note
	description: "Contiguous integer intervals"
	library: "Free implementation of ELKS library"
	status: "See notice at end of class."
	legal: "See notice at end of class."
	date: "$Date: 2019-07-05 15:26:16 +0000 (Fri, 05 Jul 2019) $"
	revision: "$Revision: 103325 $"

class 
	INTEGER_INTERVAL

inherit
	RESIZABLE [INTEGER_32]
		rename
			has as has alias "∋"
		undefine
			changeable_comparison_criterion
		redefine
			copy,
			is_equal
		end

	INDEXABLE [INTEGER_32, INTEGER_32]
		rename
			has as has alias "∋",
			item as item alias "[]",
			put as indexable_put
		undefine
			changeable_comparison_criterion
		redefine
			copy,
			index_set,
			is_equal
		select
			bag_put
		end

	SET [INTEGER_32]
		redefine
			copy,
			is_equal
		end

create 
	make

feature {NONE} -- Initialization

	make (min_index, max_index: INTEGER_32)
			-- Set up interval to have bounds min_index and
			-- max_index (empty if min_index > max_index)
		do
			if min_index <= max_index then
				lower := min_index
				upper := max_index
			else
				lower := 1
				upper := 0
			end
		ensure
			lower_defined: Lower_defined
			upper_defined: Upper_defined
			set_if_non_empty: (min_index <= max_index) implies ((lower = min_index) and (upper = max_index))
			empty_if_not_in_order: (min_index > max_index) implies is_empty
		end
	
feature -- Initialization

	adapt (other: INTEGER_INTERVAL)
			-- Reset to be the same interval as other.
		require
			other_not_void: other /= Void
		do
			lower := other.lower
			upper := other.upper
		ensure
			same_lower: lower = other.lower
			same_upper: upper = other.upper
			same_lower_defined: Lower_defined = other.Lower_defined
			same_upper_defined: Upper_defined = other.Upper_defined
		end
	
feature -- Access

	Lower_defined: BOOLEAN = True
			-- Is there a lower bound?

	lower: INTEGER_32
			-- Smallest value in interval.

	Upper_defined: BOOLEAN = True
			-- Is there an upper bound?

	upper: INTEGER_32
			-- Largest value in interval.

	item alias "[]" (i: INTEGER_32): INTEGER_32
			-- Entry at index i, if in index interval
			-- Was declared in INTEGER_INTERVAL as synonym of at.
		do
			Result := i
		end

	at alias "@" (i: INTEGER_32): INTEGER_32
			-- Entry at index i, if in index interval
			-- Was declared in INTEGER_INTERVAL as synonym of item.
		do
			Result := i
		end

	has alias "∋" (v: INTEGER_32): BOOLEAN
			-- Does v appear in interval?
			-- Was declared in INTEGER_INTERVAL as synonym of valid_index.
		do
			Result := (Upper_defined implies v <= upper) and (Lower_defined implies v >= lower)
		ensure then
			iff_within_bounds: Result = ((Upper_defined implies v <= upper) and (Lower_defined implies v >= lower))
		end

	valid_index (v: INTEGER_32): BOOLEAN
			-- Does v appear in interval?
			-- Was declared in INTEGER_INTERVAL as synonym of has.
		do
			Result := (Upper_defined implies v <= upper) and (Lower_defined implies v >= lower)
		ensure then
			iff_within_bounds: Result = ((Upper_defined implies v <= upper) and (Lower_defined implies v >= lower))
		end
	
feature -- Measurement

	occurrences (v: INTEGER_32): INTEGER_32
			-- Number of times v appears in structure
		do
			if has (v) then
				Result := 1
			end
		ensure then
			one_iff_in_bounds: Result = 1 implies has (v)
			zero_otherwise: Result /= 1 implies Result = 0
		end

	capacity: INTEGER_32
			-- Maximum number of items in interval
			-- (here the same thing as count)
		do
			check
				terminal: Upper_defined and Lower_defined
			end
			Result := count
		end

	count: INTEGER_32
			-- Number of items in interval
		do
			check
				finite: Upper_defined and Lower_defined
			end
			if Upper_defined and Lower_defined then
				Result := upper - lower + 1
			end
		ensure then
			definition: Result = upper - lower + 1
		end

	index_set: INTEGER_INTERVAL
			-- Range of acceptable indexes.
			-- (here: the interval itself)
		do
			Result := Current
		ensure then
			index_set_is_range: Result ~ Current
		end
	
feature -- Comparison

	is_equal (other: like Current): BOOLEAN
			-- Is array made of the same items as other?
		do
			Result := (Lower_defined implies (other.Lower_defined and lower = other.lower)) and (Upper_defined implies (other.Upper_defined and upper = other.upper))
		ensure then
			iff_same_bounds: Result = ((Lower_defined implies (other.Lower_defined and lower = other.lower)) and (Upper_defined implies (other.Upper_defined and upper = other.upper)))
		end
	
feature -- Status report

	all_cleared: BOOLEAN
			-- Are all items set to default values?
		do
			Result := (lower = 0) and (upper = 0)
		ensure then
			iff_at_zero: Result = ((lower = 0) and (upper = 0))
		end

	extendible: BOOLEAN
			-- May new items be added?
			-- Answer: yes
		do
			Result := True
		end

	prunable: BOOLEAN
			-- May individual items be removed?
			-- Answer: no
		do
			Result := False
		end
	
feature -- Element change

	extend (v: INTEGER_32)
			-- Make sure that interval goes all the way
			-- to v (up or down).
			-- Was declared in INTEGER_INTERVAL as synonym of put.
		do
			if v < lower then
				lower := v
			elseif v > upper then
				upper := v
			end
		ensure then
			extended_down: lower = (old lower).min (v)
			extended_up: upper = (old upper).max (v)
		end

	put (v: INTEGER_32)
			-- Make sure that interval goes all the way
			-- to v (up or down).
			-- Was declared in INTEGER_INTERVAL as synonym of extend.
		do
			if v < lower then
				lower := v
			elseif v > upper then
				upper := v
			end
		ensure then
			extended_down: lower = (old lower).min (v)
			extended_up: upper = (old upper).max (v)
		end
	
feature -- Resizing

	resize (min_index, max_index: INTEGER_32)
			-- Rearrange interval to go from at most
			-- min_index to at least max_index,
			-- encompassing previous bounds.
		do
			lower := min_index.min (lower)
			upper := max_index.max (upper)
		end

	resize_exactly (min_index, max_index: INTEGER_32)
			-- Rearrange interval to go from
			-- min_index to max_index.
		do
			lower := min_index
			upper := max_index
		end

	grow (i: INTEGER_32)
			-- Ensure that capacity is at least i.
		do
			if capacity < i then
				resize (lower, lower + i - 1)
			end
		ensure then
			no_loss_from_bottom: lower <= old lower
			no_loss_from_top: upper >= old upper
		end

	trim
			-- Decrease capacity to the minimum value.
			-- Apply to reduce allocated storage.
		do
			check
				minimal_capacity: capacity = count
			end
		end
	
feature -- Removal

	wipe_out
			-- Remove all items.
		do
			lower := 1
			upper := 0
		end
	
feature -- Conversion

	as_array: ARRAY [INTEGER_32]
			-- Plain array containing interval's items
		require
			finite: Upper_defined and Lower_defined
		local
			i, nb: INTEGER_32
		do
			from
				i := lower
				nb := upper
				create Result.make_filled (0, i, nb)
			until
				i > nb
			loop
				Result.put (i, i)
				i := i + 1
			end
		ensure
			same_lower: Result.lower = lower
			same_upper: Result.upper = upper
		end

	to_c: ANY
		obsolete "No replacement. [2017-05-31]"
			-- Address of actual sequence of values,
			-- for passing to external (non-Eiffel) routines.
		do
			Result := Current
			check
					False
			end
		end

	linear_representation: LINEAR [INTEGER_32]
			-- Representation as a linear structure
		do
			check
				terminal: Upper_defined and Lower_defined
			end
			Result := as_array.linear_representation
		end
	
feature -- Duplication

	copy (other: like Current)
			-- Reset to be the same interval as other.
		do
			if other /= Current then
				standard_copy (other)
			end
		end

	subinterval (start_pos, end_pos: INTEGER_32): like Current
			-- Interval made of items of current array within
			-- bounds start_pos and end_pos.
		do
			create Result.make (start_pos, end_pos)
		end
	
feature -- Iteration

	do_all (action: PROCEDURE [INTEGER_32])
			-- Apply action to every item of current interval.
		require
			action_exists: action /= Void
			finite: Upper_defined and Lower_defined
		local
			i, nb: INTEGER_32
		do
			from
				i := lower
				nb := upper
			until
				i > nb
			loop
				action.call ([i])
				i := i + 1
			end
		end

	for_all (condition: FUNCTION [INTEGER_32, BOOLEAN]): BOOLEAN
			-- Do all interval's values satisfy condition?
		require
			finite: Upper_defined and Lower_defined
			condition_not_void: condition /= Void
		local
			i: INTEGER_32
		do
			from
				Result := True
				i := lower
			until
				(i > upper) or else (not condition.item ([i]))
			loop
				i := i + 1
			end
			Result := i > upper
		ensure
			consistent_with_count: Result = (hold_count (condition) = count)
		end

	exists (condition: FUNCTION [INTEGER_32, BOOLEAN]): BOOLEAN
			-- Does at least one of  interval's values
			-- satisfy condition?
		require
			finite: Upper_defined and Lower_defined
			condition_not_void: condition /= Void
		local
			i: INTEGER_32
		do
			from
				i := lower
			until
				i > upper or else condition.item ([i])
			loop
				i := i + 1
			end
			Result := i <= upper
		ensure
			consistent_with_count: Result = (hold_count (condition) > 0)
		end

	exists1 (condition: FUNCTION [INTEGER_32, BOOLEAN]): BOOLEAN
			-- Does exactly one of  interval's values
			-- satisfy condition?
		require
			finite: Upper_defined and Lower_defined
			condition_not_void: condition /= Void
		do
			Result := hold_count (condition) = 1
		ensure
			consistent_with_count: Result = (hold_count (condition) = 1)
		end

	hold_count (condition: FUNCTION [INTEGER_32, BOOLEAN]): INTEGER_32
			-- Number of  interval's values that
			-- satisfy condition
		require
			finite: Upper_defined and Lower_defined
			condition_not_void: condition /= Void
		local
			i: INTEGER_32
		do
			from
				i := lower
			until
				i > upper
			loop
				if condition.item ([i]) then
					Result := Result + 1
				end
				i := i + 1
			end
		ensure
			non_negative: Result >= 0
		end
	
feature -- Inapplicable

	prune (v: INTEGER_32)
			-- Remove one occurrence of v if any.
			-- Not applicable here.
		do
		end

	indexable_put (v: INTEGER_32; k: INTEGER_32)
			-- Associate value v with key k.
			-- Not applicable here.
		do
		end
	
invariant
	count_definition: Upper_defined and Lower_defined implies count = upper - lower + 1
	not_infinite: Upper_defined and Lower_defined

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 INTEGER_INTERVAL

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