libstdc++-v3/testsuite/20_util/function/7.cc

   1 // { dg-do run { target c++11 } }
   2 // 2005-01-15 Douglas Gregor <dgregor@cs.indiana.edu>
   3 //
   4 // Copyright (C) 2005-2021 Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11 //
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING3.  If not see
  19 // <http://www.gnu.org/licenses/>.
  20
  21 // 20.7.15 polymorphic function object wrapper
  22 #include <functional>
  23 #include <testsuite_hooks.h>
  24 #include <testsuite_tr1.h>
  25
  26 template<typename T>
  27   const T&
  28   as_const(T& t)
  29   { return t; }
  30
  31 // Check that f's target is a reference_wrapper bound to obj.
  32 template<typename Function, typename T>
  33   bool
  34   wraps(Function& f, T& obj)
  35   {
  36     using ref_wrapper_type = std::reference_wrapper<T>;
  37     auto* p = f.template target<ref_wrapper_type>();
  38     return std::addressof(p->get()) == std::addressof(obj);
  39   }
  40
  41 // Put reference_wrappers to function pointers into function<> wrappers
  42 void test07()
  43 {
  44   using std::function;
  45   using std::ref;
  46   using std::cref;
  47   using std::reference_wrapper;
  48
  49   int (*fptr)(float) = __gnu_test::truncate_float;
  50
  51   function<int(float)> f1(ref(fptr));
  52   VERIFY( f1 );
  53   VERIFY( !!f1 );
  54   VERIFY( !(f1 == 0) );
  55   VERIFY( !(0 == f1) );
  56   VERIFY( f1 != 0 );
  57   VERIFY( 0 != f1 );
  58
  59   // Invocation
  60   VERIFY( f1(3.1f) == 3 );
  61
  62   // target_type and target() functions
  63   const function<int(float)>& f1c = f1;
  64   using ref_wrapper_type = reference_wrapper<int(*)(float)>;
  65   VERIFY( typeid(ref_wrapper_type) == f1.target_type() );
  66   VERIFY( f1.target<ref_wrapper_type>() != nullptr );
  67   VERIFY( wraps(f1, fptr) );
  68   VERIFY( wraps(f1c, fptr) );
  69
  70   function<int(float)> f2(cref(fptr));
  71   VERIFY( f2 );
  72   VERIFY( !!f2 );
  73   VERIFY( !(f2 == 0) );
  74   VERIFY( !(0 == f2) );
  75   VERIFY( f2 != 0 );
  76   VERIFY( 0 != f2 );
  77
  78   // Invocation
  79   VERIFY( f2(3.1f) == 3 );
  80
  81   // target_type and target() functions
  82   const function<int(float)>& f2c = f2;
  83   using cref_wrapper_type = reference_wrapper<int(* const)(float)>;
  84   VERIFY( typeid(cref_wrapper_type) == f2.target_type() );
  85   VERIFY( wraps(f2, as_const(fptr)) );
  86   VERIFY( f2c.target_type() == f2.target_type() );
  87   VERIFY( wraps(f2c, as_const(fptr)) );
  88 }
  89
  90 int main()
  91 {
  92   test07();
  93   return 0;
  94 }