Add Dart_IsExternalString and Dart_ExternalStringGetPeer to the dart

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 1990)
+++ runtime/vm/object.h	(working copy)
@@ -2463,6 +2463,12 @@
 
   bool IsSymbol() const;
 
+  virtual bool IsExternal() const { return false; }
+  virtual void* GetPeer() const {
+    UNREACHABLE();
+    return NULL;
+  }
+
   static RawString* New(const char* str, Heap::Space space = Heap::kNew);
   static RawString* New(const uint8_t* characters,
                         intptr_t len,
@@ -2743,6 +2749,11 @@
     return RoundedAllocationSize(sizeof(RawExternalOneByteString));
   }
 
+  virtual bool IsExternal() const { return true; }
+  virtual void* GetPeer() const {
+    return raw_ptr()->external_data_->peer_;

[siva, 2011/12/02 01:53:01]

Not sure what the official C++ style guide says but we have always tried to club
the 'static' methods together, so in this case the method InstanceSize would be
after these two functions.

[turnidge, 2011/12/05 17:54:28]

Done.

+  }
+
   static RawExternalOneByteString* New(const uint8_t* characters,
                                        intptr_t len,
                                        void* peer,
@@ -2780,6 +2791,11 @@
     return RoundedAllocationSize(sizeof(RawExternalTwoByteString));
   }
 
+  virtual bool IsExternal() const { return true; }
+  virtual void* GetPeer() const {
+    return raw_ptr()->external_data_->peer_;
+  }
+
   static RawExternalTwoByteString* New(const uint16_t* characters,
                                        intptr_t len,
                                        void* peer,
@@ -2817,6 +2833,11 @@
     return RoundedAllocationSize(sizeof(RawExternalFourByteString));
   }
 
+  virtual bool IsExternal() const { return true; }
+  virtual void* GetPeer() const {
+    return raw_ptr()->external_data_->peer_;
+  }
+
   static RawExternalFourByteString* New(const uint32_t* characters,
                                         intptr_t len,
                                         void* peer,