/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Copyright (c) 1996-1998
 * Silicon Graphics Computer Systems, Inc.
 *
 * Copyright (c) 1997
 * Moscow Center for SPARC Technology
 *
 * Copyright (c) 1999
 * Boris Fomitchev
 *
 * This material is provided "as is", with absolutely no warranty expressed
 * or implied. Any use is at your own risk.
 *
 * Permission to use or copy this software for any purpose is hereby granted
 * without fee, provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 *
 */

/*
 * Lifted and paraphrased from STLport - with additions from Fridrich
 * Strba and Thorsten Behrens
 */

#ifndef INCLUDED_O3TL_COMPAT_FUNCTIONAL_HXX
#define INCLUDED_O3TL_COMPAT_FUNCTIONAL_HXX

#include <functional>

namespace o3tl
{

/// Functor, given two parameters, return the first
template<class T1,class T2>
struct project1st : public std::binary_function<T1, T2, T1>
{
    T1 operator()(const T1& y, const T2&) const
    {
        return y;
    }
};

/// Functor, given two parameters, return the second
template<class T1,class T2>
struct project2nd : public std::binary_function<T1, T2, T2>
{
    T2 operator()(const T1&, const T2& x) const
    {
        return x;
    }
};

/// Select first value of a pair
template<class P>
struct select1st : public std::unary_function<P, typename P::first_type>
{
    const typename P::first_type& operator()(const P& y) const
    {
        return y.first;
    }
};

/// Select second value of a pair
template<class P>
struct select2nd : public std::unary_function<P, typename P::second_type>
{
    const typename P::second_type& operator()(const P& y) const
    {
        return y.second;
    }
};

/// Call F1 with the result of F2 applied to the one input parameter
template<class F1, class F2>
class unary_compose : public std::unary_function<typename F2::argument_type, typename F1::result_type>
{
    public:
        unary_compose(const F1& fnction1, const F2& fnction2) : ftor1(fnction1), ftor2(fnction2) {}

        typename F1::result_type operator()(const typename F2::argument_type& y) const
        {
            return ftor1(ftor2(y));
        }

    protected:
        F1 ftor1;
        F2 ftor2;
};

/// Create functor that calls F1 with the result of F2 applied to the one input parameter
template<class F1, class F2>
inline unary_compose<F1, F2> compose1(const F1& fnction1, const F2& fnction2)
{
    return unary_compose<F1, F2>(fnction1, fnction2);
}

}   // namespace o3tl

#endif

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