From 3e797a3d152b59302365a7c11c5253292cd34ee7 Mon Sep 17 00:00:00 2001
From: Maxime Coste <frrrwww@gmail.com>
Date: Thu, 23 Oct 2014 18:55:45 +0100
Subject: [PATCH] centralize bit operation support for enum used as flags

---
 src/buffer.hh            | 30 +++--------------------
 src/command_manager.hh   | 11 +++------
 src/flags.hh             | 52 ++++++++++++++++++++++++++++++++++++++++
 src/normal.cc            | 11 +++------
 src/option_manager.hh    |  7 ++----
 src/parameters_parser.hh | 11 +++------
 src/selectors.hh         |  7 +++---
 7 files changed, 69 insertions(+), 60 deletions(-)
 create mode 100644 src/flags.hh

diff --git a/src/buffer.hh b/src/buffer.hh
index 4f0da060..70bb59b7 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -2,6 +2,7 @@
 #define buffer_hh_INCLUDED
 
 #include "coord.hh"
+#include "flags.hh"
 #include "hook_manager.hh"
 #include "option_manager.hh"
 #include "keymap_manager.hh"
@@ -220,35 +221,10 @@ private:
     // Values are just data holding by the buffer, so it is part of its
     // observable state
     mutable ValueMap m_values;
-
-    friend constexpr Flags operator|(Flags lhs, Flags rhs)
-    {
-        return (Flags)((int) lhs | (int) rhs);
-    }
-
-    friend Flags& operator|=(Flags& lhs, Flags rhs)
-    {
-        (int&) lhs |= (int) rhs;
-        return lhs;
-    }
-
-    friend constexpr bool operator&(Flags lhs, Flags rhs)
-    {
-        return ((int) lhs & (int) rhs) != 0;
-    }
-
-    friend Flags& operator&=(Flags& lhs, Flags rhs)
-    {
-        (int&) lhs &= (int) rhs;
-        return lhs;
-    }
-
-    friend constexpr Flags operator~(Flags lhs)
-    {
-        return (Flags)(~(int)lhs);
-    }
 };
 
+template<> struct WithBitOps<Buffer::Flags> : std::true_type {};
+
 }
 
 #include "buffer.inl.hh"
diff --git a/src/command_manager.hh b/src/command_manager.hh
index 8d0cc957..283fec92 100644
--- a/src/command_manager.hh
+++ b/src/command_manager.hh
@@ -3,6 +3,7 @@
 
 #include "coord.hh"
 #include "completion.hh"
+#include "flags.hh"
 #include "memoryview.hh"
 #include "shell_manager.hh"
 #include "parameters_parser.hh"
@@ -28,14 +29,8 @@ enum class CommandFlags
     None   = 0,
     Hidden = 1,
 };
-constexpr CommandFlags operator|(CommandFlags lhs, CommandFlags rhs)
-{
-    return (CommandFlags)((int)lhs | (int)rhs);
-}
-constexpr bool operator&(CommandFlags lhs, CommandFlags rhs)
-{
-    return (bool)((int)lhs & (int)rhs);
-}
+
+template<> struct WithBitOps<CommandFlags> : std::true_type {};
 
 class PerArgumentCommandCompleter
 {
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
diff --git a/src/normal.cc b/src/normal.cc
index 67640b7d..a7c49b2f 100644
--- a/src/normal.cc
+++ b/src/normal.cc
@@ -8,6 +8,7 @@
 #include "context.hh"
 #include "debug.hh"
 #include "face_registry.hh"
+#include "flags.hh"
 #include "file.hh"
 #include "option_manager.hh"
 #include "register_manager.hh"
@@ -956,14 +957,8 @@ enum class SelectFlags
     Inclusive = 2,
     Extend = 4
 };
-constexpr SelectFlags operator|(SelectFlags lhs, SelectFlags rhs)
-{
-    return (SelectFlags)((int) lhs | (int) rhs);
-}
-constexpr bool operator&(SelectFlags lhs, SelectFlags rhs)
-{
-    return ((int) lhs & (int) rhs) != 0;
-}
+
+template<> struct WithBitOps<SelectFlags> : std::true_type {};
 
 template<SelectFlags flags>
 void select_to_next_char(Context& context, int param)
diff --git a/src/option_manager.hh b/src/option_manager.hh
index 32d55e70..00cd0370 100644
--- a/src/option_manager.hh
+++ b/src/option_manager.hh
@@ -3,6 +3,7 @@
 
 #include "completion.hh"
 #include "exception.hh"
+#include "flags.hh"
 #include "option_types.hh"
 #include "utils.hh"
 #include "regex.hh"
@@ -25,12 +26,8 @@ enum class OptionFlags
     None   = 0,
     Hidden = 1,
 };
-constexpr OptionFlags operator|(OptionFlags lhs, OptionFlags rhs)
-{ return (OptionFlags)((int)lhs | (int)rhs); }
-
-constexpr bool operator&(OptionFlags lhs, OptionFlags rhs)
-{ return (bool)((int)lhs & (int)rhs); }
 
+template<> struct WithBitOps<OptionFlags> : std::true_type {};
 
 class OptionDesc
 {
diff --git a/src/parameters_parser.hh b/src/parameters_parser.hh
index 219c9454..0082ada9 100644
--- a/src/parameters_parser.hh
+++ b/src/parameters_parser.hh
@@ -4,6 +4,7 @@
 #include "exception.hh"
 #include "id_map.hh"
 #include "memoryview.hh"
+#include "flags.hh"
 #include "string.hh"
 
 namespace Kakoune
@@ -51,14 +52,6 @@ struct ParameterDesc
         SwitchesOnlyAtStart = 1,
         SwitchesAsPositional = 2,
     };
-    friend constexpr Flags operator|(Flags lhs, Flags rhs)
-    {
-        return (Flags)((int) lhs | (int) rhs);
-    }
-    friend constexpr bool operator&(Flags lhs, Flags rhs)
-    {
-        return ((int) lhs & (int) rhs) != 0;
-    }
 
     ParameterDesc() = default;
     ParameterDesc(SwitchMap switches, Flags flags = Flags::None,
@@ -72,6 +65,8 @@ struct ParameterDesc
     size_t max_positionals = -1;
 };
 
+template<> struct WithBitOps<ParameterDesc::Flags> : std::true_type {};
+
 // ParametersParser provides tools to parse command parameters.
 // There are 3 types of parameters:
 //  * unnamed options, which are accessed by position (ignoring named ones)
diff --git a/src/selectors.hh b/src/selectors.hh
index 3df24f26..3dc4e5ba 100644
--- a/src/selectors.hh
+++ b/src/selectors.hh
@@ -1,6 +1,7 @@
 #ifndef selectors_hh_INCLUDED
 #define selectors_hh_INCLUDED
 
+#include "flags.hh"
 #include "selection.hh"
 #include "buffer_utils.hh"
 #include "unicode.hh"
@@ -152,10 +153,8 @@ enum class ObjectFlags
     ToEnd   = 2,
     Inner   = 4
 };
-constexpr bool operator&(ObjectFlags lhs, ObjectFlags rhs)
-{ return (bool)((int)lhs & (int) rhs); }
-constexpr ObjectFlags operator|(ObjectFlags lhs, ObjectFlags rhs)
-{ return (ObjectFlags)((int)lhs | (int) rhs); }
+
+template<> struct WithBitOps<ObjectFlags> : std::true_type {};
 
 template<WordType word_type>
 Selection select_word(const Buffer& buffer,