/**
* Function VisitVarStmt --> "var" <var_ident> ":" <type> [ ":=" <expr> ]
* It adds the new variable to the SymbleTable
* If it already exists throws an error
* If it is not initialized we put a default value : 0 for ints, "" for strings
* and false for bools
* Param : var statement to evaluate
*/
public Object VisitVarStmt(Stmt.Var stmt)
{
String name = stmt.Name.Text;
VALTYPE type = ExpectedType(stmt);
/* Case the variable is already in the symble table */
if (SymbleTable.ContainsKey(name))
{
throw new RuntimeError(stmt.Name, "This variable already exists.");
}
/* Case the variable is not initialized : assign default values */
else if (stmt.Initializer is null)
{
switch (type)
{
case VALTYPE.INT: SymbleTable.Add(name, new Value(type, 0)); break;
case VALTYPE.STRING: SymbleTable.Add(name, new Value(type, "")); break;
case VALTYPE.BOOL: SymbleTable.Add(name, new Value(type, false)); break;
}
}
/* Case the variable is initialized : evaluate the ini expression */
else
{
SymbleTable.Add(name, Evaluate(stmt.Initializer));
}
return(null);
}
/**
* Function CheckReadStatement : checks if the read value and the variable
* has the same type (int or string)
* Param : the string obj we have read
* token of the variable to store the value
* value expected token to have
* Return : the value of the variable or an error
*/
private Value CheckReadStatement(String obj, Token token, VALTYPE value)
{
/* If the value is an int we try to parse it or throw an error */
if (value.Equals(VALTYPE.INT))
{
if (int.TryParse(obj, out int output) == true)
{
return(new Value(VALTYPE.INT, output));
}
throw new RuntimeError(token, "Read value " + obj + " is not the proper type.");
}
/* If the value is a string just return it */
else if (value.Equals(VALTYPE.STRING))
{
return(new Value(VALTYPE.STRING, obj));
}
/* We cannot read bools */
else
{
throw new RuntimeError(token, "Read value " + obj + " is not the proper type.");
}
}
public Elem(int n)
{
numVal = n;
strVal = null;
_type = VALTYPE.INT;
}
public Elem(string str)
{
numVal = null;
strVal = (string)str.Clone();
_type = VALTYPE.STRING;
}
public Value(VALTYPE type, object val)
{
Type = type;
Val = val;
}
