note
	description: "Sets represented as arrayed lists"
	library: "Free implementation of ELKS library"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	names: arrayed_set, set, arrayed_list
	representation: array
	size: fixed
	access: membership
	contents: generic
	date: "$Date: 2019-07-05 15:26:16 +0000 (Fri, 05 Jul 2019) $"
	revision: "$Revision: 103325 $"

class 
	ARRAYED_SET [G]

create 
	make,
	make_from_iterable


create {ARRAYED_SET}
	make_filled

feature {NONE} -- Initialization

	default_create
			-- Process instances of classes with no creation clause.
			-- (Default: do nothing.)
			-- (from ANY)
		do
		end

	make_empty_area (n: INTEGER_32)
			-- Creates a special object for n entries.
			-- (from TO_SPECIAL)
		require -- from TO_SPECIAL
			non_negative_argument: n >= 0
		do
			create area_v2.make_empty (n)
		ensure -- from TO_SPECIAL
			area_allocated: area_v2 /= Void
			capacity_set: area_v2.capacity = n
			count_set: area_v2.count = 0
		end

	make_filled_area (a_default_value: G; n: INTEGER_32)
			-- Creates a special object for n entries.
			-- (from TO_SPECIAL)
		require -- from TO_SPECIAL
			non_negative_argument: n >= 0
		do
			create area_v2.make_filled (a_default_value, n)
		ensure -- from TO_SPECIAL
			area_allocated: area_v2 /= Void
			capacity_set: area_v2.capacity = n
			count_set: area_v2.count = n
			area_filled: area_v2.filled_with (a_default_value, 0, n - 1)
		end

	make_from_array (a: ARRAY [G])
			-- Create list from array a.
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			array_exists: a /= Void
		do
			index := 0
			area_v2 := a.area
		ensure -- from ARRAYED_LIST
			shared: area = a.area
			correct_position: before
			filled: count = a.count
		end
	
feature -- Initialization

	make (n: INTEGER_32)
			-- Allocate list with n items.
			-- (n may be zero for empty list.)
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			valid_number_of_items: n >= 0
		do
			index := 0
			create area_v2.make_empty (n)
		ensure -- from ARRAYED_LIST
			correct_position: before
			is_empty: is_empty
		end

	make_filled (n: INTEGER_32)
			-- Allocate list with n items.
			-- (n may be zero for empty list.)
			-- This list will be full.
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			valid_number_of_items: n >= 0
			has_default: ({G}).has_default
		do
			index := 0
			make_filled_area (({G}).default, n)
		ensure -- from ARRAYED_LIST
			correct_position: before
			filled: full
		end
	
feature -- Access

	area: SPECIAL [G]
			-- Access to internal storage of ARRAYED_LIST
			-- (from ARRAYED_LIST)
		do
			Result := area_v2
		end

	area_v2: SPECIAL [G]
			-- Special data zone.
			-- (from TO_SPECIAL)

	at alias "@" (i: INTEGER_32): like item assign put_i_th
			-- Item at i-th position
			-- Was declared in ARRAYED_LIST as synonym of i_th.
			-- (from ARRAYED_LIST)
		require -- from TABLE
			valid_key: valid_index (i)
		do
			Result := area_v2.item (i - 1)
		end

	array_at (i: INTEGER_32): G assign array_put
			-- Entry at index i, if in index interval.
			-- Was declared in TO_SPECIAL as synonym of item.
			-- (from TO_SPECIAL)
		require -- from TO_SPECIAL
			valid_index: array_valid_index (i)
		do
			Result := area_v2.item (i)
		end

	cursor: ARRAYED_LIST_CURSOR
			-- Current cursor position
			-- (from ARRAYED_LIST)
		do
			create Result.make (index)
		ensure -- from CURSOR_STRUCTURE
			cursor_not_void: Result /= Void
		end

	first: like item
			-- Item at first position
			-- (from ARRAYED_LIST)
		require -- from CHAIN
			not_empty: not is_empty
		do
			Result := area_v2.item (0)
		end

	generating_type: TYPE [detachable ARRAYED_SET [G]]
			-- Type of current object
			-- (type of which it is a direct instance)
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			generating_type_not_void: Result /= Void
		end

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			generator_not_void: Result /= Void
			generator_not_empty: not Result.is_empty
		end

	has (v: like item): BOOLEAN
			-- Does current include v?
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from ARRAYED_LIST)
		require -- from  CONTAINER
			True
		local
			l_area: like area_v2
			i, nb: INTEGER_32
		do
			l_area := area_v2
			nb := count
			if object_comparison and v /= Void then
				from
				until
					i >= nb or Result
				loop
					Result := v ~ l_area.item (i)
					i := i + 1
				end
			else
				from
				until
					i >= nb or Result
				loop
					Result := v = l_area.item (i)
					i := i + 1
				end
			end
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not is_empty
		end

	sequential_has (v: like item): BOOLEAN
			-- Does structure include an occurrence of v?
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from LINEAR)
		require -- from  CONTAINER
			True
		do
			start
			if not off then
				search (v)
			end
			Result := not exhausted
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not is_empty
		end

	i_th alias "[]" (i: INTEGER_32): like item assign put_i_th
			-- Item at i-th position
			-- Was declared in ARRAYED_LIST as synonym of at.
			-- (from ARRAYED_LIST)
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from READABLE_INDEXABLE
			valid_index: valid_index (i)
		do
			Result := area_v2.item (i - 1)
		end

	index: INTEGER_32
			-- Index of item, if valid.
			-- (from ARRAYED_LIST)

	index_of (v: like item; i: INTEGER_32): INTEGER_32
			-- Index of i-th occurrence of item identical to v.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- 0 if none.
			-- (from CHAIN)
		local
			pos: CURSOR
		do
			pos := cursor
			Result := sequential_index_of (v, i)
			go_to (pos)
		end

	sequential_index_of (v: like item; i: INTEGER_32): INTEGER_32
			-- Index of i-th occurrence of v.
			-- 0 if none.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from LINEAR)
		require -- from LINEAR
			positive_occurrences: i > 0
		local
			occur, pos: INTEGER_32
		do
			if object_comparison and v /= Void then
				from
					start
					pos := 1
				until
					exhausted or (occur = i)
				loop
					if item ~ v then
						occur := occur + 1
					end
					forth
					pos := pos + 1
				end
			else
				from
					start
					pos := 1
				until
					exhausted or (occur = i)
				loop
					if item = v then
						occur := occur + 1
					end
					forth
					pos := pos + 1
				end
			end
			if occur = i then
				Result := pos - 1
			end
		ensure -- from LINEAR
			non_negative_result: Result >= 0
		end

	item: G
			-- Current item
			-- (from ARRAYED_LIST)
		require -- from ACTIVE
			readable: readable
		require -- from TRAVERSABLE
			not_off: not off
		require -- from TRAVERSABLE_SUBSET
			not_off: not off
		require else -- from ARRAYED_LIST
			index_is_valid: valid_index (index)
		do
			Result := area_v2.item (index - 1)
		end

	array_item (i: INTEGER_32): G assign array_put
			-- Entry at index i, if in index interval.
			-- Was declared in TO_SPECIAL as synonym of at.
			-- (from TO_SPECIAL)
		require -- from TO_SPECIAL
			valid_index: array_valid_index (i)
		do
			Result := area_v2.item (i)
		end

	item_for_iteration: G
			-- Item at current position
			-- (from LINEAR)
		require -- from LINEAR
			not_off: not off
		do
			Result := item
		end

	last: like first
			-- Item at last position
			-- (from ARRAYED_LIST)
		require -- from CHAIN
			not_empty: not is_empty
		do
			Result := area_v2.item (count - 1)
		end

	new_cursor: ARRAYED_LIST_ITERATION_CURSOR [G]
			-- Fresh cursor associated with current structure
			-- (from ARRAYED_LIST)
		require -- from  ITERABLE
			True
		do
			create Result.make (Current)
		ensure -- from ITERABLE
			result_attached: Result /= Void
		end

	sequential_occurrences (v: like item): INTEGER_32
			-- Number of times v appears.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from LINEAR)
		require -- from  BAG
			True
		do
			from
				start
				search (v)
			until
				exhausted
			loop
				Result := Result + 1
				forth
				search (v)
			end
		ensure -- from BAG
			non_negative_occurrences: Result >= 0
		end

	to_array: ARRAY [G]
			-- Share content to be used as an ARRAY.
			-- Note that although the content is shared, it might
			-- not be shared when a resizing occur in either ARRAY or Current.
			-- (from ARRAYED_LIST)
		do
			create Result.make_from_special (area_v2)
		ensure -- from ARRAYED_LIST
			to_array_attached: Result /= Void
			array_lower_set: Result.lower = 1
			array_upper_set: Result.upper = count
			shared_area: Result.area = area
		end
	
feature {NONE} -- Measurement

	estimated_count_of (other: ITERABLE [G]): INTEGER_32
			-- Estimated number of elements in other.
			-- (from CONTAINER)
		do
			if attached {FINITE [G]} other as f then
				Result := f.count
			elseif attached {READABLE_INDEXABLE [G]} other as r then
				Result := r.upper - r.lower + 1
			end
		ensure -- from CONTAINER
			instance_free: class
			non_negative_result: Result >= 0
		end
	
feature -- Measurement

	additional_space: INTEGER_32
			-- Proposed number of additional items
			-- (from RESIZABLE)
		do
			Result := (capacity // 2).max (Minimal_increase)
		ensure -- from RESIZABLE
			at_least_one: Result >= 1
		end

	capacity: INTEGER_32
			-- Number of items that may be stored
			-- (from ARRAYED_LIST)
		do
			Result := area_v2.capacity
		ensure -- from BOUNDED
			capacity_non_negative: Result >= 0
		end

	count: INTEGER_32
			-- Number of items.
			-- (from ARRAYED_LIST)
		require -- from  SET
			True
		require -- from  FINITE
			True
		require -- from  READABLE_INDEXABLE
			True
		do
			Result := area_v2.count
		ensure -- from FINITE
			count_non_negative: Result >= 0
		end

	Growth_percentage: INTEGER_32 = 50
			-- Percentage by which structure will grow automatically
			-- (from RESIZABLE)

	index_set: INTEGER_INTERVAL
		obsolete "Use `lower' and `upper' instead. [2017-05-31]"
			-- Range of acceptable indexes.
			-- (from READABLE_INDEXABLE)
		do
			create Result.make (Lower, count)
		ensure -- from READABLE_INDEXABLE
			not_void: Result /= Void
			empty_if_not_in_order: (Lower > count) implies Result.is_empty
			same_lower_if_not_empty: (Lower <= count) implies Result.lower = Lower
			same_upper_if_not_empty: (Lower <= count) implies Result.upper = count
		end

	Lower: INTEGER_32 = 1
			-- Minimum index.
			-- (from CHAIN)

	Minimal_increase: INTEGER_32 = 5
			-- Minimal number of additional items
			-- (from RESIZABLE)

	occurrences (v: like item): INTEGER_32
			-- Number of times v appears.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from CHAIN)
		local
			pos: CURSOR
		do
			pos := cursor
			Result := sequential_occurrences (v)
			go_to (pos)
		end

	upper: INTEGER_32
			-- Maximum index.
			-- Use count instead.
			-- (from ARRAYED_LIST)
		do
			Result := area_v2.count
		ensure -- from ARRAYED_LIST
			definition: Result = count
		end
	
feature -- Comparison

	frozen deep_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.is_deep_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			shallow_implies_deep: standard_equal (a, b) implies Result
			both_or_none_void: (a = Void) implies (Result = (b = Void))
			same_type: (Result and (a /= Void)) implies (b /= Void and then a.same_type (b))
			symmetric: Result implies deep_equal (b, a)
		end

	disjoint (other: TRAVERSABLE_SUBSET [G]): BOOLEAN
			-- Do current set and other have no
			-- items in common?
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		do
			if not is_empty and not other.is_empty then
				Result := subset_strategy (other).disjoint (Current, other)
			else
				Result := True
			end
		end

	frozen equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.is_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.is_equal (b))
		end

	frozen is_deep_equal alias "≡≡≡" (other: ARRAYED_SET [G]): BOOLEAN
			-- Are Current and other attached to isomorphic object structures?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			shallow_implies_deep: standard_is_equal (other) implies Result
			same_type: Result implies same_type (other)
			symmetric: Result implies other.is_deep_equal (Current)
		end

	is_equal (other: ARRAYED_SET [G]): BOOLEAN
			-- Is array made of the same items as other?
			-- (from ARRAYED_LIST)
		require -- from ANY
			other_not_void: other /= Void
		local
			i: INTEGER_32
		do
			if other = Current then
				Result := True
			elseif count = other.count and then object_comparison = other.object_comparison then
				if object_comparison then
					from
						Result := True
						i := Lower
					until
						not Result or i > upper
					loop
						Result := i_th (i) ~ other.i_th (i)
						i := i + 1
					end
				else
					Result := area_v2.same_items (other.area_v2, 0, 0, count)
				end
			end
		ensure -- from ANY
			symmetric: Result implies other ~ Current
			consistent: standard_is_equal (other) implies Result
		ensure then -- from LIST
			indices_unchanged: index = old index and other.index = old other.index
			true_implies_same_size: Result implies count = other.count
		end

	is_subset alias "⊆" (other: TRAVERSABLE_SUBSET [G]): BOOLEAN
			-- Is current set a subset of other?
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		do
			if not other.is_empty and then count <= other.count then
				from
					start
				until
					off or else not (other ∋ item)
				loop
					forth
				end
				if off then
					Result := True
				end
			elseif is_empty then
				Result := True
			end
		end

	is_superset alias "⊇" (other: SUBSET [G]): BOOLEAN
			-- Is current set a superset of other?
			-- (from SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		do
			Result := other ⊆ Current
		end

	frozen standard_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.standard_is_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.standard_is_equal (b))
		end

	frozen standard_is_equal alias "≜" (other: ARRAYED_SET [G]): BOOLEAN
			-- Is other attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
		end
	
feature -- Status report

	after: BOOLEAN
			-- Is there no valid cursor position to the right of cursor?
			-- (from LIST)
		require -- from  LINEAR
			True
		require -- from  TRAVERSABLE_SUBSET
			True
		do
			Result := index = count + 1
		end

	all_default: BOOLEAN
			-- Are all items set to default values?
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			has_default: ({G}).has_default
		do
			Result := area_v2.filled_with (({G}).default, 0, area_v2.upper)
		end

	before: BOOLEAN
			-- Is there no valid cursor position to the left of cursor?
			-- (from LIST)
		require -- from  BILINEAR
			True
		require -- from  LINEAR_SUBSET
			True
		do
			Result := index = 0
		end

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of other (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		end

	empty: BOOLEAN
		obsolete "ELKS 2000: Use `is_empty' instead. [2017-05-31]"
			-- Is there no element?
			-- (from CONTAINER)
		do
			Result := is_empty
		end

	exhausted: BOOLEAN
			-- Has structure been completely explored?
			-- (from LINEAR)
		do
			Result := off
		ensure -- from LINEAR
			exhausted_when_off: off implies Result
		end

	extendible: BOOLEAN
			-- May new items be added? (Answer: yes.)
			-- (from DYNAMIC_CHAIN)
		require -- from  COLLECTION
			True
		do
			Result := True
		end

	full: BOOLEAN
			-- Is structure full?
			-- (from BOUNDED)
		require -- from  BOX
			True
		do
			Result := count = capacity
		end

	is_empty: BOOLEAN
			-- Is structure empty?
			-- (from FINITE)
		require -- from  CONTAINER
			True
		do
			Result := count = 0
		end

	is_inserted (v: G): BOOLEAN
			-- Has v been inserted by the most recent insertion?
			-- (By default, the value returned is equivalent to calling 
			-- has (v). However, descendants might be able to provide more
			-- efficient implementations.)
			-- (from COLLECTION)
		do
			Result := has (v)
		end

	isfirst: BOOLEAN
			-- Is cursor at first position?
			-- (from CHAIN)
		do
			Result := not is_empty and (index = 1)
		ensure -- from CHAIN
			valid_position: Result implies not is_empty
		end

	islast: BOOLEAN
			-- Is cursor at last position?
			-- (from CHAIN)
		require -- from  LINEAR_SUBSET
			True
		do
			Result := not is_empty and (index = count)
		ensure -- from CHAIN
			valid_position: Result implies not is_empty
		end

	object_comparison: BOOLEAN
			-- Must search operations use equal rather than =
			-- for comparing references? (Default: no, use =.)
			-- (from CONTAINER)

	off: BOOLEAN
			-- Is there no current item?
			-- (from CHAIN)
		require -- from  TRAVERSABLE
			True
		require -- from  TRAVERSABLE_SUBSET
			True
		do
			Result := (index = 0) or (index = count + 1)
		end

	prunable: BOOLEAN
			-- May items be removed? (Answer: yes.)
			-- (from ARRAYED_LIST)
		require -- from  COLLECTION
			True
		do
			Result := True
		end

	readable: BOOLEAN
			-- Is there a current item that may be read?
			-- (from SEQUENCE)
		require -- from  ACTIVE
			True
		do
			Result := not off
		end

	replaceable: BOOLEAN
			-- Can current item be replaced?
			-- (from ACTIVE)
		do
			Result := True
		end

	resizable: BOOLEAN
			-- May capacity be changed? (Answer: yes.)
			-- (from RESIZABLE)
		do
			Result := True
		end

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of other?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
		end

	valid_cursor (p: CURSOR): BOOLEAN
			-- Can the cursor be moved to position p?
			-- (from ARRAYED_LIST)
		do
			if attached {ARRAYED_LIST_CURSOR} p as al_c then
				Result := valid_cursor_index (al_c.index)
			end
		end

	valid_cursor_index (i: INTEGER_32): BOOLEAN
			-- Is i correctly bounded for cursor movement?
			-- (from CHAIN)
		do
			Result := (i >= 0) and (i <= count + 1)
		ensure -- from CHAIN
			valid_cursor_index_definition: Result = ((i >= 0) and (i <= count + 1))
		end

	valid_index (i: INTEGER_32): BOOLEAN
			-- Is i a valid index?
			-- (from ARRAYED_LIST)
		require -- from  READABLE_INDEXABLE
			True
		require -- from  TABLE
			True
		require -- from  LINEAR_SUBSET
			True
		do
			Result := (1 <= i) and (i <= count)
		ensure -- from READABLE_INDEXABLE
			only_if_in_index_set: Result implies (Lower <= i and i <= count)
		ensure then -- from CHAIN
			valid_index_definition: Result = ((i >= 1) and (i <= count))
		ensure -- from LINEAR_SUBSET
			index_valid: 0 <= i and i <= count + 1
		end

	array_valid_index (i: INTEGER_32): BOOLEAN
			-- Is i within the bounds of Current?
			-- (from TO_SPECIAL)
		do
			Result := area_v2.valid_index (i)
		end

	writable: BOOLEAN
			-- Is there a current item that may be modified?
			-- (from SEQUENCE)
		require -- from  ACTIVE
			True
		do
			Result := not off
		end
	
feature -- Status setting

	compare_objects
			-- Ensure that future search operations will use equal
			-- rather than = for comparing references.
			-- (from CONTAINER)
		require -- from CONTAINER
			changeable_comparison_criterion: changeable_comparison_criterion
		do
			object_comparison := True
		ensure -- from CONTAINER
				object_comparison
		end

	compare_references
			-- Ensure that future search operations will use =
			-- rather than equal for comparing references.
			-- (from CONTAINER)
		require -- from CONTAINER
			changeable_comparison_criterion: changeable_comparison_criterion
		do
			object_comparison := False
		ensure -- from CONTAINER
			reference_comparison: not object_comparison
		end
	
feature -- Cursor movement

	back
			-- Move cursor one position backward.
			-- (from ARRAYED_LIST)
		require -- from BILINEAR
			not_before: not before
		do
			index := index - 1
		end

	finish
			-- Move cursor to last position if any.
			-- (from ARRAYED_LIST)
		require -- from  LINEAR
			True
		do
			index := count
		ensure then -- from CHAIN
			at_last: not is_empty implies islast
		ensure then -- from ARRAYED_LIST
			before_when_empty: is_empty implies before
		end

	forth
			-- Move cursor one position forward.
			-- (from ARRAYED_LIST)
		require -- from LINEAR
			not_after: not after
		require -- from TRAVERSABLE_SUBSET
			not_after: not after
		do
			index := index + 1
		ensure then -- from LIST
			moved_forth: index = old index + 1
		end

	go_i_th (i: INTEGER_32)
			-- Move cursor to i-th position.
			-- (from ARRAYED_LIST)
		require -- from CHAIN
			valid_cursor_index: valid_cursor_index (i)
		require -- from LINEAR_SUBSET
			valid_index: valid_index (i)
		do
			index := i
		ensure -- from CHAIN
			position_expected: index = i
		ensure -- from LINEAR_SUBSET
			cursor_moved: index = i
		end

	go_to (p: CURSOR)
			-- Move cursor to position p.
			-- (from ARRAYED_LIST)
		require -- from CURSOR_STRUCTURE
			cursor_position_valid: valid_cursor (p)
		do
			if attached {ARRAYED_LIST_CURSOR} p as al_c then
				index := al_c.index
			else
				check
					correct_cursor_type: False
				end
			end
		end

	move (i: INTEGER_32)
			-- Move cursor i positions.
			-- (from ARRAYED_LIST)
		do
			index := index + i
			if index > count + 1 then
				index := count + 1
			elseif index < 0 then
				index := 0
			end
		ensure -- from CHAIN
			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

	search (v: like item)
			-- Move to first position (at or after current
			-- position) where item and v are equal.
			-- If structure does not include v ensure that
			-- exhausted will be true.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from ARRAYED_LIST)
		require -- from  LINEAR
			True
		local
			l_area: like area_v2
			i, nb: INTEGER_32
			l_found: BOOLEAN
		do
			l_area := area_v2
			nb := count - 1
			i := (index - 1).max (0)
			if object_comparison and v /= Void then
				from
				until
					i > nb or l_found
				loop
					l_found := v ~ l_area.item (i)
					i := i + 1
				end
			else
				from
				until
					i > nb or l_found
				loop
					l_found := v = l_area.item (i)
					i := i + 1
				end
			end
			if l_found then
				index := i
			else
				index := i + 1
			end
		ensure -- from LINEAR
			object_found: (not exhausted and object_comparison) implies v ~ item
			item_found: (not exhausted and not object_comparison) implies v = item
		end

	start
			-- Move cursor to first position if any.
			-- (from ARRAYED_LIST)
		require -- from  TRAVERSABLE
			True
		require -- from  TRAVERSABLE_SUBSET
			True
		do
			index := 1
		ensure then -- from CHAIN
			at_first: not is_empty implies isfirst
		ensure then -- from ARRAYED_LIST
			after_when_empty: is_empty implies after
		end
	
feature -- Element change

	append (s: SEQUENCE [G])
			-- Append a copy of s.
			-- (from ARRAYED_LIST)
		require -- from SEQUENCE
			argument_not_void: s /= Void
		local
			c, old_count, new_count: INTEGER_32
		do
			if attached {ARRAYED_LIST [G]} s as al then
				c := al.count
				if c > 0 then
					old_count := count
					new_count := old_count + al.count
					if new_count > area_v2.capacity then
						area_v2 := area_v2.aliased_resized_area (new_count)
					end;
					area_v2.copy_data (al.area_v2, 0, old_count, c)
				end
			else
				Precursor {DYNAMIC_LIST} (s)
			end
		ensure -- from SEQUENCE
			new_count: count >= old count
		end

	al_extend (v: like item)
			-- Add v to end.
			-- Do not move cursor.
			-- (from ARRAYED_LIST)
		require -- from COLLECTION
			extendible: extendible
		local
			i: INTEGER_32
			l_area: like area_v2
		do
			i := count + 1
			l_area := area_v2
			if i > l_area.capacity then
				l_area := l_area.aliased_resized_area (i + additional_space)
				area_v2 := l_area
			end;
			l_area.extend (v)
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
		end

	extend (v: G)
			-- Insert v if not present.
			-- Was declared in ARRAYED_SET as synonym of put.
		do
			if is_empty or else not has (v) then
				al_extend (v)
			end
		end

	fill (other: CONTAINER [G])
			-- Fill with as many items of other as possible.
			-- The representations of other and current structure
			-- need not be the same.
			-- (from CHAIN)
		require -- from COLLECTION
			other_not_void: other /= Void
			extendible: extendible
		local
			lin_rep: LINEAR [G]
			l_cursor: CURSOR
		do
			lin_rep := other.linear_representation
			from
				l_cursor := cursor;
				lin_rep.start
			until
				not extendible or else lin_rep.off
			loop
				extend (lin_rep.item)
				finish;
				lin_rep.forth
			end
			go_to (l_cursor)
		end

	force (v: like item)
			-- Add v to end.
			-- Do not move cursor.
			-- Was declared in ARRAYED_LIST as synonym of extend.
			-- (from ARRAYED_LIST)
		require -- from SEQUENCE
			extendible: extendible
		local
			i: INTEGER_32
			l_area: like area_v2
		do
			i := count + 1
			l_area := area_v2
			if i > l_area.capacity then
				l_area := l_area.aliased_resized_area (i + additional_space)
				area_v2 := l_area
			end;
			l_area.extend (v)
		ensure then -- from SEQUENCE
			new_count: count = old count + 1
			item_inserted: has (v)
		end

	merge (other: CONTAINER [G])
			-- Add all items of other.
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		local
			l: LINEAR [G]
		do
			if attached {LINEAR [G]} other as lin_rep then
				l := lin_rep
			else
				l := other.linear_representation
			end
			from
				l.start
			until
				l.off
			loop
				extend (l.item);
				l.forth
			end
		end

	merge_left (other: ARRAYED_LIST [G])
			-- Merge other into current structure before cursor.
			-- (from ARRAYED_LIST)
		require -- from DYNAMIC_CHAIN
			extendible: extendible
			not_before: not before
			other_exists: other /= Void
			not_current: other /= Current
		local
			old_index: INTEGER_32
			old_other_count: INTEGER_32
		do
			old_index := index
			old_other_count := other.count
			index := index - 1
			merge_right (other)
			index := old_index + old_other_count
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count + old other.count
			new_index: index = old index + old other.count
			other_is_empty: other.is_empty
		end

	merge_right (other: ARRAYED_LIST [G])
			-- Merge other into current structure after cursor.
			-- (from ARRAYED_LIST)
		require -- from DYNAMIC_CHAIN
			extendible: extendible
			not_after: not after
			other_exists: other /= Void
			not_current: other /= Current
		local
			l_new_count: INTEGER_32
		do
			if not other.is_empty then
				l_new_count := count + other.count
				if l_new_count > area_v2.capacity then
					area_v2 := area_v2.aliased_resized_area (l_new_count)
				end;
				area_v2.insert_data (other.area_v2, 0, index, other.count);
				other.wipe_out
			end
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count + old other.count
			same_index: index = old index
			other_is_empty: other.is_empty
		end

	move_item (v: G)
			-- Move v to the left of cursor.
			-- (from LINEAR_SUBSET)
		require -- from LINEAR_SUBSET
			item_exists: v /= Void
			item_in_set: has (v)
		local
			idx: INTEGER_32
			found: BOOLEAN
		do
			idx := index
			from
				start
			until
				found or after
			loop
				if object_comparison then
					found := v ~ item
				else
					found := v = item
				end
				if not found then
					forth
				end
			end
			check
				found: found and not after
			end
			remove
			go_i_th (idx)
			put_left (v)
		end

	put (v: G)
			-- Insert v if not present.
			-- Was declared in ARRAYED_SET as synonym of extend.
		do
			if is_empty or else not has (v) then
				al_extend (v)
			end
		end

	array_put (v: G; i: INTEGER_32)
			-- Replace i-th entry, if in index interval, by v.
			-- (from TO_SPECIAL)
		require -- from TO_SPECIAL
			valid_index: array_valid_index (i)
		do
			area_v2.put (v, i)
		ensure -- from TO_SPECIAL
			inserted: array_item (i) = v
		end

	al_put (v: like item)
			-- Replace current item by v.
			-- (Synonym for replace)
			-- (from CHAIN)
		require -- from CHAIN
			writeable: writable
			replaceable: replaceable
		do
			replace (v)
		ensure -- from CHAIN
			same_count: count = old count
			is_inserted: is_inserted (v)
		end

	sequence_put (v: like item)
			-- Add v to end.
			-- (from SEQUENCE)
		require -- from COLLECTION
			extendible: extendible
		do
			extend (v)
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
		ensure then -- from SEQUENCE
			new_count: count = old count + 1
		end

	put_front (v: like item)
			-- Add v to the beginning.
			-- Do not move cursor.
			-- (from ARRAYED_LIST)
		require -- from DYNAMIC_CHAIN
			extendible: extendible
		do
			if is_empty then
				extend (v)
			else
				insert (v, 1)
			end
			index := index + 1
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count + 1
			item_inserted: first = v
		end

	put_i_th (v: like i_th; i: INTEGER_32)
			-- Replace i-th entry, if in index interval, by v.
			-- (from ARRAYED_LIST)
		require -- from TABLE
			valid_key: valid_index (i)
		require -- from TABLE
			valid_key: valid_index (i)
		do
			area_v2.put (v, i - 1)
		ensure -- from TABLE
			inserted: i_th (i) = v
		end

	put_left (v: like item)
			-- Add v to the left of current position.
			-- Do not move cursor.
			-- (from ARRAYED_LIST)
		require -- from DYNAMIC_CHAIN
			extendible: extendible
			not_before: not before
		require -- from LINEAR_SUBSET
			item_exists: v /= Void
			not_before: not before
		do
			if after or is_empty then
				extend (v)
			else
				insert (v, index)
			end
			index := index + 1
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count + 1
			new_index: index = old index + 1
		ensure -- from LINEAR_SUBSET
			cursor_position_unchanged: index = old index + 1
		end

	put_right (v: like item)
			-- Add v to the right of current position.
			-- Do not move cursor.
			-- (from ARRAYED_LIST)
		require -- from DYNAMIC_CHAIN
			extendible: extendible
			not_after: not after
		do
			if index = count then
				extend (v)
			else
				insert (v, index + 1)
			end
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count + 1
			same_index: index = old index
		end

	replace (v: like first)
			-- Replace current item by v.
			-- (from ARRAYED_LIST)
		require -- from ACTIVE
			writable: writable
			replaceable: replaceable
		do
			put_i_th (v, index)
		ensure -- from ACTIVE
			item_replaced: item = v
		end
	
feature {NONE} -- Element change

	set_area (other: like area_v2)
			-- Make other the new area.
			-- (from TO_SPECIAL)
		do
			area_v2 := other
		ensure -- from TO_SPECIAL
			area_set: area_v2 = other
		end
	
feature -- Removal

	changeable_comparison_criterion: BOOLEAN
			-- May object_comparison be changed?
			-- (Answer: only if set empty; otherwise insertions might
			-- introduce duplicates, destroying the set property.)
			-- (from SET)
		require -- from  CONTAINER
			True
		do
			Result := is_empty
		ensure then -- from SET
			only_on_empty: Result = is_empty
		end

	prune (v: like item)
			-- Remove v if present.
		do
			start
			al_prune (v)
		end

	al_prune (v: like item)
			-- Remove first occurrence of v, if any,
			-- after cursor position.
			-- Move cursor to right neighbor.
			-- (or after if no right neighbor or v does not occur)
			-- (from ARRAYED_LIST)
		require -- from COLLECTION
			prunable: prunable
		do
			if before then
				index := 1
			end
			if object_comparison then
				from
				until
					after or else item ~ v
				loop
					forth
				end
			else
				from
				until
					after or else item = v
				loop
					forth
				end
			end
			if not after then
				remove
			end
		end

	prune_all (v: like item)
			-- Remove all occurrences of v.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from ARRAYED_LIST)
		require -- from COLLECTION
			prunable: prunable
		local
			i, nb: INTEGER_32
			offset: INTEGER_32
			res: BOOLEAN
			obj_cmp: BOOLEAN
			l_area: like area_v2
		do
			obj_cmp := object_comparison
			from
				l_area := area_v2
				i := 0
				nb := count
			until
				i = count
			loop
				if i < nb - offset then
					if offset > 0 then
						l_area.put (l_area.item (i + offset), i)
					end
					if obj_cmp then
						res := v ~ l_area.item (i)
					else
						res := v = l_area.item (i)
					end
					if res then
						offset := offset + 1
					else
						i := i + 1
					end
				else
					i := i + 1
				end
			end;
			l_area.remove_tail (offset)
			index := count + 1
		ensure -- from COLLECTION
			no_more_occurrences: not has (v)
		ensure then -- from DYNAMIC_CHAIN
			is_exhausted: exhausted
		ensure then -- from ARRAYED_LIST
			is_after: after
		end

	remove
			-- Remove current item.
			-- Move cursor to right neighbor
			-- (or after if no right neighbor)
			-- (from ARRAYED_LIST)
		require -- from ACTIVE
			prunable: prunable
			writable: writable
		require -- from TRAVERSABLE_SUBSET
			not_off: not off
		do
			if index < count then
				area_v2.move_data (index, index - 1, count - index)
			end;
			area_v2.remove_tail (1)
		ensure then -- from DYNAMIC_LIST
			after_when_empty: is_empty implies after
		ensure then -- from ARRAYED_LIST
			index: index = old index
		end

	remove_i_th (i: INTEGER_32)
			-- Remove item at index i.
			-- Move cursor to next neighbor (or after if no next neighbor) if it is at i-th position.
			-- Do not change cursor otherwise.
			-- (from ARRAYED_LIST)
		require -- from DYNAMIC_TABLE
			prunable: prunable
			valid_key: valid_index (i)
		do
			if i < count then
				area_v2.move_data (i, i - 1, count - i)
			end;
			area_v2.remove_tail (1)
			if index > i then
				index := index - 1
			end
		ensure then -- from DYNAMIC_CHAIN
			new_count: count = old count - 1
			same_index_if_below: index <= i implies index = old index
			new_index_if_above: index > i implies index = old index - 1
			same_leading_items: across
					old twin as c
				all
					c.target_index < i implies c.item = i_th (c.target_index)
				end
			same_trailing_items: across
					old twin as c
				all
					c.target_index > i implies c.item = i_th (c.target_index - 1)
				end
		end

	remove_left
			-- Remove item to the left of cursor position.
			-- Do not move cursor.
			-- (from ARRAYED_LIST)
		require -- from DYNAMIC_CHAIN
			left_exists: index > 1
		do
			index := index - 1
			remove
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count - 1
			new_index: index = old index - 1
		end

	remove_right
			-- Remove item to the right of cursor position
			-- Do not move cursor
			-- (from ARRAYED_LIST)
		require -- from DYNAMIC_CHAIN
			right_exists: index < count
		do
			index := index + 1
			remove
			index := index - 1
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count - 1
			same_index: index = old index
		end

	wipe_out
			-- Remove all items.
			-- (from ARRAYED_LIST)
		require -- from COLLECTION
			prunable: prunable
		do
			area_v2.wipe_out
			index := 0
		ensure then -- from DYNAMIC_LIST
			is_before: before
		ensure -- from COLLECTION
			wiped_out: is_empty
		end

	chain_wipe_out
			-- Remove all items.
			-- (from DYNAMIC_CHAIN)
		require -- from COLLECTION
			prunable: prunable
		do
			from
				start
			until
				is_empty
			loop
				remove
			end
		ensure -- from COLLECTION
			wiped_out: is_empty
		end
	
feature -- Resizing

	automatic_grow
			-- Change the capacity to accommodate at least
			-- Growth_percentage more items.
			-- (from RESIZABLE)
		require -- from RESIZABLE
			resizable: resizable
		do
			grow (capacity + additional_space)
		ensure -- from RESIZABLE
			increased_capacity: capacity >= old capacity + old additional_space
		end

	grow (i: INTEGER_32)
			-- Change the capacity to at least i.
			-- (from ARRAYED_LIST)
		require -- from RESIZABLE
			resizable: resizable
		do
			if i > area_v2.capacity then
				area_v2 := area_v2.aliased_resized_area (i)
			end
		ensure -- from RESIZABLE
			new_capacity: capacity >= i
		end

	resize (new_capacity: INTEGER_32)
			-- Resize list so that it can contain
			-- at least n items. Do not lose any item.
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			resizable: resizable
			new_capacity_large_enough: new_capacity >= capacity
		do
			grow (new_capacity)
		ensure -- from ARRAYED_LIST
			capacity_set: capacity >= new_capacity
		end

	trim
			-- Decrease capacity to the minimum value.
			-- Apply to reduce allocated storage.
			-- (from ARRAYED_LIST)
		require -- from  RESIZABLE
			True
		local
			n: like count
		do
			n := count
			if n < area_v2.capacity then
				area_v2 := area_v2.aliased_resized_area (n)
			end
		ensure -- from RESIZABLE
			same_count: count = old count
			minimal_capacity: capacity = count
		ensure then -- from ARRAYED_LIST
			same_items: to_array.same_items (old to_array)
		end
	
feature -- Transformation

	swap (i: INTEGER_32)
			-- Exchange item at i-th position with item
			-- at cursor position.
			-- (from ARRAYED_LIST)
		require -- from CHAIN
			not_off: not off
			valid_index: valid_index (i)
		local
			old_item: like item
		do
			old_item := item
			replace (area_v2.item (i - 1));
			area_v2.put (old_item, i - 1)
		ensure -- from CHAIN
			swapped_to_item: item = old i_th (i)
			swapped_from_item: i_th (i) = old item
		end
	
feature -- Conversion

	linear_representation: LINEAR [G]
			-- Representation as a linear structure
			-- (from LINEAR)
		require -- from  CONTAINER
			True
		do
			Result := Current
		end
	
feature -- Duplication

	frozen clone (other: detachable ANY): like other
		obsolete "Use `twin' instead. [2017-05-31]"
			-- Void if other is void; otherwise new object
			-- equal to other
			--
			-- For non-void other, clone calls copy;
			-- to change copying/cloning semantics, redefine copy.
			-- (from ANY)
		do
			if other /= Void then
				Result := other.twin
			end
		ensure -- from ANY
			instance_free: class
			equal: Result ~ other
		end

	copy (other: ARRAYED_SET [G])
			-- Reinitialize by copying all the items of other.
			-- (This is also used by clone.)
			-- (from ARRAYED_LIST)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		do
			if other /= Current then
				standard_copy (other)
				set_area (other.area_v2.twin)
			end
		ensure -- from ANY
			is_equal: Current ~ other
		ensure then -- from ARRAYED_LIST
			equal_areas: area_v2 ~ other.area_v2
		end

	frozen deep_clone (other: detachable ANY): like other
		obsolete "Use `deep_twin' instead. [2017-05-31]"
			-- Void if other is void: otherwise, new object structure
			-- recursively duplicated from the one attached to other
			-- (from ANY)
		do
			if other /= Void then
				Result := other.deep_twin
			end
		ensure -- from ANY
			instance_free: class
			deep_equal: deep_equal (other, Result)
		end

	frozen deep_copy (other: ARRAYED_SET [G])
			-- Effect equivalent to that of:
			--		copy (other . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		do
			copy (other.deep_twin)
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)
		end

	frozen deep_twin: ARRAYED_SET [G]
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			deep_twin_not_void: Result /= Void
			deep_equal: deep_equal (Current, Result)
		end

	duplicate (n: INTEGER_32): ARRAYED_SET [G]
		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-list beginning at current position
			-- and having min (n, count - index + 1) items.
			-- (from ARRAYED_LIST)
		require -- from CHAIN
			not_off_unless_after: off implies after
			valid_subchain: n >= 0
		require -- from SUBSET
			non_negative: n >= 0
		local
			m: INTEGER_32
		do
			if after then
				Result := new_filled_list (0)
			else
				m := (count - index + 1).min (n)
				Result := new_filled_list (m);
				Result.area_v2.copy_data (area_v2, index - 1, 0, m)
			end
		ensure -- from SUBSET
			correct_count_1: n <= count implies Result.count = n
			correct_count_2: n >= count implies Result.count = count
		end

	frozen standard_clone (other: detachable ANY): like other
		obsolete "Use `standard_twin' instead. [2017-05-31]"
			-- Void if other is void; otherwise new object
			-- field-by-field identical to other.
			-- Always uses default copying semantics.
			-- (from ANY)
		do
			if other /= Void then
				Result := other.standard_twin
			end
		ensure -- from ANY
			instance_free: class
			equal: standard_equal (Result, other)
		end

	frozen standard_copy (other: ARRAYED_SET [G])
			-- Copy every field of other onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		external
			"built_in"
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)
		end

	frozen standard_twin: ARRAYED_SET [G]
			-- New object field-by-field identical to other.
			-- Always uses default copying semantics.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)
		end

	frozen twin: ARRAYED_SET [G]
			-- New object equal to Current
			-- twin calls copy; to change copying/twinning semantics, redefine copy.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result ~ Current
		end
	
feature -- Basic operations

	frozen as_attached: attached ARRAYED_SET [G]
		obsolete "Remove calls to this feature. [2017-05-31]"
			-- Attached version of Current.
			-- (Can be used during transitional period to convert
			-- non-void-safe classes to void-safe ones.)
			-- (from ANY)
		do
			Result := Current
		end

	frozen default: detachable ARRAYED_SET [G]
			-- Default value of object's type
			-- (from ANY)
		do
		end

	frozen default_pointer: POINTER
			-- Default value of type POINTER
			-- (Avoid the need to write p.default for
			-- some p of type POINTER.)
			-- (from ANY)
		do
		ensure -- from ANY
			instance_free: class
		end

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)
		do
		end

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
		do
		ensure -- from ANY
			instance_free: class
		end

	intersect (other: TRAVERSABLE_SUBSET [G])
			-- Remove all items not in other.
			-- No effect if other is_empty.
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		do
			if not other.is_empty then
				from
					start;
					other.start
				until
					off
				loop
					if other ∋ item then
						forth
					else
						remove
					end
				end
			else
				wipe_out
			end
		ensure -- from SUBSET
			is_subset_other: is_subset (other)
		end

	subtract (other: TRAVERSABLE_SUBSET [G])
			-- Remove all items also in other.
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		do
			if not (other.is_empty or is_empty) then
				from
					start;
					other.start
				until
					off
				loop
					if other ∋ item then
						remove
					else
						forth
					end
				end
			end
		ensure -- from SUBSET
			is_disjoint: disjoint (other)
		end

	symdif (other: TRAVERSABLE_SUBSET [G])
			-- Remove all items also in other, and add all
			-- items of other not already present.
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		do
			if not other.is_empty then
				if is_empty then
					from
						other.start
					until
						other.after
					loop
						extend (other.item)
					end
				else
					subset_strategy (other).symdif (Current, other)
				end
			end
		end
	
feature {DYNAMIC_CHAIN} -- Inapplicable

	new_chain: ARRAYED_SET [G]
		obsolete "Use explicit creation instead. See also explanations for `duplicate`. [2018-11-30]"
			-- Unused
			-- (from ARRAYED_LIST)
		do
			Result := Current
		ensure -- from DYNAMIC_CHAIN
			result_exists: Result /= Void
		end
	
feature {NONE} -- Implementation

	force_i_th (v: like i_th; pos: INTEGER_32)
			-- (from ARRAYED_LIST)
		do
			if count + 1 > capacity then
				grow (count + additional_space)
			end;
			area_v2.force (v, pos)
		end

	insert (v: like item; pos: INTEGER_32)
			-- Add v at pos, moving subsequent items
			-- to the right.
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			index_small_enough: pos <= count
			index_large_enough: pos >= 1
		do
			if count + 1 > capacity then
				grow (count + additional_space)
			end;
			area_v2.move_data (pos - 1, pos, count - pos + 1)
			put_i_th (v, pos)
		ensure -- from ARRAYED_LIST
			new_count: count = old count + 1
			index_unchanged: index = old index
			insertion_done: i_th (pos) = v
		end

	new_filled_list (n: INTEGER_32): ARRAYED_SET [G]
		obsolete "Use explicit creation instead. See also explanations for `duplicate`. [2018-11-30]"
			-- New list with n elements.
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			n_non_negative: n >= 0
		do
			create Result.make (n)
		ensure -- from ARRAYED_LIST
			new_filled_list_not_void: Result /= Void
			new_filled_list_count_set: Result.is_empty
			new_filled_list_before: Result.before
		end

	subset_strategy (other: TRAVERSABLE_SUBSET [G]): SUBSET_STRATEGY [G]
			-- Subset strategy suitable for the type of the contained elements.
			-- (from TRAVERSABLE_SUBSET)
		require -- from TRAVERSABLE_SUBSET
			not_empty: not is_empty
		do
			start
			check
				not_off: not off
			end
			Result := subset_strategy_selection (item, other)
		end

	subset_strategy_selection (v: G; other: TRAVERSABLE_SUBSET [G]): SUBSET_STRATEGY [G]
			-- Strategy to calculate several subset features selected depending
			-- on the dynamic type of v and other
			-- (from LINEAR_SUBSET)
		require -- from TRAVERSABLE_SUBSET
			item_exists: v /= Void
			other_exists: other /= Void
		do
			if attached {HASHABLE} v as h then
				create {SUBSET_STRATEGY_HASHABLE [G]} Result
			else
				create {SUBSET_STRATEGY_GENERIC [G]} Result
			end
		ensure -- from TRAVERSABLE_SUBSET
			strategy_set: Result /= Void
		end
	
feature -- Correction

	Mismatch_information: MISMATCH_INFORMATION
			-- Original attribute values of mismatched object
			-- (from MISMATCH_CORRECTOR)
		once
			create Result
		end
	
feature {NONE} -- Creation

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

	do_all (action: PROCEDURE [G])
			-- Apply action to every item, from first to last.
			-- Semantics not guaranteed if action changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from ARRAYED_LIST)
		require -- from TRAVERSABLE
			action_exists: action /= Void
		do
			area_v2.do_all_in_bounds (action, 0, area_v2.count - 1)
		end

	do_all_with_index (action: PROCEDURE [G, INTEGER_32])
			-- Apply action to every item, from first to last.
			-- action receives item and its index.
			-- Semantics not guaranteed if action changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			action_not_void: action /= Void
		local
			i, j, nb: INTEGER_32
			l_area: like area_v2
		do
			from
				i := 0
				j := Lower
				nb := count - 1
				l_area := area_v2
			until
				i > nb
			loop
				action.call ([l_area.item (i), j])
				j := j + 1
				i := i + 1
			end
		end

	do_if (action: PROCEDURE [G]; test: FUNCTION [G, BOOLEAN])
			-- Apply action to every item that satisfies test, from first to last.
			-- Semantics not guaranteed if action or test changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from ARRAYED_LIST)
		require -- from TRAVERSABLE
			action_exists: action /= Void
			test_exists: test /= Void
		do
			area_v2.do_if_in_bounds (action, test, 0, area_v2.count - 1)
		end

	do_if_with_index (action: PROCEDURE [G, INTEGER_32]; test: FUNCTION [G, INTEGER_32, BOOLEAN])
			-- Apply action to every item that satisfies test, from first to last.
			-- action and test receive the item and its index.
			-- Semantics not guaranteed if action or test changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from ARRAYED_LIST)
		require -- from ARRAYED_LIST
			action_not_void: action /= Void
			test_not_void: test /= Void
		local
			i, j, nb: INTEGER_32
			l_area: like area_v2
		do
			from
				i := 0
				j := Lower
				nb := count - 1
				l_area := area_v2
			until
				i > nb
			loop
				if test.item ([l_area.item (i), j]) then
					action.call ([l_area.item (i), j])
				end
				j := j + 1
				i := i + 1
			end
		end

	for_all (test: FUNCTION [G, BOOLEAN]): BOOLEAN
			-- Is test true for all items?
			-- (from ARRAYED_LIST)
		require -- from TRAVERSABLE
			test_exists: test /= Void
		do
			Result := area_v2.for_all_in_bounds (test, 0, area_v2.count - 1)
		ensure then -- from LINEAR
			empty: is_empty implies Result
		end

	there_exists (test: FUNCTION [G, BOOLEAN]): BOOLEAN
			-- Is test true for at least one item?
			-- (from ARRAYED_LIST)
		require -- from TRAVERSABLE
			test_exists: test /= Void
		do
			Result := area_v2.there_exists_in_bounds (test, 0, area_v2.count - 1)
		end
	
feature -- Output

	Io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)
		once
			create Result;
			Result.set_output_default
		ensure -- from ANY
			instance_free: class
			io_not_void: Result /= Void
		end

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		do
			Result := tagged_out
		ensure -- from ANY
			out_not_void: Result /= Void
		end

	print (o: detachable ANY)
			-- Write terse external representation of o
			-- on standard output.
			-- (from ANY)
		local
			s: READABLE_STRING_8
		do
			if attached o then
				s := o.out
				if attached {READABLE_STRING_32} s as s32 then
					Io.put_string_32 (s32)
				elseif attached {READABLE_STRING_8} s as s8 then
					Io.put_string (s8)
				else
					Io.put_string_32 (s.as_string_32)
				end
			end
		ensure -- from ANY
			instance_free: class
		end

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			tagged_out_not_void: Result /= Void
		end
	
feature -- Platform

	Operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
		once
			create Result
		ensure -- from ANY
			instance_free: class
			operating_environment_not_void: Result /= Void
		end
	
feature {NONE} -- Retrieval

	frozen internal_correct_mismatch
			-- Called from runtime to perform a proper dynamic dispatch on correct_mismatch
			-- from MISMATCH_CORRECTOR.
			-- (from ANY)
		local
			l_msg: STRING_32
			l_exc: EXCEPTIONS
		do
			if attached {MISMATCH_CORRECTOR} Current as l_corrector then
				l_corrector.correct_mismatch
			else
				create l_msg.make_from_string ("Mismatch: ".as_string_32)
				create l_exc;
				l_msg.append (generating_type.name_32);
				l_exc.raise_retrieval_exception (l_msg)
			end
		end
	
feature -- Retrieval

	correct_mismatch
			-- Attempt to correct object mismatch using Mismatch_information.
			-- (from ARRAYED_LIST)
		local
			i: INTEGER_32
		do
			if not Mismatch_information.has ("area_v2") and then attached {SPECIAL [G]} Mismatch_information.item ("area") as l_area and then attached {INTEGER_32} Mismatch_information.item ("count") as l_count and then attached {BOOLEAN} Mismatch_information.item ("object_comparison") as l_comp and then attached {INTEGER_32} Mismatch_information.item ("index") as l_index then
				create area_v2.make_empty (l_count)
				from
					i := 0
				until
					i = l_count
				loop
					area_v2.extend (l_area.item (i))
					i := i + 1
				end
				object_comparison := l_comp
				index := l_index
			else
				Precursor
			end
		end
	
invariant
		-- from LINEAR_SUBSET
	before_definition: before = (index = 0)

		-- from TRAVERSABLE_SUBSET
	empty_definition: is_empty = (count = 0)
	count_range: count >= 0

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

		-- from ARRAYED_LIST
	prunable: prunable
	starts_from_one: Lower = 1

		-- from RESIZABLE
	increase_by_at_least_one: Minimal_increase >= 1

		-- from BOUNDED
	valid_count: count <= capacity
	full_definition: full = (count = capacity)

		-- from FINITE
	empty_definition: is_empty = (count = 0)

		-- from LIST
	before_definition: before = (index = 0)
	after_definition: after = (index = count + 1)

		-- from CHAIN
	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))

		-- from ACTIVE
	writable_constraint: writable implies readable
	empty_constraint: is_empty implies (not readable) and (not writable)

		-- from READABLE_INDEXABLE
	consistent_boundaries: Lower <= count or else Lower = count + 1

		-- from BILINEAR
	not_both: not (after and before)
	before_constraint: before implies off

		-- from LINEAR
	after_constraint: after implies off

		-- from TRAVERSABLE
	empty_constraint: is_empty implies off

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 ARRAYED_SET