libreoffice/sw/inc/stringhash.hxx

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you under the Apache
 *   License, Version 2.0 (the "License"); you may not use this file
 *   except in compliance with the License. You may obtain a copy of
 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
 */
#ifndef _STRINGHASH_HXX
#define _STRINGHASH_HXX

#include <tools/string.hxx>

struct StringEq
{
    sal_Bool operator() ( const String *r1,
                            const String *r2) const
    {
        return r1->Equals(*r2);
    }
};

struct StringEqRef
{
    sal_Bool operator() (const String &r1, const String &r2) const
    {
        return r1.Equals(r2);
    }
};

struct StringHash
{
    size_t operator() ( const String *rString) const
    {
        sal_Int32 h, nLen;
        h = nLen = rString->Len();
        const sal_Unicode *pStr = rString->GetBuffer();

        if ( nLen < 16 )
            while ( nLen-- > 0 )
                h = (h*37) + *(pStr++);
        else
        {
            sal_Int32               nSkip;
            const sal_Unicode* pEndStr = pStr+nLen-5;

            /* only sample some characters */
            /* the first 3, some characters between, and the last 5 */
            h = (h*39) + *(pStr++);
            h = (h*39) + *(pStr++);
            h = (h*39) + *(pStr++);

            nSkip = nLen / nLen < 32 ? 4 : 8;
            nLen -= 8;
            while ( nLen > 0 )
            {
                h = (h*39) + ( *pStr );
                pStr += nSkip;
                nLen -= nSkip;
            }

            h = (h*39) + *(pEndStr++);
            h = (h*39) + *(pEndStr++);
            h = (h*39) + *(pEndStr++);
            h = (h*39) + *(pEndStr++);
            h = (h*39) + *(pEndStr++);
        }
        return h;
    }

    size_t operator() (const String & rStr) const
    {
        return (*this)(&rStr);
    }
};

struct StringHashRef
{
    size_t operator () (const String &rStr) const
    {
        StringHash aStrHash;

        return aStrHash(&rStr);
    }
};
#endif // _STRINGHASH_HXX

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