Revert "(Pre)Parser: Simplify NewExpression handling."

src/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 28 matching lines @@
 #include "platform.h"
 #include "preparser.h"
 #include "runtime.h"
 #include "scanner-character-streams.h"
 #include "scopeinfo.h"
 #include "string-stream.h"
 
 namespace v8 {
 namespace internal {
 
+// PositionStack is used for on-stack allocation of token positions for
+// new expressions. Please look at ParseNewExpression.
+
+class PositionStack  {
+ public:
+  explicit PositionStack(bool* ok) : top_(NULL), ok_(ok) {}
+  ~PositionStack() {
+    ASSERT(!*ok_ || is_empty());
+    USE(ok_);
+  }
+
+  class Element  {
+   public:
+    Element(PositionStack* stack, int value) {
+      previous_ = stack->top();
+      value_ = value;
+      stack->set_top(this);
+    }
+
+   private:
+    Element* previous() { return previous_; }
+    int value() { return value_; }
+    friend class PositionStack;
+    Element* previous_;
+    int value_;
+  };
+
+  bool is_empty() { return top_ == NULL; }
+  int pop() {
+    ASSERT(!is_empty());
+    int result = top_->value();
+    top_ = top_->previous();
+    return result;
+  }
+
+ private:
+  Element* top() { return top_; }
+  void set_top(Element* value) { top_ = value; }
+  Element* top_;
+  bool* ok_;
+};
+
+
 RegExpBuilder::RegExpBuilder(Zone* zone)
     : zone_(zone),
       pending_empty_(false),
       characters_(NULL),
       terms_(),
       alternatives_()
 #ifdef DEBUG
     , last_added_(ADD_NONE)
 #endif
   {}
@@ skipping 3183 matching lines @@
                                      position());
   }
   return expression;
 }
 
 
 Expression* Parser::ParseLeftHandSideExpression(bool* ok) {
   // LeftHandSideExpression ::
   //   (NewExpression | MemberExpression) ...
 
-  Expression* result = ParseMemberWithNewPrefixesExpression(CHECK_OK);
+  Expression* result;
+  if (peek() == Token::NEW) {
+    result = ParseNewExpression(CHECK_OK);
+  } else {
+    result = ParseMemberExpression(CHECK_OK);
+  }
 
   while (true) {
     switch (peek()) {
       case Token::LBRACK: {
         Consume(Token::LBRACK);
         int pos = position();
         Expression* index = ParseExpression(true, CHECK_OK);
         result = factory()->NewProperty(result, index, pos);
         Expect(Token::RBRACK, CHECK_OK);
         break;
@@ skipping 48 matching lines @@
         break;
       }
 
       default:
         return result;
     }
   }
 }
 
 
-Expression* Parser::ParseMemberWithNewPrefixesExpression(bool* ok) {
+Expression* Parser::ParseNewPrefix(PositionStack* stack, bool* ok) {
   // NewExpression ::
   //   ('new')+ MemberExpression
 
-  // The grammar for new expressions is pretty warped. We can have several 'new'
-  // keywords following each other, and then a MemberExpression. When we see '('
-  // after the MemberExpression, it's associated with the rightmost unassociated
-  // 'new' to create a NewExpression with arguments. However, a NewExpression
-  // can also occur without arguments.
+  // The grammar for new expressions is pretty warped. The keyword
+  // 'new' can either be a part of the new expression (where it isn't
+  // followed by an argument list) or a part of the member expression,
+  // where it must be followed by an argument list. To accommodate
+  // this, we parse the 'new' keywords greedily and keep track of how
+  // many we have parsed. This information is then passed on to the
+  // member expression parser, which is only allowed to match argument
+  // lists as long as it has 'new' prefixes left
+  Expect(Token::NEW, CHECK_OK);
+  PositionStack::Element pos(stack, position());
 
-  // Examples of new expression:
-  // new foo.bar().baz means (new (foo.bar)()).baz
-  // new foo()() means (new foo())()
-  // new new foo()() means (new (new foo())())
-  // new new foo means new (new foo)
-  // new new foo() means new (new foo())
+  Expression* result;
+  if (peek() == Token::NEW) {
+    result = ParseNewPrefix(stack, CHECK_OK);
+  } else {
+    result = ParseMemberWithNewPrefixesExpression(stack, CHECK_OK);
+  }
 
-  if (peek() == Token::NEW) {
-    Consume(Token::NEW);
-    int new_pos = position();
-    Expression* result = ParseMemberWithNewPrefixesExpression(CHECK_OK);
-    if (peek() == Token::LPAREN) {
-      // NewExpression with arguments.
-      ZoneList<Expression*>* args = ParseArguments(CHECK_OK);
-      return factory()->NewCallNew(result, args, new_pos);
-    }
-    // NewExpression without arguments.
-    return factory()->NewCallNew(
-        result, new(zone()) ZoneList<Expression*>(0, zone()), new_pos);
+  if (!stack->is_empty()) {
+    int last = stack->pop();
+    result = factory()->NewCallNew(
+        result, new(zone()) ZoneList<Expression*>(0, zone()), last);
   }
-  // No 'new' keyword.
-  return ParseMemberExpression(ok);
+  return result;
+}
+
+
+Expression* Parser::ParseNewExpression(bool* ok) {
+  PositionStack stack(ok);
+  return ParseNewPrefix(&stack, ok);
 }
 
 
 Expression* Parser::ParseMemberExpression(bool* ok) {
+  return ParseMemberWithNewPrefixesExpression(NULL, ok);
+}
+
+
+Expression* Parser::ParseMemberWithNewPrefixesExpression(PositionStack* stack,
+                                                         bool* ok) {
   // MemberExpression ::
   //   (PrimaryExpression | FunctionLiteral)
   //     ('[' Expression ']' | '.' Identifier | Arguments)*
 
   // Parse the initial primary or function expression.
   Expression* result = NULL;
   if (peek() == Token::FUNCTION) {
     Consume(Token::FUNCTION);
     int function_token_position = position();
     bool is_generator = allow_generators() && Check(Token::MUL);
@@ skipping 39 matching lines @@
       }
       case Token::PERIOD: {
         Consume(Token::PERIOD);
         int pos = position();
         Handle<String> name = ParseIdentifierName(CHECK_OK);
         result = factory()->NewProperty(
             result, factory()->NewLiteral(name, pos), pos);
         if (fni_ != NULL) fni_->PushLiteralName(name);
         break;
       }
+      case Token::LPAREN: {
+        if ((stack == NULL) || stack->is_empty()) return result;
+        // Consume one of the new prefixes (already parsed).
+        ZoneList<Expression*>* args = ParseArguments(CHECK_OK);
+        int pos = stack->pop();
+        result = factory()->NewCallNew(result, args, pos);
+        break;
+      }
       default:
         return result;
     }
   }
 }
 
 
 DebuggerStatement* Parser::ParseDebuggerStatement(bool* ok) {
   // In ECMA-262 'debugger' is defined as a reserved keyword. In some browser
   // contexts this is used as a statement which invokes the debugger as i a
@@ skipping 1920 matching lines @@
       ASSERT(info()->isolate()->has_pending_exception());
     } else {
       result = ParseProgram();
     }
   }
   info()->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal