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/*
* libpinyin
* Library to deal with pinyin.
*
* Copyright (C) 2015 Peng Wu <alexepico@gmail.com>
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef FLEXIBLE_NGRAM_KYOTODB_H
#define FLEXIBLE_NGRAM_KYOTODB_H
#ifdef HAVE_KYOTO_CABINET
#include <kcdb.h>
#endif
#include "memory_chunk.h"
namespace pinyin{
/**
* FlexibleBigram:
* @MagicHeader: the struct type of the magic header.
* @ArrayHeader: the struct type of the array header.
* @ArrayItem: the struct type of the array item.
*
* The flexible bi-gram is mainly used for training purpose.
*
*/
template<typename MagicHeader, typename ArrayHeader,
typename ArrayItem>
class FlexibleBigram{
using kyotocabinet::BasicDB;
/* Note: some flexible bi-gram file format check should be here. */
private:
BasicDB * m_db;
MemoryChunk m_chunk;
phrase_token_t m_magic_header_index[2];
char m_magic_number[4];
void reset(){
if ( m_db ){
m_db->synchronize();
m_db->close();
m_db = NULL;
}
}
public:
/**
* FlexibleBigram::FlexibleBigram:
* @magic_number: the 4 bytes magic number of the flexible bi-gram.
*
* The constructor of the FlexibleBigram.
*
*/
FlexibleBigram(const char * magic_number){
m_db = NULL;
m_magic_header_index[0] = null_token;
m_magic_header_index[1] = null_token;
memcpy(m_magic_number, magic_number, sizeof(m_magic_number));
}
/**
* FlexibleBigram::~FlexibleBigram:
*
* The destructor of the FlexibleBigram.
*
*/
~FlexibleBigram(){
reset();
}
/**
* FlexibleBigram::attach:
* @dbfile: the path name of the flexible bi-gram.
* @flags: the attach flags for the Berkeley DB.
* @returns: whether the attach operation is successful.
*
* Attach Berkeley DB on filesystem for training purpose.
*
*/
bool attach(const char * dbfile, guint32 flags){
reset();
uint32_t mode = 0;
if (flags & ATTACH_READONLY)
mode |= BasicDB::OREADER;
if (flags & ATTACH_READWRITE) {
assert( !( flags & ATTACH_READONLY ) );
mode |= BasicDB::OREADER | BasicDB::OWRITER;
}
if (!dbfile)
return false;
m_db = new HashDB;
if (!m_db->open(dbfile, mode)) {
if (!(flags & ATTACH_CREATE)) {
delete m_db;
m_db = NULL;
return false;
}
mode |= BasicDB::OCREATE;
/* Create database file here, and write the signature. */
if (!m_db->open(dbfile, mode))
return false;
const char * kbuf = (char *) m_magic_header_index;
const size_t ksiz = sizeof(m_magic_header_index);
const char * vbuf = (char *) m_magic_number;
const size_t vsiz = sizeof(m_magic_number);
m_db->set(kbuf, ksiz, vbuf, vsiz);
return true;
}
/* check the signature. */
const char * kbuf = (char *) m_magic_header_index;
const size_t ksiz = sizeof(m_magic_header_index);
const int32_t vsiz = m_db->check(kbuf, ksiz);
m_chunk.set_size(vsiz);
char * vbuf = (char *) m_chunk.begin();
assert (vsiz == m_db->get(kbuf, sizeof(phrase_token_t),
vbuf, vsiz));
if ( memcmp(vbuf, m_magic_number,
sizeof(m_magic_number)) == 0 )
return true;
return false;
}
};
};
#endif
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