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

// Copyright (C) 2001, 2002, 2004, 2005 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 2, 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.

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

// with this library; see the file COPYING.  If not, write to the Free

// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,

// USA.

// As a special exception, you may use this file as part of a free software

// library without restriction.  Specifically, if other files instantiate

// templates or use macros or inline functions from this file, or you compile

// this file and link it with other files to produce an executable, this

// file does not by itself cause the resulting executable to be covered by

// the GNU General Public License.  This exception does not however

// invalidate any other reasons why the executable file might be covered by

// the GNU General Public License.

/*

 *

 * 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 stl_function.h

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

 *  You should not attempt to use it directly.

 */

#ifndef _FUNCTION_H

#define _FUNCTION_H 1

namespace std

{

  // 20.3.1 base classes

  /** @defgroup s20_3_1_base Functor Base Classes

   *  Function objects, or @e functors, are objects with an @c operator()

   *  defined and accessible.  They can be passed as arguments to algorithm

   *  templates and used in place of a function pointer.  Not only is the

   *  resulting expressiveness of the library increased, but the generated

   *  code can be more efficient than what you might write by hand.  When we

   *  refer to "functors," then, generally we include function pointers in

   *  the description as well.

   *

   *  Often, functors are only created as temporaries passed to algorithm

   *  calls, rather than being created as named variables.

   *

   *  Two examples taken from the standard itself follow.  To perform a

   *  by-element addition of two vectors @c a and @c b containing @c double,

   *  and put the result in @c a, use

   *  \code

   *  transform (a.begin(), a.end(), b.begin(), a.begin(), plus<double>());

   *  \endcode

   *  To negate every element in @c a, use

   *  \code

   *  transform(a.begin(), a.end(), a.begin(), negate<double>());

   *  \endcode

   *  The addition and negation functions will be inlined directly.

   *

   *  The standard functors are derived from structs named @c unary_function

   *  and @c binary_function.  These two classes contain nothing but typedefs,

   *  to aid in generic (template) programming.  If you write your own

   *  functors, you might consider doing the same.

   *

   *  @{

   */

  /**

   *  This is one of the @link s20_3_1_base functor base classes@endlink.

   */

  template <class _Arg, class _Result>

    struct unary_function

    {

      typedef _Arg argument_type;   ///< @c argument_type is the type of the

                                    ///     argument (no surprises here)

      typedef _Result result_type;  ///< @c result_type is the return type

    };

  /**

   *  This is one of the @link s20_3_1_base functor base classes@endlink.

   */

  template <class _Arg1, class _Arg2, class _Result>

    struct binary_function

    {

      typedef _Arg1 first_argument_type;   ///< the type of the first argument

                                           ///  (no surprises here)

      typedef _Arg2 second_argument_type;  ///< the type of the second argument

      typedef _Result result_type;         ///< type of the return type

    };

  /** @}  */

  // 20.3.2 arithmetic

  /** @defgroup s20_3_2_arithmetic Arithmetic Classes

   *  Because basic math often needs to be done during an algorithm, the library

   *  provides functors for those operations.  See the documentation for

   *  @link s20_3_1_base the base classes@endlink for examples of their use.

   *

   *  @{

   */

  /// One of the @link s20_3_2_arithmetic math functors@endlink.

  template <class _Tp>

    struct plus : public binary_function<_Tp, _Tp, _Tp>

    {

      _Tp

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x + __y; }

    };

  /// One of the @link s20_3_2_arithmetic math functors@endlink.

  template <class _Tp>

    struct minus : public binary_function<_Tp, _Tp, _Tp>

    {

      _Tp

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x - __y; }

    };

  /// One of the @link s20_3_2_arithmetic math functors@endlink.

  template <class _Tp>

    struct multiplies : public binary_function<_Tp, _Tp, _Tp>

    {

      _Tp

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x * __y; }

    };

  /// One of the @link s20_3_2_arithmetic math functors@endlink.

  template <class _Tp>

    struct divides : public binary_function<_Tp, _Tp, _Tp>

    {

      _Tp

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x / __y; }

    };

  /// One of the @link s20_3_2_arithmetic math functors@endlink.

  template <class _Tp>

    struct modulus : public binary_function<_Tp, _Tp, _Tp>

    {

      _Tp

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x % __y; }

    };

  /// One of the @link s20_3_2_arithmetic math functors@endlink.

  template <class _Tp>

    struct negate : public unary_function<_Tp, _Tp>

    {

      _Tp

      operator()(const _Tp& __x) const

      { return -__x; }

    };

  /** @}  */

  // 20.3.3 comparisons

  /** @defgroup s20_3_3_comparisons Comparison Classes

   *  The library provides six wrapper functors for all the basic comparisons

   *  in C++, like @c <.

   *

   *  @{

   */

  /// One of the @link s20_3_3_comparisons comparison functors@endlink.

  template <class _Tp>

    struct equal_to : public binary_function<_Tp, _Tp, bool>

    {

      bool

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x == __y; }

    };

  /// One of the @link s20_3_3_comparisons comparison functors@endlink.

  template <class _Tp>

    struct not_equal_to : public binary_function<_Tp, _Tp, bool>

    {

      bool

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x != __y; }

    };

  /// One of the @link s20_3_3_comparisons comparison functors@endlink.

  template <class _Tp>

    struct greater : public binary_function<_Tp, _Tp, bool>

    {

      bool

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x > __y; }

    };

  /// One of the @link s20_3_3_comparisons comparison functors@endlink.

  template <class _Tp>

    struct less : public binary_function<_Tp, _Tp, bool>

    {

      bool

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x < __y; }

    };

  /// One of the @link s20_3_3_comparisons comparison functors@endlink.

  template <class _Tp>

    struct greater_equal : public binary_function<_Tp, _Tp, bool>

    {

      bool

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x >= __y; }

    };

  /// One of the @link s20_3_3_comparisons comparison functors@endlink.

  template <class _Tp>

    struct less_equal : public binary_function<_Tp, _Tp, bool>

    {

      bool

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x <= __y; }

    };

  /** @}  */

  // 20.3.4 logical operations

  /** @defgroup s20_3_4_logical Boolean Operations Classes

   *  Here are wrapper functors for Boolean operations:  @c &&, @c ||, and @c !.

   *

   *  @{

   */

  /// One of the @link s20_3_4_logical Boolean operations functors@endlink.

  template <class _Tp>

    struct logical_and : public binary_function<_Tp, _Tp, bool>

    {

      bool

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x && __y; }

    };

  /// One of the @link s20_3_4_logical Boolean operations functors@endlink.

  template <class _Tp>

    struct logical_or : public binary_function<_Tp, _Tp, bool>

    {

      bool

      operator()(const _Tp& __x, const _Tp& __y) const

      { return __x || __y; }

    };

  /// One of the @link s20_3_4_logical Boolean operations functors@endlink.

  template <class _Tp>

    struct logical_not : public unary_function<_Tp, bool>

    {

      bool

      operator()(const _Tp& __x) const

      { return !__x; }

    };

  /** @}  */

  // 20.3.5 negators

  /** @defgroup s20_3_5_negators Negators

   *  The functions @c not1 and @c not2 each take a predicate functor

   *  and return an instance of @c unary_negate or

   *  @c binary_negate, respectively.  These classes are functors whose

   *  @c operator() performs the stored predicate function and then returns

   *  the negation of the result.

   *

   *  For example, given a vector of integers and a trivial predicate,

   *  \code

   *  struct IntGreaterThanThree

   *    : public std::unary_function<int, bool>

   *  {

   *      bool operator() (int x) { return x > 3; }

   *  };

   *

   *  std::find_if (v.begin(), v.end(), not1(IntGreaterThanThree()));

   *  \endcode

   *  The call to @c find_if will locate the first index (i) of @c v for which

   *  "!(v[i] > 3)" is true.

   *

   *  The not1/unary_negate combination works on predicates taking a single

   *  argument.  The not2/binary_negate combination works on predicates which

   *  take two arguments.

   *

   *  @{

   */

  /// One of the @link s20_3_5_negators negation functors@endlink.

  template <class _Predicate>

    class unary_negate

    : public unary_function<typename _Predicate::argument_type, bool>

    {

    protected:

      _Predicate _M_pred;

    public:

      explicit

      unary_negate(const _Predicate& __x) : _M_pred(__x) {}

      bool

      operator()(const typename _Predicate::argument_type& __x) const

      { return !_M_pred(__x); }

    };

  /// One of the @link s20_3_5_negators negation functors@endlink.

  template <class _Predicate>

    inline unary_negate<_Predicate>

    not1(const _Predicate& __pred)

    { return unary_negate<_Predicate>(__pred); }

  /// One of the @link s20_3_5_negators negation functors@endlink.

  template <class _Predicate>

    class binary_negate

    : public binary_function<typename _Predicate::first_argument_type,

                             typename _Predicate::second_argument_type,

                             bool>

    {

    protected:

      _Predicate _M_pred;

    public:

      explicit

      binary_negate(const _Predicate& __x)

      : _M_pred(__x) { }

      bool

      operator()(const typename _Predicate::first_argument_type& __x,

                 const typename _Predicate::second_argument_type& __y) const

      { return !_M_pred(__x, __y); }

    };

  /// One of the @link s20_3_5_negators negation functors@endlink.

  template <class _Predicate>

    inline binary_negate<_Predicate>

    not2(const _Predicate& __pred)

    { return binary_negate<_Predicate>(__pred); }

  /** @}  */

  // 20.3.6 binders

  /** @defgroup s20_3_6_binder Binder Classes

   *  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 "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 "1.3 - x" 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 s20_3_6_binder binder functors@endlink.

  template <class _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); }

    };

  /// One of the @link s20_3_6_binder binder functors@endlink.

  template <class _Operation, class _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 s20_3_6_binder binder functors@endlink.

  template <class _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); }

    };

  /// One of the @link s20_3_6_binder binder functors@endlink.

  template <class _Operation, class _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));

    }

  /** @}  */

  // 20.3.7 adaptors pointers functions

  /** @defgroup s20_3_7_adaptors Adaptors for pointers to functions

   *  The advantage of function objects over pointers to functions is that

   *  the objects in the standard library declare nested typedefs describing

   *  their argument and result types with uniform names (e.g., @c result_type

   *  from the base classes @c unary_function and @c binary_function).

   *  Sometimes those typedefs are required, not just optional.

   *

   *  Adaptors are provided to turn pointers to unary (single-argument) and

   *  binary (double-argument) functions into function objects.  The

   *  long-winded functor @c pointer_to_unary_function is constructed with a

   *  function pointer @c f, and its @c operator() called with argument @c x

   *  returns @c f(x).  The functor @c pointer_to_binary_function does the same

   *  thing, but with a double-argument @c f and @c operator().

   *

   *  The function @c ptr_fun takes a pointer-to-function @c f and constructs

   *  an instance of the appropriate functor.

   *

   *  @{

   */

  /// One of the @link s20_3_7_adaptors adaptors for function pointers@endlink.

  template <class _Arg, class _Result>

    class pointer_to_unary_function : public unary_function<_Arg, _Result>

    {

    protected:

      _Result (*_M_ptr)(_Arg);

    public:

      pointer_to_unary_function() {}

      explicit

      pointer_to_unary_function(_Result (*__x)(_Arg))

      : _M_ptr(__x) {}

      _Result

      operator()(_Arg __x) const

      { return _M_ptr(__x); }

    };

  /// One of the @link s20_3_7_adaptors adaptors for function pointers@endlink.

  template <class _Arg, class _Result>

    inline pointer_to_unary_function<_Arg, _Result>

    ptr_fun(_Result (*__x)(_Arg))

    { return pointer_to_unary_function<_Arg, _Result>(__x); }

  /// One of the @link s20_3_7_adaptors adaptors for function pointers@endlink.

  template <class _Arg1, class _Arg2, class _Result>

    class pointer_to_binary_function

    : public binary_function<_Arg1, _Arg2, _Result>

    {

    protected:

      _Result (*_M_ptr)(_Arg1, _Arg2);

    public:

      pointer_to_binary_function() {}

      explicit

      pointer_to_binary_function(_Result (*__x)(_Arg1, _Arg2))

      : _M_ptr(__x) {}

      _Result

      operator()(_Arg1 __x, _Arg2 __y) const

      { return _M_ptr(__x, __y); }

    };

  /// One of the @link s20_3_7_adaptors adaptors for function pointers@endlink.

  template <class _Arg1, class _Arg2, class _Result>

    inline pointer_to_binary_function<_Arg1, _Arg2, _Result>

    ptr_fun(_Result (*__x)(_Arg1, _Arg2))

    { return pointer_to_binary_function<_Arg1, _Arg2, _Result>(__x); }

  /** @}  */

  template <class _Tp>

    struct _Identity : public unary_function<_Tp,_Tp>

    {

      _Tp&

      operator()(_Tp& __x) const

      { return __x; }

      const _Tp&

      operator()(const _Tp& __x) const

      { return __x; }

    };

  template <class _Pair>

    struct _Select1st : public unary_function<_Pair,

                                              typename _Pair::first_type>

    {

      typename _Pair::first_type&

      operator()(_Pair& __x) const

      { return __x.first; }

      const typename _Pair::first_type&

      operator()(const _Pair& __x) const

      { return __x.first; }

    };

  template <class _Pair>

    struct _Select2nd : public unary_function<_Pair,

                                              typename _Pair::second_type>

    {

      typename _Pair::second_type&

      operator()(_Pair& __x) const

      { return __x.second; }

      const typename _Pair::second_type&

      operator()(const _Pair& __x) const

      { return __x.second; }

    };

  // 20.3.8 adaptors pointers members

  /** @defgroup s20_3_8_memadaptors Adaptors for pointers to members

   *  There are a total of 8 = 2^3 function objects in this family.

   *   (1) Member functions taking no arguments vs member functions taking

   *        one argument.

   *   (2) Call through pointer vs call through reference.

   *   (3) Const vs non-const member function.

   *

   *  All of this complexity is in the function objects themselves.  You can

   *   ignore it by using the helper function mem_fun and mem_fun_ref,

   *   which create whichever type of adaptor is appropriate.

   *

   *  @{

   */

  /// One of the @link s20_3_8_memadaptors adaptors for member pointers@endlink.

  template <class _Ret, class _Tp>

    class mem_fun_t : public unary_function<_Tp*, _Ret>

    {

    public:

      explicit

      mem_fun_t(_Ret (_Tp::*__pf)())

      : _M_f(__pf) {}

      _Ret

      operator()(_Tp* __p) const

      { return (__p->*_M_f)(); }

    private:

      _Ret (_Tp::*_M_f)();

    };

  /// One of the @link s20_3_8_memadaptors adaptors for member pointers@endlink.

  template <class _Ret, class _Tp>

    class const_mem_fun_t : public unary_function<const _Tp*, _Ret>

    {

    public:

      explicit

      const_mem_fun_t(_Ret (_Tp::*__pf)() const)

      : _M_f(__pf) {}

      _Ret

      operator()(const _Tp* __p) const

      { return (__p->*_M_f)(); }

    private:

      _Ret (_Tp::*_M_f)() const;

    };

  /// One of the @link s20_3_8_memadaptors adaptors for member pointers@endlink.

  template <class _Ret, class _Tp>

    class mem_fun_ref_t : public unary_function<_Tp, _Ret>

    {

    public:

      explicit

      mem_fun_ref_t(_Ret (_Tp::*__pf)())

      : _M_f(__pf) {}

      _Ret

      operator()(_Tp& __r) const

      { return (__r.*_M_f)(); }

    private:

      _Ret (_Tp::*_M_f)();

  };

  /// One of the @link s20_3_8_memadaptors adaptors for member pointers@endlink.

  template <class _Ret, class _Tp>

    class const_mem_fun_ref_t : public unary_function<_Tp, _Ret>

    {

    public:

      explicit

      const_mem_fun_ref_t(_Ret (_Tp::*__pf)() const)

      : _M_f(__pf) {}

      _Ret

      operator()(const _Tp& __r) const

      { return (__r.*_M_f)(); }

    private:

      _Ret (_Tp::*_M_f)() const;

    };

  /// One of the @link s20_3_8_memadaptors adaptors for member pointers@endlink.

  template <class _Ret, class _Tp, class _Arg>

    class mem_fun1_t : public binary_function<_Tp*, _Arg, _Ret>

    {

    public:

      explicit

      mem_fun1_t(_Ret (_Tp::*__pf)(_Arg))

      : _M_f(__pf) {}

      _Ret

      operator()(_Tp* __p, _Arg __x) const

      { return (__p->*_M_f)(__x); }

    private:

      _Ret (_Tp::*_M_f)(_Arg);

    };

  /// One of the @link s20_3_8_memadaptors adaptors for member pointers@endlink.

  template <class _Ret, class _Tp, class _Arg>

    class const_mem_fun1_t : public binary_function<const _Tp*, _Arg, _Ret>

    {

    public:

      explicit

      const_mem_fun1_t(_Ret (_Tp::*__pf)(_Arg) const)

      : _M_f(__pf) {}

      _Ret

      operator()(const _Tp* __p, _Arg __x) const

      { return (__p->*_M_f)(__x); }

    private:

      _Ret (_Tp::*_M_f)(_Arg) const;

    };

  /// One of the @link s20_3_8_memadaptors adaptors for member pointers@endlink.

  template <class _Ret, class _Tp, class _Arg>

    class mem_fun1_ref_t : public binary_function<_Tp, _Arg, _Ret>

    {

    public:

      explicit

      mem_fun1_ref_t(_Ret (_Tp::*__pf)(_Arg))

      : _M_f(__pf) {}

      _Ret

      operator()(_Tp& __r, _Arg __x) const

      { return (__r.*_M_f)(__x); }

    private:

      _Ret (_Tp::*_M_f)(_Arg);

    };

  /// One of the @link s20_3_8_memadaptors adaptors for member pointers@endlink.

  template <class _Ret, class _Tp, class _Arg>

    class const_mem_fun1_ref_t : public binary_function<_Tp, _Arg, _Ret>

    {

    public:

      explicit

      const_mem_fun1_ref_t(_Ret (_Tp::*__pf)(_Arg) const)

      : _M_f(__pf) {}

      _Ret

      operator()(const _Tp& __r, _Arg __x) const

      { return (__r.*_M_f)(__x); }

    private:

      _Ret (_Tp::*_M_f)(_Arg) const;

    };

  // Mem_fun adaptor helper functions.  There are only two:

  // mem_fun and mem_fun_ref.

  template <class _Ret, class _Tp>

    inline mem_fun_t<_Ret, _Tp>

    mem_fun(_Ret (_Tp::*__f)())

    { return mem_fun_t<_Ret, _Tp>(__f); }

  template <class _Ret, class _Tp>

    inline const_mem_fun_t<_Ret, _Tp>

    mem_fun(_Ret (_Tp::*__f)() const)

    { return const_mem_fun_t<_Ret, _Tp>(__f); }

  template <class _Ret, class _Tp>