Add class NotOwningEntryRef

A entry_ref subclass that avoids cloning the entry name.

headers/private/storage/NotOwningEntryRef.h

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2013, Haiku, Inc. All Rights Reserved.
+ * Distributed under the terms of the MIT License.
+ *
+ * Authors:
+ *		Ingo Weinhold <[email protected]>
+ */
+#ifndef _NOT_OWNING_ENTRY_REF_H
+#define _NOT_OWNING_ENTRY_REF_H
+
+
+#include <Entry.h>
+#include <Node.h>
+
+
+namespace BPrivate {
+
+
+/*!	entry_ref subclass that avoids cloning the entry name.
+
+	Therefore initialization is cheaper and cannot fail. It derives from
+	entry_ref for convenience. However, care must be taken that:
+	 - the name remains valid while the object is in use,
+	 - the object isn't passed as an entry_ref to a function that modifies it.
+ */
+class NotOwningEntryRef : public entry_ref {
+public:
+	NotOwningEntryRef()
+	{
+	}
+
+	NotOwningEntryRef(dev_t device, ino_t directory, const char* name)
+	{
+		SetTo(device, directory, name);
+	}
+
+	NotOwningEntryRef(const node_ref& directoryRef, const char* name)
+	{
+		SetTo(directoryRef, name);
+	}
+
+	NotOwningEntryRef(const entry_ref& other)
+	{
+		*this = other;
+	}
+
+	~NotOwningEntryRef()
+	{
+		name = NULL;
+	}
+
+	NotOwningEntryRef& SetTo(dev_t device, ino_t directory, const char* name)
+	{
+		this->device = device;
+		this->directory = directory;
+		this->name = const_cast<char*>(name);
+		return *this;
+	}
+
+	NotOwningEntryRef& SetTo(const node_ref& directoryRef, const char* name)
+	{
+		return SetTo(directoryRef.device, directoryRef.node, name);
+	}
+
+	node_ref DirectoryNodeRef() const
+	{
+		return node_ref(device, directory);
+	}
+
+	NotOwningEntryRef& SetDirectoryNodeRef(const node_ref& directoryRef)
+	{
+		device = directoryRef.device;
+		directory = directoryRef.node;
+		return *this;
+	}
+
+	NotOwningEntryRef& operator=(const entry_ref& other)
+	{
+		return SetTo(other.device, other.directory, other.name);
+	}
+};
+
+
+} // namespace BPrivate
+
+
+using BPrivate::NotOwningEntryRef;
+
+
+#endif	// _NOT_OWNING_ENTRY_REF_H