Title: Preserving order in non-order preserving parsers
A non-order preserving(NOP) parser returns a result that cannot
be mapped back to the original input, because the order of elements
may have changed. For reasons of reporting errors it is desirable to
preserve the initial order in some way. We show how to combine
several existing parsers to construct a NOP parser that preserves the
initial order by building a reordering functions while parsing.