refactor: describe AccessKind, ConstexprKind, ParamDirection, StorageClassKind

Replace manual toString and tag_invoke overloads with
MRDOCS_DESCRIBE_ENUM for four enums whose kebab-case names match the
existing string representations.

The XML writer now emits these fields (e.g. <access>public</access>,
<constexpr>constexpr</constexpr>) where they were previously silently
skipped. None/none sentinel values are suppressed via a generic
has_none_enumerator check.

TypeKind stays manual because toKebabCase("LValueReference") produces
"l-value-reference", not the established "lvalue-reference".

Author: gennaroprota

include/mrdocs/Metadata/DocComment/Block/ParamDirection.hpp

@@ -16,6 +16,7 @@
 
 #include <mrdocs/Platform.hpp>
 #include <mrdocs/Dom.hpp>
+#include <mrdocs/Support/Describe.hpp>
 
 namespace mrdocs::doc {
 
@@ -33,23 +34,7 @@ enum class ParamDirection
     inout
 };
 
-/** Return the name of the ParamDirection as a string.
-*/
-MRDOCS_DECL
-dom::String
-toString(ParamDirection kind) noexcept;
-
-/** Return the ParamDirection from a @ref dom::Value string.
-*/
-inline
-void
-tag_invoke(
-    dom::ValueFromTag,
-    dom::Value& v,
-    ParamDirection const kind)
-{
-    v = toString(kind);
-}
+MRDOCS_DESCRIBE_ENUM(ParamDirection, none, in, out, inout)
 
 } // mrdocs::doc
 

include/mrdocs/Metadata/Specifiers/AccessKind.hpp

@@ -14,7 +14,7 @@
 
 #include <mrdocs/Platform.hpp>
 #include <mrdocs/Dom.hpp>
-#include <string>
+#include <mrdocs/Support/Describe.hpp>
 
 namespace mrdocs {
 
@@ -41,25 +41,7 @@ enum class AccessKind
     Private,
 };
 
-/** Convert access specifier to its string form.
-*/
-MRDOCS_DECL
-dom::String
-toString(AccessKind kind) noexcept;
-
-/** Return the AccessKind as a @ref dom::Value string.
-*/
-inline
-void
-tag_invoke(
-    dom::ValueFromTag,
-    dom::Value& v,
-    AccessKind const kind)
-{
-    v = toString(kind);
-}
-
-
+MRDOCS_DESCRIBE_ENUM(AccessKind, None, Public, Protected, Private)
 
 } // mrdocs
 

include/mrdocs/Metadata/Specifiers/ConstexprKind.hpp

@@ -13,7 +13,7 @@
 #define MRDOCS_API_METADATA_SPECIFIERS_CONSTEXPRKIND_HPP
 
 #include <mrdocs/Platform.hpp>
-#include <string>
+#include <mrdocs/Support/Describe.hpp>
 
 namespace mrdocs {
 
@@ -33,23 +33,7 @@ enum class ConstexprKind
     Consteval,
 };
 
-/** Convert a constexpr/consteval specifier kind to a string.
-*/
-MRDOCS_DECL
-dom::String
-toString(ConstexprKind kind) noexcept;
-
-/** Return the ConstexprKind as a @ref dom::Value string.
-*/
-inline
-void
-tag_invoke(
-    dom::ValueFromTag,
-    dom::Value& v,
-    ConstexprKind const kind)
-{
-    v = toString(kind);
-}
+MRDOCS_DESCRIBE_ENUM(ConstexprKind, None, Constexpr, Consteval)
 
 } // mrdocs
 

include/mrdocs/Metadata/Specifiers/StorageClassKind.hpp

@@ -14,7 +14,7 @@
 
 #include <mrdocs/Platform.hpp>
 #include <mrdocs/Dom.hpp>
-#include <string>
+#include <mrdocs/Support/Describe.hpp>
 
 namespace mrdocs {
 
@@ -40,23 +40,7 @@ enum class StorageClassKind
     Register
 };
 
-/** Convert a storage class kind to its string form.
-*/
-MRDOCS_DECL
-dom::String
-toString(StorageClassKind kind) noexcept;
-
-/** Return the StorageClassKind as a @ref dom::Value string.
-*/
-inline
-void
-tag_invoke(
-    dom::ValueFromTag,
-    dom::Value& v,
-    StorageClassKind const kind)
-{
-    v = toString(kind);
-}
+MRDOCS_DESCRIBE_ENUM(StorageClassKind, None, Extern, Static, Auto, Register)
 
 } // mrdocs
 

include/mrdocs/Metadata/Type/TypeKind.hpp

@@ -29,9 +29,9 @@ MRDOCS_DECL
 dom::String
 toString(TypeKind kind) noexcept;
 
-inline
 /** Map a TypeKind into a DOM value.
 */
+inline
 void
 tag_invoke(
     dom::ValueFromTag,

include/mrdocs/Support/MapReflectedType.hpp

@@ -15,6 +15,8 @@
 #include <mrdocs/Dom/LazyArray.hpp>
 #include <mrdocs/Dom/LazyObject.hpp>
 #include <mrdocs/Metadata/Expression.hpp>
+#include <mrdocs/Metadata/DocComment/Block/ParamDirection.hpp>
+#include <mrdocs/Metadata/Specifiers/AccessKind.hpp>
 #include <mrdocs/Metadata/Specifiers/ConstexprKind.hpp>
 #include <mrdocs/Metadata/Specifiers/ReferenceKind.hpp>
 #include <mrdocs/Metadata/Specifiers/StorageClassKind.hpp>
@@ -114,6 +116,10 @@ shouldMapValue(T const& value)
     {
         return !value.empty();
     }
+    else if constexpr (std::is_same_v<T, AccessKind>)
+    {
+        return value != AccessKind::None;
+    }
     else if constexpr (std::is_same_v<T, ConstexprKind>)
     {
         return value != ConstexprKind::None;
@@ -126,6 +132,10 @@ shouldMapValue(T const& value)
     {
         return value != StorageClassKind::None;
     }
+    else if constexpr (std::is_same_v<T, doc::ParamDirection>)
+    {
+        return value != doc::ParamDirection::none;
+    }
     else if constexpr (std::is_same_v<T, ExprInfo>)
     {
         return !value.Written.empty();

src/lib/Gen/xml/XMLWriter.cpp

@@ -55,6 +55,24 @@ std::string tagName()
     return toKebabCase(name);
 }
 
+/** True if the described enum has an enumerator named "None" or "none". */
+template <typename E>
+constexpr bool has_none_enumerator()
+{
+    bool result = false;
+    describe::for_each(
+        describe::describe_enumerators<E>{},
+        [&](auto const& D)
+        {
+            std::string_view name(D.name);
+            if (name == "None" || name == "none")
+            {
+                result = true;
+            }
+        });
+    return result;
+}
+
 } // unnamed namespace
 
 //------------------------------------------------
@@ -175,6 +193,16 @@ XMLWriter::writeElement(std::string_view tag, T const& value)
         { if (value.empty()) return; }
     else if constexpr (std::is_base_of_v<ExprInfo, Type>)
         { if (value.Written.empty()) return; }
+    else if constexpr (describe::has_describe_enumerators<Type>::value)
+    {
+        if constexpr (has_none_enumerator<Type>())
+        {
+            if (toString(value) == "none")
+            {
+                return;
+            }
+        }
+    }
 
     // Primitives inline, compounds wrapped.
     if constexpr (std::is_base_of_v<ExprInfo, Type>)

src/lib/Metadata/DocComment.cpp

@@ -46,24 +46,6 @@ toString(AdmonitionKind kind) noexcept
     }
 }
 
-dom::String
-toString(ParamDirection kind) noexcept
-{
-    switch(kind)
-    {
-    case ParamDirection::none:
-        return "";
-    case ParamDirection::in:
-        return "in";
-    case ParamDirection::out:
-        return "out";
-    case ParamDirection::inout:
-        return "inout";
-    default:
-        MRDOCS_UNREACHABLE();
-    }
-}
-
 dom::String
 toString(Parts kind) noexcept
 {

src/lib/Metadata/Specifiers.cpp

@@ -15,45 +15,6 @@
 
 namespace mrdocs {
 
-dom::String toString(AccessKind kind) noexcept
-{
-    switch(kind)
-    {
-    case AccessKind::Public:    return "public";
-    case AccessKind::Private:   return "private";
-    case AccessKind::Protected: return "protected";
-    case AccessKind::None:      return "";
-    default:
-        MRDOCS_UNREACHABLE();
-    }
-}
-
-dom::String toString(StorageClassKind kind) noexcept
-{
-    switch(kind)
-    {
-    case StorageClassKind::None:     return "";
-    case StorageClassKind::Extern:   return "extern";
-    case StorageClassKind::Static:   return "static";
-    case StorageClassKind::Auto:     return "auto";
-    case StorageClassKind::Register: return "register";
-    default:
-        MRDOCS_UNREACHABLE();
-    }
-}
-
-dom::String toString(ConstexprKind kind) noexcept
-{
-    switch(kind)
-    {
-    case ConstexprKind::None:      return "";
-    case ConstexprKind::Constexpr: return "constexpr";
-    case ConstexprKind::Consteval: return "consteval";
-    default:
-        MRDOCS_UNREACHABLE();
-    }
-}
-
 dom::String toString(ExplicitKind kind) noexcept
 {
     switch(kind)

src/lib/Support/Debug.hpp

@@ -47,7 +47,7 @@ struct std::formatter<mrdocs::AccessKind> : std::formatter<std::string> {
   template <class FmtContext>
   std::format_context::iterator format(mrdocs::AccessKind a,
                                        FmtContext &ctx) const {
-    return std::formatter<std::string>::format(toString(a).str(), ctx);
+    return std::formatter<std::string>::format(toString(a), ctx);
   }
 };