/// <summary>
/// Checks the static semantic constraints of an AssignNode.
/// </summary>
/// <returns>An ISemanticCheckValue.</returns>
/// <param name="node">Node.</param>
public ISemanticCheckValue VisitAssignNode(AssignNode node)
{
// Check that the id property in this AssignNode is ok.
IProperty property = getVariableProperty(node);
// if the property was voidProperty, return at this point,
// an error has been reported already
if (property == voidProperty)
{
return(voidProperty);
}
VariableIdNode idNode = node.IDNode;
// check that the id variable is declared
checkPropertyDeclared(idNode, property, true);
// check that the id property we should be assigning to is not constant
// at this point of its lifecycle (i.e. not a current block's control variable)
if (property.Constant)
{
analyzer.notifyError(new IllegalAssignmentError(node));
}
// evaluate the type of this property
IProperty evaluated = node.Accept(this.typeChecker).asProperty();
// check the type of the expression in the assign node matches the one in the symbol table
if (!checkPropertyType(property, evaluated.GetTokenType()))
{
analyzer.notifyError(new IllegalTypeError(idNode));
}
return(voidProperty);
}
/// <summary>
/// Visits the IO read node.
/// </summary>
/// <returns>An ISemanticCheckValue.</returns>
/// <param name="node">Node.</param>
public ISemanticCheckValue VisitIOReadNode(IOReadNode node)
{
// read an input
string input = reader.readLine();
// select the first word of the input
input = input.Split(new[] { ' ', '\t', '\n' })[0];
// set the input to the ioreadnode's assignment
AssignNode assignNode = node.AssignNode;
setAssignValue(input, assignNode);
// execute the assign node
assignNode.Accept(this);
return(voidProperty);
}
