public LITERAL ToNode()
{
if (!category.isLiteral())
{
return(null);
}
LITERAL result = new LITERAL(this.value, span, code);
// result.setSpan(this);
// result.code = this.code;
return(result);
}
/// <summary>
///
/// </summary>
/// <returns></returns>
public static new EXPRESSION parse(Token first, iSCOPE context)
{
EXPRESSION result = null;
Token token = (first == null) ? get() : first;
Token begin = token;
switch (token.code)
{
case TokenCode.This:
forget();
UNIT unit = Context.unit();
if (unit == null)
{
// Error message!
result = new THIS(null);
}
else
{
result = new THIS(unit);
result.setSpan(token);
}
break;
case TokenCode.Return:
if (!ENTITY.weAreWithinEnsure)
{
break;
}
forget();
ROUTINE routine = Context.routine();
if (routine == null)
{
} // error
else
{
result = new RETURN_EXPR(routine);
result.setSpan(token);
}
break;
case TokenCode.Old:
forget();
result = EXPRESSION.parse(null, context);
Span end = result.span;
OLD old = new OLD(result);
result.parent = old;
result = old;
result.setSpan(begin.span, end);
break;
case TokenCode.If:
result = CONDITIONAL.parse(context);
break;
case TokenCode.LParen:
forget();
Span start_tuple = token.span;
result = EXPRESSION.parse(null, context);
token = get();
if (token.code == TokenCode.Comma)
{
// Seems to be a tuple
forget();
TUPLE_EXPR tuple = new TUPLE_EXPR();
tuple.add(result);
while (true)
{
EXPRESSION expr = EXPRESSION.parse(null, context);
tuple.add(expr);
token = get();
if (token.code != TokenCode.Comma)
{
break;
}
forget();
}
result = tuple;
}
end = expect(TokenCode.RParen).span;
result.setSpan(token.span, end);
break;
case TokenCode.Identifier:
if (first == null)
{
forget(); ////// perhaps the same condition should be added for all cases?
}
DECLARATION d = Context.find(token);
if (d == null)
{
result = new UNRESOLVED(context, new IDENTIFIER(token));
}
else
{
result = new REFERENCE(d);
}
Token token2 = get();
if (token2.code == TokenCode.LBracket)
{
UNIT_REF unitRef = UNIT_REF.parse(token, false, context);
result = new NEW(unitRef);
result.setSpan(unitRef.span);
}
else
{
result.setSpan(token);
}
break;
case TokenCode.Integer:
case TokenCode.Real:
case TokenCode.String:
case TokenCode.Character:
result = new LITERAL(token.value, token.span, token.code);
result.setSpan(token);
forget();
break;
default:
return(null);
}
// result.setSpan(token);
return(result);
}
