private void VisitNode(PrimaryExpression node)
{
AbstractNode child = node.Child;
child.Accept(this);
node.TypeDescriptor = child.TypeDescriptor;
}
private TypeDescriptor AssignmentExp(AbstractNode qualName, AbstractNode exp)
{
QualifiedName name = qualName as QualifiedName;
Expression expression = exp as Expression;
PrimaryExpression primaryExp = exp as PrimaryExpression;
TypeDescriptor nameDesc;
if (name != null && (expression != null || primaryExp != null))
{
Attributes nameAttr = Table.lookup(name.GetStringName());
qualName.AttributesRef = nameAttr;
qualName.TypeDescriptor = nameAttr.TypeDescriptor;
exp.Accept(this);
// Check for errors
// if both types are Error Descriptors, combine errors
ErrorDescriptor nameErrDesc =
nameAttr.TypeDescriptor as ErrorDescriptor;
ErrorDescriptor expErrDesc =
exp.TypeDescriptor as ErrorDescriptor;
if (nameErrDesc != null && expErrDesc != null)
{
nameDesc = nameErrDesc.CombineErrors(expErrDesc);
}
// if one or the other is an error, propagate the error up
else if (nameErrDesc != null)
{
nameDesc = nameAttr.TypeDescriptor;
}
else if (expErrDesc != null)
{
nameDesc = exp.TypeDescriptor;
}
// check that the variable being assigned to is assignable
else if (nameAttr.IsAssignable)
{
// if types compatible, assign successfully assigned type
if (TypesCompatible(nameAttr.TypeDescriptor,
exp.TypeDescriptor))
{
nameDesc = GetAssignmentDesc(nameAttr.TypeDescriptor,
exp.TypeDescriptor);
}
// otherwise, assign new error for incompatible types
else
{
nameDesc = new ErrorDescriptor("Incompatible types: " +
"cannot assign " + GetSimpleName(exp.TypeDescriptor)
+ " to " + GetSimpleName(nameAttr.TypeDescriptor) +
" variable");
}
}
// variable is not assignable
else
{
nameDesc = new ErrorDescriptor(nameAttr +
" is not assigable. Cannot assign as " +
GetSimpleName(exp.TypeDescriptor));
}
}
// Assignment not made up of correct parts
else
{
string message = "";
if (name == null && expression == null)
{
message += "EQUALS expression expects 'QualifiedName' " +
"on LHS, but has: " + qualName.GetType().Name +
" & 'Expression' or 'PrimaryExression' on " +
"RHS, but has " + exp.GetType().Name;
}
else if (name == null)
{
message += "EQUALS expression expects 'QualifiedName' on" +
" LHS, but has: " + qualName.GetType().Name;
}
else
{
message += "EQUALS expression expects 'Expression' or " +
"'PrimaryExpression' on RHS, but has: " +
exp.GetType().Name;
}
nameDesc = new ErrorDescriptor(message);
}
return(nameDesc);
}
private void VisitNode(PrimaryExpression node)
{
node.TypeDescriptor = PrimaryExp(node);
}