Stxxl  1.3.2
algo/copy_and_sort_file.cpp

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

/***************************************************************************
* algo/copy_and_sort_file.cpp
*
* Part of the STXXL. See http://stxxl.sourceforge.net
*
* Copyright (C) 2010 Andreas Beckmann <[email protected]>
*
* 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 <limits>
#include <stxxl/io>
#include <stxxl/vector>
#include <stxxl/stream>
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)());
}
};
inline bool operator < (const my_type & a, const my_type & b)
{
return a.key() < b.key();
}
inline bool operator == (const my_type & a, const my_type & b)
{
return a.key() == b.key();
}
struct Cmp
{
typedef my_type first_argument_type;
typedef my_type second_argument_type;
typedef bool result_type;
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(int argc, char ** argv)
{
if (argc < 3)
{
std::cout << "Usage: " << argv[0] << " infile outfile" << std::endl;
return -1;
}
const unsigned memory_to_use = 512 * 1024 * 1024;
const unsigned int block_size = sizeof(my_type) * 4096;
typedef stxxl::vector<my_type, 1, stxxl::lru_pager<2>, block_size> vector_type;
stxxl::syscall_file in_file(argv[1], stxxl::file::DIRECT | stxxl::file::RDONLY);
stxxl::syscall_file out_file(argv[2], stxxl::file::DIRECT | stxxl::file::RDWR | stxxl::file::CREAT);
vector_type input(&in_file);
vector_type output(&out_file);
output.resize(input.size());
#ifdef BOOST_MSVC
typedef stxxl::stream::streamify_traits<vector_type::iterator>::stream_type input_stream_type;
#else
typedef __typeof__(stxxl::stream::streamify(input.begin(), input.end())) input_stream_type;
#endif
input_stream_type input_stream = stxxl::stream::streamify(input.begin(), input.end());
typedef Cmp comparator_type;
typedef stxxl::stream::sort<input_stream_type, comparator_type, block_size> sort_stream_type;
sort_stream_type sort_stream(input_stream, comparator_type(), memory_to_use);
vector_type::iterator o = stxxl::stream::materialize(sort_stream, output.begin(), output.end());
assert(o == output.end());
if (1) {
STXXL_MSG("Checking order...");
STXXL_MSG((stxxl::is_sorted(output.begin(), output.end(), comparator_type()) ? "OK" : "WRONG"));
}
return 0;
}
// vim: et:ts=4:sw=4