containers/test_migr_stack.cpp

This is an example of how to use stxxl::STACK_GENERATOR class to generate an migrating stack with critical size critical_size , external implementation normal_stack , four blocks per page, block size 4096 bytes, and internal implementation std::stack<int>

/***************************************************************************
 *  containers/test_migr_stack.cpp
 *
 *  Part of the STXXL. See http://stxxl.sourceforge.net
 *
 *  Copyright (C) 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/stack>


int main()
{
    const unsigned critical_size = 8 * 4096;
    typedef stxxl::STACK_GENERATOR<int, stxxl::migrating, stxxl::normal, 4, 4096, std::stack<int>, critical_size>::result migrating_stack_type;

    STXXL_MSG("Starting test.");

    migrating_stack_type my_stack;
    int test_size = 1 * 1024 * 1024 / sizeof(int), i;

    STXXL_MSG("Filling stack.");

    for (i = 0; i < test_size; i++)
    {
        my_stack.push(i);
        assert(my_stack.top() == i);
        assert(my_stack.size() == i + 1);
        assert((my_stack.size() >= critical_size) == my_stack.external());
    }

    STXXL_MSG("Testing swap.");
    // test swap
    migrating_stack_type my_stack2;
    std::swap(my_stack2, my_stack);
    std::swap(my_stack2, my_stack);

    STXXL_MSG("Removing elements from " <<
              (my_stack.external() ? "external" : "internal") << " stack");
    for (i = test_size - 1; i >= 0; i--)
    {
        assert(my_stack.top() == i);
        assert(my_stack.size() == i + 1);
        my_stack.pop();
        assert(my_stack.size() == i);
        assert(my_stack.external() == (test_size >= int(critical_size)));
    }

    STXXL_MSG("Test passed.");

    return 0;
}

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