headers/private/shared/HashString.h

   1 /*
   2  * Copyright 2004-2007, Ingo Weinhold, bonefish@users.sf.net. All rights reserved.
   3  * Distributed under the terms of the MIT License.
   4  */
   5 #ifndef HASH_STRING_H
   6 #define HASH_STRING_H
   7
   8 #include <SupportDefs.h>
   9
  10 // string_hash
  11 //
  12 // from the Dragon Book: a slightly modified hashpjw()
  13 static inline
  14 uint32
  15 string_hash(const char *name)
  16 {
  17         uint32 h = 0;
  18         if (name) {
  19                 for (; *name; name++) {
  20                         uint32 g = h & 0xf0000000;
  21                         if (g)
  22                                 h ^= g >> 24;
  23                         h = (h << 4) + *name;
  24                 }
  25         }
  26         return h;
  27 }
  28
  29 #ifdef __cplusplus
  30
  31 namespace BPrivate {
  32
  33 // HashString
  34 class HashString {
  35 public:
  36         HashString();
  37         HashString(const HashString &string);
  38         HashString(const char *string, int32 length = -1);
  39         ~HashString();
  40
  41         bool SetTo(const char *string, int32 maxLength = -1);
  42         void Unset();
  43
  44         void Truncate(int32 newLength);
  45
  46         const char *GetString() const;
  47         int32 GetLength() const { return fLength; }
  48
  49         uint32 GetHashCode() const      { return string_hash(GetString()); }
  50
  51         HashString &operator=(const HashString &string);
  52         bool operator==(const HashString &string) const;
  53         bool operator!=(const HashString &string) const { return !(*this == string); }
  54
  55 private:
  56         bool _SetTo(const char *string, int32 length);
  57
  58 private:
  59         int32   fLength;
  60         char    *fString;
  61 };
  62
  63 }       // namespace BPrivate
  64
  65 using BPrivate::HashString;
  66
  67 #endif  // __cplusplus
  68
  69 #endif  // HASH_STRING_H