/// <summary>
/// <whilestmt>::= while “(“ <Bexpr> ”)” “{“ <Statments> “}”
/// </summary>
/// <param name="pb"></param>
/// <returns></returns>
public Stmt ParseWhileStatement(ProcedureBuilder pb)
{
GetNext();
Exp exp = BExpr(pb);
if (pb.TypeCheck(exp) != TYPE_INFO.TYPE_BOOL)
{
throw new Exception("Expects a boolean expression");
}
if (Current_Token != TOKEN.TOK_OCBR)
{
throw new Exception("{ Expected in if stmt");
}
GetNext();//Skip {
/////******///
ArrayList body = StatementList(pb);
if ((Current_Token != TOKEN.TOK_CCBR))
{
throw new Exception("} Expected ");
}
return(new WhileStatement(exp, body));
}
/// <summary>
/// <ifstmt>::=if <Bexpr> “{“<Statments> } [ else “{“<Statments>“}”]
/// </summary>
/// <param name="pb"></param>
/// <returns></returns>
public Stmt ParseIfStatement(ProcedureBuilder pb)
{
GetNext();
ArrayList true_part = null;
ArrayList false_part = null;
Exp exp = BExpr(pb); // Evaluate Expression
if (pb.TypeCheck(exp) != TYPE_INFO.TYPE_BOOL)
{
throw new Exception("in function " + pb.Name + "\tExpects a boolean expression");
}
if (Current_Token != TOKEN.TOK_OCBR)
{
throw new Exception("in function " + pb.Name + "\t { Expected in if stmt");
}
// skip {
GetNext();
true_part = StatementList(pb); //{.......}
GetNext(); // skip }
// no else stmt
if (Current_Token == TOKEN.TOK_CCBR)
{// return fals stmt as null
return(new IfStatement(exp, true_part, false_part));
}
if (Current_Token != TOKEN.TOK_ELSE)
{
throw new Exception("in function " + pb.Name + "\tELSE expected");
}
GetNext(); // remove else
GetNext(); // remove {
false_part = StatementList(pb);
if (Current_Token != TOKEN.TOK_CCBR)
{
throw new Exception("in function" + pb.Name + "\t} Expected");
}
return(new IfStatement(exp, true_part, false_part));
}
/// <summary>
/// <rexpr>=<Bexpr> |fun “(“ <arglist>“)” <retType> <Statments> “;”
/// </summary>
/// <param name="pb"></param>
/// <returns></returns>
public Stmt ParseReturnStatement(ProcedureBuilder pb)
{
GetNext();
//return fun (x numeric)numeric{.....
if (Current_Token == TOKEN.TOK_FUNCTION)
{
GetNext();
pb.InitClsr();
pb.clsoure.Name = pb.Name + "1";
///////////////////now parse for parameters////////////////////////////
if (Current_Token != TOKEN.TOK_OPAREN)
{
return(null);
}
GetNext(); // remove (
//(a int)||()
ArrayList lst_types = new ArrayList();
while (Current_Token == TOKEN.TOK_UNQUOTED_STRING)
{
SYMBOL_INFO inf = new SYMBOL_INFO();
inf.SymbolName = last_str;
GetNext();
if (Current_Token == TOKEN.TOK_VAR_BOOL ||
Current_Token == TOKEN.TOK_VAR_NUMBER ||
Current_Token == TOKEN.TOK_VAR_STRING)
{
inf.Type = (Current_Token == TOKEN.TOK_VAR_BOOL) ?
TYPE_INFO.TYPE_BOOL : (Current_Token == TOKEN.TOK_VAR_NUMBER) ?
TYPE_INFO.TYPE_NUMERIC : TYPE_INFO.TYPE_STRING;
}
else
{
return(null);
}
lst_types.Add(inf.Type);
pb.clsoure.AddFormals(inf);
pb.clsoure.AddLocal(inf);
GetNext();
if (Current_Token != TOKEN.TOK_COMMA)
{
break;
}
GetNext();
}
if (Current_Token != TOKEN.TOK_CPAREN)
{
return(null);
}
GetNext();
//parse for return type (= number/bool/function)
if (!(Current_Token == TOKEN.TOK_VAR_BOOL ||
Current_Token == TOKEN.TOK_VAR_NUMBER ||
Current_Token == TOKEN.TOK_VAR_STRING ||
Current_Token == TOKEN.TOK_FUNCTION))
{
return(null);
}
///-------- Assign the return type
pb.clsoure.TYPE = (Current_Token == TOKEN.TOK_VAR_BOOL) ?
TYPE_INFO.TYPE_BOOL : (Current_Token == TOKEN.TOK_VAR_NUMBER) ?
TYPE_INFO.TYPE_NUMERIC : (Current_Token == TOKEN.TOK_FUNCTION) ?TYPE_INFO.TYPE_FUNCTION:TYPE_INFO.TYPE_STRING;
////////////////////////////////////
GetNext();
if (Current_Token != TOKEN.TOK_OCBR)
{
return(null);
}
GetNext();
////***********/********************************************
///add statments
ArrayList lst = StatementList(pb.clsoure);
foreach (Stmt st in lst)
{
pb.clsoure.AddStatement(st);
}
//ClsrStmt:
if (Current_Token != TOKEN.TOK_CCBR)
{
throw new Exception("} expected in the function");
}
return(null);
}
else
{
Exp exp = BExpr(pb);
if (Current_Token != TOKEN.TOK_SEMI)
{
throw new Exception(pb.Name + "; expected ");
}
pb.TypeCheck(exp);
return(new ReturnStatement(exp));
}
}
