include/svl/typedwhich.hxx

   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 #ifndef INCLUDED_SVL_TYPEDWHICH_HXX
  10 #define INCLUDED_SVL_TYPEDWHICH_HXX
  11
  12 #include <sal/config.h>
  13 #include <sal/types.h>
  14 #include <type_traits>
  15
  16 /**
  17  * A very thin wrapper around the sal_uInt16 WhichId whose purpose is mostly to carry type information,
  18  * so that we Put() and Get() the right subclasses of SfxPoolItem for each WhichId.
  19  */
  20 template <class T> class TypedWhichId final
  21 {
  22 public:
  23     explicit constexpr TypedWhichId(sal_uInt16 nWhich)
  24         : mnWhich(nWhich)
  25     {
  26     }
  27
  28     /** Up-casting conversion constructor
  29     */
  30     template <class derived_type>
  31     constexpr TypedWhichId(TypedWhichId<derived_type> other,
  32                            std::enable_if_t<std::is_base_of_v<T, derived_type>, int> = 0)
  33         : mnWhich(sal_uInt16(other))
  34     {
  35     }
  36
  37     constexpr operator sal_uInt16() const { return mnWhich; }
  38
  39 private:
  40     sal_uInt16 mnWhich;
  41 };
  42
  43 template <class T> constexpr bool operator==(TypedWhichId<T> const& lhs, TypedWhichId<T> rhs)
  44 {
  45     return sal_uInt16(lhs) == sal_uInt16(rhs);
  46 }
  47 template <class T> constexpr bool operator!=(TypedWhichId<T> const& lhs, TypedWhichId<T> rhs)
  48 {
  49     return sal_uInt16(lhs) != sal_uInt16(rhs);
  50 }
  51 template <class T> constexpr bool operator==(sal_uInt16 lhs, TypedWhichId<T> const& rhs)
  52 {
  53     return lhs == sal_uInt16(rhs);
  54 }
  55 template <class T> constexpr bool operator!=(sal_uInt16 lhs, TypedWhichId<T> const& rhs)
  56 {
  57     return lhs != sal_uInt16(rhs);
  58 }
  59 template <class T> constexpr bool operator==(TypedWhichId<T> const& lhs, sal_uInt16 rhs)
  60 {
  61     return sal_uInt16(lhs) == rhs;
  62 }
  63 template <class T> constexpr bool operator!=(TypedWhichId<T> const& lhs, sal_uInt16 rhs)
  64 {
  65     return sal_uInt16(lhs) != rhs;
  66 }
  67
  68 #endif // INCLUDED_SVL_TYPEDWHICH_HXX
  69
  70 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */