public abstract void VisitConstant(Constant constant);
public abstract void VisitConstant(Constant constant);
Expression factor()
{
Expression e;
Token temp = next;
switch (t)
{
case TokenKind.Real:
e = new Constant(((Real)next).value, next.line, next.col);
move();
return e;
case TokenKind.StringLiteral:
e = new Constant(((StringLiteral)next).value, next.line, next.col);
move();
return e;
case TokenKind.Identifier:
if (peek().t == TokenKind.OpeningParenthesis)
{
string str = next.lexeme;
if (!Context.Resources.FunctionExists(str))
{
error(Error.UnknownFunction, str);
}
move(); move();
List<Expression> exprs = new List<Expression>();
if (t != TokenKind.ClosingParenthesis && t != TokenKind.Eof)
{
exprs.Add(expr());
}
while (t == TokenKind.Comma)
{
move();
exprs.Add(expr());
}
match(Token.ClosingParenthesis);
IFunction f = Context.Resources.GetFunction(str);
if ((f.Argc != -1 && exprs.Count != f.Argc) || exprs.Count > 16)
error(Error.WrongArgumentNumber);
return new Call(f, exprs.ToArray(), temp.line, temp.col);
}
else
{
Expression x = new Id(next.lexeme, next.line, next.col);
move();
return x;
}
case TokenKind.OpeningParenthesis:
move();
e = new Grouping(expr(), next.line, next.col);
match(Token.ClosingParenthesis, Error.UnexpectedSymbolInExpression);
return e;
default:
throw new ProgramError(Error.UnexpectedSymbolInExpression, ErrorSeverity.CompilationError, next.line, next.col);
}
}