Add method Action::ASTNode::empty()

opm/input/eclipse/Schedule/Action/ASTNode.hpp

@@ -28,6 +28,8 @@ public:
     FuncType func_type;
     void add_child(const ASTNode& child);
     size_t size() const;
+    bool empty() const;
+
     std::string func;
     void required_summary(std::unordered_set<std::string>& required_summary) const;
 

src/opm/input/eclipse/Schedule/Action/ASTNode.cpp

@@ -89,6 +89,9 @@ size_t ASTNode::size() const {
     return this->children.size();
 }
 
+bool ASTNode::empty() const {
+    return this->size() == 0;
+}
 
 void ASTNode::add_child(const ASTNode& child) {
     this->children.push_back(child);