[RFC] Enum improvements

[Yuriy Skalko]

>> The first bit, involving headers, looks most useful.
> 
> 
> I agree that the first one is the most promising.

Sure. But as it turns out C++ disallows forward declarations for 
in-class enums. So these should be moved out of classes (and most common 
ones maybe placed into separate headers).

> Another thing to look at: we have plenty of enums used a bitfields where we have defined special operators (some are mine) I only realized recently that it does not make sense. A good example is KeyModifier. I suspect that we should use 'int' instead of casting back to the original enum type. There are complex tamplate-based solutions to this, but I am not sure they are worth the hassle.
> 
> 
> JMarc

Like in attached patch? I think `unsigned` instead of `int` will be 
better for bit fiddling.


Yuriy

-------------- next part --------------
From 41ec9e10bcd1df00fec1b317d50b8333aac85cdc Mon Sep 17 00:00:00 2001
From: Yuriy Skalko <yuriy.skalko at gmail.com>
Date: Sun, 29 Nov 2020 10:19:58 +0200
Subject: [PATCH] Simplify KeyModifier

---
 src/frontends/KeyModifier.h | 31 +++++++++----------------------
 1 file changed, 9 insertions(+), 22 deletions(-)

diff --git a/src/frontends/KeyModifier.h b/src/frontends/KeyModifier.h
index fba80bec2a..bdae991e63 100644
--- a/src/frontends/KeyModifier.h
+++ b/src/frontends/KeyModifier.h
@@ -16,31 +16,18 @@
 
 namespace lyx {
 
-/// modifier key states
+/// Set of KeyModifierFlags
+typedef unsigned KeyModifier;
 
-enum KeyModifier {
-	NoModifier       = 0, //< no modifiers held
-	ControlModifier  = 1, //< control button held
-	AltModifier      = 2, //< alt key held
-	ShiftModifier    = 4, //< shift key held
-	MetaModifier     = 8  //< meta key held
+/// modifier key states
+enum KeyModifierFlags : unsigned {
+	NoModifier       = 0,      //< no modifiers held
+	ControlModifier  = 1 << 0, //< control button held
+	AltModifier      = 1 << 1, //< alt key held
+	ShiftModifier    = 1 << 2, //< shift key held
+	MetaModifier     = 1 << 3  //< meta key held
 };
 
-
-inline KeyModifier operator|(KeyModifier s1, KeyModifier s2)
-{
-	int const i1 = static_cast<int>(s1);
-	int const i2 = static_cast<int>(s2);
-	return static_cast<KeyModifier>(i1 | i2);
-}
-
-
-inline void operator|=(KeyModifier & s1, KeyModifier s2)
-{
-	s1 = static_cast<KeyModifier>(s1 | s2);
-}
-
-
 } // namespace lyx
 
 #endif // KEYMODIFIER_H
-- 
2.28.0.windows.1