private Node and_or_ast(Terminal op, Node nleft, Node nright)
{
Node n = null;
switch (op.TokenType) {
case TokenType.and:
var lbljmpzero = newLabel();
n = new Node(op,
nleft,
new Node(nilterminal(),
new Node(new Terminal(TokenType.jmpzero, lbljmpzero, currenttoken.LN, currenttoken.CP)),
new Node(nilterminal(),
nright,
new Node(new Terminal(TokenType.label, lbljmpzero, currenttoken.LN, currenttoken.CP)))));
break;
case TokenType.or:
var lbljmpnotz = newLabel();
n = new Node(op,
nleft,
new Node(nilterminal(),
new Node(new Terminal(TokenType.jmpnotz, lbljmpnotz, currenttoken.LN, currenttoken.CP)),
new Node(nilterminal(),
nright,
new Node(new Terminal(TokenType.label, lbljmpnotz, currenttoken.LN, currenttoken.CP)))));
break;
}
return n;
}
Node assignment()
{
var s = currenttoken.Value.ToString();
nexttoken();
expect(TokenType.assig);
var op = new Terminal(TokenType.assig, s, currenttoken.LN, currenttoken.CP);
nexttoken();
var r = new Node(new Terminal(TokenType.identlocal, s, currenttoken.LN, currenttoken.CP));
var l = expression_single();
return new Node(op, l, r);
}
Node call(Node nleft)
{
if (currenttoken.TokenType == TokenType.lparen) {
var tl = new Terminal(TokenType.list, currenttoken.LN, currenttoken.CP);
var bindings = new Node(tl);
nexttoken();
if (currenttoken.TokenType != TokenType.rparen) {
bindings = build_list();
}
expect(TokenType.rparen);
nexttoken();
var op = new Terminal(TokenType.eval, currenttoken.LN, currenttoken.CP);
var deep = new Node(op, bindings, nleft);
// keep consuming evaluations.
return call(deep);
} else
return nleft;
}
public Node(Terminal o, Node izq, Node der)
{
this.o = o;
this.left = izq;
this.right = der;
}
Node term()
{
Node nleft = factor_negated();
if (currenttoken.TokenType == TokenType.times || currenttoken.TokenType == TokenType.slash ||
currenttoken.TokenType == TokenType.perc) {
Terminal op = currenttoken;
nexttoken();
Node nright = term();
Node n = new Node(op, nleft, nright);
return n;
} else
return nleft;
}
Node factor_negated()
{
Node nleft = null;
if (currenttoken.TokenType == TokenType.not) {
Terminal op = currenttoken;
nexttoken();
nleft = expression_evaluated();
Node n = new Node(op, nleft, null);
return n;
} else
return expression_evaluated();
}
Node factor()
{
Node f = null;
switch (currenttoken.TokenType) {
case TokenType.ident:
f = new Node(currenttoken);
break;
case TokenType.number:
f = new Node(currenttoken);
break;
case TokenType.str:
f = new Node(currenttoken);
break;
case TokenType.lbrac:
nexttoken();
if (currenttoken.TokenType == TokenType.rbrac) {
var empty = new Terminal(TokenType.list, currenttoken.LN, currenttoken.CP);
f = new Node(empty);
} else
f = build_list();
expect(TokenType.rbrac);
break;
case TokenType.lparen:
nexttoken();
f = expression();
expect(TokenType.rparen);
break;
case TokenType.lcurly:
nexttoken();
expect(TokenType.ident);
f = new Node(currenttoken);
nexttoken();
expect(TokenType.rcurly);
break;
default:
var msg = string.Format(Strings.Expression_Syntax_error,
currenttoken.LN, currenttoken.CP);
error(msg);
break;
}
nexttoken();
return f;
}
Node expression_sum()
{
Node nleft = term();
if (currenttoken.TokenType == TokenType.plus || currenttoken.TokenType == TokenType.minus) {
Terminal op = currenttoken;
nexttoken();
Node nright = expression_sum();
Node n = new Node(op, nleft, nright);
return n;
} else
return nleft;
}
Node expression_logic()
{
Node nleft = expression_sum();
if (currenttoken.TokenType == TokenType.eq || currenttoken.TokenType == TokenType.gt ||
currenttoken.TokenType == TokenType.gteq || currenttoken.TokenType == TokenType.lt ||
currenttoken.TokenType == TokenType.lteq || currenttoken.TokenType == TokenType.neq) {
Terminal op = currenttoken;
nexttoken();
Node nright = expression_logic();
Node n = new Node(op, nleft, nright);
return n;
} else
return nleft;
}
Node expression_cond()
{
Node whentrue = expression_andor();
if (currenttoken.TokenType == TokenType.iff) {
nexttoken();
Node condition = expression_andor();
expect(TokenType.els);
nexttoken();
Node whenfalse = expression_cond();
var n = new Node(new Terminal(TokenType.iff, currenttoken.LN, currenttoken.CP),
and_or_ast(new Terminal(TokenType.or, currenttoken.LN, currenttoken.CP),
and_or_ast(new Terminal(TokenType.and, currenttoken.LN, currenttoken.CP),
condition,
whentrue),
whenfalse),
null);
return n;
} else
return whentrue;
}