added enum19 fmt support

arBmind · arBmind · commit 0e57afa9f3e9 · 2020-07-27T11:43:39.000+02:00
diff --git a/src/enum19.lib/enum19/Enum.fmt.h b/src/enum19.lib/enum19/Enum.fmt.h
@@ -0,0 +1,20 @@
+#pragma once
+#include "Enum.names.h"
+#include "string19/StringView.fmt.h"
+
+/// noto: for this header you need fmt library (not included as library dependency)
+#include <fmt/format.h>
+
+namespace fmt {
+
+/// adds strong support for fmt
+template<enum19::HasMetaEnum T, class char_type> struct formatter<T, char_type> {
+    constexpr auto parse(format_parse_context& ctx) { return ctx.begin(); }
+
+    template<typename FormatCtx> auto format(const T& v, FormatCtx& ctx) {
+        auto underlying = static_cast<std::underlying_type_t<T>>(v);
+        return format_to(ctx.out(), "{} ({})", valueName(v), underlying);
+    }
+};
+
+} // namespace fmt
diff --git a/src/enum19.lib/enum19/Enum.h b/src/enum19.lib/enum19/Enum.h
@@ -34,6 +34,8 @@ template<class T> constexpr void metaEnumFor(ADL*, T*) {
 
 template<class T> constexpr auto meta_enum_for = metaEnumFor(adl, nullptr_to<T>);
 
+template<class T> concept HasMetaEnum = requires(T v) { {meta_enum_for<T>}; };
+
 template<class Enum> struct MetaEnumMember {
     size_t index;
     StringView name;
diff --git a/src/enum19.lib/enum19/enum19.qbs b/src/enum19.lib/enum19/enum19.qbs
@@ -2,10 +2,12 @@
 Product {
     Depends { name: "cpp" }
     Depends { name: "string19" }
+    Depends { name: "fmt"; required: false }
 
     files: [
         "ADL.h",
         "Enum.extras.ostream.h",
+        "Enum.fmt.h",
         "Enum.h",
         "Enum.names.h",
         "Enum.ostream.h",
