Use std::set for IdList.

This enforces an ordered, deterministic container for identifier lists and consolidates the type via the IdList typedef.

Author: agarny

src/internaltypes.h

@@ -18,7 +18,6 @@ limitations under the License.
 
 #include <map>
 #include <set>
-#include <unordered_set>
 #include <vector>
 
 #include "libcellml/component.h"
@@ -54,7 +53,7 @@ using VariablePtrs = std::vector<VariablePtr>; /**< Type definition for list of
 
 using IdMap = std::map<std::string, std::pair<int, std::vector<std::string>>>; /**< Type definition for map of IDs in Validator. **/
 using ImportLibrary = std::map<std::string, ModelPtr>; /** Type definition for library map of imported models. */
-using IdList = std::unordered_set<std::string>; /**< Type definition for list of identifiers. */
+using IdList = std::set<std::string>; /**< Type definition for list of identifiers. */
 
 using ResetOrderMap = std::map<VariablePtr, std::vector<int>>; /** Type definition for map of variable to reset order. **/
 

src/utilities.cpp

@@ -950,7 +950,7 @@ IdList listIds(const ModelPtr &model)
     // Collect all existing identifiers in a list and return. NB can't use a map or a set as we need to be able to print
     // invalid models (with duplicated identifiers) too.
 
-    std::unordered_set<std::string> idList;
+    IdList idList;
     // Model.
     std::string id = model->id();
     if (!id.empty()) {