libc/src/__support/CPP/utility/forward.h

   1 //===-- forward utility -----------------------------------------*- C++ -*-===//
   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 #ifndef LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_FORWARD_H
   9 #define LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_FORWARD_H
  10
  11 #include "src/__support/CPP/type_traits/is_lvalue_reference.h"
  12 #include "src/__support/CPP/type_traits/remove_reference.h"
  13 #include "src/__support/macros/attributes.h"
  14
  15 namespace LIBC_NAMESPACE::cpp {
  16
  17 // forward
  18 template <typename T>
  19 LIBC_INLINE constexpr T &&forward(remove_reference_t<T> &value) {
  20   return static_cast<T &&>(value);
  21 }
  22
  23 template <typename T>
  24 LIBC_INLINE constexpr T &&forward(remove_reference_t<T> &&value) {
  25   static_assert(!is_lvalue_reference_v<T>,
  26                 "cannot forward an rvalue as an lvalue");
  27   return static_cast<T &&>(value);
  28 }
  29
  30 } // namespace LIBC_NAMESPACE::cpp
  31
  32 #endif // LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_FORWARD_H