Re: [boost] [mpl] multiset

26 Feb 2015

      AMDG

On 02/26/2015 05:25 AM, Ganesh Prasad wrote:
...
<snip>
After all TMP is turing complete, hence,
random access containers should not be non-existent.
Turing completeness does not guarantee the
existence of random access.  Complexity
classes (i.e. L, P, NP) are invariant
across computation models, but random access
is not a distinct complexity class.

With that being said, mpl emulates random
access like this:

template
struct v_item;

template
struct v_item : Base { typedef T item0; };
template
struct v_item : Base { typedef T item1; };
...

This can also be acheived using overload resolution
and decltype:
template
struct v_item : Base {
  using Base::item;
  wrap<T> item(int_<N>);
};

This isn't actually constant time, however, because
of the way most compilers implement overload resolution.

In Christ,
Steven Watanabe