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// Functor implementations -*- C++ -*-

// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010

// Free Software Foundation, Inc.

//

// This file is part of the GNU ISO C++ Library.  This library 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 3, or (at your option)

// any later version.

// This library 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.

// Under Section 7 of GPL version 3, you are granted additional

// permissions described in the GCC Runtime Library Exception, version

// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and

// a copy of the GCC Runtime Library Exception along with this program;

// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

// <http://www.gnu.org/licenses/>.

/*

 *

 * Copyright (c) 1994

 * Hewlett-Packard Company

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Hewlett-Packard Company makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 *

 *

 * Copyright (c) 1996-1998

 * Silicon Graphics Computer Systems, Inc.

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 */

/** @file backward/binders.h

 *  This is an internal header file, included by other library headers.

 *  You should not attempt to use it directly.

 */

#ifndef _BACKWARD_BINDERS_H

#define _BACKWARD_BINDERS_H 1

_GLIBCXX_BEGIN_NAMESPACE(std)

  // 20.3.6 binders

  /** @defgroup binders Binder Classes

   * @ingroup functors

   *

   *  Binders turn functions/functors with two arguments into functors

   *  with a single argument, storing an argument to be applied later.

   *  For example, a variable @c B of type @c binder1st is constructed

   *  from a functor @c f and an argument @c x. Later, B's @c

   *  operator() is called with a single argument @c y. The return

   *  value is the value of @c f(x,y). @c B can be @a called with

   *  various arguments (y1, y2, ...) and will in turn call @c

   *  f(x,y1), @c f(x,y2), ...

   *

   *  The function @c bind1st is provided to save some typing. It takes the

   *  function and an argument as parameters, and returns an instance of

   *  @c binder1st.

   *

   *  The type @c binder2nd and its creator function @c bind2nd do the same

   *  thing, but the stored argument is passed as the second parameter instead

   *  of the first, e.g., @c bind2nd(std::minus<float>,1.3) will create a

   *  functor whose @c operator() accepts a floating-point number, subtracts

   *  1.3 from it, and returns the result. (If @c bind1st had been used,

   *  the functor would perform <em>1.3 - x</em> instead.

   *

   *  Creator-wrapper functions like @c bind1st are intended to be used in

   *  calling algorithms. Their return values will be temporary objects.

   *  (The goal is to not require you to type names like

   *  @c std::binder1st<std::plus<int>> for declaring a variable to hold the

   *  return value from @c bind1st(std::plus<int>,5).

   *

   *  These become more useful when combined with the composition functions.

   *

   *  @{

   */

  /// One of the @link binders binder functors@endlink.

  template<typename _Operation>

    class binder1st

    : public unary_function<typename _Operation::second_argument_type,

                            typename _Operation::result_type>

    {

    protected:

      _Operation op;

      typename _Operation::first_argument_type value;

    public:

      binder1st(const _Operation& __x,

                const typename _Operation::first_argument_type& __y)

      : op(__x), value(__y) { }

      typename _Operation::result_type

      operator()(const typename _Operation::second_argument_type& __x) const

      { return op(value, __x); }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS

      // 109.  Missing binders for non-const sequence elements

      typename _Operation::result_type

      operator()(typename _Operation::second_argument_type& __x) const

      { return op(value, __x); }

    } _GLIBCXX_DEPRECATED_ATTR;

  /// One of the @link binders binder functors@endlink.

  template<typename _Operation, typename _Tp>

    inline binder1st<_Operation>

    bind1st(const _Operation& __fn, const _Tp& __x)

    {

      typedef typename _Operation::first_argument_type _Arg1_type;

      return binder1st<_Operation>(__fn, _Arg1_type(__x));

    }

  /// One of the @link binders binder functors@endlink.

  template<typename _Operation>

    class binder2nd

    : public unary_function<typename _Operation::first_argument_type,

                            typename _Operation::result_type>

    {

    protected:

      _Operation op;

      typename _Operation::second_argument_type value;

    public:

      binder2nd(const _Operation& __x,

                const typename _Operation::second_argument_type& __y)

      : op(__x), value(__y) { }

      typename _Operation::result_type

      operator()(const typename _Operation::first_argument_type& __x) const

      { return op(__x, value); }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS

      // 109.  Missing binders for non-const sequence elements

      typename _Operation::result_type

      operator()(typename _Operation::first_argument_type& __x) const

      { return op(__x, value); }

    } _GLIBCXX_DEPRECATED_ATTR;

  /// One of the @link binders binder functors@endlink.

  template<typename _Operation, typename _Tp>

    inline binder2nd<_Operation>

    bind2nd(const _Operation& __fn, const _Tp& __x)

    {

      typedef typename _Operation::second_argument_type _Arg2_type;

      return binder2nd<_Operation>(__fn, _Arg2_type(__x));

    }

  /** @}  */

_GLIBCXX_END_NAMESPACE

#endif /* _BACKWARD_BINDERS_H */