Make GetImplementationFlags more useful/extensible by changing the default implementation to return zero rather than returning the flags from the shared buffer handle, and add a constant for one expected future use. b=109571 r=jag sr=scc

string/public/nsAString.h

@@ -114,8 +114,15 @@ class NS_COM nsAString
       // nsAString( const self_type& );         // auto-generated copy-constructor OK (again, only because we're abstract)
       virtual ~nsAString() { }                  // ...yes, I expect to be sub-classed
 
-
+      enum {
+        kHasStackBuffer = 0x00000001  // Has and is using a buffer on
+                                      // the stack (that could be copied
+                                      // to the heap if
+                                      // GetSharedBufferHandle() is
+                                      // called).
+      };
       virtual PRUint32                          GetImplementationFlags() const;
+
       virtual const        buffer_handle_type*  GetFlatBufferHandle()    const;
       virtual const        buffer_handle_type*  GetBufferHandle()        const;
       virtual const shared_buffer_handle_type*  GetSharedBufferHandle()  const;
@@ -358,8 +365,15 @@ class NS_COM nsACString
       // nsACString( const self_type& );        // auto-generated copy-constructor OK (again, only because we're abstract)
       virtual ~nsACString() { }                 // ...yes, I expect to be sub-classed
 
-
+      enum {
+        kHasStackBuffer = 0x00000001  // Has and is using a buffer on
+                                      // the stack (that could be copied
+                                      // to the heap if
+                                      // GetSharedBufferHandle() is
+                                      // called).
+      };
       virtual PRUint32                          GetImplementationFlags() const;
+
       virtual const        buffer_handle_type*  GetFlatBufferHandle()    const;
       virtual const        buffer_handle_type*  GetBufferHandle()        const;
       virtual const shared_buffer_handle_type*  GetSharedBufferHandle()  const;

string/src/nsAString.cpp

@@ -106,11 +106,7 @@ nsAString::GetBufferHandle() const
 PRUint32
 nsAString::GetImplementationFlags() const
   {
-    PRUint32 flags = 0;
+    return 0;
-    const shared_buffer_handle_type* handle = GetSharedBufferHandle();
-    if ( handle )
-      flags = handle->GetImplementationFlags();
-    return flags;
   }
 
 
@@ -605,11 +601,7 @@ nsACString::GetBufferHandle() const
 PRUint32
 nsACString::GetImplementationFlags() const
   {
-    PRUint32 flags = 0;
+    return 0;
-    const shared_buffer_handle_type* handle = GetSharedBufferHandle();
-    if ( handle )
-      flags = handle->GetImplementationFlags();
-    return flags;
   }
 
 

xpcom/string/public/nsAString.h

@@ -114,8 +114,15 @@ class NS_COM nsAString
       // nsAString( const self_type& );         // auto-generated copy-constructor OK (again, only because we're abstract)
       virtual ~nsAString() { }                  // ...yes, I expect to be sub-classed
 
-
+      enum {
+        kHasStackBuffer = 0x00000001  // Has and is using a buffer on
+                                      // the stack (that could be copied
+                                      // to the heap if
+                                      // GetSharedBufferHandle() is
+                                      // called).
+      };
       virtual PRUint32                          GetImplementationFlags() const;
+
       virtual const        buffer_handle_type*  GetFlatBufferHandle()    const;
       virtual const        buffer_handle_type*  GetBufferHandle()        const;
       virtual const shared_buffer_handle_type*  GetSharedBufferHandle()  const;
@@ -358,8 +365,15 @@ class NS_COM nsACString
       // nsACString( const self_type& );        // auto-generated copy-constructor OK (again, only because we're abstract)
       virtual ~nsACString() { }                 // ...yes, I expect to be sub-classed
 
-
+      enum {
+        kHasStackBuffer = 0x00000001  // Has and is using a buffer on
+                                      // the stack (that could be copied
+                                      // to the heap if
+                                      // GetSharedBufferHandle() is
+                                      // called).
+      };
       virtual PRUint32                          GetImplementationFlags() const;
+
       virtual const        buffer_handle_type*  GetFlatBufferHandle()    const;
       virtual const        buffer_handle_type*  GetBufferHandle()        const;
       virtual const shared_buffer_handle_type*  GetSharedBufferHandle()  const;

xpcom/string/src/nsAString.cpp

@@ -106,11 +106,7 @@ nsAString::GetBufferHandle() const
 PRUint32
 nsAString::GetImplementationFlags() const
   {
-    PRUint32 flags = 0;
+    return 0;
-    const shared_buffer_handle_type* handle = GetSharedBufferHandle();
-    if ( handle )
-      flags = handle->GetImplementationFlags();
-    return flags;
   }
 
 
@@ -605,11 +601,7 @@ nsACString::GetBufferHandle() const
 PRUint32
 nsACString::GetImplementationFlags() const
   {
-    PRUint32 flags = 0;
+    return 0;
-    const shared_buffer_handle_type* handle = GetSharedBufferHandle();
-    if ( handle )
-      flags = handle->GetImplementationFlags();
-    return flags;
   }