centralize bit operation support for enum used as flags

1 files changed, 52 insertions, 0 deletions

diff --git a/src/flags.hh b/src/flags.hh
new file mode 100644
index 00000000..a3cbc5e0
--- /dev/null
+++ b/src/flags.hh
@@ -0,0 +1,52 @@
+#ifndef flags_hh_INCLUDED
+#define flags_hh_INCLUDED
+
+#include <type_traits>
+
+namespace Kakoune
+{
+
+template<typename Flags>
+struct WithBitOps : std::false_type {};
+
+template<typename Flags>
+using EnumStorageType = typename std::underlying_type<Flags>::type;
+
+template<typename Flags>
+using EnableIfWithBitOps = typename std::enable_if<WithBitOps<Flags>::value>::type;
+
+template<typename Flags, typename = EnableIfWithBitOps<Flags>>
+constexpr Flags operator|(Flags lhs, Flags rhs)
+{
+    return (Flags)((EnumStorageType<Flags>) lhs | (EnumStorageType<Flags>) rhs);
+}
+
+template<typename Flags, typename = EnableIfWithBitOps<Flags>>
+Flags& operator|=(Flags& lhs, Flags rhs)
+{
+    (EnumStorageType<Flags>&) lhs |= (EnumStorageType<Flags>) rhs;
+    return lhs;
+}
+
+template<typename Flags, typename = EnableIfWithBitOps<Flags>>
+constexpr bool operator&(Flags lhs, Flags rhs)
+{
+    return ((EnumStorageType<Flags>) lhs & (EnumStorageType<Flags>) rhs) != 0;
+}
+
+template<typename Flags, typename = EnableIfWithBitOps<Flags>>
+Flags& operator&=(Flags& lhs, Flags rhs)
+{
+    (EnumStorageType<Flags>&) lhs &= (EnumStorageType<Flags>) rhs;
+    return lhs;
+}
+
+template<typename Flags, typename = EnableIfWithBitOps<Flags>>
+constexpr Flags operator~(Flags lhs)
+{
+    return (Flags)(~(EnumStorageType<Flags>)lhs);
+}
+
+}
+
+#endif // flags_hh_INCLUDED