Add a version of get_item that dynamic_casts the result

[libs/core.git] / source / core / maputils.h

diff --git a/source/core/maputils.h b/source/core/maputils.h
index 8c642fb9c57a1f9acda6ba5ab2d0dc5311316306..66b4e3baf82c50d815f5bcf4ce0615729ebbf0fb 100644 (file)
--- a/source/core/maputils.h
+++ b/source/core/maputils.h
@@ -9,11 +9,17 @@ namespace Msp {
 
 namespace MapUtilsInternal {
 
+/* This dummy struct is used to introduce a conversion, making the overloaded
+operator below worse than the templated one provided in lexicalcast.h. */
+struct Any
+{
+       template<typename T>
+       Any(const T &) { }
+};
+
 /* This must be hidden in the internal namespace to avoid interfering with
-other things.  There may be problems if a key type has operator<< for ostream
-but not LexicalConverter. */
-template<typename T>
-void operator<<(LexicalConverter &, const T &)
+other things. */
+inline void operator<<(LexicalConverter &, Any)
 { }
 
 template<typename T>
@@ -68,8 +74,14 @@ const typename T::mapped_type &get_item(const T &map, const typename T::key_type
        return i->second;
 }
 
+template<typename D, typename T>
+D *get_item(const T &map, const typename T::key_type &key)
+{
+       return dynamic_cast<D *>(get_item(map, key));
+}
+
 template<typename T>
-const typename T::iterator insert_unique(T &map, const typename T::key_type &key, const typename T::mapped_type &item)
+typename T::iterator insert_unique(T &map, const typename T::key_type &key, const typename T::mapped_type &item)
 {
        if(map.count(key))
                throw key_error(key);
@@ -77,6 +89,15 @@ const typename T::iterator insert_unique(T &map, const typename T::key_type &key
        return map.insert(typename T::value_type(key, item)).first;
 }
 
+template<typename T>
+void remove_existing(T &map, const typename T::key_type &key)
+{
+       if(!map.count(key))
+               throw key_error(key);
+
+       map.erase(key);
+}
+
 } // namespace Msp
 
 #endif