libstdc++-v3/testsuite/20_util/function/6.cc

   1 // { dg-do run { target c++11 } }
   2 // { dg-require-effective-target hosted }
   3
   4 // 2005-01-15 Douglas Gregor <dgregor@cs.indiana.edu>
   5 //
   6 // Copyright (C) 2005-2023 Free Software Foundation, Inc.
   7 //
   8 // This file is part of the GNU ISO C++ Library.  This library is free
   9 // software; you can redistribute it and/or modify it under the
  10 // terms of the GNU General Public License as published by the
  11 // Free Software Foundation; either version 3, or (at your option)
  12 // any later version.
  13 //
  14 // This library is distributed in the hope that it will be useful,
  15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 // GNU General Public License for more details.
  18 //
  19 // You should have received a copy of the GNU General Public License along
  20 // with this library; see the file COPYING3.  If not see
  21 // <http://www.gnu.org/licenses/>.
  22
  23 // 20.7.15 polymorphic function object wrapper
  24 #include <functional>
  25 #include <testsuite_hooks.h>
  26
  27 template<typename T>
  28   const T&
  29   as_const(T& t)
  30   { return t; }
  31
  32 // Check that f's target is a reference_wrapper bound to obj.
  33 template<typename Function, typename T>
  34   bool
  35   wraps(Function& f, T& obj)
  36   {
  37     using ref_wrapper_type = std::reference_wrapper<T>;
  38     auto* p = f.template target<ref_wrapper_type>();
  39     return std::addressof(p->get()) == std::addressof(obj);
  40   }
  41
  42 struct secret {};
  43
  44 struct noncopyable_function_object_type
  45 {
  46   noncopyable_function_object_type(secret) {}
  47
  48   int operator()() const { return 42; }
  49   int operator()()       { return 17; }
  50
  51  private:
  52   noncopyable_function_object_type();
  53   noncopyable_function_object_type(const noncopyable_function_object_type&);
  54   void operator=(const noncopyable_function_object_type&);
  55 };
  56
  57 // Put reference_wrappers into function<> wrappers
  58 void test06()
  59 {
  60   using std::function;
  61   using std::ref;
  62   using std::cref;
  63
  64   secret password;
  65   noncopyable_function_object_type x(password);
  66
  67   function<int()> f(ref(x));
  68   VERIFY( f );
  69   VERIFY( f() == 17 );
  70 #if __cpp_rtti
  71   VERIFY( f.target_type() == typeid(std::ref(x)) ); // LWG 2781
  72 #endif
  73   VERIFY( wraps(f, x) );
  74
  75   function<int()> g = f;
  76   VERIFY( g );
  77   VERIFY( g() == 17 );
  78 #if __cpp_rtti
  79   VERIFY( g.target_type() == f.target_type() );
  80 #endif
  81   VERIFY( wraps(g, x) );
  82
  83   function<int()> h = cref(x);
  84   VERIFY( h );
  85   VERIFY( h() == 42 );
  86 #if __cpp_rtti
  87   VERIFY( h.target_type() == typeid(std::cref(x)) );
  88 #endif
  89   VERIFY( wraps(h, as_const(x)) );
  90
  91   const function<int()>& hc = h;
  92 #if __cpp_rtti
  93   VERIFY( hc.target_type() == h.target_type() );
  94 #endif
  95   VERIFY( wraps(hc, as_const(x)) );
  96 }
  97
  98 int main()
  99 {
 100   test06();
 101   return 0;
 102 }