public IColumn diff(IColumn column) {
IColumn columnDiff = new SuperColumn(column.name());
Collection<IColumn> columns = column.getSubColumns();
for (IColumn subColumn : columns) {
IColumn columnInternal = columns_.get(subColumn.name());
if (columnInternal == null) {
columnDiff.addColumn(subColumn.name(), subColumn);
} else {
IColumn subColumnDiff = columnInternal.diff(subColumn);
if (subColumnDiff != null) {
columnDiff.addColumn(subColumn.name(), subColumnDiff);
}
}
}
if (columnDiff.getSubColumns().size() != 0) return columnDiff;
else return null;
}
