bakkot, 2016/09/13 22:05:04]

Done.

+        return impl()->ParsePrivateFieldReference(
+            impl()->ThisExpression(beg_pos), ok);
+      }
+      break;
+
     default:
       break;
   }
 
   ReportUnexpectedToken(Next());
   *ok = false;
   return impl()->EmptyExpression();
 }
 
 template <typename Impl>
@@ skipping 266 matching lines @@
   impl()->PushLiteralName(*name);
 
   uint32_t index;
   return impl()->IsArrayIndex(*name, &index)
              ? factory()->NewNumberLiteral(index, pos)
              : factory()->NewStringLiteral(*name, pos);
 }
 
 template <typename Impl>
 typename ParserBase<Impl>::ClassLiteralPropertyT
-ParserBase<Impl>::ParseClassPropertyDefinition(ClassLiteralChecker* checker,
-                                               bool has_extends,
-                                               bool* is_computed_name,
-                                               bool* has_seen_constructor,
-                                               bool* ok) {
+ParserBase<Impl>::ParseClassPropertyDefinition(
+    ClassLiteralChecker* checker, bool has_extends, IdentifierT* private_name,
+    bool* is_computed_name, bool* has_seen_constructor, bool* ok) {
+  DCHECK(!allow_harmony_private_class_fields() || private_name != nullptr);
   DCHECK(has_seen_constructor != nullptr);
   bool is_get = false;
   bool is_set = false;
   bool is_generator = false;
   bool is_async = false;
   bool is_static = false;
   PropertyKind kind = PropertyKind::kNotSet;
 
   Token::Value name_token = peek();
 
   IdentifierT name = impl()->EmptyIdentifier();
   ExpressionT name_expression;
   if (name_token == Token::STATIC) {
     Consume(Token::STATIC);
     if (peek() == Token::LPAREN) {
       kind = PropertyKind::kMethodProperty;
       name = impl()->GetSymbol();  // TODO(bakkot) specialize on 'static'
       name_expression = factory()->NewStringLiteral(name, position());
     } else if (peek() == Token::ASSIGN || peek() == Token::SEMICOLON ||
                peek() == Token::RBRACE) {
       name = impl()->GetSymbol();  // TODO(bakkot) specialize on 'static'
       name_expression = factory()->NewStringLiteral(name, position());
     } else {
       is_static = true;
       name_expression = ParsePropertyName(
           &name, &kind, &is_generator, &is_get, &is_set, &is_async,
           is_computed_name, CHECK_OK_CUSTOM(EmptyClassLiteralProperty));
     }
+  } else if (allow_harmony_private_class_fields() &&
+             name_token == Token::HASH) {
+    Consume(Token::HASH);
+    // Private field
+    *private_name = ParseIdentifierName(CHECK_OK_CUSTOM(
+        EmptyClassLiteralProperty));  // TODO(bakkot) IdentifierPart
+    name_expression = impl()->EmptyExpression();
+
+    bool has_initializer = Check(Token::ASSIGN);
+    FunctionLiteralT function_literal = ParseClassFieldForInitializer(
+        has_initializer, CHECK_OK_CUSTOM(EmptyClassLiteralProperty));
+    ExpectSemicolon(CHECK_OK_CUSTOM(EmptyClassLiteralProperty));
+    return factory()->NewClassLiteralProperty(name_expression, function_literal,
+                                              ClassLiteralProperty::FIELD,
+                                              false, *is_computed_name);

[Dan Ehrenberg, 2016/09/10 04:30:28]

Don't you want to pass true for is_computed_name? Maybe you get by anyway
because fields are always treated like computed names.

[bakkot, 2016/09/13 01:05:38]

It really doesn't matter, yeah. I don't believe property->is_computed_name()
ever gets read for private fields. I've set it to false explicitly to avoid the
pointer dereference, though.

   } else {
     name_expression = ParsePropertyName(
         &name, &kind, &is_generator, &is_get, &is_set, &is_async,
         is_computed_name, CHECK_OK_CUSTOM(EmptyClassLiteralProperty));
   }
 
   switch (kind) {
     case PropertyKind::kClassField:
     case PropertyKind::kNotSet:  // This case is a name followed by a name or
                                  // other property. Here we have to assume
@@ skipping 1305 matching lines @@
         Expect(Token::RBRACK, CHECK_OK);
         break;
       }
       case Token::PERIOD: {
         *is_async = false;
         impl()->RewriteNonPattern(CHECK_OK);
         BindingPatternUnexpectedToken();
         ArrowFormalParametersUnexpectedToken();
 
         Consume(Token::PERIOD);
+        if (allow_harmony_private_class_fields() && peek() == Token::HASH) {
+          expression = impl()->ParsePrivateFieldReference(expression, CHECK_OK);
+          break;
+        }
         int pos = position();
         IdentifierT name = ParseIdentifierName(CHECK_OK);
         expression = factory()->NewProperty(
             expression, factory()->NewStringLiteral(name, pos), pos);
         impl()->PushLiteralName(name);
         break;
       }
       case Token::TEMPLATE_SPAN:
       case Token::TEMPLATE_TAIL: {
         *is_async = false;
@@ skipping 923 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H