[BL] handle maps with unique keys

BaseLib/uniqueInsert.h

@@ -17,6 +17,8 @@
 
 #include <algorithm>
 
+#include "StringTools.h"
+
 namespace BaseLib {
 
 template<typename Container>
@@ -26,6 +28,56 @@ void uniquePushBack(Container& container, typename Container::value_type const&
         container.push_back(element);
 }
 
+
+//! Inserts the given \c key with the given \c value into the \c map if an entry with the
+//! given \c key does not yet exist; otherwise an \c error_message is printed and the
+//! program is aborted.
+template<typename Map, typename Key, typename Value>
+void insertIfKeyUniqueElseError(
+	Map& map, Key const& key, Value&& value,
+	std::string const& error_message)
+{
+	auto const inserted = map.emplace(key, std::forward<Value>(value));
+	if (!inserted.second) { // insertion failed, i.e., key already exists
+		ERR("%s Key `%s' already exists.", error_message.c_str(), tostring(key).c_str());
+		std::abort();
+	}
+}
+
+//! Returns the value of \c key from the given \c map if such an entry exists;
+//! otherwise an \c error_message is printed and the program is aborted.
+//! Cf. also the const overload below.
+//! \remark Use as: \code{.cpp} get_or_error<Value>(some_map, some_key, "error message") \endcode
+template<typename Map, typename Key>
+typename Map::mapped_type&
+getOrError(
+	Map& map, Key const& key,
+	std::string const& error_message)
+{
+	auto it = map.find(key);
+	if (it == map.end()) {
+		ERR("%s Key `%s' does not exist.", error_message.c_str(), tostring(key).c_str());
+		std::abort();
+	}
+
+	return it->second;
+}
+//! \overload
+template<typename Map, typename Key>
+typename Map::mapped_type const&
+getOrError(
+	Map const& map, Key const& key,
+	std::string const& error_message)
+{
+	auto it = map.find(key);
+	if (it == map.end()) {
+		ERR("%s Key `%s' does not exist.", error_message.c_str(), tostring(key).c_str());
+		std::abort();
+	}
+
+	return it->second;
+}
+
 } // end namespace BaseLib
 
 #endif /* UNIQUELISTINSERT_H_ */