1 files changed, 62 insertions, 0 deletions
diff --git a/include/svl/typedwhich.hxx b/include/svl/typedwhich.hxx
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+++ b/include/svl/typedwhich.hxx
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+#ifndef INCLUDED_SVL_TYPEDWHICH_HXX
+#define INCLUDED_SVL_TYPEDWHICH_HXX
+
+#include <sal/config.h>
+#include <sal/types.h>
+#include <type_traits>
+
+/**
+ * A very thin wrapper around the sal_uInt16 WhichId whose purpose is mostly to carry type information,
+ * so that we Put() and Get() the right subclasses of SfxPoolItem for each WhichId.
+ */
+template <class T> class TypedWhichId final
+{
+public:
+    explicit constexpr TypedWhichId(sal_uInt16 nWhich)
+        : mnWhich(nWhich)
+    {
+    }
+
+    /** Up-casting conversion constructor
+    */
+    template <class derived_type>
+    constexpr TypedWhichId(TypedWhichId<derived_type> other,
+                           std::enable_if_t<std::is_base_of_v<T, derived_type>, int> = 0)
+        : mnWhich(sal_uInt16(other))
+    {
+    }
+
+    constexpr operator sal_uInt16() const { return mnWhich; }
+
+private:
+    sal_uInt16 mnWhich;
+};
+
+template <class T> constexpr bool operator==(sal_uInt16 lhs, TypedWhichId<T> const& rhs)
+{
+    return lhs == sal_uInt16(rhs);
+}
+template <class T> constexpr bool operator!=(sal_uInt16 lhs, TypedWhichId<T> const& rhs)
+{
+    return lhs != sal_uInt16(rhs);
+}
+template <class T> constexpr bool operator==(TypedWhichId<T> const& lhs, sal_uInt16 rhs)
+{
+    return sal_uInt16(lhs) == rhs;
+}
+template <class T> constexpr bool operator!=(TypedWhichId<T> const& lhs, sal_uInt16 rhs)
+{
+    return sal_uInt16(lhs) != rhs;
+}
+
+#endif // INCLUDED_SVL_TYPEDWHICH_HXX
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */