libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.isbind/specialization.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11
  10
  11 // <functional>
  12
  13 // template<class T> struct is_bind_expression;
  14 //   A program may specialize this template for a program-defined type T
  15 //   to have a base characteristic of true_type to indicate that T should
  16 //   be treated as a subexpression in a bind call.
  17 //   https://llvm.org/PR51753
  18
  19 #include <cassert>
  20 #include <functional>
  21 #include <type_traits>
  22 #include <utility>
  23
  24 struct MyBind {
  25     int operator()(int x, int y) const { return 10*x + y; }
  26 };
  27 template<> struct std::is_bind_expression<MyBind> : std::true_type {};
  28
  29 int main(int, char**)
  30 {
  31   {
  32     auto f = [](auto x) { return 10*x + 9; };
  33     MyBind bindexpr;
  34     auto bound = std::bind(f, bindexpr);
  35     assert(bound(7, 8) == 789);
  36   }
  37   {
  38     auto f = [](auto x) { return 10*x + 9; };
  39     const MyBind bindexpr;
  40     auto bound = std::bind(f, bindexpr);
  41     assert(bound(7, 8) == 789);
  42   }
  43   {
  44     auto f = [](auto x) { return 10*x + 9; };
  45     MyBind bindexpr;
  46     auto bound = std::bind(f, std::move(bindexpr));
  47     assert(bound(7, 8) == 789);
  48   }
  49   {
  50     auto f = [](auto x) { return 10*x + 9; };
  51     const MyBind bindexpr;
  52     auto bound = std::bind(f, std::move(bindexpr));
  53     assert(bound(7, 8) == 789);
  54   }
  55
  56   return 0;
  57 }