sw/inc/stringhash.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19 #ifndef _STRINGHASH_HXX
  20 #define _STRINGHASH_HXX
  21
  22 #include <tools/string.hxx>
  23
  24 struct StringEq
  25 {
  26     sal_Bool operator() ( const String *r1,
  27                             const String *r2) const
  28     {
  29         return r1->Equals(*r2);
  30     }
  31 };
  32
  33 struct StringEqRef
  34 {
  35     sal_Bool operator() (const String &r1, const String &r2) const
  36     {
  37         return r1.Equals(r2);
  38     }
  39 };
  40
  41 struct StringHash
  42 {
  43     size_t operator() ( const String *rString) const
  44     {
  45         sal_Int32 h, nLen;
  46         h = nLen = rString->Len();
  47         const sal_Unicode *pStr = rString->GetBuffer();
  48
  49         if ( nLen < 16 )
  50             while ( nLen-- > 0 )
  51                 h = (h*37) + *(pStr++);
  52         else
  53         {
  54             sal_Int32               nSkip;
  55             const sal_Unicode* pEndStr = pStr+nLen-5;
  56
  57             /* only sample some characters */
  58             /* the first 3, some characters between, and the last 5 */
  59             h = (h*39) + *(pStr++);
  60             h = (h*39) + *(pStr++);
  61             h = (h*39) + *(pStr++);
  62
  63             nSkip = nLen / nLen < 32 ? 4 : 8;
  64             nLen -= 8;
  65             while ( nLen > 0 )
  66             {
  67                 h = (h*39) + ( *pStr );
  68                 pStr += nSkip;
  69                 nLen -= nSkip;
  70             }
  71
  72             h = (h*39) + *(pEndStr++);
  73             h = (h*39) + *(pEndStr++);
  74             h = (h*39) + *(pEndStr++);
  75             h = (h*39) + *(pEndStr++);
  76             h = (h*39) + *(pEndStr++);
  77         }
  78         return h;
  79     }
  80
  81     size_t operator() (const String & rStr) const
  82     {
  83         return (*this)(&rStr);
  84     }
  85 };
  86
  87 struct StringHashRef
  88 {
  89     size_t operator () (const String &rStr) const
  90     {
  91         StringHash aStrHash;
  92
  93         return aStrHash(&rStr);
  94     }
  95 };
  96 #endif // _STRINGHASH_HXX
  97
  98 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */