indexing
	description: "Unbounded queues, implemented by resizable arrays"
	names: dispenser, array
	representation: array
	access: fixed, fifo, membership
	size: fixed
	contents: generic

class interface
	ARRAYED_QUEUE [G]

create 

	make (n: INTEGER)
			-- Create queue for at most n items.
		require
			non_negative_argument: n >= 0
		ensure
			capacity_expected: capacity = n

feature -- Initialization

	make (n: INTEGER)
			-- Create queue for at most n items.
		require
			non_negative_argument: n >= 0
		ensure
			capacity_expected: capacity = n

	setup (other: like Current)
			-- Perform actions on a freshly created object so that
			-- the contents of other can be safely copied onto it.
			-- (from ARRAY)
		ensure -- from GENERAL
			consistent (other)
	
feature -- Access

	has (v: like item): BOOLEAN
			-- Does queue include v?
			-- (Reference or object equality,
			-- based on object_comparison.)
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not empty

	item: G
			-- Oldest item.
		require -- from ACTIVE
			readable: readable
	
feature -- Measurement

	count: INTEGER
			-- Number of items.

	occurrences (v: G): INTEGER
			-- Number of times v appears in structure
			-- (from ARRAY)
		ensure -- from BAG
			non_negative_occurrences: Result >= 0
	
feature -- Comparison

	is_equal (other: like Current): BOOLEAN
			-- Is array made of the same items as other?
			-- (from ARRAY)
		require -- from GENERAL
			other_not_void: other /= void
		ensure -- from GENERAL
			symmetric: Result implies other.is_equal (Current);
			consistent: standard_is_equal (other) implies Result
	
feature -- Status report

	changeable_comparison_criterion: BOOLEAN
			-- May object_comparison be changed?
			-- (Answer: yes by default.)
			-- (from CONTAINER)

	consistent (other: like Current): BOOLEAN
			-- Is object in a consistent state so that other
			-- may be copied onto it? (Default answer: yes).
			-- (from ARRAY)

	empty: BOOLEAN
			-- Is the structure empty?
			-- Was declared in ARRAYED_QUEUE as synonym of empty and off.

	extendible: BOOLEAN
			-- May items be added? (Answer: yes.)

	full: BOOLEAN
			-- Is structure filled to capacity?
			-- (Answer: no.)

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

	off: BOOLEAN
			-- Is the structure empty?
			-- Was declared in ARRAYED_QUEUE as synonym of empty and off.

	prunable: BOOLEAN
			-- May items be removed? (Answer: yes.)

	readable: BOOLEAN
			-- Is there a current item that may be read?
			-- (from DISPENSER)

	writable: BOOLEAN
			-- Is there a current item that may be modified?
			-- (from DISPENSER)
	
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
		ensure -- from CONTAINER
			object_comparison

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

	append (s: SEQUENCE [G])
			-- Append a copy of s.
			-- (Synonym for fill)
			-- (from DISPENSER)

	extend (v: G)
			-- Add v as newest item.
			-- Was declared in ARRAYED_QUEUE as synonym of extend, put and force.
		require -- from COLLECTION
			extendible: extendible
		ensure -- from COLLECTION
			item_inserted: has (v)
		ensure then -- from BAG
			one_more_occurrence: occurrences (v) = old (occurrences (v)) + 1

	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 COLLECTION)
		require -- from COLLECTION
			other_not_void: other /= void;
			extendible

	force (v: G)
			-- Add v as newest item.
			-- Was declared in ARRAYED_QUEUE as synonym of extend, put and force.

	put (v: G)
			-- Add v as newest item.
			-- Was declared in ARRAYED_QUEUE as synonym of extend, put and force.
		require -- from COLLECTION
			extendible: extendible
		ensure -- from COLLECTION
			item_inserted: has (v)

	replace (v: like item)
			-- Replace oldest item by v.
		require -- from ACTIVE
			writable: writable
		ensure -- from ACTIVE
			item_replaced: item = v
	
feature -- Removal

	remove
			-- Remove oldest item.
		require -- from ACTIVE
			prunable: prunable;
			writable: writable

	wipe_out
			-- Remove all items.
		require -- from COLLECTION
			prunable
		ensure -- from COLLECTION
			wiped_out: empty
	
feature -- Conversion

	linear_representation: ARRAYED_LIST [G]
			-- Representation as a linear structure
			-- (in the original insertion order)
	
feature -- Duplication

	copy (other: like Current)
			-- Reinitialize by copying all the items of other.
			-- (This is also used by clone.)
			-- (from ARRAY)
		require -- ARRAY
			precursor: True
		require -- from GENERAL
			other_not_void: other /= void;
			type_identity: same_type (other)
ensure -- from GENERAL
			is_equal: is_equal (other)

invariant

		-- from GENERAL
	reflexive_equality: standard_is_equal (Current);
	reflexive_conformance: conforms_to (Current);
	not_full: not full;
	extendible: extendible;
	prunable: prunable;
		-- from DISPENSER
	readable_definition: readable = not empty;
	writable_definition: writable = not empty;
		-- from ACTIVE
	writable_constraint: writable implies readable;
	empty_constraint: empty implies (not readable) and (not writable);
		-- from FINITE
	empty_definition: empty = (count = 0);
	non_negative_count: count >= 0;
		-- from ARRAY
non_negative_count: count >= 0;

end -- class ARRAYED_QUEUE