libcxx/test/support/invocable_with_telemetry.h

   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 #ifndef TEST_SUPPORT_INVOCABLE_WITH_TELEMETRY_H
  10 #define TEST_SUPPORT_INVOCABLE_WITH_TELEMETRY_H
  11
  12 #include <cassert>
  13 #include <concepts>
  14 #include <functional>
  15 #include <utility>
  16
  17 #if TEST_STD_VER < 20
  18 #  error invocable_with_telemetry requires C++20
  19 #else
  20 struct invocable_telemetry {
  21   int invocations;
  22   int moves;
  23   int copies;
  24 };
  25
  26 template <class F>
  27 class invocable_with_telemetry {
  28 public:
  29   constexpr invocable_with_telemetry(F f, invocable_telemetry& telemetry) : f_(f), telemetry_(&telemetry) {}
  30
  31   constexpr invocable_with_telemetry(invocable_with_telemetry&& other)
  32     requires std::move_constructible<F>
  33       : f_(std::move(other.f_)),
  34         telemetry_(assert(other.telemetry_ != nullptr), std::exchange(other.telemetry_, nullptr)) {
  35     ++telemetry_->moves;
  36   }
  37
  38   constexpr invocable_with_telemetry(invocable_with_telemetry const& other)
  39     requires std::copy_constructible<F>
  40       : f_(other.f_), telemetry_((assert(other.telemetry_ != nullptr), other.telemetry_)) {
  41     ++telemetry_->copies;
  42   }
  43
  44   constexpr invocable_with_telemetry& operator=(invocable_with_telemetry&& other)
  45     requires std::movable<F>
  46   {
  47     // Not using move-and-swap idiom to ensure that copies and moves remain accurate.
  48     assert(&other != this);
  49     assert(other.telemetry_ != nullptr);
  50
  51     f_         = std::move(other.f_);
  52     telemetry_ = std::exchange(other.telemetry_, nullptr);
  53
  54     ++telemetry_->moves;
  55     return *this;
  56   }
  57
  58   constexpr invocable_with_telemetry& operator=(invocable_with_telemetry const& other)
  59     requires std::copyable<F>
  60   {
  61     // Not using copy-and-swap idiom to ensure that copies and moves remain accurate.
  62     assert(&other != this);
  63     assert(other.telemetry_ != nullptr);
  64
  65     f_         = other.f_;
  66     telemetry_ = other.telemetry_;
  67
  68     ++telemetry_->copies;
  69     return *this;
  70   }
  71
  72   template <class... Args>
  73     requires std::invocable<F&, Args...>
  74   constexpr decltype(auto) operator()(Args&&... args) noexcept(std::is_nothrow_invocable_v<F&, Args...>) {
  75     assert(telemetry_);
  76     ++telemetry_->invocations;
  77     return std::invoke(f_, std::forward<Args>(args)...);
  78   }
  79
  80 private:
  81   F f_                            = F();
  82   invocable_telemetry* telemetry_ = nullptr;
  83 };
  84
  85 template <class F>
  86 invocable_with_telemetry(F f, int& invocations, int& moves, int& copies) -> invocable_with_telemetry<F>;
  87
  88 #endif // TEST_STD_VER < 20
  89 #endif // TEST_SUPPORT_INVOCABLE_WITH_TELEMETRY_H