public Object Visit_BinaryExpr(BinaryExpr expr)
{
Object left = Evaluate(expr.left);
Object right = Evaluate(expr.right);
switch (expr.op.type)
{
case TokenType.Greater:
CheckNumberOperands(expr.op, left, right);
return((double)left > (double)right);
case TokenType.GreaterEqual:
return((double)left >= (double)right);
case TokenType.Less:
return((double)left < (double)right);
case TokenType.LessEqual:
return((double)left <= (double)right);
case TokenType.Minus:
CheckNumberOperand(expr.op, right);
return((double)left - (double)right);
case TokenType.Plus:
if (left is Double && right is Double)
{
return((double)left + (double)right);
}
if (left is String && right is String)
{
return((String)left + (String)right);
}
throw new RuntimeException(expr.op.line, expr.op.column, "Operands must be two numbers or two strings.");
case TokenType.Slash: return((double)left / (double)right);
case TokenType.Star: return((double)left * (double)right);
case TokenType.BangEqual: return(!IsEqual(left, right));
case TokenType.EqualEqual: return(IsEqual(left, right));
}
throw new Exception("Unhandled case");
}
public Void Visit_BinaryExpr(BinaryExpr expr)
{
Resolve(expr.left);
Resolve(expr.right);
return(null);
}
public string Visit_BinaryExpr(BinaryExpr expr)
{
return(Parenthesize(expr.op.ToText(), expr.left, expr.right));
}