Refactored config option to separate file

src/config/option.h

@@ -0,0 +1,69 @@
+/**
+ * src/config/option.h
+ *
+ * Copyright (c) 2021-2022 Bartek Kryza <bkryza@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+
+namespace clanguml {
+namespace config {
+
+template <typename T> void append_value(T &l, const T &r) { l = r; }
+
+enum class option_inherit_mode { override, append };
+
+template <typename T> struct option {
+    option(const std::string &name_,
+        option_inherit_mode im = option_inherit_mode::override)
+        : name{name_}
+        , value{{}}
+    {
+    }
+    option(const std::string &name_, const T &initial_value,
+        option_inherit_mode im = option_inherit_mode::override)
+        : name{name_}
+        , value{initial_value}
+    {
+    }
+
+    void set(const T &v)
+    {
+        value = v;
+        is_declared = true;
+    }
+
+    void override(const option<T> &o)
+    {
+        if (!is_declared && o.is_declared) {
+            if (inheritance_mode == option_inherit_mode::append)
+                append_value(value, o.value);
+            else
+                value = o.value;
+
+            is_declared = true;
+        }
+    }
+
+    T &operator()() { return value; }
+
+    const T &operator()() const { return value; }
+
+    std::string name;
+    T value;
+    bool is_declared{false};
+    option_inherit_mode inheritance_mode;
+};
+}
+}