note description: "[ Strategies for calculating several features for subsets containing HASHABLEs. ]" library: "Free implementation of ELKS library" legal: "See notice at end of class." status: "See notice at end of class." date: "$Date$" revision: "$Revision$" class SUBSET_STRATEGY_HASHABLE [G] inherit SUBSET_STRATEGY [G] feature -- Comparison disjoint (set1, set2: TRAVERSABLE_SUBSET [G]): BOOLEAN -- Are `set1' and `set2' disjoint? local hash: HASH_TABLE [G, INTEGER] c: INTEGER do create hash.make (set1.count + set2.count) if set1.object_comparison then hash.compare_objects end from Result := True set1.start set2.start until not Result or else (set1.after and set2.after) loop if not set1.after then if attached {HASHABLE} set1.item as h1 then c := h1.hash_code else check hashable_item: False -- Because this strategy is used for hashable -- objects only. end end Result := not hash.has (c) if Result then hash.put (set1.item, c) else hash.search (c) check item_found: hash.found -- Because `has' has been queried before. end if set1.object_comparison then Result := set1.item /~ hash.found_item else Result := set1.item /= hash.found_item end end set1.forth end if Result and then not set2.after then if attached {HASHABLE} set2.item as h2 then c := h2.hash_code else check hashable_item: False -- Because this strategy is used for hashable -- objects only. end end hash.search (c) Result := not hash.found if Result then hash.put (set2.item, c) else if set1.object_comparison then Result := set2.item /~ hash.found_item else Result := set2.item /= hash.found_item end end set2.forth end end end feature -- Basic operations symdif (set1, set2: TRAVERSABLE_SUBSET [G]) -- Remove all items of `set1' that are also in `set2', and add all -- items of `set2' not already present in `set1'. local hash: HASH_TABLE [G, INTEGER] c: INTEGER eq: BOOLEAN h: detachable G do create hash.make (set1.count + set2.count) if set1.object_comparison then hash.compare_objects end from set1.start until set1.after loop if attached {HASHABLE} set1.item as h1 then hash.put (set1.item, h1.hash_code) else check hashable_item: False -- Because this strategy is only used when items -- are hashable. end end set1.forth end from set2.start until set2.after loop if attached {HASHABLE} set2.item as h2 then c := h2.hash_code hash.search (c) if hash.found then if set1.object_comparison then eq := set2.item ~ hash.found_item else eq := set2.item = hash.found_item end if eq then hash.remove (c) end else hash.put (set2.item, c) end else check hashable_item: False -- Because this strategy is only used when items -- are hashable. end end set2.forth end set1.wipe_out from hash.start until hash.after loop h := hash.item_for_iteration if h /= Void then set1.extend (h) end hash.forth end end note copyright: "Copyright (c) 1984-2012, Eiffel Software and others" license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)" source: "[ Eiffel Software 5949 Hollister Ave., Goleta, CA 93117 USA Telephone 805-685-1006, Fax 805-685-6869 Website http://www.eiffel.com Customer support http://support.eiffel.com ]" end