[parser] Only track parsing-mode (and possibly switch to the preparser) in the parser

src/parsing/parser.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_H_
 #define V8_PARSING_PARSER_H_
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/base/compiler-specific.h"
@@ skipping 217 matching lines @@
 
  private:
   friend class ParserBase<Parser>;
   friend class v8::internal::ExpressionClassifier<ParserTypes<Parser>>;
 
   bool AllowsLazyParsingWithoutUnresolvedVariables() const {
     return scope()->AllowsLazyParsingWithoutUnresolvedVariables(
         original_scope_);
   }
 
+  class ParsingModeScope BASE_EMBEDDED {
+   public:
+    ParsingModeScope(Parser* parser, Mode mode)
+        : parser_(parser), old_mode_(parser->mode()) {

[vogelheim, 2016/11/07 14:56:17]

Why not just access parser_->mode_, since we're directly accessing/modifying
parser_mode_ elsewhere in this class anyhow?

+      parser_->mode_ = mode;
+    }
+    ~ParsingModeScope() { parser_->mode_ = old_mode_; }
+
+   private:
+    Parser* parser_;
+    Mode old_mode_;
+  };
+
+  Mode mode() const { return mode_; }
+
   // Runtime encoding of different completion modes.
   enum CompletionKind {
     kNormalCompletion,
     kThrowCompletion,
     kAbruptCompletion
   };
 
   Variable* NewTemporary(const AstRawString* name) {
     return scope()->NewTemporary(name);
   }
@@ skipping 864 matching lines @@
   }
 
   // Parser's private field members.
   friend class DiscardableZoneScope;  // Uses reusable_preparser_.
   // FIXME(marja): Make reusable_preparser_ always use its own temp Zone (call
   // DeleteAll after each function), so this won't be needed.
 
   Scanner scanner_;
   PreParser* reusable_preparser_;
   Scope* original_scope_;  // for ES5 function declarations in sloppy eval
+  Mode mode_;

[vogelheim, 2016/11/07 14:56:17]

If Parser/parser.h "owns" the parsing mode now, it probably makes sense to move
the Mode enum from ParserBase<> into Parser, too.

 
   friend class ParserTarget;
   friend class ParserTargetScope;
   ParserTarget* target_stack_;  // for break, continue statements
 
   ScriptCompiler::CompileOptions compile_options_;
   ParseData* cached_parse_data_;
 
   PendingCompilationErrorHandler pending_error_handler_;
 
@@ skipping 44 matching lines @@
 
  private:
   ParserTarget** variable_;
   ParserTarget* previous_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_H_