private Node parseExp(Token t)
{
token t = Scanner.getNextToken();
if(t == null)
return null;
else if(t.getType == TokenType.LPAREN)
return parseRest();
else if(t.getType == TokenType.TRUE)
return new BoolLit(true);
else if(t.getType == TokenType.FALSE)
return new BoolLit(false);
else if(t.getType == TokenType.INT)
return new IntLit(t.getIntVal());
else if(t.getType == TokenType.IDENT)
return new Ident(t.getName());
else if(t.getType == TokenType.QUOTE)
return new Cons(new Ident("quote"), new Cons(parseExp(), null));
else if(t.getType == TokenType.STRING)
return new StrLit(t.getStringVal());
else if(t.getType == TokenType.RPAREN || t.getType == DOT)
Console.write("Error, can't have right parenthesis");
return null;
//INCLUDE RPAREN AND DOT ERRORS
}
private Node parseExp(Token t)
{
if (t == null)
{
//Console.Error.WriteLine("Warning null token!!!");
return null;
}
else if (t.getType() == TokenType.LPAREN)
{
return parseRest();
}
else if (t.getType() == TokenType.FALSE)
{
return BoolLit.getFalse();
}
else if (t.getType() == TokenType.TRUE)
{
return BoolLit.getTrue();
}
else if (t.getType() == TokenType.QUOTE)
{
// quote token does not have a name, so give it name "quote"
// cons
// / \
// quote cons
// / \
// exp Nil
return new Cons(new Ident("quote"), new Cons(parseExp(), Nil.getNil()));
}
else if (t.getType() == TokenType.INT)
{
return new IntLit(t.getIntVal());
}
else if (t.getType() == TokenType.STRING)
{
return new StringLit(t.getStringVal());
}
else if (t.getType() == TokenType.IDENT)
{
return new Ident(t.getName());
}
else if (t.getType() == TokenType.DOT)
{
Console.Error.WriteLine("Warning illegal DOT token");
return parseExp();
}
else if (t.getType() == TokenType.RPAREN)
{
Console.Error.WriteLine("Warning illegal RPAREN token");
return parseExp();
}
else
{
Console.Error.WriteLine("Warning illegal token");
return parseExp();
}
}
private Node parseExp(Token token)
{
if(token == null)
{
return null;
}
else if(token.getType() == TokenType.LPAREN)
{
return parseRest();
}
else if(token.getType() == TokenType.IDENT)
{
return new Ident(token.getName());
}
else if(token.getType() == TokenType.TRUE)
{
return new BoolLit(true);
}
else if(token.getType() == TokenType.FALSE)
{
return new BoolLit(false);
}
else if(token.getType() == TokenType.INT)
{
return new IntLit(token.getIntVal());
}
else if(token.getType() == TokenType.STRING)
{
return new StringLit(token.getStringVal());
}
else if(token.getType() == TokenType.QUOTE) {
// return new Cons(new Ident("\'"), new Cons(parseExp(), new Nil()));
return new Cons(new Ident("\'"), parseExp());
}
else
{
Console.Error.WriteLine("PARSING ERROR in parseExp: ");
return null;
}
}
// Takes a token as input and makes a node out of it
public Node makeExp(Token t)
{
if (t == null) return nodeNil;
TokenType tt = t.getType();
// If this token is a LPAREN, parse the rest of the list
if (tt == TokenType.LPAREN) { return parseRest(); }
// If token is TRUE or FALSE,
// return pointers to the nodes we initialized at the beginning
else if (tt == TokenType.FALSE) { return nodeFalse; }
else if (tt == TokenType.TRUE) { return nodeTrue; }
// If this token in a QUOTE, make a Cons node
// with ' as its car
// and the parsing of a node (or node tree) as its cdr
// because what follows a QUOTE token should be treated
// as a regular list to parse.
else if (tt == TokenType.QUOTE) {
return new Cons (
new Ident ("\'"),
parseExp ()
);
}
// For INT, STRING, and IDENT tokens,
// just return their respective nodes while keeping node data
// consistent with the original token values
else if (tt == TokenType.INT) return new IntLit(t.getIntVal());
else if (tt == TokenType.STRING) return new StringLit(t.getStringVal());
else /*(tt == TokenType.IDENT)*/ return new Ident(t.getName());
}
private Node parseExp(Token tok)
{
if (tok.getType() == TokenType.INT)
return new IntLit(tok.getIntVal());
else if (tok.getType() == TokenType.STRING)
return new StringLit(tok.getStringVal());
else if (tok.getType() == TokenType.TRUE)
return BoolLit.getTrue();
else if (tok.getType() == TokenType.FALSE)
return BoolLit.getFalse();
else if (tok.getType() == TokenType.QUOTE)
return new Cons(new Ident("'"), parseExp());
else if (tok.getType() == TokenType.IDENT)
return new Ident(tok.getName());
else if (tok.getType() == TokenType.LPAREN)
return parseRest();
return null;
}
