1// Functional extensions -*- C++ -*-
2
3// Copyright (C) 2002-2014 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25/*
26 *
27 * Copyright (c) 1994
28 * Hewlett-Packard Company
29 *
30 * Permission to use, copy, modify, distribute and sell this software
31 * and its documentation for any purpose is hereby granted without fee,
32 * provided that the above copyright notice appear in all copies and
33 * that both that copyright notice and this permission notice appear
34 * in supporting documentation.  Hewlett-Packard Company makes no
35 * representations about the suitability of this software for any
36 * purpose.  It is provided "as is" without express or implied warranty.
37 *
38 *
39 * Copyright (c) 1996
40 * Silicon Graphics Computer Systems, Inc.
41 *
42 * Permission to use, copy, modify, distribute and sell this software
43 * and its documentation for any purpose is hereby granted without fee,
44 * provided that the above copyright notice appear in all copies and
45 * that both that copyright notice and this permission notice appear
46 * in supporting documentation.  Silicon Graphics makes no
47 * representations about the suitability of this software for any
48 * purpose.  It is provided "as is" without express or implied warranty.
49 */
50
51/** @file ext/functional
52 *  This file is a GNU extension to the Standard C++ Library (possibly
53 *  containing extensions from the HP/SGI STL subset).
54 */
55
56#ifndef _EXT_FUNCTIONAL
57#define _EXT_FUNCTIONAL 1
58
59#pragma GCC system_header
60
61#include <functional>
62
63namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
64{
65_GLIBCXX_BEGIN_NAMESPACE_VERSION
66
67  using std::size_t;
68  using std::unary_function;
69  using std::binary_function;
70  using std::mem_fun1_t;
71  using std::const_mem_fun1_t;
72  using std::mem_fun1_ref_t;
73  using std::const_mem_fun1_ref_t;
74
75  /** The @c identity_element functions are not part of the C++
76   *  standard; SGI provided them as an extension.  Its argument is an
77   *  operation, and its return value is the identity element for that
78   *  operation.  It is overloaded for addition and multiplication,
79   *  and you can overload it for your own nefarious operations.
80   *
81   *  @addtogroup SGIextensions
82   *  @{
83   */
84  /// An \link SGIextensions SGI extension \endlink.
85  template <class _Tp>
86    inline _Tp
87    identity_element(std::plus<_Tp>)
88    { return _Tp(0); }
89
90  /// An \link SGIextensions SGI extension \endlink.
91  template <class _Tp>
92    inline _Tp
93    identity_element(std::multiplies<_Tp>)
94    { return _Tp(1); }
95  /** @}  */
96
97  /** As an extension to the binders, SGI provided composition functors and
98   *  wrapper functions to aid in their creation.  The @c unary_compose
99   *  functor is constructed from two functions/functors, @c f and @c g.
100   *  Calling @c operator() with a single argument @c x returns @c f(g(x)).
101   *  The function @c compose1 takes the two functions and constructs a
102   *  @c unary_compose variable for you.
103   *
104   *  @c binary_compose is constructed from three functors, @c f, @c g1,
105   *  and @c g2.  Its @c operator() returns @c f(g1(x),g2(x)).  The function
106   *  compose2 takes f, g1, and g2, and constructs the @c binary_compose
107   *  instance for you.  For example, if @c f returns an int, then
108   *  \code
109   *  int answer = (compose2(f,g1,g2))(x);
110   *  \endcode
111   *  is equivalent to
112   *  \code
113   *  int temp1 = g1(x);
114   *  int temp2 = g2(x);
115   *  int answer = f(temp1,temp2);
116   *  \endcode
117   *  But the first form is more compact, and can be passed around as a
118   *  functor to other algorithms.
119   *
120   *  @addtogroup SGIextensions
121   *  @{
122   */
123  /// An \link SGIextensions SGI extension \endlink.
124  template <class _Operation1, class _Operation2>
125    class unary_compose
126    : public unary_function<typename _Operation2::argument_type,
127			    typename _Operation1::result_type>
128    {
129    protected:
130      _Operation1 _M_fn1;
131      _Operation2 _M_fn2;
132
133    public:
134      unary_compose(const _Operation1& __x, const _Operation2& __y)
135      : _M_fn1(__x), _M_fn2(__y) {}
136
137      typename _Operation1::result_type
138      operator()(const typename _Operation2::argument_type& __x) const
139      { return _M_fn1(_M_fn2(__x)); }
140    };
141
142  /// An \link SGIextensions SGI extension \endlink.
143  template <class _Operation1, class _Operation2>
144    inline unary_compose<_Operation1, _Operation2>
145    compose1(const _Operation1& __fn1, const _Operation2& __fn2)
146    { return unary_compose<_Operation1,_Operation2>(__fn1, __fn2); }
147
148  /// An \link SGIextensions SGI extension \endlink.
149  template <class _Operation1, class _Operation2, class _Operation3>
150    class binary_compose
151    : public unary_function<typename _Operation2::argument_type,
152			    typename _Operation1::result_type>
153    {
154    protected:
155      _Operation1 _M_fn1;
156      _Operation2 _M_fn2;
157      _Operation3 _M_fn3;
158
159    public:
160      binary_compose(const _Operation1& __x, const _Operation2& __y,
161		     const _Operation3& __z)
162      : _M_fn1(__x), _M_fn2(__y), _M_fn3(__z) { }
163
164      typename _Operation1::result_type
165      operator()(const typename _Operation2::argument_type& __x) const
166      { return _M_fn1(_M_fn2(__x), _M_fn3(__x)); }
167    };
168
169  /// An \link SGIextensions SGI extension \endlink.
170  template <class _Operation1, class _Operation2, class _Operation3>
171    inline binary_compose<_Operation1, _Operation2, _Operation3>
172    compose2(const _Operation1& __fn1, const _Operation2& __fn2,
173	     const _Operation3& __fn3)
174    { return binary_compose<_Operation1, _Operation2, _Operation3>
175	(__fn1, __fn2, __fn3); }
176  /** @}  */
177
178  /** As an extension, SGI provided a functor called @c identity.  When a
179   *  functor is required but no operations are desired, this can be used as a
180   *  pass-through.  Its @c operator() returns its argument unchanged.
181   *
182   *  @addtogroup SGIextensions
183   */
184  template <class _Tp>
185    struct identity
186    : public std::_Identity<_Tp> {};
187
188  /** @c select1st and @c select2nd are extensions provided by SGI.  Their
189   *  @c operator()s
190   *  take a @c std::pair as an argument, and return either the first member
191   *  or the second member, respectively.  They can be used (especially with
192   *  the composition functors) to @a strip data from a sequence before
193   *  performing the remainder of an algorithm.
194   *
195   *  @addtogroup SGIextensions
196   *  @{
197   */
198  /// An \link SGIextensions SGI extension \endlink.
199  template <class _Pair>
200    struct select1st
201    : public std::_Select1st<_Pair> {};
202
203  /// An \link SGIextensions SGI extension \endlink.
204  template <class _Pair>
205    struct select2nd
206    : public std::_Select2nd<_Pair> {};
207
208  /** @}  */
209
210  // extension documented next
211  template <class _Arg1, class _Arg2>
212    struct _Project1st : public binary_function<_Arg1, _Arg2, _Arg1>
213    {
214      _Arg1
215      operator()(const _Arg1& __x, const _Arg2&) const
216      { return __x; }
217    };
218
219  template <class _Arg1, class _Arg2>
220    struct _Project2nd : public binary_function<_Arg1, _Arg2, _Arg2>
221    {
222      _Arg2
223      operator()(const _Arg1&, const _Arg2& __y) const
224      { return __y; }
225    };
226
227  /** The @c operator() of the @c project1st functor takes two arbitrary
228   *  arguments and returns the first one, while @c project2nd returns the
229   *  second one.  They are extensions provided by SGI.
230   *
231   *  @addtogroup SGIextensions
232   *  @{
233   */
234
235  /// An \link SGIextensions SGI extension \endlink.
236  template <class _Arg1, class _Arg2>
237    struct project1st : public _Project1st<_Arg1, _Arg2> {};
238
239  /// An \link SGIextensions SGI extension \endlink.
240  template <class _Arg1, class _Arg2>
241    struct project2nd : public _Project2nd<_Arg1, _Arg2> {};
242  /** @}  */
243
244  // extension documented next
245  template <class _Result>
246    struct _Constant_void_fun
247    {
248      typedef _Result result_type;
249      result_type _M_val;
250
251      _Constant_void_fun(const result_type& __v) : _M_val(__v) {}
252
253      const result_type&
254      operator()() const
255      { return _M_val; }
256    };
257
258  template <class _Result, class _Argument>
259    struct _Constant_unary_fun
260    {
261      typedef _Argument argument_type;
262      typedef  _Result  result_type;
263      result_type _M_val;
264
265      _Constant_unary_fun(const result_type& __v) : _M_val(__v) {}
266
267      const result_type&
268      operator()(const _Argument&) const
269      { return _M_val; }
270    };
271
272  template <class _Result, class _Arg1, class _Arg2>
273    struct _Constant_binary_fun
274    {
275      typedef  _Arg1   first_argument_type;
276      typedef  _Arg2   second_argument_type;
277      typedef  _Result result_type;
278      _Result _M_val;
279
280      _Constant_binary_fun(const _Result& __v) : _M_val(__v) {}
281
282      const result_type&
283      operator()(const _Arg1&, const _Arg2&) const
284      { return _M_val; }
285    };
286
287  /** These three functors are each constructed from a single arbitrary
288   *  variable/value.  Later, their @c operator()s completely ignore any
289   *  arguments passed, and return the stored value.
290   *  - @c constant_void_fun's @c operator() takes no arguments
291   *  - @c constant_unary_fun's @c operator() takes one argument (ignored)
292   *  - @c constant_binary_fun's @c operator() takes two arguments (ignored)
293   *
294   *  The helper creator functions @c constant0, @c constant1, and
295   *  @c constant2 each take a @a result argument and construct variables of
296   *  the appropriate functor type.
297   *
298   *  @addtogroup SGIextensions
299   *  @{
300   */
301  /// An \link SGIextensions SGI extension \endlink.
302  template <class _Result>
303    struct constant_void_fun
304    : public _Constant_void_fun<_Result>
305    {
306      constant_void_fun(const _Result& __v)
307      : _Constant_void_fun<_Result>(__v) {}
308    };
309
310  /// An \link SGIextensions SGI extension \endlink.
311  template <class _Result, class _Argument = _Result>
312    struct constant_unary_fun : public _Constant_unary_fun<_Result, _Argument>
313    {
314      constant_unary_fun(const _Result& __v)
315      : _Constant_unary_fun<_Result, _Argument>(__v) {}
316    };
317
318  /// An \link SGIextensions SGI extension \endlink.
319  template <class _Result, class _Arg1 = _Result, class _Arg2 = _Arg1>
320    struct constant_binary_fun
321    : public _Constant_binary_fun<_Result, _Arg1, _Arg2>
322    {
323      constant_binary_fun(const _Result& __v)
324      : _Constant_binary_fun<_Result, _Arg1, _Arg2>(__v) {}
325    };
326
327  /// An \link SGIextensions SGI extension \endlink.
328  template <class _Result>
329    inline constant_void_fun<_Result>
330    constant0(const _Result& __val)
331    { return constant_void_fun<_Result>(__val); }
332
333  /// An \link SGIextensions SGI extension \endlink.
334  template <class _Result>
335    inline constant_unary_fun<_Result, _Result>
336    constant1(const _Result& __val)
337    { return constant_unary_fun<_Result, _Result>(__val); }
338
339  /// An \link SGIextensions SGI extension \endlink.
340  template <class _Result>
341    inline constant_binary_fun<_Result,_Result,_Result>
342    constant2(const _Result& __val)
343    { return constant_binary_fun<_Result, _Result, _Result>(__val); }
344  /** @}  */
345
346  /** The @c subtractive_rng class is documented on
347   *  <a href="http://www.sgi.com/tech/stl/">SGI's site</a>.
348   *  Note that this code assumes that @c int is 32 bits.
349   *
350   *  @ingroup SGIextensions
351   */
352  class subtractive_rng
353  : public unary_function<unsigned int, unsigned int>
354  {
355  private:
356    unsigned int _M_table[55];
357    size_t _M_index1;
358    size_t _M_index2;
359
360  public:
361    /// Returns a number less than the argument.
362    unsigned int
363    operator()(unsigned int __limit)
364    {
365      _M_index1 = (_M_index1 + 1) % 55;
366      _M_index2 = (_M_index2 + 1) % 55;
367      _M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2];
368      return _M_table[_M_index1] % __limit;
369    }
370
371    void
372    _M_initialize(unsigned int __seed)
373    {
374      unsigned int __k = 1;
375      _M_table[54] = __seed;
376      size_t __i;
377      for (__i = 0; __i < 54; __i++)
378	{
379	  size_t __ii = (21 * (__i + 1) % 55) - 1;
380	  _M_table[__ii] = __k;
381	  __k = __seed - __k;
382	  __seed = _M_table[__ii];
383	}
384      for (int __loop = 0; __loop < 4; __loop++)
385	{
386	  for (__i = 0; __i < 55; __i++)
387            _M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55];
388	}
389      _M_index1 = 0;
390      _M_index2 = 31;
391    }
392
393    /// Ctor allowing you to initialize the seed.
394    subtractive_rng(unsigned int __seed)
395    { _M_initialize(__seed); }
396
397    /// Default ctor; initializes its state with some number you don't see.
398    subtractive_rng()
399    { _M_initialize(161803398u); }
400  };
401
402  // Mem_fun adaptor helper functions mem_fun1 and mem_fun1_ref,
403  // provided for backward compatibility, they are no longer part of
404  // the C++ standard.
405
406  template <class _Ret, class _Tp, class _Arg>
407    inline mem_fun1_t<_Ret, _Tp, _Arg>
408    mem_fun1(_Ret (_Tp::*__f)(_Arg))
409    { return mem_fun1_t<_Ret, _Tp, _Arg>(__f); }
410
411  template <class _Ret, class _Tp, class _Arg>
412    inline const_mem_fun1_t<_Ret, _Tp, _Arg>
413    mem_fun1(_Ret (_Tp::*__f)(_Arg) const)
414    { return const_mem_fun1_t<_Ret, _Tp, _Arg>(__f); }
415
416  template <class _Ret, class _Tp, class _Arg>
417    inline mem_fun1_ref_t<_Ret, _Tp, _Arg>
418    mem_fun1_ref(_Ret (_Tp::*__f)(_Arg))
419    { return mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); }
420
421  template <class _Ret, class _Tp, class _Arg>
422    inline const_mem_fun1_ref_t<_Ret, _Tp, _Arg>
423    mem_fun1_ref(_Ret (_Tp::*__f)(_Arg) const)
424    { return const_mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); }
425
426_GLIBCXX_END_NAMESPACE_VERSION
427} // namespace
428
429#endif
430
431