* put some more useful utility classes into "shared". I tried to make sure

that OpenHashTable.h does not collide with all the other places that this
  is used, it seems everything still builds fine. Most problematic could be
  the OpenHashTable.h at kernel/util, but it seems it the target using
  that are not affected.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21792 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/shared/HashString.h

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2004-2007, Ingo Weinhold, [email protected]. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef HASH_STRING_H
+#define HASH_STRING_H
+
+#include <SupportDefs.h>
+
+// string_hash
+//
+// from the Dragon Book: a slightly modified hashpjw()
+static inline
+uint32
+string_hash(const char *name)
+{
+	uint32 h = 0;
+	if (name) {
+		for (; *name; name++) {
+			uint32 g = h & 0xf0000000;
+			if (g)
+				h ^= g >> 24;
+			h = (h << 4) + *name;
+		}
+	}
+	return h;
+}
+
+#ifdef __cplusplus
+
+namespace BPrivate {
+
+// HashString
+class HashString {
+public:
+	HashString();
+	HashString(const HashString &string);
+	HashString(const char *string, int32 length = -1);
+	~HashString();
+
+	bool SetTo(const char *string, int32 maxLength = -1);
+	void Unset();
+
+	void Truncate(int32 newLength);
+
+	const char *GetString() const;
+	int32 GetLength() const	{ return fLength; }
+
+	uint32 GetHashCode() const	{ return string_hash(GetString()); }
+
+	HashString &operator=(const HashString &string);
+	bool operator==(const HashString &string) const;
+	bool operator!=(const HashString &string) const { return !(*this == string); }
+
+private:
+	bool _SetTo(const char *string, int32 length);
+
+private:
+	int32	fLength;
+	char	*fString;
+};
+
+}	// namespace BPrivate
+
+using BPrivate::HashString;
+
+#endif	// __cplusplus
+
+#endif	// HASH_STRING_H