1// <functional> -*- C++ -*-
2
3// Copyright (C) 2001-2020 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 * Copyright (c) 1997
27 * Silicon Graphics Computer Systems, Inc.
28 *
29 * Permission to use, copy, modify, distribute and sell this software
30 * and its documentation for any purpose is hereby granted without fee,
31 * provided that the above copyright notice appear in all copies and
32 * that both that copyright notice and this permission notice appear
33 * in supporting documentation.  Silicon Graphics makes no
34 * representations about the suitability of this software for any
35 * purpose.  It is provided "as is" without express or implied warranty.
36 *
37 */
38
39/** @file include/functional
40 *  This is a Standard C++ Library header.
41 */
42
43#ifndef _GLIBCXX_FUNCTIONAL
44#define _GLIBCXX_FUNCTIONAL 1
45
46#pragma GCC system_header
47
48#include <bits/c++config.h>
49#include <bits/stl_function.h>
50
51#if __cplusplus >= 201103L
52
53#include <new>
54#include <tuple>
55#include <type_traits>
56#include <bits/functional_hash.h>
57#include <bits/invoke.h>
58#include <bits/refwrap.h>	// std::reference_wrapper and _Mem_fn_traits
59#include <bits/std_function.h>	// std::function
60#if __cplusplus > 201402L
61# include <unordered_map>
62# include <vector>
63# include <array>
64# include <utility>
65# include <bits/stl_algo.h>
66#endif
67#if __cplusplus > 201703L
68# include <bits/range_cmp.h>
69# include <compare>
70#endif
71
72namespace std _GLIBCXX_VISIBILITY(default)
73{
74_GLIBCXX_BEGIN_NAMESPACE_VERSION
75
76#if __cplusplus >= 201703L
77# define __cpp_lib_invoke 201411L
78# if __cplusplus > 201703L
79#  define __cpp_lib_constexpr_functional 201907L
80# endif
81
82  /// Invoke a callable object.
83  template<typename _Callable, typename... _Args>
84    inline _GLIBCXX20_CONSTEXPR invoke_result_t<_Callable, _Args...>
85    invoke(_Callable&& __fn, _Args&&... __args)
86    noexcept(is_nothrow_invocable_v<_Callable, _Args...>)
87    {
88      return std::__invoke(std::forward<_Callable>(__fn),
89			   std::forward<_Args>(__args)...);
90    }
91#endif // C++17
92
93  template<typename _MemFunPtr,
94	   bool __is_mem_fn = is_member_function_pointer<_MemFunPtr>::value>
95    class _Mem_fn_base
96    : public _Mem_fn_traits<_MemFunPtr>::__maybe_type
97    {
98      using _Traits = _Mem_fn_traits<_MemFunPtr>;
99
100      using _Arity = typename _Traits::__arity;
101      using _Varargs = typename _Traits::__vararg;
102
103      template<typename _Func, typename... _BoundArgs>
104	friend struct _Bind_check_arity;
105
106      _MemFunPtr _M_pmf;
107
108    public:
109
110      using result_type = typename _Traits::__result_type;
111
112      explicit constexpr
113      _Mem_fn_base(_MemFunPtr __pmf) noexcept : _M_pmf(__pmf) { }
114
115      template<typename... _Args>
116	_GLIBCXX20_CONSTEXPR
117	auto
118	operator()(_Args&&... __args) const
119	noexcept(noexcept(
120	      std::__invoke(_M_pmf, std::forward<_Args>(__args)...)))
121	-> decltype(std::__invoke(_M_pmf, std::forward<_Args>(__args)...))
122	{ return std::__invoke(_M_pmf, std::forward<_Args>(__args)...); }
123    };
124
125  // Partial specialization for member object pointers.
126  template<typename _MemObjPtr>
127    class _Mem_fn_base<_MemObjPtr, false>
128    {
129      using _Arity = integral_constant<size_t, 0>;
130      using _Varargs = false_type;
131
132      template<typename _Func, typename... _BoundArgs>
133	friend struct _Bind_check_arity;
134
135      _MemObjPtr _M_pm;
136
137    public:
138      explicit constexpr
139      _Mem_fn_base(_MemObjPtr __pm) noexcept : _M_pm(__pm) { }
140
141      template<typename _Tp>
142	_GLIBCXX20_CONSTEXPR
143	auto
144	operator()(_Tp&& __obj) const
145	noexcept(noexcept(std::__invoke(_M_pm, std::forward<_Tp>(__obj))))
146	-> decltype(std::__invoke(_M_pm, std::forward<_Tp>(__obj)))
147	{ return std::__invoke(_M_pm, std::forward<_Tp>(__obj)); }
148    };
149
150  template<typename _MemberPointer>
151    struct _Mem_fn; // undefined
152
153  template<typename _Res, typename _Class>
154    struct _Mem_fn<_Res _Class::*>
155    : _Mem_fn_base<_Res _Class::*>
156    {
157      using _Mem_fn_base<_Res _Class::*>::_Mem_fn_base;
158    };
159
160  // _GLIBCXX_RESOLVE_LIB_DEFECTS
161  // 2048.  Unnecessary mem_fn overloads
162  /**
163   *  @brief Returns a function object that forwards to the member
164   *  pointer @a pm.
165   *  @ingroup functors
166   */
167  template<typename _Tp, typename _Class>
168    _GLIBCXX20_CONSTEXPR
169    inline _Mem_fn<_Tp _Class::*>
170    mem_fn(_Tp _Class::* __pm) noexcept
171    {
172      return _Mem_fn<_Tp _Class::*>(__pm);
173    }
174
175  /**
176   *  @brief Determines if the given type _Tp is a function object that
177   *  should be treated as a subexpression when evaluating calls to
178   *  function objects returned by bind().
179   *
180   *  C++11 [func.bind.isbind].
181   *  @ingroup binders
182   */
183  template<typename _Tp>
184    struct is_bind_expression
185    : public false_type { };
186
187  /**
188   *  @brief Determines if the given type _Tp is a placeholder in a
189   *  bind() expression and, if so, which placeholder it is.
190   *
191   *  C++11 [func.bind.isplace].
192   *  @ingroup binders
193   */
194  template<typename _Tp>
195    struct is_placeholder
196    : public integral_constant<int, 0>
197    { };
198
199#if __cplusplus > 201402L
200  template <typename _Tp> inline constexpr bool is_bind_expression_v
201    = is_bind_expression<_Tp>::value;
202  template <typename _Tp> inline constexpr int is_placeholder_v
203    = is_placeholder<_Tp>::value;
204#endif // C++17
205
206  /** @brief The type of placeholder objects defined by libstdc++.
207   *  @ingroup binders
208   */
209  template<int _Num> struct _Placeholder { };
210
211  /** @namespace std::placeholders
212   *  @brief ISO C++ 2011 namespace for std::bind placeholders.
213   *  @ingroup binders
214   */
215  namespace placeholders
216  {
217  /* Define a large number of placeholders. There is no way to
218   * simplify this with variadic templates, because we're introducing
219   * unique names for each.
220   */
221    extern const _Placeholder<1> _1;
222    extern const _Placeholder<2> _2;
223    extern const _Placeholder<3> _3;
224    extern const _Placeholder<4> _4;
225    extern const _Placeholder<5> _5;
226    extern const _Placeholder<6> _6;
227    extern const _Placeholder<7> _7;
228    extern const _Placeholder<8> _8;
229    extern const _Placeholder<9> _9;
230    extern const _Placeholder<10> _10;
231    extern const _Placeholder<11> _11;
232    extern const _Placeholder<12> _12;
233    extern const _Placeholder<13> _13;
234    extern const _Placeholder<14> _14;
235    extern const _Placeholder<15> _15;
236    extern const _Placeholder<16> _16;
237    extern const _Placeholder<17> _17;
238    extern const _Placeholder<18> _18;
239    extern const _Placeholder<19> _19;
240    extern const _Placeholder<20> _20;
241    extern const _Placeholder<21> _21;
242    extern const _Placeholder<22> _22;
243    extern const _Placeholder<23> _23;
244    extern const _Placeholder<24> _24;
245    extern const _Placeholder<25> _25;
246    extern const _Placeholder<26> _26;
247    extern const _Placeholder<27> _27;
248    extern const _Placeholder<28> _28;
249    extern const _Placeholder<29> _29;
250  }
251
252  /**
253   *  Partial specialization of is_placeholder that provides the placeholder
254   *  number for the placeholder objects defined by libstdc++.
255   *  @ingroup binders
256   */
257  template<int _Num>
258    struct is_placeholder<_Placeholder<_Num> >
259    : public integral_constant<int, _Num>
260    { };
261
262  template<int _Num>
263    struct is_placeholder<const _Placeholder<_Num> >
264    : public integral_constant<int, _Num>
265    { };
266
267
268  // Like tuple_element_t but SFINAE-friendly.
269  template<std::size_t __i, typename _Tuple>
270    using _Safe_tuple_element_t
271      = typename enable_if<(__i < tuple_size<_Tuple>::value),
272			   tuple_element<__i, _Tuple>>::type::type;
273
274  /**
275   *  Maps an argument to bind() into an actual argument to the bound
276   *  function object [func.bind.bind]/10. Only the first parameter should
277   *  be specified: the rest are used to determine among the various
278   *  implementations. Note that, although this class is a function
279   *  object, it isn't entirely normal because it takes only two
280   *  parameters regardless of the number of parameters passed to the
281   *  bind expression. The first parameter is the bound argument and
282   *  the second parameter is a tuple containing references to the
283   *  rest of the arguments.
284   */
285  template<typename _Arg,
286	   bool _IsBindExp = is_bind_expression<_Arg>::value,
287	   bool _IsPlaceholder = (is_placeholder<_Arg>::value > 0)>
288    class _Mu;
289
290  /**
291   *  If the argument is reference_wrapper<_Tp>, returns the
292   *  underlying reference.
293   *  C++11 [func.bind.bind] p10 bullet 1.
294   */
295  template<typename _Tp>
296    class _Mu<reference_wrapper<_Tp>, false, false>
297    {
298    public:
299      /* Note: This won't actually work for const volatile
300       * reference_wrappers, because reference_wrapper::get() is const
301       * but not volatile-qualified. This might be a defect in the TR.
302       */
303      template<typename _CVRef, typename _Tuple>
304	_GLIBCXX20_CONSTEXPR
305	_Tp&
306	operator()(_CVRef& __arg, _Tuple&) const volatile
307	{ return __arg.get(); }
308    };
309
310  /**
311   *  If the argument is a bind expression, we invoke the underlying
312   *  function object with the same cv-qualifiers as we are given and
313   *  pass along all of our arguments (unwrapped).
314   *  C++11 [func.bind.bind] p10 bullet 2.
315   */
316  template<typename _Arg>
317    class _Mu<_Arg, true, false>
318    {
319    public:
320      template<typename _CVArg, typename... _Args>
321	_GLIBCXX20_CONSTEXPR
322	auto
323	operator()(_CVArg& __arg,
324		   tuple<_Args...>& __tuple) const volatile
325	-> decltype(__arg(declval<_Args>()...))
326	{
327	  // Construct an index tuple and forward to __call
328	  typedef typename _Build_index_tuple<sizeof...(_Args)>::__type
329	    _Indexes;
330	  return this->__call(__arg, __tuple, _Indexes());
331	}
332
333    private:
334      // Invokes the underlying function object __arg by unpacking all
335      // of the arguments in the tuple.
336      template<typename _CVArg, typename... _Args, std::size_t... _Indexes>
337	_GLIBCXX20_CONSTEXPR
338	auto
339	__call(_CVArg& __arg, tuple<_Args...>& __tuple,
340	       const _Index_tuple<_Indexes...>&) const volatile
341	-> decltype(__arg(declval<_Args>()...))
342	{
343	  return __arg(std::get<_Indexes>(std::move(__tuple))...);
344	}
345    };
346
347  /**
348   *  If the argument is a placeholder for the Nth argument, returns
349   *  a reference to the Nth argument to the bind function object.
350   *  C++11 [func.bind.bind] p10 bullet 3.
351   */
352  template<typename _Arg>
353    class _Mu<_Arg, false, true>
354    {
355    public:
356      template<typename _Tuple>
357	_GLIBCXX20_CONSTEXPR
358	_Safe_tuple_element_t<(is_placeholder<_Arg>::value - 1), _Tuple>&&
359	operator()(const volatile _Arg&, _Tuple& __tuple) const volatile
360	{
361	  return
362	    ::std::get<(is_placeholder<_Arg>::value - 1)>(std::move(__tuple));
363	}
364    };
365
366  /**
367   *  If the argument is just a value, returns a reference to that
368   *  value. The cv-qualifiers on the reference are determined by the caller.
369   *  C++11 [func.bind.bind] p10 bullet 4.
370   */
371  template<typename _Arg>
372    class _Mu<_Arg, false, false>
373    {
374    public:
375      template<typename _CVArg, typename _Tuple>
376	_GLIBCXX20_CONSTEXPR
377	_CVArg&&
378	operator()(_CVArg&& __arg, _Tuple&) const volatile
379	{ return std::forward<_CVArg>(__arg); }
380    };
381
382  // std::get<I> for volatile-qualified tuples
383  template<std::size_t _Ind, typename... _Tp>
384    inline auto
385    __volget(volatile tuple<_Tp...>& __tuple)
386    -> __tuple_element_t<_Ind, tuple<_Tp...>> volatile&
387    { return std::get<_Ind>(const_cast<tuple<_Tp...>&>(__tuple)); }
388
389  // std::get<I> for const-volatile-qualified tuples
390  template<std::size_t _Ind, typename... _Tp>
391    inline auto
392    __volget(const volatile tuple<_Tp...>& __tuple)
393    -> __tuple_element_t<_Ind, tuple<_Tp...>> const volatile&
394    { return std::get<_Ind>(const_cast<const tuple<_Tp...>&>(__tuple)); }
395
396  /// Type of the function object returned from bind().
397  template<typename _Signature>
398    struct _Bind;
399
400   template<typename _Functor, typename... _Bound_args>
401    class _Bind<_Functor(_Bound_args...)>
402    : public _Weak_result_type<_Functor>
403    {
404      typedef typename _Build_index_tuple<sizeof...(_Bound_args)>::__type
405	_Bound_indexes;
406
407      _Functor _M_f;
408      tuple<_Bound_args...> _M_bound_args;
409
410      // Call unqualified
411      template<typename _Result, typename... _Args, std::size_t... _Indexes>
412	_GLIBCXX20_CONSTEXPR
413	_Result
414	__call(tuple<_Args...>&& __args, _Index_tuple<_Indexes...>)
415	{
416	  return std::__invoke(_M_f,
417	      _Mu<_Bound_args>()(std::get<_Indexes>(_M_bound_args), __args)...
418	      );
419	}
420
421      // Call as const
422      template<typename _Result, typename... _Args, std::size_t... _Indexes>
423	_GLIBCXX20_CONSTEXPR
424	_Result
425	__call_c(tuple<_Args...>&& __args, _Index_tuple<_Indexes...>) const
426	{
427	  return std::__invoke(_M_f,
428	      _Mu<_Bound_args>()(std::get<_Indexes>(_M_bound_args), __args)...
429	      );
430	}
431
432      // Call as volatile
433      template<typename _Result, typename... _Args, std::size_t... _Indexes>
434	_Result
435	__call_v(tuple<_Args...>&& __args,
436		 _Index_tuple<_Indexes...>) volatile
437	{
438	  return std::__invoke(_M_f,
439	      _Mu<_Bound_args>()(__volget<_Indexes>(_M_bound_args), __args)...
440	      );
441	}
442
443      // Call as const volatile
444      template<typename _Result, typename... _Args, std::size_t... _Indexes>
445	_Result
446	__call_c_v(tuple<_Args...>&& __args,
447		   _Index_tuple<_Indexes...>) const volatile
448	{
449	  return std::__invoke(_M_f,
450	      _Mu<_Bound_args>()(__volget<_Indexes>(_M_bound_args), __args)...
451	      );
452	}
453
454      template<typename _BoundArg, typename _CallArgs>
455	using _Mu_type = decltype(
456	    _Mu<typename remove_cv<_BoundArg>::type>()(
457	      std::declval<_BoundArg&>(), std::declval<_CallArgs&>()) );
458
459      template<typename _Fn, typename _CallArgs, typename... _BArgs>
460	using _Res_type_impl
461	  = typename result_of< _Fn&(_Mu_type<_BArgs, _CallArgs>&&...) >::type;
462
463      template<typename _CallArgs>
464	using _Res_type = _Res_type_impl<_Functor, _CallArgs, _Bound_args...>;
465
466      template<typename _CallArgs>
467	using __dependent = typename
468	  enable_if<bool(tuple_size<_CallArgs>::value+1), _Functor>::type;
469
470      template<typename _CallArgs, template<class> class __cv_quals>
471	using _Res_type_cv = _Res_type_impl<
472	  typename __cv_quals<__dependent<_CallArgs>>::type,
473	  _CallArgs,
474	  typename __cv_quals<_Bound_args>::type...>;
475
476     public:
477      template<typename... _Args>
478	explicit _GLIBCXX20_CONSTEXPR
479	_Bind(const _Functor& __f, _Args&&... __args)
480	: _M_f(__f), _M_bound_args(std::forward<_Args>(__args)...)
481	{ }
482
483      template<typename... _Args>
484	explicit _GLIBCXX20_CONSTEXPR
485	_Bind(_Functor&& __f, _Args&&... __args)
486	: _M_f(std::move(__f)), _M_bound_args(std::forward<_Args>(__args)...)
487	{ }
488
489      _Bind(const _Bind&) = default;
490      _Bind(_Bind&&) = default;
491
492      // Call unqualified
493      template<typename... _Args,
494	       typename _Result = _Res_type<tuple<_Args...>>>
495	_GLIBCXX20_CONSTEXPR
496	_Result
497	operator()(_Args&&... __args)
498	{
499	  return this->__call<_Result>(
500	      std::forward_as_tuple(std::forward<_Args>(__args)...),
501	      _Bound_indexes());
502	}
503
504      // Call as const
505      template<typename... _Args,
506	       typename _Result = _Res_type_cv<tuple<_Args...>, add_const>>
507	_GLIBCXX20_CONSTEXPR
508	_Result
509	operator()(_Args&&... __args) const
510	{
511	  return this->__call_c<_Result>(
512	      std::forward_as_tuple(std::forward<_Args>(__args)...),
513	      _Bound_indexes());
514	}
515
516#if __cplusplus > 201402L
517# define _GLIBCXX_DEPR_BIND \
518      [[deprecated("std::bind does not support volatile in C++17")]]
519#else
520# define _GLIBCXX_DEPR_BIND
521#endif
522      // Call as volatile
523      template<typename... _Args,
524	       typename _Result = _Res_type_cv<tuple<_Args...>, add_volatile>>
525	_GLIBCXX_DEPR_BIND
526	_Result
527	operator()(_Args&&... __args) volatile
528	{
529	  return this->__call_v<_Result>(
530	      std::forward_as_tuple(std::forward<_Args>(__args)...),
531	      _Bound_indexes());
532	}
533
534      // Call as const volatile
535      template<typename... _Args,
536	       typename _Result = _Res_type_cv<tuple<_Args...>, add_cv>>
537	_GLIBCXX_DEPR_BIND
538	_Result
539	operator()(_Args&&... __args) const volatile
540	{
541	  return this->__call_c_v<_Result>(
542	      std::forward_as_tuple(std::forward<_Args>(__args)...),
543	      _Bound_indexes());
544	}
545    };
546
547  /// Type of the function object returned from bind<R>().
548  template<typename _Result, typename _Signature>
549    struct _Bind_result;
550
551  template<typename _Result, typename _Functor, typename... _Bound_args>
552    class _Bind_result<_Result, _Functor(_Bound_args...)>
553    {
554      typedef typename _Build_index_tuple<sizeof...(_Bound_args)>::__type
555	_Bound_indexes;
556
557      _Functor _M_f;
558      tuple<_Bound_args...> _M_bound_args;
559
560      // Call unqualified
561      template<typename _Res, typename... _Args, std::size_t... _Indexes>
562	_GLIBCXX20_CONSTEXPR
563	_Res
564	__call(tuple<_Args...>&& __args, _Index_tuple<_Indexes...>)
565	{
566	  return std::__invoke_r<_Res>(_M_f, _Mu<_Bound_args>()
567		      (std::get<_Indexes>(_M_bound_args), __args)...);
568	}
569
570      // Call as const
571      template<typename _Res, typename... _Args, std::size_t... _Indexes>
572	_GLIBCXX20_CONSTEXPR
573	_Res
574	__call(tuple<_Args...>&& __args, _Index_tuple<_Indexes...>) const
575	{
576	  return std::__invoke_r<_Res>(_M_f, _Mu<_Bound_args>()
577		      (std::get<_Indexes>(_M_bound_args), __args)...);
578	}
579
580      // Call as volatile
581      template<typename _Res, typename... _Args, std::size_t... _Indexes>
582	_GLIBCXX20_CONSTEXPR
583	_Res
584	__call(tuple<_Args...>&& __args, _Index_tuple<_Indexes...>) volatile
585	{
586	  return std::__invoke_r<_Res>(_M_f, _Mu<_Bound_args>()
587		      (__volget<_Indexes>(_M_bound_args), __args)...);
588	}
589
590      // Call as const volatile
591      template<typename _Res, typename... _Args, std::size_t... _Indexes>
592	_GLIBCXX20_CONSTEXPR
593	_Res
594	__call(tuple<_Args...>&& __args,
595	       _Index_tuple<_Indexes...>) const volatile
596	{
597	  return std::__invoke_r<_Res>(_M_f, _Mu<_Bound_args>()
598		      (__volget<_Indexes>(_M_bound_args), __args)...);
599	}
600
601    public:
602      typedef _Result result_type;
603
604      template<typename... _Args>
605	explicit _GLIBCXX20_CONSTEXPR
606	_Bind_result(const _Functor& __f, _Args&&... __args)
607	: _M_f(__f), _M_bound_args(std::forward<_Args>(__args)...)
608	{ }
609
610      template<typename... _Args>
611	explicit _GLIBCXX20_CONSTEXPR
612	_Bind_result(_Functor&& __f, _Args&&... __args)
613	: _M_f(std::move(__f)), _M_bound_args(std::forward<_Args>(__args)...)
614	{ }
615
616      _Bind_result(const _Bind_result&) = default;
617      _Bind_result(_Bind_result&&) = default;
618
619      // Call unqualified
620      template<typename... _Args>
621	_GLIBCXX20_CONSTEXPR
622	result_type
623	operator()(_Args&&... __args)
624	{
625	  return this->__call<_Result>(
626	      std::forward_as_tuple(std::forward<_Args>(__args)...),
627	      _Bound_indexes());
628	}
629
630      // Call as const
631      template<typename... _Args>
632	_GLIBCXX20_CONSTEXPR
633	result_type
634	operator()(_Args&&... __args) const
635	{
636	  return this->__call<_Result>(
637	      std::forward_as_tuple(std::forward<_Args>(__args)...),
638	      _Bound_indexes());
639	}
640
641      // Call as volatile
642      template<typename... _Args>
643	_GLIBCXX_DEPR_BIND
644	result_type
645	operator()(_Args&&... __args) volatile
646	{
647	  return this->__call<_Result>(
648	      std::forward_as_tuple(std::forward<_Args>(__args)...),
649	      _Bound_indexes());
650	}
651
652      // Call as const volatile
653      template<typename... _Args>
654	_GLIBCXX_DEPR_BIND
655	result_type
656	operator()(_Args&&... __args) const volatile
657	{
658	  return this->__call<_Result>(
659	      std::forward_as_tuple(std::forward<_Args>(__args)...),
660	      _Bound_indexes());
661	}
662    };
663#undef _GLIBCXX_DEPR_BIND
664
665  /**
666   *  @brief Class template _Bind is always a bind expression.
667   *  @ingroup binders
668   */
669  template<typename _Signature>
670    struct is_bind_expression<_Bind<_Signature> >
671    : public true_type { };
672
673  /**
674   *  @brief Class template _Bind is always a bind expression.
675   *  @ingroup binders
676   */
677  template<typename _Signature>
678    struct is_bind_expression<const _Bind<_Signature> >
679    : public true_type { };
680
681  /**
682   *  @brief Class template _Bind is always a bind expression.
683   *  @ingroup binders
684   */
685  template<typename _Signature>
686    struct is_bind_expression<volatile _Bind<_Signature> >
687    : public true_type { };
688
689  /**
690   *  @brief Class template _Bind is always a bind expression.
691   *  @ingroup binders
692   */
693  template<typename _Signature>
694    struct is_bind_expression<const volatile _Bind<_Signature>>
695    : public true_type { };
696
697  /**
698   *  @brief Class template _Bind_result is always a bind expression.
699   *  @ingroup binders
700   */
701  template<typename _Result, typename _Signature>
702    struct is_bind_expression<_Bind_result<_Result, _Signature>>
703    : public true_type { };
704
705  /**
706   *  @brief Class template _Bind_result is always a bind expression.
707   *  @ingroup binders
708   */
709  template<typename _Result, typename _Signature>
710    struct is_bind_expression<const _Bind_result<_Result, _Signature>>
711    : public true_type { };
712
713  /**
714   *  @brief Class template _Bind_result is always a bind expression.
715   *  @ingroup binders
716   */
717  template<typename _Result, typename _Signature>
718    struct is_bind_expression<volatile _Bind_result<_Result, _Signature>>
719    : public true_type { };
720
721  /**
722   *  @brief Class template _Bind_result is always a bind expression.
723   *  @ingroup binders
724   */
725  template<typename _Result, typename _Signature>
726    struct is_bind_expression<const volatile _Bind_result<_Result, _Signature>>
727    : public true_type { };
728
729  template<typename _Func, typename... _BoundArgs>
730    struct _Bind_check_arity { };
731
732  template<typename _Ret, typename... _Args, typename... _BoundArgs>
733    struct _Bind_check_arity<_Ret (*)(_Args...), _BoundArgs...>
734    {
735      static_assert(sizeof...(_BoundArgs) == sizeof...(_Args),
736                   "Wrong number of arguments for function");
737    };
738
739  template<typename _Ret, typename... _Args, typename... _BoundArgs>
740    struct _Bind_check_arity<_Ret (*)(_Args......), _BoundArgs...>
741    {
742      static_assert(sizeof...(_BoundArgs) >= sizeof...(_Args),
743                   "Wrong number of arguments for function");
744    };
745
746  template<typename _Tp, typename _Class, typename... _BoundArgs>
747    struct _Bind_check_arity<_Tp _Class::*, _BoundArgs...>
748    {
749      using _Arity = typename _Mem_fn<_Tp _Class::*>::_Arity;
750      using _Varargs = typename _Mem_fn<_Tp _Class::*>::_Varargs;
751      static_assert(_Varargs::value
752		    ? sizeof...(_BoundArgs) >= _Arity::value + 1
753		    : sizeof...(_BoundArgs) == _Arity::value + 1,
754		    "Wrong number of arguments for pointer-to-member");
755    };
756
757  // Trait type used to remove std::bind() from overload set via SFINAE
758  // when first argument has integer type, so that std::bind() will
759  // not be a better match than ::bind() from the BSD Sockets API.
760  template<typename _Tp, typename _Tp2 = typename decay<_Tp>::type>
761    using __is_socketlike = __or_<is_integral<_Tp2>, is_enum<_Tp2>>;
762
763  template<bool _SocketLike, typename _Func, typename... _BoundArgs>
764    struct _Bind_helper
765    : _Bind_check_arity<typename decay<_Func>::type, _BoundArgs...>
766    {
767      typedef typename decay<_Func>::type __func_type;
768      typedef _Bind<__func_type(typename decay<_BoundArgs>::type...)> type;
769    };
770
771  // Partial specialization for is_socketlike == true, does not define
772  // nested type so std::bind() will not participate in overload resolution
773  // when the first argument might be a socket file descriptor.
774  template<typename _Func, typename... _BoundArgs>
775    struct _Bind_helper<true, _Func, _BoundArgs...>
776    { };
777
778  /**
779   *  @brief Function template for std::bind.
780   *  @ingroup binders
781   */
782  template<typename _Func, typename... _BoundArgs>
783    inline _GLIBCXX20_CONSTEXPR typename
784    _Bind_helper<__is_socketlike<_Func>::value, _Func, _BoundArgs...>::type
785    bind(_Func&& __f, _BoundArgs&&... __args)
786    {
787      typedef _Bind_helper<false, _Func, _BoundArgs...> __helper_type;
788      return typename __helper_type::type(std::forward<_Func>(__f),
789					  std::forward<_BoundArgs>(__args)...);
790    }
791
792  template<typename _Result, typename _Func, typename... _BoundArgs>
793    struct _Bindres_helper
794    : _Bind_check_arity<typename decay<_Func>::type, _BoundArgs...>
795    {
796      typedef typename decay<_Func>::type __functor_type;
797      typedef _Bind_result<_Result,
798			   __functor_type(typename decay<_BoundArgs>::type...)>
799	type;
800    };
801
802  /**
803   *  @brief Function template for std::bind<R>.
804   *  @ingroup binders
805   */
806  template<typename _Result, typename _Func, typename... _BoundArgs>
807    inline _GLIBCXX20_CONSTEXPR
808    typename _Bindres_helper<_Result, _Func, _BoundArgs...>::type
809    bind(_Func&& __f, _BoundArgs&&... __args)
810    {
811      typedef _Bindres_helper<_Result, _Func, _BoundArgs...> __helper_type;
812      return typename __helper_type::type(std::forward<_Func>(__f),
813					  std::forward<_BoundArgs>(__args)...);
814    }
815
816#if __cplusplus > 201703L
817#define __cpp_lib_bind_front 201907L
818
819  template<typename _Fd, typename... _BoundArgs>
820    struct _Bind_front
821    {
822      static_assert(is_move_constructible_v<_Fd>);
823      static_assert((is_move_constructible_v<_BoundArgs> && ...));
824
825      // First parameter is to ensure this constructor is never used
826      // instead of the copy/move constructor.
827      template<typename _Fn, typename... _Args>
828	explicit constexpr
829	_Bind_front(int, _Fn&& __fn, _Args&&... __args)
830	noexcept(__and_<is_nothrow_constructible<_Fd, _Fn>,
831			is_nothrow_constructible<_BoundArgs, _Args>...>::value)
832	: _M_fd(std::forward<_Fn>(__fn)),
833	  _M_bound_args(std::forward<_Args>(__args)...)
834	{ static_assert(sizeof...(_Args) == sizeof...(_BoundArgs)); }
835
836      _Bind_front(const _Bind_front&) = default;
837      _Bind_front(_Bind_front&&) = default;
838      _Bind_front& operator=(const _Bind_front&) = default;
839      _Bind_front& operator=(_Bind_front&&) = default;
840      ~_Bind_front() = default;
841
842      template<typename... _CallArgs>
843	constexpr
844	invoke_result_t<_Fd&, _BoundArgs&..., _CallArgs...>
845	operator()(_CallArgs&&... __call_args) &
846	noexcept(is_nothrow_invocable_v<_Fd&, _BoundArgs&..., _CallArgs...>)
847	{
848	  return _S_call(*this, _BoundIndices(),
849	      std::forward<_CallArgs>(__call_args)...);
850	}
851
852      template<typename... _CallArgs>
853	constexpr
854	invoke_result_t<const _Fd&, const _BoundArgs&..., _CallArgs...>
855	operator()(_CallArgs&&... __call_args) const &
856	noexcept(is_nothrow_invocable_v<const _Fd&, const _BoundArgs&...,
857					_CallArgs...>)
858	{
859	  return _S_call(*this, _BoundIndices(),
860	      std::forward<_CallArgs>(__call_args)...);
861	}
862
863      template<typename... _CallArgs>
864	constexpr
865	invoke_result_t<_Fd, _BoundArgs..., _CallArgs...>
866	operator()(_CallArgs&&... __call_args) &&
867	noexcept(is_nothrow_invocable_v<_Fd, _BoundArgs..., _CallArgs...>)
868	{
869	  return _S_call(std::move(*this), _BoundIndices(),
870	      std::forward<_CallArgs>(__call_args)...);
871	}
872
873      template<typename... _CallArgs>
874	constexpr
875	invoke_result_t<const _Fd, const _BoundArgs..., _CallArgs...>
876	operator()(_CallArgs&&... __call_args) const &&
877	noexcept(is_nothrow_invocable_v<const _Fd, const _BoundArgs...,
878					_CallArgs...>)
879	{
880	  return _S_call(std::move(*this), _BoundIndices(),
881	      std::forward<_CallArgs>(__call_args)...);
882	}
883
884    private:
885      using _BoundIndices = index_sequence_for<_BoundArgs...>;
886
887      template<typename _Tp, size_t... _Ind, typename... _CallArgs>
888	static constexpr
889	decltype(auto)
890	_S_call(_Tp&& __g, index_sequence<_Ind...>, _CallArgs&&... __call_args)
891	{
892	  return std::invoke(std::forward<_Tp>(__g)._M_fd,
893	      std::get<_Ind>(std::forward<_Tp>(__g)._M_bound_args)...,
894	      std::forward<_CallArgs>(__call_args)...);
895	}
896
897      _Fd _M_fd;
898      std::tuple<_BoundArgs...> _M_bound_args;
899    };
900
901  template<typename _Fn, typename... _Args>
902    using _Bind_front_t
903      = _Bind_front<decay_t<_Fn>, decay_t<_Args>...>;
904
905  template<typename _Fn, typename... _Args>
906    constexpr _Bind_front_t<_Fn, _Args...>
907    bind_front(_Fn&& __fn, _Args&&... __args)
908    noexcept(is_nothrow_constructible_v<_Bind_front_t<_Fn, _Args...>,
909					int, _Fn, _Args...>)
910    {
911      return _Bind_front_t<_Fn, _Args...>(0, std::forward<_Fn>(__fn),
912					  std::forward<_Args>(__args)...);
913    }
914#endif
915
916#if __cplusplus >= 201402L
917  /// Generalized negator.
918  template<typename _Fn>
919    class _Not_fn
920    {
921      template<typename _Fn2, typename... _Args>
922	using __inv_res_t = typename __invoke_result<_Fn2, _Args...>::type;
923
924      template<typename _Tp>
925	static decltype(!std::declval<_Tp>())
926	_S_not() noexcept(noexcept(!std::declval<_Tp>()));
927
928    public:
929      template<typename _Fn2>
930	constexpr
931	_Not_fn(_Fn2&& __fn, int)
932	: _M_fn(std::forward<_Fn2>(__fn)) { }
933
934      _Not_fn(const _Not_fn& __fn) = default;
935      _Not_fn(_Not_fn&& __fn) = default;
936      ~_Not_fn() = default;
937
938      // Macro to define operator() with given cv-qualifiers ref-qualifiers,
939      // forwarding _M_fn and the function arguments with the same qualifiers,
940      // and deducing the return type and exception-specification.
941#define _GLIBCXX_NOT_FN_CALL_OP( _QUALS )				\
942      template<typename... _Args>					\
943	_GLIBCXX20_CONSTEXPR						\
944	decltype(_S_not<__inv_res_t<_Fn _QUALS, _Args...>>())		\
945	operator()(_Args&&... __args) _QUALS				\
946	noexcept(__is_nothrow_invocable<_Fn _QUALS, _Args...>::value	\
947	    && noexcept(_S_not<__inv_res_t<_Fn _QUALS, _Args...>>()))	\
948	{								\
949	  return !std::__invoke(std::forward< _Fn _QUALS >(_M_fn),	\
950				std::forward<_Args>(__args)...);	\
951	}
952      _GLIBCXX_NOT_FN_CALL_OP( & )
953      _GLIBCXX_NOT_FN_CALL_OP( const & )
954      _GLIBCXX_NOT_FN_CALL_OP( && )
955      _GLIBCXX_NOT_FN_CALL_OP( const && )
956#undef _GLIBCXX_NOT_FN_CALL_OP
957
958    private:
959      _Fn _M_fn;
960    };
961
962  template<typename _Tp, typename _Pred>
963    struct __is_byte_like : false_type { };
964
965  template<typename _Tp>
966    struct __is_byte_like<_Tp, equal_to<_Tp>>
967    : __bool_constant<sizeof(_Tp) == 1 && is_integral<_Tp>::value> { };
968
969  template<typename _Tp>
970    struct __is_byte_like<_Tp, equal_to<void>>
971    : __bool_constant<sizeof(_Tp) == 1 && is_integral<_Tp>::value> { };
972
973#if __cplusplus >= 201703L
974  // Declare std::byte (full definition is in <cstddef>).
975  enum class byte : unsigned char;
976
977  template<>
978    struct __is_byte_like<byte, equal_to<byte>>
979    : true_type { };
980
981  template<>
982    struct __is_byte_like<byte, equal_to<void>>
983    : true_type { };
984
985#define __cpp_lib_not_fn 201603
986  /// [func.not_fn] Function template not_fn
987  template<typename _Fn>
988    _GLIBCXX20_CONSTEXPR
989    inline auto
990    not_fn(_Fn&& __fn)
991    noexcept(std::is_nothrow_constructible<std::decay_t<_Fn>, _Fn&&>::value)
992    {
993      return _Not_fn<std::decay_t<_Fn>>{std::forward<_Fn>(__fn), 0};
994    }
995
996  // Searchers
997#define __cpp_lib_boyer_moore_searcher 201603
998
999  template<typename _ForwardIterator1, typename _BinaryPredicate = equal_to<>>
1000    class default_searcher
1001    {
1002    public:
1003      _GLIBCXX20_CONSTEXPR
1004      default_searcher(_ForwardIterator1 __pat_first,
1005		       _ForwardIterator1 __pat_last,
1006		       _BinaryPredicate __pred = _BinaryPredicate())
1007      : _M_m(__pat_first, __pat_last, std::move(__pred))
1008      { }
1009
1010      template<typename _ForwardIterator2>
1011	_GLIBCXX20_CONSTEXPR
1012	pair<_ForwardIterator2, _ForwardIterator2>
1013	operator()(_ForwardIterator2 __first, _ForwardIterator2 __last) const
1014	{
1015	  _ForwardIterator2 __first_ret =
1016	    std::search(__first, __last, std::get<0>(_M_m), std::get<1>(_M_m),
1017			std::get<2>(_M_m));
1018	  auto __ret = std::make_pair(__first_ret, __first_ret);
1019	  if (__ret.first != __last)
1020	    std::advance(__ret.second, std::distance(std::get<0>(_M_m),
1021						     std::get<1>(_M_m)));
1022	  return __ret;
1023	}
1024
1025    private:
1026      tuple<_ForwardIterator1, _ForwardIterator1, _BinaryPredicate> _M_m;
1027    };
1028
1029  template<typename _Key, typename _Tp, typename _Hash, typename _Pred>
1030    struct __boyer_moore_map_base
1031    {
1032      template<typename _RAIter>
1033	__boyer_moore_map_base(_RAIter __pat, size_t __patlen,
1034			       _Hash&& __hf, _Pred&& __pred)
1035	: _M_bad_char{ __patlen, std::move(__hf), std::move(__pred) }
1036	{
1037	  if (__patlen > 0)
1038	    for (__diff_type __i = 0; __i < __patlen - 1; ++__i)
1039	      _M_bad_char[__pat[__i]] = __patlen - 1 - __i;
1040	}
1041
1042      using __diff_type = _Tp;
1043
1044      __diff_type
1045      _M_lookup(_Key __key, __diff_type __not_found) const
1046      {
1047	auto __iter = _M_bad_char.find(__key);
1048	if (__iter == _M_bad_char.end())
1049	  return __not_found;
1050	return __iter->second;
1051      }
1052
1053      _Pred
1054      _M_pred() const { return _M_bad_char.key_eq(); }
1055
1056      _GLIBCXX_STD_C::unordered_map<_Key, _Tp, _Hash, _Pred> _M_bad_char;
1057    };
1058
1059  template<typename _Tp, size_t _Len, typename _Pred>
1060    struct __boyer_moore_array_base
1061    {
1062      template<typename _RAIter, typename _Unused>
1063	__boyer_moore_array_base(_RAIter __pat, size_t __patlen,
1064				 _Unused&&, _Pred&& __pred)
1065	: _M_bad_char{ _GLIBCXX_STD_C::array<_Tp, _Len>{}, std::move(__pred) }
1066	{
1067	  std::get<0>(_M_bad_char).fill(__patlen);
1068	  if (__patlen > 0)
1069	    for (__diff_type __i = 0; __i < __patlen - 1; ++__i)
1070	      {
1071		auto __ch = __pat[__i];
1072		using _UCh = make_unsigned_t<decltype(__ch)>;
1073		auto __uch = static_cast<_UCh>(__ch);
1074		std::get<0>(_M_bad_char)[__uch] = __patlen - 1 - __i;
1075	      }
1076	}
1077
1078      using __diff_type = _Tp;
1079
1080      template<typename _Key>
1081	__diff_type
1082	_M_lookup(_Key __key, __diff_type __not_found) const
1083	{
1084	  auto __ukey = static_cast<make_unsigned_t<_Key>>(__key);
1085	  if (__ukey >= _Len)
1086	    return __not_found;
1087	  return std::get<0>(_M_bad_char)[__ukey];
1088	}
1089
1090      const _Pred&
1091      _M_pred() const { return std::get<1>(_M_bad_char); }
1092
1093      tuple<_GLIBCXX_STD_C::array<_Tp, _Len>, _Pred> _M_bad_char;
1094    };
1095
1096  // Use __boyer_moore_array_base when pattern consists of narrow characters
1097  // (or std::byte) and uses std::equal_to as the predicate.
1098  template<typename _RAIter, typename _Hash, typename _Pred,
1099           typename _Val = typename iterator_traits<_RAIter>::value_type,
1100	   typename _Diff = typename iterator_traits<_RAIter>::difference_type>
1101    using __boyer_moore_base_t
1102      = conditional_t<__is_byte_like<_Val, _Pred>::value,
1103		      __boyer_moore_array_base<_Diff, 256, _Pred>,
1104		      __boyer_moore_map_base<_Val, _Diff, _Hash, _Pred>>;
1105
1106  template<typename _RAIter, typename _Hash
1107	     = hash<typename iterator_traits<_RAIter>::value_type>,
1108	   typename _BinaryPredicate = equal_to<>>
1109    class boyer_moore_searcher
1110    : __boyer_moore_base_t<_RAIter, _Hash, _BinaryPredicate>
1111    {
1112      using _Base = __boyer_moore_base_t<_RAIter, _Hash, _BinaryPredicate>;
1113      using typename _Base::__diff_type;
1114
1115    public:
1116      boyer_moore_searcher(_RAIter __pat_first, _RAIter __pat_last,
1117			   _Hash __hf = _Hash(),
1118			   _BinaryPredicate __pred = _BinaryPredicate());
1119
1120      template<typename _RandomAccessIterator2>
1121        pair<_RandomAccessIterator2, _RandomAccessIterator2>
1122	operator()(_RandomAccessIterator2 __first,
1123		   _RandomAccessIterator2 __last) const;
1124
1125    private:
1126      bool
1127      _M_is_prefix(_RAIter __word, __diff_type __len,
1128		   __diff_type __pos)
1129      {
1130	const auto& __pred = this->_M_pred();
1131	__diff_type __suffixlen = __len - __pos;
1132	for (__diff_type __i = 0; __i < __suffixlen; ++__i)
1133	  if (!__pred(__word[__i], __word[__pos + __i]))
1134	    return false;
1135	return true;
1136      }
1137
1138      __diff_type
1139      _M_suffix_length(_RAIter __word, __diff_type __len,
1140		       __diff_type __pos)
1141      {
1142	const auto& __pred = this->_M_pred();
1143	__diff_type __i = 0;
1144	while (__pred(__word[__pos - __i], __word[__len - 1 - __i])
1145	       && __i < __pos)
1146	  {
1147	    ++__i;
1148	  }
1149	return __i;
1150      }
1151
1152      template<typename _Tp>
1153	__diff_type
1154	_M_bad_char_shift(_Tp __c) const
1155	{ return this->_M_lookup(__c, _M_pat_end - _M_pat); }
1156
1157      _RAIter _M_pat;
1158      _RAIter _M_pat_end;
1159      _GLIBCXX_STD_C::vector<__diff_type> _M_good_suffix;
1160    };
1161
1162  template<typename _RAIter, typename _Hash
1163	     = hash<typename iterator_traits<_RAIter>::value_type>,
1164	   typename _BinaryPredicate = equal_to<>>
1165    class boyer_moore_horspool_searcher
1166    : __boyer_moore_base_t<_RAIter, _Hash, _BinaryPredicate>
1167    {
1168      using _Base = __boyer_moore_base_t<_RAIter, _Hash, _BinaryPredicate>;
1169      using typename _Base::__diff_type;
1170
1171    public:
1172      boyer_moore_horspool_searcher(_RAIter __pat,
1173				    _RAIter __pat_end,
1174				    _Hash __hf = _Hash(),
1175				    _BinaryPredicate __pred
1176				    = _BinaryPredicate())
1177      : _Base(__pat, __pat_end - __pat, std::move(__hf), std::move(__pred)),
1178	_M_pat(__pat), _M_pat_end(__pat_end)
1179      { }
1180
1181      template<typename _RandomAccessIterator2>
1182        pair<_RandomAccessIterator2, _RandomAccessIterator2>
1183	operator()(_RandomAccessIterator2 __first,
1184		   _RandomAccessIterator2 __last) const
1185	{
1186	  const auto& __pred = this->_M_pred();
1187	  auto __patlen = _M_pat_end - _M_pat;
1188	  if (__patlen == 0)
1189	    return std::make_pair(__first, __first);
1190	  auto __len = __last - __first;
1191	  while (__len >= __patlen)
1192	    {
1193	      for (auto __scan = __patlen - 1;
1194		   __pred(__first[__scan], _M_pat[__scan]); --__scan)
1195		if (__scan == 0)
1196		  return std::make_pair(__first, __first + __patlen);
1197	      auto __shift = _M_bad_char_shift(__first[__patlen - 1]);
1198	      __len -= __shift;
1199	      __first += __shift;
1200	    }
1201	  return std::make_pair(__last, __last);
1202	}
1203
1204    private:
1205      template<typename _Tp>
1206	__diff_type
1207	_M_bad_char_shift(_Tp __c) const
1208	{ return this->_M_lookup(__c, _M_pat_end - _M_pat); }
1209
1210      _RAIter _M_pat;
1211      _RAIter _M_pat_end;
1212    };
1213
1214  template<typename _RAIter, typename _Hash, typename _BinaryPredicate>
1215    boyer_moore_searcher<_RAIter, _Hash, _BinaryPredicate>::
1216    boyer_moore_searcher(_RAIter __pat, _RAIter __pat_end,
1217			 _Hash __hf, _BinaryPredicate __pred)
1218    : _Base(__pat, __pat_end - __pat, std::move(__hf), std::move(__pred)),
1219      _M_pat(__pat), _M_pat_end(__pat_end), _M_good_suffix(__pat_end - __pat)
1220    {
1221      auto __patlen = __pat_end - __pat;
1222      if (__patlen == 0)
1223	return;
1224      __diff_type __last_prefix = __patlen - 1;
1225      for (__diff_type __p = __patlen - 1; __p >= 0; --__p)
1226	{
1227	  if (_M_is_prefix(__pat, __patlen, __p + 1))
1228	    __last_prefix = __p + 1;
1229	  _M_good_suffix[__p] = __last_prefix + (__patlen - 1 - __p);
1230	}
1231      for (__diff_type __p = 0; __p < __patlen - 1; ++__p)
1232	{
1233	  auto __slen = _M_suffix_length(__pat, __patlen, __p);
1234	  auto __pos = __patlen - 1 - __slen;
1235	  if (!__pred(__pat[__p - __slen], __pat[__pos]))
1236	    _M_good_suffix[__pos] = __patlen - 1 - __p + __slen;
1237	}
1238    }
1239
1240  template<typename _RAIter, typename _Hash, typename _BinaryPredicate>
1241  template<typename _RandomAccessIterator2>
1242    pair<_RandomAccessIterator2, _RandomAccessIterator2>
1243    boyer_moore_searcher<_RAIter, _Hash, _BinaryPredicate>::
1244    operator()(_RandomAccessIterator2 __first,
1245	       _RandomAccessIterator2 __last) const
1246    {
1247      auto __patlen = _M_pat_end - _M_pat;
1248      if (__patlen == 0)
1249	return std::make_pair(__first, __first);
1250      const auto& __pred = this->_M_pred();
1251      __diff_type __i = __patlen - 1;
1252      auto __stringlen = __last - __first;
1253      while (__i < __stringlen)
1254	{
1255	  __diff_type __j = __patlen - 1;
1256	  while (__j >= 0 && __pred(__first[__i], _M_pat[__j]))
1257	    {
1258	      --__i;
1259	      --__j;
1260	    }
1261	  if (__j < 0)
1262	    {
1263	      const auto __match = __first + __i + 1;
1264	      return std::make_pair(__match, __match + __patlen);
1265	    }
1266	  __i += std::max(_M_bad_char_shift(__first[__i]),
1267			  _M_good_suffix[__j]);
1268	}
1269      return std::make_pair(__last, __last);
1270    }
1271
1272#endif // C++17
1273#endif // C++14
1274
1275_GLIBCXX_END_NAMESPACE_VERSION
1276} // namespace std
1277
1278#endif // C++11
1279
1280#endif // _GLIBCXX_FUNCTIONAL
1281