+#endif
+private: // Types
+#ifdef MC_PAGE_STORE_MD4
+ // We are using a secure hash to identify a page.
+ // We assume there will not be any collision: we need to map a hash
+ // to a single page index.
+ typedef boost::unordered_map<hash_type, size_t> pages_map_type;
+#else
+ // We are using a cheap hash to index a page.
+ // We should expect collision and we need to associate multiple page indices
+ // to the same hash.
+ typedef boost::unordered_set<size_t> page_set_type;