public void Visit(ArithmeticOperationNode node)
        {
            node.LeftOperand.Accept(this);
            node.RightOperand.Accept(this);

            if (node.LeftOperand.StaticType.Text != node.RightOperand.StaticType.Text)
            {
                errors.Add(SemanticError.InvalidUseOfOperator(node, node.LeftOperand.StaticType, node.RightOperand.StaticType));
            }

            else if (node.LeftOperand.StaticType.Text != "Int" || node.RightOperand.StaticType.Text != "Int")
            {
                errors.Add(SemanticError.InvalidUseOfOperator(node));
            }

            else if (!scope.IsDefinedType("Int", out node.StaticType))
            {
                errors.Add(SemanticError.NotDeclaredType(new TypeNode(node.Line, node.Column, "Int")));
            }
        }
        public void Visit(MethodNode node)
        {
            if (!scope.IsDefinedType(node.TypeReturn.Text, out TypeInfo typeReturn))
            {
                errors.Add(SemanticError.NotDeclaredType(node.TypeReturn));
            }

            node.TypeReturn = new TypeNode(node.TypeReturn.Line, node.TypeReturn.Column, typeReturn.Text);

            TypeInfo[] typeArgs = new TypeInfo[node.Arguments.Count];
            for (int i = 0; i < node.Arguments.Count; ++i)
            {
                if (!scope.IsDefinedType(node.Arguments[i].Type.Text, out typeArgs[i]))
                {
                    errors.Add(SemanticError.NotDeclaredType(node.Arguments[i].Type));
                }
            }

            scope.Define(node.Id.Text, typeArgs, typeReturn);
        }
        public void Visit(ProgramNode node)
        {
            if (!SemanticAlgorithm.TopologicalSort(node.Classes, errors))
            {
                return;
            }

            node.Classes.ForEach(cclass => scope.AddType(cclass.TypeClass.Text, new TypeInfo(cclass.TypeClass.Text, scope.GetType(cclass.TypeInherit.Text), cclass)));

            int idMain = -1;

            for (int i = 0; i < node.Classes.Count; ++i)
            {
                if (node.Classes[i].TypeClass.Text == "Main")
                {
                    idMain = i;
                }
            }

            if (idMain == -1)
            {
                errors.Add(SemanticError.NotFoundClassMain());
                return;
            }

            bool mainOK = false;

            foreach (var item in node.Classes[idMain].FeatureNodes)
            {
                if (item is MethodNode)
                {
                    var method = item as MethodNode;
                    if (method.Id.Text == "main" && method.Arguments.Count == 0)
                    {
                        mainOK = true;
                    }
                }
            }

            if (!mainOK)
            {
                errors.Add(SemanticError.NotFoundMethodmain(node.Classes[idMain]));
            }

            foreach (var cclass in node.Classes)
            {
                if (!scope.IsDefinedType(cclass.TypeInherit.Text, out TypeInfo type))
                {
                    errors.Add(SemanticError.NotDeclaredType(cclass.TypeInherit));
                    return;
                }
                if (new List <string> {
                    "Bool", "Int", "String"
                }.Contains(type.Text))
                {
                    errors.Add(SemanticError.NotInheritsOf(cclass, type));
                    return;
                }
                cclass.Accept(this);
            }
        }