[Boost-users] [boost-users][multi-index] iterating though index keys

From: Igor R (boost.lists_at_[hidden])
Date: 2008-06-12 07:15:00

Hi,

I'm trying to replace few data structures and types defined in my
application in terms of std containers, with the
mutli_index_container. Some of those types look like this:

struct Entry
{
  int someForeignKey;
  int data1;
  std::string data2;
  //....
};
typedef std::deque<Entry> Entries;
typedef std::map<int, Entries> EntriesByForeignKey;

I'd like to rewrite the above map as follows:

typedef mi::multi_index_container
<
  Entry,
  mi::indexed_by
  <
    mi::hashed_non_unique<mi::tag<foreignKey>, mi::member<Entry, int,
&Entry::someForeignKey> >
  >
> Entries;

typedef Entries::index<foreignKey>::type EntriesByForeignKey;

Now, I'd like to iterate through the *keys* of this index, and for
each key - iterate through all its values. IIUC, the second part can
be accomplished like this:

{
  Entries entries;
  EntriesByForeignKey::iterator begin =
entries.get<foreignKey>().find(theKey), end =
entries.get<foreignKey>().end();
  for_each (begin, end, ....);
}
...but how can I iterate through all the keys of this index? Or should
I define another index for this purpose (sequenced one?) ?

Thank you,

Igor'.