private static string FindAs(Expression e) {
string result = null;
e.VisitAll<AsExpression>(x => result = x.Name);
return result;
}
public void AddColumn(Expression col) {
string asName = FindAs(col);
string colName = asName;
if (asName == null) colName = "col_" + (myColumns.Count + 1);
bool binded = false;
col.VisitAll<BindExpression>(x => {
x.BindColumn.Name = colName;
binded = true;
});
myColumns.Add(new KeyValuePair<string, Expression>(
(binded || asName != null) ? colName : null,
col));
}