From db9b863222dbd51154c422cf85bc8fafacd5b25b Mon Sep 17 00:00:00 2001
From: Maxime Coste <mawww@kakoune.org>
Date: Wed, 15 Mar 2017 17:55:34 +0000
Subject: [PATCH] Migrate WithBitOps template specialization to with_bit_ops
 function

This way we dont depend on knowing the base template to enable bit ops
on an enum type.
---
 src/buffer.hh            | 3 +--
 src/command_manager.hh   | 2 +-
 src/completion.hh        | 2 +-
 src/context.hh           | 3 +--
 src/event_manager.cc     | 1 +
 src/event_manager.hh     | 4 ++--
 src/face.hh              | 2 +-
 src/file.hh              | 2 +-
 src/flags.hh             | 8 +++++---
 src/input_handler.hh     | 5 ++---
 src/keys.hh              | 2 +-
 src/main.cc              | 2 +-
 src/normal.cc            | 2 +-
 src/option_manager.cc    | 1 +
 src/option_manager.hh    | 3 +--
 src/option_types.hh      | 5 ++---
 src/parameters_parser.hh | 3 +--
 src/ranked_match.cc      | 2 --
 src/ranked_match.hh      | 2 ++
 src/selectors.hh         | 2 +-
 src/shell_manager.cc     | 1 +
 src/shell_manager.hh     | 4 +---
 22 files changed, 29 insertions(+), 32 deletions(-)

diff --git a/src/buffer.hh b/src/buffer.hh
index bc960b20..f535c387 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -115,6 +115,7 @@ public:
         Debug    = 1 << 5,
         ReadOnly = 1 << 6,
     };
+    friend constexpr bool with_bit_ops(Meta::Type<Flags>) { return true; }
 
     Buffer(String name, Flags flags, StringView data = {},
            timespec fs_timestamp = InvalidTime);
@@ -283,8 +284,6 @@ private:
     mutable ValueMap m_values;
 };
 
-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 5269ca39..36cfe423 100644
--- a/src/command_manager.hh
+++ b/src/command_manager.hh
@@ -37,7 +37,7 @@ enum class CommandFlags
     Hidden = 1,
 };
 
-template<> struct WithBitOps<CommandFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<CommandFlags>) { return true; }
 
 struct CommandInfo { String name, info; };
 
diff --git a/src/completion.hh b/src/completion.hh
index 95dc7deb..281c120f 100644
--- a/src/completion.hh
+++ b/src/completion.hh
@@ -40,7 +40,7 @@ enum class CompletionFlags
     Start = 1 << 2,
 };
 
-template<> struct WithBitOps<CompletionFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<CompletionFlags>) { return true; }
 
 using Completer = std::function<Completions (const Context&, CompletionFlags,
                                              StringView, ByteCount)>;
diff --git a/src/context.hh b/src/context.hh
index a50eb87f..ba981f69 100644
--- a/src/context.hh
+++ b/src/context.hh
@@ -183,8 +183,7 @@ private:
     NestedBool m_history_disabled;
 };
 
-template<>
-struct WithBitOps<Context::Flags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<Context::Flags>) { return true; }
 
 struct ScopedEdition
 {
diff --git a/src/event_manager.cc b/src/event_manager.cc
index 11fb5c44..7a0614dc 100644
--- a/src/event_manager.cc
+++ b/src/event_manager.cc
@@ -1,6 +1,7 @@
 #include "event_manager.hh"
 
 #include "containers.hh"
+#include "flags.hh"
 
 #include <unistd.h>
 
diff --git a/src/event_manager.hh b/src/event_manager.hh
index f4fa503e..e83672b9 100644
--- a/src/event_manager.hh
+++ b/src/event_manager.hh
@@ -2,8 +2,8 @@
 #define event_manager_hh_INCLUDED
 
 #include "clock.hh"
+#include "meta.hh"
 #include "utils.hh"
-#include "flags.hh"
 #include "vector.hh"
 
 #include <functional>
@@ -28,7 +28,7 @@ enum class FdEvents
     Except = 1 << 2,
 };
 
-template<> struct WithBitOps<FdEvents> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<FdEvents>) { return true; }
 
 class FDWatcher
 {
diff --git a/src/face.hh b/src/face.hh
index 806089a9..dc38192c 100644
--- a/src/face.hh
+++ b/src/face.hh
@@ -19,7 +19,7 @@ enum class Attribute : int
     Italic    = 1 << 7,
 };
 
-template<> struct WithBitOps<Attribute> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<Attribute>) { return true; }
 
 struct Face
 {
diff --git a/src/file.hh b/src/file.hh
index a103d61f..1ecb1090 100644
--- a/src/file.hh
+++ b/src/file.hh
@@ -79,7 +79,7 @@ enum class FilenameFlags
     Expand = 1 << 1
 };
 
-template<> struct WithBitOps<FilenameFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<FilenameFlags>) { return true; }
 
 CandidateList complete_filename(StringView prefix, const Regex& ignore_regex,
                                 ByteCount cursor_pos = -1,
diff --git a/src/flags.hh b/src/flags.hh
index d9755efa..74a7188f 100644
--- a/src/flags.hh
+++ b/src/flags.hh
@@ -3,20 +3,22 @@
 
 #include <type_traits>
 
+#include "meta.hh"
+
 namespace Kakoune
 {
 
 template<typename Flags>
-struct WithBitOps : std::false_type {};
+constexpr bool with_bit_ops(Meta::Type<Flags>) { return false; }
 
 template<typename Flags>
 using UnderlyingType = typename std::underlying_type<Flags>::type;
 
 template<typename Flags, typename T = void>
-using EnableIfWithBitOps = typename std::enable_if<WithBitOps<Flags>::value, T>::type;
+using EnableIfWithBitOps = typename std::enable_if<with_bit_ops(Meta::Type<Flags>{}), T>::type;
 
 template<typename Flags, typename T = void>
-using EnableIfWithoutBitOps = typename std::enable_if<not WithBitOps<Flags>::value, T>::type;
+using EnableIfWithoutBitOps = typename std::enable_if<not with_bit_ops(Meta::Type<Flags>{}), T>::type;
 
 template<typename Flags, typename = EnableIfWithBitOps<Flags>>
 constexpr Flags operator|(Flags lhs, Flags rhs)
diff --git a/src/input_handler.hh b/src/input_handler.hh
index fd13a5a0..2962ac12 100644
--- a/src/input_handler.hh
+++ b/src/input_handler.hh
@@ -35,7 +35,7 @@ enum class PromptFlags
     Password = 1 << 0,
     DropHistoryEntriesWithBlankPrefix = 1 << 1
 };
-template<> struct WithBitOps<PromptFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<PromptFlags>) { return true; }
 
 
 using KeyCallback = std::function<void (Key, Context&)>;
@@ -131,8 +131,7 @@ enum class AutoInfo
     Normal  = 1 << 2
 };
 
-template<>
-struct WithBitOps<AutoInfo> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<AutoInfo>) { return true; }
 
 constexpr Array<EnumDesc<AutoInfo>, 3> enum_desc(Meta::Type<AutoInfo>)
 {
diff --git a/src/keys.hh b/src/keys.hh
index 39378c22..02df20a6 100644
--- a/src/keys.hh
+++ b/src/keys.hh
@@ -84,7 +84,7 @@ struct Key
     Optional<Codepoint> codepoint() const;
 };
 
-template<> struct WithBitOps<Key::Modifiers> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<Key::Modifiers>) { return true; }
 
 using KeyList = Vector<Key, MemoryDomain::Mapping>;
 
diff --git a/src/main.cc b/src/main.cc
index f7cbdd54..426e7809 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -493,7 +493,7 @@ enum class ServerFlags
     ReadOnly    = 1 << 2,
     StartupInfo = 1 << 3,
 };
-template<> struct WithBitOps<ServerFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<ServerFlags>) { return true; }
 
 int run_server(StringView session,
                StringView init_cmds, Optional<BufferCoord> init_coord,
diff --git a/src/normal.cc b/src/normal.cc
index 0ee22f59..03826487 100644
--- a/src/normal.cc
+++ b/src/normal.cc
@@ -1261,7 +1261,7 @@ enum class SelectFlags
     Extend = 4
 };
 
-template<> struct WithBitOps<SelectFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<SelectFlags>) { return true; }
 
 template<SelectFlags flags>
 void select_to_next_char(Context& context, NormalParams params)
diff --git a/src/option_manager.cc b/src/option_manager.cc
index eb50bfcb..d842a254 100644
--- a/src/option_manager.cc
+++ b/src/option_manager.cc
@@ -1,6 +1,7 @@
 #include "option_manager.hh"
 
 #include "assert.hh"
+#include "flags.hh"
 
 namespace Kakoune
 {
diff --git a/src/option_manager.hh b/src/option_manager.hh
index e794a3c9..b20303b0 100644
--- a/src/option_manager.hh
+++ b/src/option_manager.hh
@@ -4,7 +4,6 @@
 #include "completion.hh"
 #include "containers.hh"
 #include "exception.hh"
-#include "flags.hh"
 #include "option_types.hh"
 #include "vector.hh"
 
@@ -22,7 +21,7 @@ enum class OptionFlags
     Hidden = 1,
 };
 
-template<> struct WithBitOps<OptionFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<OptionFlags>) { return true; }
 
 class OptionDesc
 {
diff --git a/src/option_types.hh b/src/option_types.hh
index ab2c35fa..1a55fb17 100644
--- a/src/option_types.hh
+++ b/src/option_types.hh
@@ -28,7 +28,7 @@ template<typename Enum>
 typename std::enable_if<std::is_enum<Enum>::value, String>::type
 option_type_name(Meta::Type<Enum>)
 {
-    constexpr StringView type = WithBitOps<Enum>::value ? "flags" : "enum";
+    constexpr StringView type = with_bit_ops(Meta::Type<Enum>{}) ? "flags" : "enum";
     auto name = enum_desc(Meta::Type<Enum>{});
     return type + "(" + join(name | transform(std::mem_fn(&EnumDesc<Enum>::name)), '|') + ")";
 }
@@ -244,8 +244,7 @@ enum class DebugFlags
     Keys = 1 << 3,
 };
 
-template<>
-struct WithBitOps<DebugFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<DebugFlags>) { return true; }
 
 constexpr Array<EnumDesc<DebugFlags>, 4> enum_desc(Meta::Type<DebugFlags>)
 {
diff --git a/src/parameters_parser.hh b/src/parameters_parser.hh
index f45c0410..a790aa6e 100644
--- a/src/parameters_parser.hh
+++ b/src/parameters_parser.hh
@@ -53,6 +53,7 @@ struct ParameterDesc
         SwitchesOnlyAtStart = 1,
         SwitchesAsPositional = 2,
     };
+    friend constexpr bool with_bit_ops(Meta::Type<Flags>) { return true; }
 
     ParameterDesc() = default;
     ParameterDesc(SwitchMap switches, Flags flags = Flags::None,
@@ -66,8 +67,6 @@ 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/ranked_match.cc b/src/ranked_match.cc
index 1de8713e..3b1d9645 100644
--- a/src/ranked_match.cc
+++ b/src/ranked_match.cc
@@ -9,8 +9,6 @@
 namespace Kakoune
 {
 
-template<> struct WithBitOps<RankedMatch::Flags> : std::true_type {};
-
 UsedLetters used_letters(StringView str)
 {
     UsedLetters res = 0;
diff --git a/src/ranked_match.hh b/src/ranked_match.hh
index bac6bc39..9d0e3b73 100644
--- a/src/ranked_match.hh
+++ b/src/ranked_match.hh
@@ -2,6 +2,7 @@
 #define ranked_match_hh_INCLUDED
 
 #include "string.hh"
+#include "meta.hh"
 
 namespace Kakoune
 {
@@ -43,6 +44,7 @@ private:
         Prefix           = 1 << 4,
         FullMatch        = 1 << 5,
     };
+    friend constexpr bool with_bit_ops(Meta::Type<Flags>) { return true; }
 
     StringView m_candidate{};
     Flags m_flags = Flags::None;
diff --git a/src/selectors.hh b/src/selectors.hh
index e0bbb5b5..e873d9ab 100644
--- a/src/selectors.hh
+++ b/src/selectors.hh
@@ -60,7 +60,7 @@ enum class ObjectFlags
     Inner   = 4
 };
 
-template<> struct WithBitOps<ObjectFlags> : std::true_type {};
+constexpr bool with_bit_ops(Meta::Type<ObjectFlags>) { return true; }
 
 template<WordType word_type>
 Optional<Selection>
diff --git a/src/shell_manager.cc b/src/shell_manager.cc
index a663c59f..78147d76 100644
--- a/src/shell_manager.cc
+++ b/src/shell_manager.cc
@@ -7,6 +7,7 @@
 #include "event_manager.hh"
 #include "face_registry.hh"
 #include "file.hh"
+#include "flags.hh"
 #include "regex.hh"
 
 #include <cstring>
diff --git a/src/shell_manager.hh b/src/shell_manager.hh
index 1336ca9b..df2429d6 100644
--- a/src/shell_manager.hh
+++ b/src/shell_manager.hh
@@ -3,7 +3,6 @@
 
 #include "array_view.hh"
 #include "env_vars.hh"
-#include "flags.hh"
 #include "string.hh"
 #include "utils.hh"
 #include "completion.hh"
@@ -31,6 +30,7 @@ public:
         None = 0,
         WaitForStdout = 1
     };
+    friend constexpr bool with_bit_ops(Meta::Type<Flags>) { return true; }
 
     std::pair<String, int> eval(StringView cmdline, const Context& context,
                                 StringView input = {},
@@ -49,8 +49,6 @@ private:
     Vector<EnvVarDesc, MemoryDomain::EnvVars> m_env_vars;
 };
 
-template<> struct WithBitOps<ShellManager::Flags> : std::true_type {};
-
 }
 
 #endif // shell_manager_hh_INCLUDED