Stxxl  1.2.1
algo/sort_file.cpp

This example imports a file into an stxxl::vector without copying its content and then sorts it using stxxl::sort.

/***************************************************************************
* algo/sort_file.cpp
*
* Part of the STXXL. See http://stxxl.sourceforge.net
*
* Copyright (C) 2002-2003 Roman Dementiev <dementiev@mpi-sb.mpg.de>
*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
**************************************************************************/
#include <stxxl/io>
#include <stxxl/mng>
#include <stxxl/ksort>
#include <stxxl/sort>
#include <stxxl/vector>
struct my_type
{
typedef unsigned key_type;
key_type _key;
char _data[128 - sizeof(key_type)];
key_type key() const
{
return _key;
}
my_type() { }
my_type(key_type __key) : _key(__key) { }
static my_type min_value()
{
return my_type((std::numeric_limits<key_type>::min)());
}
static my_type max_value()
{
return my_type((std::numeric_limits<key_type>::max)());
}
};
bool operator < (const my_type & a, const my_type & b)
{
return a.key() < b.key();
}
struct Cmp
{
bool operator () (const my_type & a, const my_type & b) const
{
return a < b;
}
static my_type min_value()
{
return my_type::min_value();
}
static my_type max_value()
{
return my_type::max_value();
}
};
std::ostream & operator << (std::ostream & o, const my_type & obj)
{
o << obj._key;
return o;
}
int main()
{
stxxl::syscall_file f("./in", stxxl::file::DIRECT | stxxl::file::RDWR);
unsigned memory_to_use = 50 * 1024 * 1024;
typedef stxxl::vector<my_type> vector_type;
{
vector_type v(&f);
/*
STXXL_MSG("Printing...");
for(stxxl::int64 i=0; i < v.size(); i++)
STXXL_MSG(v[i].key());
*/
STXXL_MSG("Checking order...");
STXXL_MSG(((stxxl::is_sorted(v.begin(), v.end())) ? "OK" : "WRONG"));
STXXL_MSG("Sorting...");
stxxl::ksort(v.begin(), v.end(), memory_to_use);
//stxxl::sort(v.begin(),v.end()-101,Cmp(),memory_to_use);
STXXL_MSG("Checking order...");
STXXL_MSG(((stxxl::is_sorted(v.begin(), v.end())) ? "OK" : "WRONG"));
}
STXXL_MSG("OK");
return 0;
}