lib: improve printability for some types

A little fmt pixie dust

lib/message/mu-fields.hh

@@ -207,7 +207,10 @@ struct Field {
 	}
 };
 
-static inline bool operator==(const Field& f1, const Field& f2) { return f1.id == f2.id; }
+// equality
+static inline constexpr bool operator==(const Field& f1, const Field& f2) { return f1.id == f2.id; }
+static inline constexpr bool operator==(const Field& f1, const Field::Id id) { return f1.id == id; }
+
 
 MU_ENABLE_BITOPS(Field::Flag);
 
@@ -594,20 +597,5 @@ Option<Field> field_from_number(size_t id)
 }
 
 
-/**
- * Get a fmt-printable representation of Field for fmt
- *
- * @param field a Field
- *
- * @return a printable representation
- */
-static inline constexpr auto format_as(const Field& field) {
-	return field.name;
-}
-static inline constexpr auto format_as(const Field::Id id) {
-	return format_as(field_from_id(id));
-}
-
-
 } // namespace Mu
 #endif /* MU_FIELDS_HH__ */

lib/mu-store.hh

@@ -467,6 +467,13 @@ private:
 MU_ENABLE_BITOPS(Store::Options);
 MU_ENABLE_BITOPS(Store::MoveOptions);
 
+static inline std::string
+format_as(const Store& store)
+{
+	return mu_format("store ({}/{})", format_as(store.xapian_db()),
+			 store.root_maildir());
+}
+
 } // namespace Mu
 
 #endif /* __MU_STORE_HH__ */

lib/mu-xapian-db.cc

@@ -101,4 +101,6 @@ XapianDb::XapianDb(const std::string& db_path, Flavor flavor) :
 
 	if (flavor == Flavor::CreateOverwrite)
 		set_timestamp(MetadataIface::created_key);
+
+	mu_debug("created {} / {}", flavor, *this);
 }

lib/mu-xapian-db.hh

@@ -192,6 +192,16 @@ public:
 	 */
 	const std::string& path() const;
 
+	/**
+	 * Get a description of the Xapian database
+	 *
+	 * @return description
+	 */
+	const std::string description() const {
+		return db().get_description();
+	}
+
+
 	/**
 	 * Get the number of documents (messages) in the database
 	 *
@@ -399,6 +409,27 @@ private:
 	DbType db_;
 };
 
+constexpr std::string_view
+format_as(XapianDb::Flavor flavor)
+{
+	switch(flavor) {
+	case XapianDb::Flavor::CreateOverwrite:
+		return "create-overwrite";
+	case XapianDb::Flavor::Open:
+		return "open";
+	case XapianDb::Flavor::ReadOnly:
+		return "read-only";
+	default:
+		return "??";
+	}
+}
+
+static inline std::string
+format_as(const XapianDb& db)
+{
+	return mu_format("{} @ {}", db.description(), db.path());
+}
+
 } // namespace Mu
 
 #endif /* MU_XAPIAN_DB_HH__ */