Automatic generation produced by ISE Eiffel
indexing description: "[ Possibly circular sequences of items, without commitment to a particular representation ]" status: "See notice at end of class" names: chain, sequence access: index, cursor, membership contents: generic date: "$Date: 2001-11-16 20:32:23 +0000 (Fri, 16 Nov 2001) $" revision: "$Revision: 51435 $" deferred class CHAIN [G] inherit CURSOR_STRUCTURE [G] undefine prune_all select put end INDEXABLE [G, INTEGER] rename item as i_th, put as put_i_th undefine prune_all end SEQUENCE [G] rename put as sequence_put export {NONE} sequence_put redefine index_of, has, off, occurrences select index_of, has, occurrences end SEQUENCE [G] rename put as sequence_put, index_of as sequential_index_of, has as sequential_has, occurrences as sequential_occurrences export {NONE} sequential_index_of, sequential_has, sequence_put redefine off end feature -- Access first: like item is -- Item at first position require not_empty: not is_empty local pos: CURSOR do pos := cursor start Result := item go_to (pos) end last: like item is -- Item at last position require not_empty: not is_empty local pos: CURSOR do pos := cursor finish Result := item go_to (pos) end has (v: like item): BOOLEAN is -- Does chain include v? -- (Reference or object equality, -- based on object_comparison.) local pos: CURSOR do pos := cursor Result := sequential_has (v) go_to (pos) end index_of (v: like item; i: INTEGER): INTEGER is -- Index of i-th occurrence of item identical to v. -- (Reference or object equality, -- based on object_comparison.) -- 0 if none. local pos: CURSOR do pos := cursor Result := sequential_index_of (v, i) go_to (pos) end i_th (i: INTEGER): like item is -- Item at i-th position -- Was declared in CHAIN as synonym of @. local pos: CURSOR do pos := cursor go_i_th (i) Result := item go_to (pos) end infix "@" (i: INTEGER): like item is -- Item at i-th position -- Was declared in CHAIN as synonym of i_th. local pos: CURSOR do pos := cursor go_i_th (i) Result := item go_to (pos) end index: INTEGER is -- Current cursor index deferred end feature -- Measurement occurrences (v: like item): INTEGER is -- Number of times v appears. -- (Reference or object equality, -- based on object_comparison.) local pos: CURSOR do pos := cursor Result := sequential_occurrences (v) go_to (pos) end index_set: INTEGER_INTERVAL is -- Range of acceptable indexes do create Result.make (1, count) ensure then count_definition: Result.count = count end feature -- Cursor movement start is -- Move cursor to first position. -- (No effect if empty) do if not is_empty then go_i_th (1) end ensure then at_first: not is_empty implies isfirst end finish is -- Move cursor to last position. -- (No effect if empty) do if not is_empty then go_i_th (count) end ensure then at_last: not is_empty implies islast end move (i: INTEGER) is -- Move cursor i positions. The cursor -- may end up off if the absolute value of i -- is too big. local counter, pos, final: INTEGER do if i > 0 then from until (counter = i) or else off loop forth counter := counter + 1 end elseif i < 0 then final := index + i; if final <= 0 then start; back else from start pos := 1 until pos = final loop forth pos := pos + 1 end end end ensure too_far_right: (old index + i > count) implies exhausted too_far_left: (old index + i < 1) implies exhausted expected_index: (not exhausted) implies (index = old index + i) end go_i_th (i: INTEGER) is -- Move cursor to i-th position. require valid_cursor_index: valid_cursor_index (i) do move (i - index) ensure position_expected: index = i end feature -- Status report valid_index (i: INTEGER): BOOLEAN is -- Is i within allowable bounds? do Result := (i >= 1) and (i <= count) ensure then valid_index_definition: Result = ((i >= 1) and (i <= count)) end isfirst: BOOLEAN is -- Is cursor at first position? do Result := not is_empty and (index = 1) ensure valid_position: Result implies not is_empty end islast: BOOLEAN is -- Is cursor at last position? do Result := not is_empty and (index = count) ensure valid_position: Result implies not is_empty end off: BOOLEAN is -- Is there no current item? do Result := (index = 0) or (index = count + 1) end valid_cursor_index (i: INTEGER): BOOLEAN is -- Is i correctly bounded for cursor movement? do Result := (i >= 0) and (i <= count + 1) ensure valid_cursor_index_definition: Result = ((i >= 0) and (i <= count + 1)) end feature -- Element change put (v: like item) is -- Replace current item by v. -- (Synonym for replace) do replace (v) ensure then same_count: count = old count end put_i_th (v: like item; i: INTEGER) is -- Put v at i-th position. local pos: CURSOR do pos := cursor go_i_th (i) replace (v) go_to (pos) end feature -- Transformation swap (i: INTEGER) is -- Exchange item at i-th position with item -- at cursor position. require not_off: not off valid_index: valid_index (i) local old_item, new_item: like item pos: CURSOR do pos := cursor old_item := item go_i_th (i) new_item := item replace (old_item) go_to (pos) replace (new_item) ensure swapped_to_item: item = old i_th (i) swapped_from_item: i_th (i) = old item end feature -- Duplication duplicate (n: INTEGER): like Current is -- Copy of sub-chain beginning at current position -- and having min (n, from_here) items, -- where from_here is the number of items -- at or to the right of current position. require not_off_unless_after: off implies after valid_subchain: n >= 0 deferred end feature {NONE} -- Inapplicable remove is -- Remove current item. do end invariant non_negative_index: index >= 0 index_small_enough: index <= count + 1 off_definition: off = ((index = 0) or (index = count + 1)) isfirst_definition: isfirst = ((not is_empty) and (index = 1)) islast_definition: islast = ((not is_empty) and (index = count)) item_corresponds_to_index: (not off) implies (item = i_th (index)) index_set_has_same_count: index_set.count = count indexing library: "[ EiffelBase: Library of reusable components for Eiffel. ]" status: "[ Copyright 1986-2001 Interactive Software Engineering (ISE). For ISE customers the original versions are an ISE product covered by the ISE Eiffel license and support agreements. ]" license: "[ EiffelBase may now be used by anyone as FREE SOFTWARE to develop any product, public-domain or commercial, without payment to ISE, under the terms of the ISE Free Eiffel Library License (IFELL) at http://eiffel.com/products/base/license.html. ]" source: "[ Interactive Software Engineering Inc. ISE Building 360 Storke Road, Goleta, CA 93117 USA Telephone 805-685-1006, Fax 805-685-6869 Electronic mail <info@eiffel.com> Customer support http://support.eiffel.com ]" info: "[ For latest info see award-winning pages: http://eiffel.com ]" end -- class CHAIN -- Generated by ISE Eiffel --
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