LibreOffice Module o3tl (master)  1
unsafe_downcast.hxx
Go to the documentation of this file.
1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
2 /*
3  * This file is part of the LibreOffice project.
4  *
5  * This Source Code Form is subject to the terms of the Mozilla Public
6  * License, v. 2.0. If a copy of the MPL was not distributed with this
7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8  */
9 
10 #ifndef INCLUDED_O3TL_UNSAFE_DOWNCAST_HXX
11 #define INCLUDED_O3TL_UNSAFE_DOWNCAST_HXX
12 
13 #include <cassert>
14 #include <type_traits>
15 
16 namespace o3tl
17 {
18 // Do a downcast from polymorphic `BasePtr` to `DerivedPtr` when it is known that `p` is actually
19 // pointing to an object of derived type (or is a nullptr). This is potentially cheaper than
20 // dynamic_cast and helps to avoid Coverity warnings about unchecked dynamic_cast.
21 template <typename DerivedPtr, typename BasePtr>
22 std::enable_if_t<
23  (std::is_pointer_v<
24  DerivedPtr> && std::is_pointer_v<BasePtr> && std::is_base_of_v<std::remove_pointer_t<BasePtr>, std::remove_pointer_t<DerivedPtr>>),
25  DerivedPtr>
26 unsafe_downcast(BasePtr p)
27 {
28  assert(p == nullptr || dynamic_cast<DerivedPtr>(p) != nullptr);
29  return static_cast<DerivedPtr>(p);
30 }
31 }
32 
33 #endif
34 
35 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
std::enable_if_t< (std::is_pointer_v< DerivedPtr > &&std::is_pointer_v< BasePtr > &&std::is_base_of_v< std::remove_pointer_t< BasePtr >, std::remove_pointer_t< DerivedPtr >>), DerivedPtr > unsafe_downcast(BasePtr p)