public static _OpTree Combine(_OpTree Left, Operator Operator, Expression Right)
{
if (Left.Operator == null || Left.Operator.Precedence >= Operator.Precedence)
return new _OpTree(Operator, Left, new _OpTree(Right));
else
return new _OpTree(Left.Operator, Left.Left, Combine(Left.Right, Operator, Right));
}