types/description: add is_fundamental_match for descriptions

types/description.hpp

@@ -274,6 +274,49 @@ namespace cruft::types {
             };
         }
     }
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    /// Tests if the underlying scalar value specified by two descriptions
+    /// matches.
+    ///
+    /// This deliberately ignores arity, alignment, and index.
+    ///
+    /// It is provided to assist systems that needs to coerce values and
+    /// assumes the caller is prepared to deal with indexing, alignment, and
+    /// interpretation.
+    inline bool
+    is_fundamental_match (description const &a, description const &b)
+    {
+        // Both categories must match, or one must be ENUM and the other must
+        // be INTEGER.
+        if (a.category != b.category) {
+            if (a.category == category::ENUM)
+                if (b.category != category::INTEGER)
+                    return false;
+
+            if (b.category == category::ENUM)
+                if (a.category != category::INTEGER)
+                    return false;
+        }
+
+        return a.signedness == b.signedness &&
+               a.width      == b.width;
+    }
+
+
+    ///------------------------------------------------------------------------
+    /// Tests if a type matches the underlying scalar value specified by a
+    /// description.
+    ///
+    /// This exists as a convenience wrapper for `is_fundemental_wrapper`
+    /// with two descriptions.
+    template <typename ValueT>
+    bool
+    is_fundamental_match (description const &desc)
+    {
+        return is_fundamental_match (desc, make_description<ValueT> ());
+    }
 }