1 // Functor implementations -*- C++ -*-
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009
4 // Free Software Foundation, Inc.
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23 // library without restriction. Specifically, if other files instantiate
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45 * Copyright (c) 1996-1998
46 * Silicon Graphics Computer Systems, Inc.
48 * Permission to use, copy, modify, distribute and sell this software
49 * and its documentation for any purpose is hereby granted without fee,
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57 /** @file stl_function.h
58 * This is an internal header file, included by other library headers.
59 * You should not attempt to use it directly.
62 #ifndef _STL_FUNCTION_H
63 #define _STL_FUNCTION_H 1
65 _GLIBCXX_BEGIN_NAMESPACE(std
)
67 // 20.3.1 base classes
68 /** @defgroup functors Function Objects
71 * Function objects, or @e functors, are objects with an @c operator()
72 * defined and accessible. They can be passed as arguments to algorithm
73 * templates and used in place of a function pointer. Not only is the
74 * resulting expressiveness of the library increased, but the generated
75 * code can be more efficient than what you might write by hand. When we
76 * refer to "functors," then, generally we include function pointers in
77 * the description as well.
79 * Often, functors are only created as temporaries passed to algorithm
80 * calls, rather than being created as named variables.
82 * Two examples taken from the standard itself follow. To perform a
83 * by-element addition of two vectors @c a and @c b containing @c double,
84 * and put the result in @c a, use
86 * transform (a.begin(), a.end(), b.begin(), a.begin(), plus<double>());
88 * To negate every element in @c a, use
90 * transform(a.begin(), a.end(), a.begin(), negate<double>());
92 * The addition and negation functions will be inlined directly.
94 * The standard functors are derived from structs named @c unary_function
95 * and @c binary_function. These two classes contain nothing but typedefs,
96 * to aid in generic (template) programming. If you write your own
97 * functors, you might consider doing the same.
102 * This is one of the @link functors functor base classes@endlink.
104 template<typename _Arg
, typename _Result
>
105 struct unary_function
107 typedef _Arg argument_type
; ///< @c argument_type is the type of the
108 /// argument (no surprises here)
110 typedef _Result result_type
; ///< @c result_type is the return type
114 * This is one of the @link functors functor base classes@endlink.
116 template<typename _Arg1
, typename _Arg2
, typename _Result
>
117 struct binary_function
119 typedef _Arg1 first_argument_type
; ///< the type of the first argument
120 /// (no surprises here)
122 typedef _Arg2 second_argument_type
; ///< the type of the second argument
123 typedef _Result result_type
; ///< type of the return type
128 /** @defgroup arithmetic_functors Arithmetic Classes
131 * Because basic math often needs to be done during an algorithm,
132 * the library provides functors for those operations. See the
133 * documentation for @link functors the base classes@endlink
134 * for examples of their use.
138 /// One of the @link arithmetic_functors math functors@endlink.
139 template<typename _Tp
>
140 struct plus
: public binary_function
<_Tp
, _Tp
, _Tp
>
143 operator()(const _Tp
& __x
, const _Tp
& __y
) const
144 { return __x
+ __y
; }
147 /// One of the @link arithmetic_functors math functors@endlink.
148 template<typename _Tp
>
149 struct minus
: public binary_function
<_Tp
, _Tp
, _Tp
>
152 operator()(const _Tp
& __x
, const _Tp
& __y
) const
153 { return __x
- __y
; }
156 /// One of the @link arithmetic_functors math functors@endlink.
157 template<typename _Tp
>
158 struct multiplies
: public binary_function
<_Tp
, _Tp
, _Tp
>
161 operator()(const _Tp
& __x
, const _Tp
& __y
) const
162 { return __x
* __y
; }
165 /// One of the @link arithmetic_functors math functors@endlink.
166 template<typename _Tp
>
167 struct divides
: public binary_function
<_Tp
, _Tp
, _Tp
>
170 operator()(const _Tp
& __x
, const _Tp
& __y
) const
171 { return __x
/ __y
; }
174 /// One of the @link arithmetic_functors math functors@endlink.
175 template<typename _Tp
>
176 struct modulus
: public binary_function
<_Tp
, _Tp
, _Tp
>
179 operator()(const _Tp
& __x
, const _Tp
& __y
) const
180 { return __x
% __y
; }
183 /// One of the @link arithmetic_functors math functors@endlink.
184 template<typename _Tp
>
185 struct negate
: public unary_function
<_Tp
, _Tp
>
188 operator()(const _Tp
& __x
) const
193 // 20.3.3 comparisons
194 /** @defgroup comparison_functors Comparison Classes
197 * The library provides six wrapper functors for all the basic comparisons
202 /// One of the @link comparison_functors comparison functors@endlink.
203 template<typename _Tp
>
204 struct equal_to
: public binary_function
<_Tp
, _Tp
, bool>
207 operator()(const _Tp
& __x
, const _Tp
& __y
) const
208 { return __x
== __y
; }
211 /// One of the @link comparison_functors comparison functors@endlink.
212 template<typename _Tp
>
213 struct not_equal_to
: public binary_function
<_Tp
, _Tp
, bool>
216 operator()(const _Tp
& __x
, const _Tp
& __y
) const
217 { return __x
!= __y
; }
220 /// One of the @link comparison_functors comparison functors@endlink.
221 template<typename _Tp
>
222 struct greater
: public binary_function
<_Tp
, _Tp
, bool>
225 operator()(const _Tp
& __x
, const _Tp
& __y
) const
226 { return __x
> __y
; }
229 /// One of the @link comparison_functors comparison functors@endlink.
230 template<typename _Tp
>
231 struct less
: public binary_function
<_Tp
, _Tp
, bool>
234 operator()(const _Tp
& __x
, const _Tp
& __y
) const
235 { return __x
< __y
; }
238 /// One of the @link comparison_functors comparison functors@endlink.
239 template<typename _Tp
>
240 struct greater_equal
: public binary_function
<_Tp
, _Tp
, bool>
243 operator()(const _Tp
& __x
, const _Tp
& __y
) const
244 { return __x
>= __y
; }
247 /// One of the @link comparison_functors comparison functors@endlink.
248 template<typename _Tp
>
249 struct less_equal
: public binary_function
<_Tp
, _Tp
, bool>
252 operator()(const _Tp
& __x
, const _Tp
& __y
) const
253 { return __x
<= __y
; }
257 // 20.3.4 logical operations
258 /** @defgroup logical_functors Boolean Operations Classes
261 * Here are wrapper functors for Boolean operations: @c &&, @c ||,
266 /// One of the @link logical_functors Boolean operations functors@endlink.
267 template<typename _Tp
>
268 struct logical_and
: public binary_function
<_Tp
, _Tp
, bool>
271 operator()(const _Tp
& __x
, const _Tp
& __y
) const
272 { return __x
&& __y
; }
275 /// One of the @link logical_functors Boolean operations functors@endlink.
276 template<typename _Tp
>
277 struct logical_or
: public binary_function
<_Tp
, _Tp
, bool>
280 operator()(const _Tp
& __x
, const _Tp
& __y
) const
281 { return __x
|| __y
; }
284 /// One of the @link logical_functors Boolean operations functors@endlink.
285 template<typename _Tp
>
286 struct logical_not
: public unary_function
<_Tp
, bool>
289 operator()(const _Tp
& __x
) const
294 // _GLIBCXX_RESOLVE_LIB_DEFECTS
295 // DR 660. Missing Bitwise Operations.
296 template<typename _Tp
>
297 struct bit_and
: public binary_function
<_Tp
, _Tp
, _Tp
>
300 operator()(const _Tp
& __x
, const _Tp
& __y
) const
301 { return __x
& __y
; }
304 template<typename _Tp
>
305 struct bit_or
: public binary_function
<_Tp
, _Tp
, _Tp
>
308 operator()(const _Tp
& __x
, const _Tp
& __y
) const
309 { return __x
| __y
; }
312 template<typename _Tp
>
313 struct bit_xor
: public binary_function
<_Tp
, _Tp
, _Tp
>
316 operator()(const _Tp
& __x
, const _Tp
& __y
) const
317 { return __x
^ __y
; }
321 /** @defgroup negators Negators
324 * The functions @c not1 and @c not2 each take a predicate functor
325 * and return an instance of @c unary_negate or
326 * @c binary_negate, respectively. These classes are functors whose
327 * @c operator() performs the stored predicate function and then returns
328 * the negation of the result.
330 * For example, given a vector of integers and a trivial predicate,
332 * struct IntGreaterThanThree
333 * : public std::unary_function<int, bool>
335 * bool operator() (int x) { return x > 3; }
338 * std::find_if (v.begin(), v.end(), not1(IntGreaterThanThree()));
340 * The call to @c find_if will locate the first index (i) of @c v for which
341 * "!(v[i] > 3)" is true.
343 * The not1/unary_negate combination works on predicates taking a single
344 * argument. The not2/binary_negate combination works on predicates which
345 * take two arguments.
349 /// One of the @link negators negation functors@endlink.
350 template<typename _Predicate
>
352 : public unary_function
<typename
_Predicate::argument_type
, bool>
359 unary_negate(const _Predicate
& __x
) : _M_pred(__x
) { }
362 operator()(const typename
_Predicate::argument_type
& __x
) const
363 { return !_M_pred(__x
); }
366 /// One of the @link negators negation functors@endlink.
367 template<typename _Predicate
>
368 inline unary_negate
<_Predicate
>
369 not1(const _Predicate
& __pred
)
370 { return unary_negate
<_Predicate
>(__pred
); }
372 /// One of the @link negators negation functors@endlink.
373 template<typename _Predicate
>
375 : public binary_function
<typename
_Predicate::first_argument_type
,
376 typename
_Predicate::second_argument_type
, bool>
383 binary_negate(const _Predicate
& __x
) : _M_pred(__x
) { }
386 operator()(const typename
_Predicate::first_argument_type
& __x
,
387 const typename
_Predicate::second_argument_type
& __y
) const
388 { return !_M_pred(__x
, __y
); }
391 /// One of the @link negators negation functors@endlink.
392 template<typename _Predicate
>
393 inline binary_negate
<_Predicate
>
394 not2(const _Predicate
& __pred
)
395 { return binary_negate
<_Predicate
>(__pred
); }
398 // 20.3.7 adaptors pointers functions
399 /** @defgroup pointer_adaptors Adaptors for pointers to functions
402 * The advantage of function objects over pointers to functions is that
403 * the objects in the standard library declare nested typedefs describing
404 * their argument and result types with uniform names (e.g., @c result_type
405 * from the base classes @c unary_function and @c binary_function).
406 * Sometimes those typedefs are required, not just optional.
408 * Adaptors are provided to turn pointers to unary (single-argument) and
409 * binary (double-argument) functions into function objects. The
410 * long-winded functor @c pointer_to_unary_function is constructed with a
411 * function pointer @c f, and its @c operator() called with argument @c x
412 * returns @c f(x). The functor @c pointer_to_binary_function does the same
413 * thing, but with a double-argument @c f and @c operator().
415 * The function @c ptr_fun takes a pointer-to-function @c f and constructs
416 * an instance of the appropriate functor.
420 /// One of the @link pointer_adaptors adaptors for function pointers@endlink.
421 template<typename _Arg
, typename _Result
>
422 class pointer_to_unary_function
: public unary_function
<_Arg
, _Result
>
425 _Result (*_M_ptr
)(_Arg
);
428 pointer_to_unary_function() { }
431 pointer_to_unary_function(_Result (*__x
)(_Arg
))
435 operator()(_Arg __x
) const
436 { return _M_ptr(__x
); }
439 /// One of the @link pointer_adaptors adaptors for function pointers@endlink.
440 template<typename _Arg
, typename _Result
>
441 inline pointer_to_unary_function
<_Arg
, _Result
>
442 ptr_fun(_Result (*__x
)(_Arg
))
443 { return pointer_to_unary_function
<_Arg
, _Result
>(__x
); }
445 /// One of the @link pointer_adaptors adaptors for function pointers@endlink.
446 template<typename _Arg1
, typename _Arg2
, typename _Result
>
447 class pointer_to_binary_function
448 : public binary_function
<_Arg1
, _Arg2
, _Result
>
451 _Result (*_M_ptr
)(_Arg1
, _Arg2
);
454 pointer_to_binary_function() { }
457 pointer_to_binary_function(_Result (*__x
)(_Arg1
, _Arg2
))
461 operator()(_Arg1 __x
, _Arg2 __y
) const
462 { return _M_ptr(__x
, __y
); }
465 /// One of the @link pointer_adaptors adaptors for function pointers@endlink.
466 template<typename _Arg1
, typename _Arg2
, typename _Result
>
467 inline pointer_to_binary_function
<_Arg1
, _Arg2
, _Result
>
468 ptr_fun(_Result (*__x
)(_Arg1
, _Arg2
))
469 { return pointer_to_binary_function
<_Arg1
, _Arg2
, _Result
>(__x
); }
472 template<typename _Tp
>
473 struct _Identity
: public unary_function
<_Tp
,_Tp
>
476 operator()(_Tp
& __x
) const
480 operator()(const _Tp
& __x
) const
484 template<typename _Pair
>
485 struct _Select1st
: public unary_function
<_Pair
,
486 typename
_Pair::first_type
>
488 typename
_Pair::first_type
&
489 operator()(_Pair
& __x
) const
490 { return __x
.first
; }
492 const typename
_Pair::first_type
&
493 operator()(const _Pair
& __x
) const
494 { return __x
.first
; }
497 template<typename _Pair
>
498 struct _Select2nd
: public unary_function
<_Pair
,
499 typename
_Pair::second_type
>
501 typename
_Pair::second_type
&
502 operator()(_Pair
& __x
) const
503 { return __x
.second
; }
505 const typename
_Pair::second_type
&
506 operator()(const _Pair
& __x
) const
507 { return __x
.second
; }
510 // 20.3.8 adaptors pointers members
511 /** @defgroup memory_adaptors Adaptors for pointers to members
514 * There are a total of 8 = 2^3 function objects in this family.
515 * (1) Member functions taking no arguments vs member functions taking
517 * (2) Call through pointer vs call through reference.
518 * (3) Const vs non-const member function.
520 * All of this complexity is in the function objects themselves. You can
521 * ignore it by using the helper function mem_fun and mem_fun_ref,
522 * which create whichever type of adaptor is appropriate.
526 /// One of the @link memory_adaptors adaptors for member
527 /// pointers@endlink.
528 template<typename _Ret
, typename _Tp
>
529 class mem_fun_t
: public unary_function
<_Tp
*, _Ret
>
533 mem_fun_t(_Ret (_Tp::*__pf
)())
537 operator()(_Tp
* __p
) const
538 { return (__p
->*_M_f
)(); }
544 /// One of the @link memory_adaptors adaptors for member
545 /// pointers@endlink.
546 template<typename _Ret
, typename _Tp
>
547 class const_mem_fun_t
: public unary_function
<const _Tp
*, _Ret
>
551 const_mem_fun_t(_Ret (_Tp::*__pf
)() const)
555 operator()(const _Tp
* __p
) const
556 { return (__p
->*_M_f
)(); }
559 _Ret (_Tp::*_M_f
)() const;
562 /// One of the @link memory_adaptors adaptors for member
563 /// pointers@endlink.
564 template<typename _Ret
, typename _Tp
>
565 class mem_fun_ref_t
: public unary_function
<_Tp
, _Ret
>
569 mem_fun_ref_t(_Ret (_Tp::*__pf
)())
573 operator()(_Tp
& __r
) const
574 { return (__r
.*_M_f
)(); }
580 /// One of the @link memory_adaptors adaptors for member
581 /// pointers@endlink.
582 template<typename _Ret
, typename _Tp
>
583 class const_mem_fun_ref_t
: public unary_function
<_Tp
, _Ret
>
587 const_mem_fun_ref_t(_Ret (_Tp::*__pf
)() const)
591 operator()(const _Tp
& __r
) const
592 { return (__r
.*_M_f
)(); }
595 _Ret (_Tp::*_M_f
)() const;
598 /// One of the @link memory_adaptors adaptors for member
599 /// pointers@endlink.
600 template<typename _Ret
, typename _Tp
, typename _Arg
>
601 class mem_fun1_t
: public binary_function
<_Tp
*, _Arg
, _Ret
>
605 mem_fun1_t(_Ret (_Tp::*__pf
)(_Arg
))
609 operator()(_Tp
* __p
, _Arg __x
) const
610 { return (__p
->*_M_f
)(__x
); }
613 _Ret (_Tp::*_M_f
)(_Arg
);
616 /// One of the @link memory_adaptors adaptors for member
617 /// pointers@endlink.
618 template<typename _Ret
, typename _Tp
, typename _Arg
>
619 class const_mem_fun1_t
: public binary_function
<const _Tp
*, _Arg
, _Ret
>
623 const_mem_fun1_t(_Ret (_Tp::*__pf
)(_Arg
) const)
627 operator()(const _Tp
* __p
, _Arg __x
) const
628 { return (__p
->*_M_f
)(__x
); }
631 _Ret (_Tp::*_M_f
)(_Arg
) const;
634 /// One of the @link memory_adaptors adaptors for member
635 /// pointers@endlink.
636 template<typename _Ret
, typename _Tp
, typename _Arg
>
637 class mem_fun1_ref_t
: public binary_function
<_Tp
, _Arg
, _Ret
>
641 mem_fun1_ref_t(_Ret (_Tp::*__pf
)(_Arg
))
645 operator()(_Tp
& __r
, _Arg __x
) const
646 { return (__r
.*_M_f
)(__x
); }
649 _Ret (_Tp::*_M_f
)(_Arg
);
652 /// One of the @link memory_adaptors adaptors for member
653 /// pointers@endlink.
654 template<typename _Ret
, typename _Tp
, typename _Arg
>
655 class const_mem_fun1_ref_t
: public binary_function
<_Tp
, _Arg
, _Ret
>
659 const_mem_fun1_ref_t(_Ret (_Tp::*__pf
)(_Arg
) const)
663 operator()(const _Tp
& __r
, _Arg __x
) const
664 { return (__r
.*_M_f
)(__x
); }
667 _Ret (_Tp::*_M_f
)(_Arg
) const;
670 // Mem_fun adaptor helper functions. There are only two:
671 // mem_fun and mem_fun_ref.
672 template<typename _Ret
, typename _Tp
>
673 inline mem_fun_t
<_Ret
, _Tp
>
674 mem_fun(_Ret (_Tp::*__f
)())
675 { return mem_fun_t
<_Ret
, _Tp
>(__f
); }
677 template<typename _Ret
, typename _Tp
>
678 inline const_mem_fun_t
<_Ret
, _Tp
>
679 mem_fun(_Ret (_Tp::*__f
)() const)
680 { return const_mem_fun_t
<_Ret
, _Tp
>(__f
); }
682 template<typename _Ret
, typename _Tp
>
683 inline mem_fun_ref_t
<_Ret
, _Tp
>
684 mem_fun_ref(_Ret (_Tp::*__f
)())
685 { return mem_fun_ref_t
<_Ret
, _Tp
>(__f
); }
687 template<typename _Ret
, typename _Tp
>
688 inline const_mem_fun_ref_t
<_Ret
, _Tp
>
689 mem_fun_ref(_Ret (_Tp::*__f
)() const)
690 { return const_mem_fun_ref_t
<_Ret
, _Tp
>(__f
); }
692 template<typename _Ret
, typename _Tp
, typename _Arg
>
693 inline mem_fun1_t
<_Ret
, _Tp
, _Arg
>
694 mem_fun(_Ret (_Tp::*__f
)(_Arg
))
695 { return mem_fun1_t
<_Ret
, _Tp
, _Arg
>(__f
); }
697 template<typename _Ret
, typename _Tp
, typename _Arg
>
698 inline const_mem_fun1_t
<_Ret
, _Tp
, _Arg
>
699 mem_fun(_Ret (_Tp::*__f
)(_Arg
) const)
700 { return const_mem_fun1_t
<_Ret
, _Tp
, _Arg
>(__f
); }
702 template<typename _Ret
, typename _Tp
, typename _Arg
>
703 inline mem_fun1_ref_t
<_Ret
, _Tp
, _Arg
>
704 mem_fun_ref(_Ret (_Tp::*__f
)(_Arg
))
705 { return mem_fun1_ref_t
<_Ret
, _Tp
, _Arg
>(__f
); }
707 template<typename _Ret
, typename _Tp
, typename _Arg
>
708 inline const_mem_fun1_ref_t
<_Ret
, _Tp
, _Arg
>
709 mem_fun_ref(_Ret (_Tp::*__f
)(_Arg
) const)
710 { return const_mem_fun1_ref_t
<_Ret
, _Tp
, _Arg
>(__f
); }
714 _GLIBCXX_END_NAMESPACE
716 #if !defined(__GXX_EXPERIMENTAL_CXX0X__) || _GLIBCXX_DEPRECATED
717 # include <backward/binders.h>
720 #endif /* _STL_FUNCTION_H */