Version 2.2.11...

src/objects.h

 // Copyright 2006-2009 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 3983 matching lines @@
   // Such strings may appear when the embedder prefers two-byte
   // representations even for ascii data.
   inline bool IsExternalTwoByteStringWithAsciiChars();
 
   // Get and set individual two byte chars in the string.
   inline void Set(int index, uint16_t value);
   // Get individual two byte char in the string.  Repeated calls
   // to this method are not efficient unless the string is flat.
   inline uint16_t Get(int index);
 
-  // Try to flatten the top level ConsString that is hiding behind this
-  // string.  This is a no-op unless the string is a ConsString.  Flatten
-  // mutates the ConsString and might return a failure.
-  Object* SlowTryFlatten(PretenureFlag pretenure);
+  // Try to flatten the string.  Checks first inline to see if it is
+  // necessary.  Does nothing if the string is not a cons string.
+  // Flattening allocates a sequential string with the same data as
+  // the given string and mutates the cons string to a degenerate
+  // form, where the first component is the new sequential string and
+  // the second component is the empty string.  If allocation fails,
+  // this function returns a failure.  If flattening succeeds, this
+  // function returns the sequential string that is now the first
+  // component of the cons string.
+  //
+  // Degenerate cons strings are handled specially by the garbage
+  // collector (see IsShortcutCandidate).
+  //
+  // Use FlattenString from Handles.cc to flatten even in case an
+  // allocation failure happens.
+  inline Object* TryFlatten(PretenureFlag pretenure = NOT_TENURED);
 
-  // Try to flatten the string.  Checks first inline to see if it is necessary.
-  // Do not handle allocation failures.  After calling TryFlatten, the
-  // string could still be a ConsString, in which case a failure is returned.
-  // Use FlattenString from Handles.cc to be sure to flatten.
-  inline Object* TryFlatten(PretenureFlag pretenure = NOT_TENURED);
+  // Convenience function.  Has exactly the same behavior as
+  // TryFlatten(), except in the case of failure returns the original
+  // string.
+  inline String* TryFlattenGetString(PretenureFlag pretenure = NOT_TENURED);
 
   Vector<const char> ToAsciiVector();
   Vector<const uc16> ToUC16Vector();
 
   // Mark the string as an undetectable object. It only applies to
   // ascii and two byte string types.
   bool MarkAsUndetectable();
 
   // Return a substring.
   Object* SubString(int from, int to, PretenureFlag pretenure = NOT_TENURED);
@@ skipping 166 matching lines @@
   static inline const unibrow::byte* ReadBlock(String* input,
                                                ReadBlockBuffer* buffer,
                                                unsigned* offset,
                                                unsigned max_chars);
   static void ReadBlockIntoBuffer(String* input,
                                   ReadBlockBuffer* buffer,
                                   unsigned* offset_ptr,
                                   unsigned max_chars);
 
  private:
+  // Try to flatten the top level ConsString that is hiding behind this
+  // string.  This is a no-op unless the string is a ConsString.  Flatten
+  // mutates the ConsString and might return a failure.
+  Object* SlowTryFlatten(PretenureFlag pretenure);
+
   // Slow case of String::Equals.  This implementation works on any strings
   // but it is most efficient on strings that are almost flat.
   bool SlowEquals(String* other);
 
   // Slow case of AsArrayIndex.
   bool SlowAsArrayIndex(uint32_t* index);
 
   // Compute and set the hash code.
   uint32_t ComputeAndSetHash();
 
@@ skipping 953 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_