Extend ValueNode interface for ranged containers.

Add an IsContainerRangeFixed() hook which specifies whether or not
the container in question can only display elements within a fixed
lower/upper bound, i.e. B{Object}List.

src/apps/debugger/value/ValueNode.cpp

@@ -70,6 +70,13 @@ ValueNode::IsRangedContainer() const
 }
 
 
+bool
+ValueNode::IsContainerRangeFixed() const
+{
+	return false;
+}
+
+
 void
 ValueNode::ClearChildren()
 {

src/apps/debugger/value/ValueNode.h

@@ -62,6 +62,10 @@ public:
 	// node types to allow the upper layers to be aware of this, and to be
 	// able to request that only a subset of children be created.
 	virtual	bool				IsRangedContainer() const;
+	virtual	bool				IsContainerRangeFixed() const;
+									// indicates that the user can't
+									// arbitrarily go outside of the
+									// specified/supported range.
 	virtual	void				ClearChildren();
 	virtual	status_t			CreateChildrenInRange(int32 lowIndex,
 									int32 highIndex);

src/apps/debugger/value/value_nodes/BListValueNode.cpp

@@ -330,6 +330,13 @@ BListValueNode::IsRangedContainer() const
 }
 
 
+bool
+BListValueNode::IsContainerRangeFixed() const
+{
+	return true;
+}
+
+
 void
 BListValueNode::ClearChildren()
 {

src/apps/debugger/value/value_nodes/BListValueNode.h

@@ -37,6 +37,7 @@ public:
 	virtual ValueNodeChild*			ChildAt(int32 index) const;
 
 	virtual	bool					IsRangedContainer() const;
+	virtual	bool					IsContainerRangeFixed() const;
 	virtual	void					ClearChildren();
 	virtual	status_t				CreateChildrenInRange(int32 lowIndex,
 										int32 highIndex);