diff options
Diffstat (limited to 'decoder/indices_after.h')
| -rwxr-xr-x | decoder/indices_after.h | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/decoder/indices_after.h b/decoder/indices_after.h index ad94c576..dec94cc0 100755 --- a/decoder/indices_after.h +++ b/decoder/indices_after.h @@ -3,6 +3,7 @@ #include <boost/config.hpp> // STATIC_CONSTANT #include <algorithm> //swap +#include <iterator> // iterator wrapper. inverts boolean value. template <class AB> @@ -47,7 +48,8 @@ unsigned new_indices(KEEP keep,O out) { return new_indices(keep.begin(),keep.end(),out); } -// given a vector and a parallel sequence of bools where true means keep, keep only the marked elements while maintaining order +// given a vector and a parallel sequence of bools where true means keep, keep only the marked elements while maintaining order. +// this is done with a parallel sequence to the input, marked with positions the kept items would map into in a destination array, with removed items marked with the index -1. the reverse would be more compact (parallel to destination array, index of input item that goes into it) but would require the input sequence be random access. struct indices_after { BOOST_STATIC_CONSTANT(unsigned,REMOVED=(unsigned)-1); @@ -142,6 +144,21 @@ struct indices_after to[map[i]]=v[i]; } + //transform collection of indices into what we're remapping. (input/output iterators) + template <class IndexI,class IndexO> + void reindex(IndexI i,IndexI const end,IndexO o) const { + for(;i<end;++i) { + unsigned m=map[*i]; + if (m!=REMOVED) + *o++=m; + } + } + + template <class VecI,class VecO> + void reindex_push_back(VecI const& i,VecO &o) const { + reindex(i.begin(),i.end(),std::back_inserter(o)); + } + private: indices_after(indices_after const& o) { |