Sensei <senseiwa <at> gmail.com> writes:
Dear all,
I am experimenting with MultiIndex, and I am happy with my custom classes.
Now I am wondering, can I index integers without a custom class?
For instance, say we have a 32 bit unsigned integer, how can I index these with respect to the MSB or LSB? [...]
You can define a function that does the MSB/LSB extraction and either pack it as a custom key extractor: http://www.boost.org/libs/multi_index/doc/ tutorial/key_extraction.html#user_defined_key_extractors or plug it into boost::multi_index::global_fun: http://www.boost.org/libs/multi_index/doc/ tutorial/key_extraction.html#global_fun The following example shows the latter approach for a multi_index_container of uint32_t's --you can easily adapt this to your particular scenario where the uint32_t's are members of a larger class. #include <boost/multi_index_container.hpp> #include <boost/multi_index/global_fun.hpp> #include <boost/multi_index/ordered_index.hpp> #include <cstdint> #include <iostream> using namespace boost::multi_index; inline uint16_t ls16half(uint32_t n) { return static_cast<uint16_t>(n&0xFFFFul); } inline uint16_t ms16half(uint32_t n) { return static_cast<uint16_t>(n>>16); } typedef multi_index_container< uint32_t, indexed_by< ordered_non_unique<global_fun<uint32_t,uint16_t,ls16half>>, ordered_non_unique<global_fun<uint32_t,uint16_t,ms16half>>
multi_t;
int main() { multi_t m={0x00030000ul,0x00020001ul,0x00010002ul,0x00000003ul}; std::cout<<std::hex; for(auto n:m.get<0>())std::cout<<n<<" "; std::cout<<"\n"; for(auto n:m.get<1>())std::cout<<n<<" "; std::cout<<"\n"; } Joaquín M López Muñoz Telefónica