indexing
	description: "Two-dimensional arrays"
	status: "See notice at end of class"
	names: array2, matrix, table
	representation: array
	access: index, row_and_column, membership
	size: resizable
	contents: generic
	date: "$Date$"
	revision: "$Revision$"

class interface
	ARRAY2 [G]

create

	make (nb_rows, nb_columns: INTEGER)
			-- Create a two dimensional array which has nb_rows
			-- rows and nb_columns columns,
			-- with lower bounds starting at 1.
		require
			not_flat: nb_rows > 0
			not_thin: nb_columns > 0
		ensure
			new_count: count = height * width

feature -- Initialization

	initialize (v: G)
			-- Make each entry have value v.

	make (nb_rows, nb_columns: INTEGER)
			-- Create a two dimensional array which has nb_rows
			-- rows and nb_columns columns,
			-- with lower bounds starting at 1.
		require
			not_flat: nb_rows > 0
			not_thin: nb_columns > 0
		ensure
			new_count: count = height * width

	make_from_array (a: ARRAY [G])
			-- Initialize from the items of a.
			-- (Useful in proper descendants of class ARRAY,
			-- to initialize an array-like object from a manifest array.)
			-- (from ARRAY)
		require -- from ARRAY
			array_exists: a /= void

feature -- Access

	entry (i: INTEGER): G
			-- Entry at index i, if in index interval
			-- (from ARRAY)
		require -- from ARRAY
			valid_key: valid_index (i)

	has (v: G): BOOLEAN
			-- Does v appear in array?
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from ARRAY)
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not is_empty

	item (row, column: INTEGER): G
			-- Entry at coordinates (row, column)
		require
			valid_row: (1 <= row) and (row <= height)
			valid_column: (1 <= column) and (column <= width)

	infix "@" (i: INTEGER): G
			-- Entry at index i, if in index interval
			-- Was declared in ARRAY as synonym of item.
			-- (from ARRAY)
		require -- from TABLE
			valid_key: valid_index (k)

feature  -- Access

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

feature -- Measurement

	additional_space: INTEGER
			-- Proposed number of additional items
			-- (from RESIZABLE)
		ensure -- from RESIZABLE
			at_least_one: Result >= 1

	capacity: INTEGER
			-- Number of available indices
			-- Was declared in ARRAY as synonym of count.
			-- (from ARRAY)
		ensure then -- from ARRAY
			consistent_with_bounds: Result = upper - lower + 1

	count: INTEGER
			-- Number of available indices
			-- Was declared in ARRAY as synonym of capacity.
			-- (from ARRAY)
		ensure then -- from ARRAY
			consistent_with_bounds: Result = upper - lower + 1

	Growth_percentage: INTEGER is 50
			-- Percentage by which structure will grow automatically
			-- (from RESIZABLE)

	height: INTEGER
			-- Number of rows

	index_set: INTEGER_INTERVAL
			-- Range of acceptable indexes
			-- (from ARRAY)
		ensure -- from INDEXABLE
			not_void: Result /= void
		ensure then -- from ARRAY
			same_count: Result.count = count
			same_bounds: ((Result.lower = lower) and (Result.upper = upper))

	lower: INTEGER
			-- Minimum index
			-- (from ARRAY)

	Minimal_increase: INTEGER is 5
			-- Minimal number of additional items
			-- (from RESIZABLE)

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

	upper: INTEGER
			-- Maximum index
			-- (from ARRAY)

	width: INTEGER
			-- Number of columns

feature  -- Comparison

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

feature -- Status report

	all_default: BOOLEAN
			-- Are all items set to default values?
			-- (from ARRAY)
		ensure -- from ARRAY
			definition: Result = (count = 0 or else ((array_item (upper) = void or else array_item (upper) = array_item (upper).default) and subarray (lower, upper - 1).all_default))

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

	extendible: BOOLEAN
			-- May items be added?
			-- (Answer: no, although array may be resized.)
			-- (from ARRAY)

	full: BOOLEAN
			-- Is structure filled to capacity? (Answer: yes)
			-- (from ARRAY)

	is_empty: BOOLEAN
			-- Is structure empty?
			-- (from FINITE)

	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)

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

	prunable: BOOLEAN
			-- May items be removed? (Answer: no.)
			-- (from ARRAY)

	resizable: BOOLEAN
			-- May capacity be changed? (Answer: yes.)
			-- (from RESIZABLE)

	same_items (other: like Current): BOOLEAN
			-- Do other and Current have same items?
			-- (from ARRAY)
		require -- from ARRAY
			other_not_void: other /= void
		ensure -- from ARRAY
			definition: Result = ((count = other.count) and then (count = 0 or else (array_item (upper) = other.array_item (other.upper) and subarray (lower, upper - 1).same_items (other.subarray (other.lower, other.upper - 1)))))

	valid_index (i: INTEGER): BOOLEAN
			-- Is i within the bounds of the array?
			-- (from ARRAY)
		ensure then -- from INDEXABLE
			only_if_in_index_set: Result implies ((i >= index_set.lower) and (i <= index_set.upper))

	valid_index_set: BOOLEAN
			-- (from ARRAY)

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

	enter (v: like array_item; i: INTEGER)
			-- Replace i-th entry, if in index interval, by v.
			-- (from ARRAY)
		require -- from ARRAY
			valid_key: valid_index (i)

	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: like item; row, column: INTEGER)
			-- Assign item v at coordinates (row, column).
			-- Resize if necessary.
		require
			row_large_enough: 1 <= row
			column_large_enough: 1 <= column

	put (v: like item; row, column: INTEGER)
			-- Assign item v at coordinates (row, column).
		require
			valid_row: 1 <= row and row <= height
			valid_column: 1 <= column and column <= width

	subcopy (other: like Current; start_pos, end_pos, index_pos: INTEGER)
			-- Copy items of other within bounds start_pos and end_pos
			-- to current array starting at index index_pos.
			-- (from ARRAY)
		require -- from ARRAY
			other_not_void: other /= void
			valid_start_pos: other.valid_index (start_pos)
			valid_end_pos: other.valid_index (end_pos)
			valid_bounds: (start_pos <= end_pos) or (start_pos = end_pos + 1)
			valid_index_pos: valid_index (index_pos)
			enough_space: (upper - index_pos) >= (end_pos - start_pos)

feature -- Removal

	clear_all
			-- Reset all items to default values.
			-- (from ARRAY)
		ensure -- from ARRAY
			stable_lower: lower = old lower
			stable_upper: upper = old upper
			default_items: all_default

	discard_items
			-- Reset all items to default values with reallocation.
			-- (from ARRAY)
		ensure -- from ARRAY
			default_items: all_default

	prune_all (v: G)
			-- Remove all occurrences of v.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from COLLECTION)
		require -- from COLLECTION
			prunable
		ensure -- from COLLECTION
			no_more_occurrences: not has (v)

	wipe_out
			-- Remove all items.

feature -- Resizing

	automatic_grow
			-- Change the capacity to accommodate at least
			-- Growth_percentage more items.
			-- (from RESIZABLE)
		ensure -- from RESIZABLE
			increased_capacity: capacity >= old capacity + old capacity * growth_percentage // 100

	grow (i: INTEGER)
			-- Change the capacity to at least i.
			-- (from ARRAY)
		ensure -- from RESIZABLE
			new_capacity: capacity >= i

	resize (nb_rows, nb_columns: INTEGER)
			-- Rearrange array so that it can accommodate
			-- nb_rows rows and nb_columns columns,
			-- without losing any previously
			-- entered items, nor changing their coordinates;
			-- do nothing if not possible.
		require
			valid_row: nb_rows >= 1
			valid_column: nb_columns >= 1

feature  -- Conversion

	to_c: ANY
			-- Address of actual sequence of values,
			-- for passing to external (non-Eiffel) routines.
			-- (from ARRAY)

feature -- Conversion

	linear_representation: LINEAR [G]
			-- Representation as a linear structure
			-- (from ARRAY)

feature  -- Duplication

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

feature -- Duplication

	subarray (start_pos, end_pos: INTEGER): like Current
			-- Array made of items of current array within
			-- bounds start_pos and end_pos.
			-- (from ARRAY)
		require -- from ARRAY
			valid_start_pos: valid_index (start_pos)
			valid_end_pos: valid_index (end_pos)
			valid_bounds: (start_pos <= end_pos) or (start_pos = end_pos + 1)
		ensure -- from ARRAY
			lower: Result.lower = start_pos
			upper: Result.upper = end_pos

invariant

	items_number: count = width * height
		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)
		-- from ARRAY
	area_exists: area /= void
	consistent_size: capacity = upper - lower + 1
	non_negative_count: count >= 0
	index_set_has_same_count: valid_index_set
		-- 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)
	non_negative_count: count >= 0
		-- from INDEXABLE
	index_set_not_void: index_set /= void

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 ARRAY2