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#ifndef TAGCOLL_STRING_INDEX_H
#define TAGCOLL_STRING_INDEX_H
/** \file
* Fast mapping from its to strings
*/
/*
* Copyright (C) 2006 Enrico Zini <enrico@debian.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <tagcoll/Exception.h>
#include <tagcoll/Serializer.h>
#include <tagcoll/MMapIndex.h>
#include <set>
namespace Tagcoll
{
/**
* MMap-based index of int -> string mappings
*
* The layout is:
*
* [offset of string for item 0, offset of string for item 1...]
* [0-terminated string 1][0-terminated string 2][...]
* [number of items in the mapping]
*
* The index of a string not present in the index is assumed to be -1
* The string corresponding to an invalid index is ""
*/
class StringIndex : public MMapIndex, public Converter<int, std::string>, public Converter<std::string, int>
{
protected:
int offset(int val) const { return ((const int*)m_buf)[val]; }
mutable std::vector<std::string> stringCache;
public:
StringIndex(const MasterMMapIndex& master, int idx) : MMapIndex(master, idx), stringCache(size()) {}
virtual ~StringIndex() {}
virtual std::string operator()(const int& id) const
{
if (id < 0)
return std::string();
if (stringCache.size() <= (unsigned)id)
stringCache.resize(id + 1);
if (stringCache[id].empty())
if (const char* s = data(id))
stringCache[id] = std::string(s, size(id));
return stringCache[id];
}
virtual int operator()(const std::string& item) const { return data(item.c_str()); }
const char* data(int val) const { return (val >= 0 && (unsigned)val < size()) ? m_buf + offset(val) : ""; }
size_t size(int val) const
{
if (val < 0 || (unsigned)val >= size())
return 0;
if ((unsigned)val == size() - 1)
return m_size - offset(val) - 1;
else
return offset(val + 1) - offset(val) - 1;
}
int data(const char* str) const;
size_t size() const { return *(unsigned int*)m_buf / sizeof(int); }
};
/**
* Creates an on-disk index to use for IntIndex
*/
class StringIndexer : public MMapIndexer, public Converter<int, std::string>, public Converter<std::string, int>
{
protected:
std::vector<std::string> data;
public:
virtual std::string operator()(const int& item) const { return data[item]; }
virtual int operator()(const std::string& item) const;
/// Store the key->val mapping into the indexer
void map(const std::string& str);
/// Return the size of the encoded index data
int encodedSize() const;
/// Write the index data in the given buffer, which should be at least
/// encodedSize bytes
void encode(char* buf) const;
};
};
// vim:set ts=4 sw=4:
#endif
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