note
	description: "[
		Sets whose items may be compared according to a total order relation;
		implemented as sorted two-way lists.
	]"
	library: "Free implementation of ELKS library"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	names: sorted_set, set, two_way_list
	representation: linked
	access: membership, min, max
	contents: generic
	date: "$Date: 2019-07-05 15:26:16 +0000 (Fri, 05 Jul 2019) $"
	revision: "$Revision: 103325 $"

class 
	TWO_WAY_SORTED_SET [G -> COMPARABLE]

inherit
	COMPARABLE_SET [G]
		rename
			symdif as subset_symdif
		export
			{NONE} subset_symdif
		undefine
			search,
			has,
			index,
			off,
			min,
			max,
			index_of,
			prune_all,
			occurrences,
			is_equal,
			fill,
			copy
		select
			extend,
			put,
			prune
		end

	LINEAR_SUBSET [G]
		undefine
			is_equal,
			prune_all,
			fill,
			copy
		redefine
			merge,
			intersect,
			subtract
		select
			symdif
		end

	SORTED_TWO_WAY_LIST [G]
		rename
			extend as stwl_extend,
			has as has alias "∋",
			put as stwl_put,
			prune as stwl_prune,
			merge as stwl_merge
		export
			{NONE} stwl_extend, stwl_put, stwl_prune, stwl_merge
			{ANY} min, max, index, after, before, forth, finish, start, item, is_empty, empty, back, remove, search, off, go_i_th
		undefine
			changeable_comparison_criterion
		redefine
			duplicate,
			make_from_iterable
		end

create 
	make,
	make_from_iterable


create {TWO_WAY_SORTED_SET}
	make_sublist

feature {NONE} -- Creation

	make_from_iterable (other: ITERABLE [G])
			-- Create a stack with all items obtained from other.
		do
			make
			across
				other as o
			loop
				extend (o.item)
			end
		end
	
feature -- Element change

	extend (v: G)
			-- Ensure that structure includes v.
			-- Was declared in TWO_WAY_SORTED_SET as synonym of put.
		local
			found: BOOLEAN
			b: BOOLEAN
		do
			search_after (v)
			b := after
			if not b then
				b := item /~ v
			end
			if b then
				put_left (v)
				back
			end
			if object_comparison then
				if after or else item /~ v then
					put_left (v)
					back
				end
			else
				from
				until
					found or after or else item /~ v
				loop
					found := item = v
					forth
				end
				if not found then
					put_left (v)
				end
				back
			end
		end

	put (v: G)
			-- Ensure that structure includes v.
			-- Was declared in TWO_WAY_SORTED_SET as synonym of extend.
		local
			found: BOOLEAN
			b: BOOLEAN
		do
			search_after (v)
			b := after
			if not b then
				b := item /~ v
			end
			if b then
				put_left (v)
				back
			end
			if object_comparison then
				if after or else item /~ v then
					put_left (v)
					back
				end
			else
				from
				until
					found or after or else item /~ v
				loop
					found := item = v
					forth
				end
				if not found then
					put_left (v)
				end
				back
			end
		end

	merge (other: TRAVERSABLE_SUBSET [G])
			-- Add all items of other.
		local
			mode: BOOLEAN
			other_item: like item
			b: BOOLEAN
		do
			from
				mode := object_comparison
				start;
				other.start
			until
				after or other.after
			loop
				other_item := other.item
				if item < other_item then
					search_after (other_item)
				end
				if not after then
					b := not mode and then item = other_item
					if not b and then mode then
						b := item ~ other_item
					end
					if b then
						forth;
						other.forth
					else
						from
						until
							other.after or else other.item >= item
						loop
							put_left (other.item);
							other.forth
						end
					end
				end
			end
			from
			until
				other.after
			loop
				put_left (other.item);
				other.forth
			end
		end
	
feature -- Removal

	prune (v: like item)
			-- Remove v if present.
		do
			start
			stwl_prune (v)
		end
	
feature -- Duplication

	duplicate (n: INTEGER_32): like Current
		obsolete "[
			Create a new container explicitly using `make_from_iterable` if available.
			Otherwise, replace a call to the feature with code that creates and initializes container.
			[2018-11-30]
		]"
			-- Copy of sub-set beginning at cursor position
			-- and having min (n, count - index + 1) items
		local
			pos: CURSOR
			counter: INTEGER_32
		do
			pos := cursor
			Result := new_chain;
			Result.finish;
			Result.forth
			from
			until
				(counter = n) or else after
			loop
				Result.put_left (item)
				forth
				counter := counter + 1
			end
			go_to (pos)
		end
	
feature -- Basic operations

	intersect (other: like Current)
			-- Remove all items not in other.
		do
			from
				start;
				other.start
			until
				after or other.after
			loop
				from
				until
					after or item >= other.item
				loop
					remove
				end
				if not after then
					from
					until
						other.after or else other.item >= item
					loop
						other.forth
					end
					if not other.after and then item ~ other.item then
						forth;
						other.forth
					end
				end
			end
			if other.after then
				from
				until
					after
				loop
					remove
				end
			end
		end

	subtract (other: like Current)
			-- Remove all items also in other.
		local
			other_item: like item
		do
			from
				start;
				other.start
			until
				after or other.after
			loop
				other_item := other.item
				if item < other_item then
					search_after (other_item)
				end
				if not after and then item ~ other_item then
					remove
				end;
				other.forth
			end
		end
	
feature -- Inapplicable

	subset_symdif (other: SUBSET [G])
			-- Inapplicable symdif.
		do
		end
	
note
	copyright: "Copyright (c) 1984-2019, 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 -- class TWO_WAY_SORTED_SET

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