1 // Functional extensions -*- C++ -*-
3 // Copyright (C) 2002, 2004, 2005 Free Software Foundation, Inc.
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 2, or (at your option)
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.
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18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
21 // As a special exception, you may use this file as part of a free software
22 // library without restriction. Specifically, if other files instantiate
23 // templates or use macros or inline functions from this file, or you compile
24 // this file and link it with other files to produce an executable, this
25 // file does not by itself cause the resulting executable to be covered by
26 // the GNU General Public License. This exception does not however
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28 // the GNU General Public License.
33 * Hewlett-Packard Company
35 * Permission to use, copy, modify, distribute and sell this software
36 * and its documentation for any purpose is hereby granted without fee,
37 * provided that the above copyright notice appear in all copies and
38 * that both that copyright notice and this permission notice appear
39 * in supporting documentation. Hewlett-Packard Company makes no
40 * representations about the suitability of this software for any
41 * purpose. It is provided "as is" without express or implied warranty.
45 * Silicon Graphics Computer Systems, Inc.
47 * Permission to use, copy, modify, distribute and sell this software
48 * and its documentation for any purpose is hereby granted without fee,
49 * provided that the above copyright notice appear in all copies and
50 * that both that copyright notice and this permission notice appear
51 * in supporting documentation. Silicon Graphics makes no
52 * representations about the suitability of this software for any
53 * purpose. It is provided "as is" without express or implied warranty.
56 /** @file ext/functional
57 * This file is a GNU extension to the Standard C++ Library (possibly
58 * containing extensions from the HP/SGI STL subset).
61 #ifndef _EXT_FUNCTIONAL
62 #define _EXT_FUNCTIONAL 1
64 #pragma GCC system_header
68 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
71 using std::unary_function;
72 using std::binary_function;
73 using std::mem_fun1_t;
74 using std::const_mem_fun1_t;
75 using std::mem_fun1_ref_t;
76 using std::const_mem_fun1_ref_t;
78 /** The @c identity_element functions are not part of the C++
79 * standard; SGI provided them as an extension. Its argument is an
80 * operation, and its return value is the identity element for that
81 * operation. It is overloaded for addition and multiplication,
82 * and you can overload it for your own nefarious operations.
84 * @addtogroup SGIextensions
87 /// An \link SGIextensions SGI extension \endlink.
90 identity_element(std::plus<_Tp>)
93 /// An \link SGIextensions SGI extension \endlink.
96 identity_element(std::multiplies<_Tp>)
100 /** As an extension to the binders, SGI provided composition functors and
101 * wrapper functions to aid in their creation. The @c unary_compose
102 * functor is constructed from two functions/functors, @c f and @c g.
103 * Calling @c operator() with a single argument @c x returns @c f(g(x)).
104 * The function @c compose1 takes the two functions and constructs a
105 * @c unary_compose variable for you.
107 * @c binary_compose is constructed from three functors, @c f, @c g1,
108 * and @c g2. Its @c operator() returns @c f(g1(x),g2(x)). The function
109 * @compose2 takes f, g1, and g2, and constructs the @c binary_compose
110 * instance for you. For example, if @c f returns an int, then
112 * int answer = (compose2(f,g1,g2))(x);
118 * int answer = f(temp1,temp2);
120 * But the first form is more compact, and can be passed around as a
121 * functor to other algorithms.
123 * @addtogroup SGIextensions
126 /// An \link SGIextensions SGI extension \endlink.
127 template <class _Operation1, class _Operation2>
129 : public unary_function<typename _Operation2::argument_type,
130 typename _Operation1::result_type>
137 unary_compose(const _Operation1& __x, const _Operation2& __y)
138 : _M_fn1(__x), _M_fn2(__y) {}
140 typename _Operation1::result_type
141 operator()(const typename _Operation2::argument_type& __x) const
142 { return _M_fn1(_M_fn2(__x)); }
145 /// An \link SGIextensions SGI extension \endlink.
146 template <class _Operation1, class _Operation2>
147 inline unary_compose<_Operation1, _Operation2>
148 compose1(const _Operation1& __fn1, const _Operation2& __fn2)
149 { return unary_compose<_Operation1,_Operation2>(__fn1, __fn2); }
151 /// An \link SGIextensions SGI extension \endlink.
152 template <class _Operation1, class _Operation2, class _Operation3>
154 : public unary_function<typename _Operation2::argument_type,
155 typename _Operation1::result_type>
163 binary_compose(const _Operation1& __x, const _Operation2& __y,
164 const _Operation3& __z)
165 : _M_fn1(__x), _M_fn2(__y), _M_fn3(__z) { }
167 typename _Operation1::result_type
168 operator()(const typename _Operation2::argument_type& __x) const
169 { return _M_fn1(_M_fn2(__x), _M_fn3(__x)); }
172 /// An \link SGIextensions SGI extension \endlink.
173 template <class _Operation1, class _Operation2, class _Operation3>
174 inline binary_compose<_Operation1, _Operation2, _Operation3>
175 compose2(const _Operation1& __fn1, const _Operation2& __fn2,
176 const _Operation3& __fn3)
177 { return binary_compose<_Operation1, _Operation2, _Operation3>
178 (__fn1, __fn2, __fn3); }
181 /** As an extension, SGI provided a functor called @c identity. When a
182 * functor is required but no operations are desired, this can be used as a
183 * pass-through. Its @c operator() returns its argument unchanged.
185 * @addtogroup SGIextensions
188 struct identity : public std::_Identity<_Tp> {};
190 /** @c select1st and @c select2nd are extensions provided by SGI. Their
192 * take a @c std::pair as an argument, and return either the first member
193 * or the second member, respectively. They can be used (especially with
194 * the composition functors) to "strip" data from a sequence before
195 * performing the remainder of an algorithm.
197 * @addtogroup SGIextensions
200 /// An \link SGIextensions SGI extension \endlink.
201 template <class _Pair>
202 struct select1st : public std::_Select1st<_Pair> {};
204 /// An \link SGIextensions SGI extension \endlink.
205 template <class _Pair>
206 struct select2nd : public std::_Select2nd<_Pair> {};
209 // extension documented next
210 template <class _Arg1, class _Arg2>
211 struct _Project1st : public binary_function<_Arg1, _Arg2, _Arg1>
214 operator()(const _Arg1& __x, const _Arg2&) const
218 template <class _Arg1, class _Arg2>
219 struct _Project2nd : public binary_function<_Arg1, _Arg2, _Arg2>
222 operator()(const _Arg1&, const _Arg2& __y) const
226 /** The @c operator() of the @c project1st functor takes two arbitrary
227 * arguments and returns the first one, while @c project2nd returns the
228 * second one. They are extensions provided by SGI.
230 * @addtogroup SGIextensions
234 /// An \link SGIextensions SGI extension \endlink.
235 template <class _Arg1, class _Arg2>
236 struct project1st : public _Project1st<_Arg1, _Arg2> {};
238 /// An \link SGIextensions SGI extension \endlink.
239 template <class _Arg1, class _Arg2>
240 struct project2nd : public _Project2nd<_Arg1, _Arg2> {};
243 // extension documented next
244 template <class _Result>
245 struct _Constant_void_fun
247 typedef _Result result_type;
250 _Constant_void_fun(const result_type& __v) : _M_val(__v) {}
257 template <class _Result, class _Argument>
258 struct _Constant_unary_fun
260 typedef _Argument argument_type;
261 typedef _Result result_type;
264 _Constant_unary_fun(const result_type& __v) : _M_val(__v) {}
267 operator()(const _Argument&) const
271 template <class _Result, class _Arg1, class _Arg2>
272 struct _Constant_binary_fun
274 typedef _Arg1 first_argument_type;
275 typedef _Arg2 second_argument_type;
276 typedef _Result result_type;
279 _Constant_binary_fun(const _Result& __v) : _M_val(__v) {}
282 operator()(const _Arg1&, const _Arg2&) const
286 /** These three functors are each constructed from a single arbitrary
287 * variable/value. Later, their @c operator()s completely ignore any
288 * arguments passed, and return the stored value.
289 * - @c constant_void_fun's @c operator() takes no arguments
290 * - @c constant_unary_fun's @c operator() takes one argument (ignored)
291 * - @c constant_binary_fun's @c operator() takes two arguments (ignored)
293 * The helper creator functions @c constant0, @c constant1, and
294 * @c constant2 each take a "result" argument and construct variables of
295 * the appropriate functor type.
297 * @addtogroup SGIextensions
300 /// An \link SGIextensions SGI extension \endlink.
301 template <class _Result>
302 struct constant_void_fun
303 : public _Constant_void_fun<_Result>
305 constant_void_fun(const _Result& __v)
306 : _Constant_void_fun<_Result>(__v) {}
309 /// An \link SGIextensions SGI extension \endlink.
310 template <class _Result, class _Argument = _Result>
311 struct constant_unary_fun : public _Constant_unary_fun<_Result, _Argument>
313 constant_unary_fun(const _Result& __v)
314 : _Constant_unary_fun<_Result, _Argument>(__v) {}
317 /// An \link SGIextensions SGI extension \endlink.
318 template <class _Result, class _Arg1 = _Result, class _Arg2 = _Arg1>
319 struct constant_binary_fun
320 : public _Constant_binary_fun<_Result, _Arg1, _Arg2>
322 constant_binary_fun(const _Result& __v)
323 : _Constant_binary_fun<_Result, _Arg1, _Arg2>(__v) {}
326 /// An \link SGIextensions SGI extension \endlink.
327 template <class _Result>
328 inline constant_void_fun<_Result>
329 constant0(const _Result& __val)
330 { return constant_void_fun<_Result>(__val); }
332 /// An \link SGIextensions SGI extension \endlink.
333 template <class _Result>
334 inline constant_unary_fun<_Result, _Result>
335 constant1(const _Result& __val)
336 { return constant_unary_fun<_Result, _Result>(__val); }
338 /// An \link SGIextensions SGI extension \endlink.
339 template <class _Result>
340 inline constant_binary_fun<_Result,_Result,_Result>
341 constant2(const _Result& __val)
342 { return constant_binary_fun<_Result, _Result, _Result>(__val); }
345 /** The @c subtractive_rng class is documented on
346 * <a href="http://www.sgi.com/tech/stl/">SGI's site</a>.
347 * Note that this code assumes that @c int is 32 bits.
349 * @ingroup SGIextensions
351 class subtractive_rng
352 : public unary_function<unsigned int, unsigned int>
355 unsigned int _M_table[55];
360 /// Returns a number less than the argument.
362 operator()(unsigned int __limit)
364 _M_index1 = (_M_index1 + 1) % 55;
365 _M_index2 = (_M_index2 + 1) % 55;
366 _M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2];
367 return _M_table[_M_index1] % __limit;
371 _M_initialize(unsigned int __seed)
373 unsigned int __k = 1;
374 _M_table[54] = __seed;
376 for (__i = 0; __i < 54; __i++)
378 size_t __ii = (21 * (__i + 1) % 55) - 1;
379 _M_table[__ii] = __k;
381 __seed = _M_table[__ii];
383 for (int __loop = 0; __loop < 4; __loop++)
385 for (__i = 0; __i < 55; __i++)
386 _M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55];
392 /// Ctor allowing you to initialize the seed.
393 subtractive_rng(unsigned int __seed)
394 { _M_initialize(__seed); }
396 /// Default ctor; initializes its state with some number you don't see.
398 { _M_initialize(161803398u); }
401 // Mem_fun adaptor helper functions mem_fun1 and mem_fun1_ref,
402 // provided for backward compatibility, they are no longer part of
405 template <class _Ret, class _Tp, class _Arg>
406 inline mem_fun1_t<_Ret, _Tp, _Arg>
407 mem_fun1(_Ret (_Tp::*__f)(_Arg))
408 { return mem_fun1_t<_Ret, _Tp, _Arg>(__f); }
410 template <class _Ret, class _Tp, class _Arg>
411 inline const_mem_fun1_t<_Ret, _Tp, _Arg>
412 mem_fun1(_Ret (_Tp::*__f)(_Arg) const)
413 { return const_mem_fun1_t<_Ret, _Tp, _Arg>(__f); }
415 template <class _Ret, class _Tp, class _Arg>
416 inline mem_fun1_ref_t<_Ret, _Tp, _Arg>
417 mem_fun1_ref(_Ret (_Tp::*__f)(_Arg))
418 { return mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); }
420 template <class _Ret, class _Tp, class _Arg>
421 inline const_mem_fun1_ref_t<_Ret, _Tp, _Arg>
422 mem_fun1_ref(_Ret (_Tp::*__f)(_Arg) const)
423 { return const_mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); }
425 _GLIBCXX_END_NAMESPACE