Re-land r93365 - add RefCountedString

base/memory/ref_counted_memory.h

Index: base/memory/ref_counted_memory.h
diff --git a/base/memory/ref_counted_memory.h b/base/memory/ref_counted_memory.h
index 1a0f51eec4aebf8784f7ed02e6b91c5964fb18c5..d917d54e7ad20c37cdc9c9085ad40894014d396b 100644
--- a/base/memory/ref_counted_memory.h
+++ b/base/memory/ref_counted_memory.h
@@ -6,6 +6,7 @@
 #define BASE_MEMORY_REF_COUNTED_MEMORY_H_
 #pragma once
 
+#include <string>
 #include <vector>
 
 #include "base/base_api.h"
@@ -40,9 +41,9 @@ class BASE_API RefCountedStaticMemory : public RefCountedMemory {
   RefCountedStaticMemory()
       : data_(NULL), length_(0) {}
   RefCountedStaticMemory(const unsigned char* data, size_t length)
-      : data_(data), length_(length) {}
+      : data_(length ? data : NULL), length_(length) {}
 
-  // Overriden from RefCountedMemory:
+  // Overridden from RefCountedMemory:
   virtual const unsigned char* front() const;
   virtual size_t size() const;
 
@@ -67,18 +68,49 @@ class BASE_API RefCountedBytes : public RefCountedMemory {
   // vector.)
   static RefCountedBytes* TakeVector(std::vector<unsigned char>* to_destroy);
 
-  // Overriden from RefCountedMemory:
+  // Overridden from RefCountedMemory:
   virtual const unsigned char* front() const;
   virtual size_t size() const;
 
-  std::vector<unsigned char> data;
+  std::vector<unsigned char>* data() { return &data_; }
 
- protected:
+ private:
   friend class base::RefCountedThreadSafe<RefCountedBytes>;
   virtual ~RefCountedBytes();
 
- private:
+  std::vector<unsigned char> data_;
+
   DISALLOW_COPY_AND_ASSIGN(RefCountedBytes);
 };
 
+namespace base {
+
+// An implementation of RefCountedMemory, where the bytes are stored in an STL
+// string. Use this if your data naturally arrives in that format.
+class BASE_API RefCountedString : public RefCountedMemory {
+ public:
+  RefCountedString();
+
+  // Constructs a RefCountedString object by performing a swap. (To non
+  // destructively build a RefCountedString, use the default constructor and
+  // copy into object->data()).
+  static RefCountedString* TakeString(std::string* to_destroy);
+
+  // Overridden from RefCountedMemory:
+  virtual const unsigned char* front() const;
+  virtual size_t size() const;
+
+  std::string* data() { return &data_; }

[brettw, 2011/07/19 19:58:45]

Is there any reason not to return this as a ref? I guess I would have done:
  const std::string& data() const { return data_; }
  std::string& data() { return data_; }
Maybe the same for RefCountedBytes, which would clean up some of the callers?
What do you think?

[joth, 2011/07/20 12:53:03]

I was overpowered by the "references must be const" rule.
Done. This does mean I'm now sometimes taking the address of the returned ref
which is a little odd in my eye, but technically fine.

+
+ private:
+  friend class base::RefCountedThreadSafe<RefCountedString>;
+  virtual ~RefCountedString();
+
+  std::string data_;
+
+  DISALLOW_COPY_AND_ASSIGN(RefCountedString);
+};
+
+}  // namespace
+
 #endif  // BASE_MEMORY_REF_COUNTED_MEMORY_H_