Provide some extra comments about the STORE_Memory STORE method.

#include <openssl/err.h>

#include "str_locl.h"

/* The memory store is currently highly experimental.  It's meant to become

   a base store used by other stores for internal caching (for full caching

   support, aging needs to be added).

   The database use is meant to support as much attribute association as

   possible, while providing for as small search ranges as possible.

   This is currently provided for by sorting the entries by numbers that

   are composed of bits set at the positions indicated by attribute type

   codes.  This provides for ranges determined by the highest attribute

   type code value.  A better idea might be to sort by values computed

   from the range of attributes associated with the object (basically,

   the difference between the highest and lowest attribute type code)

   and it's distance from a base (basically, the lowest associated

   attribute type code).

*/

struct mem_object_data_st

	{

	STORE_OBJECT *object;

struct mem_data_st

	{

	STACK *data;		/* A stack of mem_object_data_st,

				   potentially sorted with a wrapper

				   around STORE_ATTR_INFO_cmp(). */

				   sorted with STORE_ATTR_INFO_compare(). */

	unsigned int compute_components : 1; /* Currently unused, but can

						be used to add attributes

						from parts of the data. */

	STOREerr(STORE_F_MEM_DELETE, STORE_R_NOT_IMPLEMENTED);

	return 0;

	}

/* The list functions may be the hardest to nuderstand.  Basically,

   mem_list_start compiles a stack of attribute info elements, and

   puts that stack into the context to be returned.  mem_list_next

   will then find the first matching element in the store, and then

   walk all the way to the end of the store (since any combination

   of attribute bits above the starting point may match the searched

   for bit pattern...). */

static void *mem_list_start(STORE *s, STORE_OBJECT_TYPES type,

	OPENSSL_ITEM attributes[])

	{