Flat string reader

src/objects.h

 // Copyright 2006-2008 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 3572 matching lines @@
   // Support for StringInputBuffer.
   void ExternalTwoByteStringReadBlockIntoBuffer(ReadBlockBuffer* buffer,
                                                 unsigned* offset_ptr,
                                                 unsigned chars);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalTwoByteString);
 };
 
 
+class FlatStringReader {
+public:
+  explicit FlatStringReader(Handle<String> str);

[Erik Corry, 2008/11/19 09:45:38]

FlatStringReaders can only be stack allocated, right?  So it should be marked as
such.  Also if it is used with some kinds of handles there could be issues
around the lifetime of the handle vs lifetime of the FlatStringReader.  That
deserves a comment.

+  explicit FlatStringReader(Vector<const char> input);
+  ~FlatStringReader();
+  void RefreshState();
+  inline uc32 Get(int index);
+  int length() { return length_; }
+  static void PostGarbageCollectionProcessing();
+private:
+  String** str_;
+  bool is_ascii_;
+  int length_;
+  const void* start_;
+  FlatStringReader* prev_;
+  static FlatStringReader* top_;
+};
+
+
 // Note that StringInputBuffers are not valid across a GC!  To fix this
 // it would have to store a String Handle instead of a String* and
 // AsciiStringReadBlock would have to be modified to use memcpy.
 //
 // StringInputBuffer is able to traverse any string regardless of how
 // deeply nested a sequence of ConsStrings it is made of.  However,
 // performance will be better if deep strings are flattened before they
 // are traversed.  Since flattening requires memory allocation this is
 // not always desirable, however (esp. in debugging situations).
 class StringInputBuffer: public unibrow::InputBuffer<String, String*, 1024> {
@@ skipping 574 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_