1 files changed, 8 insertions, 0 deletions
diff --git a/impl/Expression.hpp b/impl/Expression.hpp
index 00bc9cd..0d48d70 100644
--- a/impl/Expression.hpp
+++ b/impl/Expression.hpp
@@ -27,6 +27,10 @@ struct Expression {
     return NULL;
   }
 
+  virtual MaxExpression<Domain>* toMaxExpression() {
+    return NULL;
+  }
+
   virtual Domain eval(const VariableAssignment<Domain>&) const = 0;
   virtual Domain eval(const VariableAssignment<Domain>& rho,
                       const MaxStrategy<Domain>&) const {
@@ -145,6 +149,10 @@ struct MaxExpression : public OperatorExpression<Domain> {
   MaxExpression(const unsigned int& id, const Maximum<Domain>& op, const std::vector<Expression<Domain>*>& arguments)
     : OperatorExpression<Domain>(op, arguments), _id(id) { }
 
+  MaxExpression* toMaxExpression() {
+    return this;
+  }
+
   const MaxExpression* toMaxExpression() const {
     return this;
   }