/**
* Function VisitAssignStmt --> <var_ident> := <expr>
* It updates the value of the identifier in the SymbleTable
* Throws an error if the variable was not previous declarated
* Param : assign statement to evaluate
*/
public Object VisitAssignStmt(Stmt.Assign stmt)
{
String name = stmt.Name.Text;
/* If the var is already in the table we change its value */
if (SymbleTable.ContainsKey(name))
{
Value val = Evaluate(stmt.Value);
if (val.Type.Equals(SymbleTable[name].Type))
{
SymbleTable[name] = val;
}
/* If the expected type and the type of the new assign do not match */
else
{
throw new RuntimeError(stmt.Name, "Expected " + SymbleTable[name].Type.ToString()
+ " but found " + val.Type.ToString());
}
}
/* Otherwise it was not declarated before so it is an error */
else
{
throw new RuntimeError(stmt.Name, "This variable does not exist. Not prevoius declared.");
}
return(null);
}
/**
* Function VisitAssignStmt : it checks that the variable and the assignment
* has the same type. Also it throws an error if we try to assign a new value
* for the loop counter inside the loop or if the type is wrong
* Param : assign statement to check
*/
public object VisitAssignStmt(Stmt.Assign stmt)
{
/* Error when trying to assign to the loop counter inside the loop */
if (illegalAssignments.Contains(stmt.Name.Text))
{
throw new TypeError(stmt.Name, "Cannot assign to " + stmt.Name.Text + " in a for loop where it is used as a loop counter.");
}
/* Check that the var to assign already exists */
if (SymbleTypeTable.ContainsKey(stmt.Name.Text))
{
/* Check that the var and the assigment have same type */
VALTYPE right = GetType(stmt.Value);
if (right.Equals(SymbleTypeTable[stmt.Name.Text]))
{
return(null);
}
else
{
throw new TypeError(stmt.Name, stmt.Name.Text + " has type " + SymbleTypeTable[stmt.Name.Text] + " but was tried to assign type: " + right.ToString());
}
}
else
{
throw new TypeError(stmt.Name, "The var '" + stmt.Name.Text + "' does not exist. Cannot assign not pervious declared variables.");
}
}