indexing
	description: "References to objects containing an integer value coded on 8 bits"
	library: "Free implementation of ELKS library"
	copyright: "Copyright (c) 1986-2008, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see forum.txt)"
	date: "$Date: 2008-05-23 17:24:07 -0700 (Fri, 23 May 2008) $"
	revision: "$Revision: 170 $"

class interface
	NATURAL_8_REF


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

feature -- Access

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generating_type_not_void: Result /= Void
			generating_type_not_empty: not Result.is_empty

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

	hash_code: INTEGER_32
			-- Hash code value
		ensure -- from HASHABLE
			good_hash_value: Result >= 0

	item: NATURAL_8
			-- Integer value

	max_value: NATURAL_8 is 255
			-- Minimum and Maximum value hold in item.

	min_value: NATURAL_8 is 0

	one: like Current
			-- Neutral element for "*" and "/"
		ensure -- from NUMERIC
			result_exists: Result /= Void

	sign: INTEGER_32
			-- Sign value (0, -1 or 1)
		ensure
			three_way: Result = three_way_comparison (zero)

	zero: like Current
			-- Neutral element for "+" and "-"
		ensure -- from NUMERIC
			result_exists: Result /= Void
	
feature -- Comparison

	frozen deep_equal (some: ?ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			shallow_implies_deep: standard_equal (some, other) implies Result
			both_or_none_void: (some = Void) implies (Result = (other = Void))
			same_type: (Result and (some /= Void)) implies (other /= Void and then some.same_type (other))
			symmetric: Result implies deep_equal (other, some)

	frozen equal (some: ?ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

	frozen is_deep_equal (other: NATURAL_8_REF): BOOLEAN
			-- Are `Current' and `other' attached to isomorphic object structures?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		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)

	is_equal (other: like Current): BOOLEAN
			-- Is `other' attached to an object of the same type
			-- as current object and identical to it?
		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
		ensure then -- from COMPARABLE
			trichotomy: Result = (not (Current < other) and not (other < Current))

	max (other: NATURAL_8_REF): NATURAL_8_REF
			-- The greater of current object and `other'
			-- (from COMPARABLE)
		require -- from COMPARABLE
			other_exists: other /= Void
		ensure -- from COMPARABLE
			current_if_not_smaller: Current >= other implies Result = Current
			other_if_smaller: Current < other implies Result = other

	min (other: NATURAL_8_REF): NATURAL_8_REF
			-- The smaller of current object and `other'
			-- (from COMPARABLE)
		require -- from COMPARABLE
			other_exists: other /= Void
		ensure -- from COMPARABLE
			current_if_not_greater: Current <= other implies Result = Current
			other_if_greater: Current > other implies Result = other

	frozen standard_equal (some: ?ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

	frozen standard_is_equal (other: NATURAL_8_REF): 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
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)

	three_way_comparison (other: NATURAL_8_REF): INTEGER_32
			-- If current object equal to `other', 0;
			-- if smaller, -1; if greater, 1
			-- (from COMPARABLE)
		require -- from COMPARABLE
			other_exists: other /= Void
		ensure -- from COMPARABLE
			equal_zero: (Result = 0) = is_equal (other)
			smaller_negative: (Result = -1) = (Current < other)
			greater_positive: (Result = 1) = (Current > other)

	infix "<" (other: like Current): BOOLEAN
			-- Is current integer less than `other'?
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			asymmetric: Result implies not (other < Current)

	infix "<=" (other: NATURAL_8_REF): BOOLEAN
			-- Is current object less than or equal to `other'?
			-- (from COMPARABLE)
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			definition: Result = ((Current < other) or is_equal (other))

	infix ">" (other: NATURAL_8_REF): BOOLEAN
			-- Is current object greater than `other'?
			-- (from COMPARABLE)
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			definition: Result = (other < Current)

	infix ">=" (other: NATURAL_8_REF): BOOLEAN
			-- Is current object greater than or equal to `other'?
			-- (from COMPARABLE)
		require -- from PART_COMPARABLE
			other_exists: other /= Void
		ensure then -- from COMPARABLE
			definition: Result = (other <= Current)
	
feature -- Status report

	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

	divisible (other: like Current): BOOLEAN
			-- May current object be divided by `other'?
		require -- from NUMERIC
			other_exists: other /= Void
		ensure then
			value: Result = (other.item /= 0)

	exponentiable (other: NUMERIC): BOOLEAN
			-- May current object be elevated to the power `other'?
		require -- from NUMERIC
			other_exists: other /= Void
		ensure then
			safe_values: ((other.conforms_to (0) and item /= 0) or (other.conforms_to (0.0) and item > 0)) implies Result

	is_hashable: BOOLEAN
			-- May current object be hashed?
			-- (True if it is not its type's default.)

	is_valid_character_32_code: BOOLEAN
			-- Does current object represent a character?

	is_valid_character_8_code: BOOLEAN
			-- Does current object represent a CHARACTER_8?

	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
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
	
feature -- Element change

	set_item (i: NATURAL_8)
			-- Make `i' the item value.
		ensure
			item_set: item = i
	
feature -- Conversion

	as_integer_16: INTEGER_16
			-- Convert item into an INTEGER_16 value.

	as_integer_32: INTEGER_32
			-- Convert item into an INTEGER_32 value.

	as_integer_64: INTEGER_64
			-- Convert item into an INTEGER_64 value.

	as_integer_8: INTEGER_8
			-- Convert item into an INTEGER_8 value.

	as_natural_16: NATURAL_16
			-- Convert item into an NATURAL_16 value.

	as_natural_32: NATURAL_32
			-- Convert item into an NATURAL_32 value.

	as_natural_64: NATURAL_64
			-- Convert item into an NATURAL_64 value.

	as_natural_8: NATURAL_8
			-- Convert item into an NATURAL_8 value.

	frozen to_boolean: BOOLEAN
			-- True if not zero.

	to_character_32: CHARACTER_32
			-- Associated character in 32 bit version.
		require
			valid_character: is_valid_character_32_code

	to_character_8: CHARACTER_8
			-- Associated character in 8 bit version.
		require
			valid_character: is_valid_character_8_code

	to_hex_character: CHARACTER_8
			-- Convert item into an hexadecimal character.
		require
			in_bounds: 0 <= item and item <= 15
		ensure
			valid_character: ("0123456789ABCDEF").has (Result)

	to_hex_string: STRING_8
			-- Convert item into an hexadecimal string.
		ensure
			result_not_void: Result /= Void
			result_valid_count: Result.count = 2

	frozen to_integer_16: INTEGER_16
			-- Convert item into an INTEGER_16 value.

	frozen to_integer_32: INTEGER_32
			-- Convert item into an INTEGER_32 value.

	frozen to_integer_64: INTEGER_64
			-- Convert item into an INTEGER_64 value.

	frozen to_integer_8: INTEGER_8
			-- Convert item into an INTEGER_8 value.
		require
			not_too_big: item <= {INTEGER_8}.max_value.to_natural_8

	frozen to_natural_16: NATURAL_16
			-- Convert item into an NATURAL_16 value.

	frozen to_natural_32: NATURAL_32
			-- Convert item into an NATURAL_32 value.

	frozen to_natural_64: NATURAL_64
			-- Convert item into an NATURAL_64 value.

	frozen to_natural_8: NATURAL_8
			-- Convert item into an NATURAL_8 value.

	to_real_32: REAL_32
			-- Convert item into a REAL_32

	to_real_64: REAL_64
			-- Convert item into a REAL_64

	to_reference: NATURAL_8_REF
			-- Associated reference of Current
		ensure
			to_reference_not_void: Result /= Void
	
feature -- Duplication

	copy (other: NATURAL_8_REF)
			-- Update current object using fields of object attached
			-- to `other', so as to yield equal objects.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: is_equal (other)

	frozen deep_copy (other: NATURAL_8_REF)
			-- Effect equivalent to that of:
			--		copy (`other' . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)

	frozen deep_twin: NATURAL_8_REF
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_twin_not_void: Result /= Void
			deep_equal: deep_equal (Current, Result)

	frozen standard_copy (other: NATURAL_8_REF)
			-- 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)
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)

	frozen standard_twin: NATURAL_8_REF
			-- New object field-by-field identical to `other'.
			-- Always uses default copying semantics.
			-- (from ANY)
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)

	frozen twin: NATURAL_8_REF
			-- New object equal to `Current'
			-- twin calls copy; to change copying/twining semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result.is_equal (Current)
	
feature -- Basic operations

	frozen default: ?NATURAL_8_REF
			-- Default value of object's type
			-- (from ANY)

	frozen default_pointer: POINTER
			-- Default value of type `POINTER'
			-- (Avoid the need to write `p'.default for
			-- some `p' of type `POINTER'.)
			-- (from ANY)

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

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)

	unapplicable_minus_prefix: like Current
			-- Unary minus
		require -- from  NUMERIC
			True
		ensure -- from NUMERIC
			result_exists: Result /= Void
		ensure then
			not_applicable: False

	infix "*" (other: like Current): like Current
			-- Product by `other'
		require -- from NUMERIC
			other_exists: other /= Void
		ensure -- from NUMERIC
			result_exists: Result /= Void

	prefix "+": like Current
			-- Unary plus
		ensure -- from NUMERIC
			result_exists: Result /= Void

	infix "+" (other: like Current): like Current
			-- Sum with `other'
		require -- from NUMERIC
			other_exists: other /= Void
		ensure -- from NUMERIC
			result_exists: Result /= Void
			commutative: equal (Result, other + Current)

	infix "-" (other: like Current): like Current
			-- Result of subtracting `other'
		require -- from NUMERIC
			other_exists: other /= Void
		ensure -- from NUMERIC
			result_exists: Result /= Void

	infix "/" (other: like Current): REAL_64
			-- Division by `other'
		require
			other_exists: other /= Void
			good_divisor: divisible (other)

	infix "//" (other: like Current): like Current
			-- Integer division of Current by `other'
		require -- from NUMERIC
			other_exists: other /= Void
			good_divisor: divisible (other)
		ensure -- from NUMERIC
			result_exists: Result /= Void

	infix "\\" (other: like Current): like Current
			-- Remainder of the integer division of Current by `other'
		require
			other_exists: other /= Void
			good_divisor: divisible (other)
		ensure
			result_exists: Result /= Void

	infix "^" (other: REAL_64): REAL_64
			-- Integer power of Current by `other'

	infix "|..|" (other: INTEGER_32): INTEGER_INTERVAL
			-- Interval from current element to `other'
			-- (empty if `other' less than current integer)
	
feature -- Bit operations

	bit_and (i: like Current): like Current
			-- Bitwise and between Current' and `i'.
		require
			i_not_void: i /= Void
		ensure
			bitwise_and_not_void: Result /= Void

	bit_not: like Current
			-- One's complement of Current.
		ensure
			bit_not_not_void: Result /= Void

	bit_or (i: like Current): like Current
			-- Bitwise or between Current' and `i'.
		require
			i_not_void: i /= Void
		ensure
			bitwise_or_not_void: Result /= Void

	frozen bit_shift (n: INTEGER_32): NATURAL_8
			-- Shift Current from `n' position to right if `n' positive,
			-- to left otherwise.
		require
			n_less_or_equal_to_8: n <= 8
			n_greater_or_equal_to_minus_8: n >= -8

	bit_shift_left (n: INTEGER_32): like Current
			-- Shift Current from `n' position to left.
		require
			n_nonnegative: n >= 0
			n_less_or_equal_to_8: n <= 8
		ensure
			bit_shift_left_not_void: Result /= Void

	bit_shift_right (n: INTEGER_32): like Current
			-- Shift Current from `n' position to right.
		require
			n_nonnegative: n >= 0
			n_less_or_equal_to_8: n <= 8
		ensure
			bit_shift_right_not_void: Result /= Void

	frozen bit_test (n: INTEGER_32): BOOLEAN
			-- Test `n'-th position of Current.
		require
			n_nonnegative: n >= 0
			n_less_than_8: n < 8

	bit_xor (i: like Current): like Current
			-- Bitwise xor between Current' and `i'.
		require
			i_not_void: i /= Void
		ensure
			bitwise_xor_not_void: Result /= Void

	frozen set_bit (b: BOOLEAN; n: INTEGER_32): NATURAL_8
			-- Copy of current with `n'-th position
			-- set to 1 if `b', 0 otherwise.
		require
			n_nonnegative: n >= 0
			n_less_than_8: n < 8

	frozen set_bit_with_mask (b: BOOLEAN; m: NATURAL_8): NATURAL_8
			-- Copy of current with all 1 bits of m set to 1
			-- if `b', 0 otherwise.

	frozen infix "&" (i: like Current): like Current
			-- Bitwise and between Current' and `i'.
		require
			i_not_void: i /= Void
		ensure
			bitwise_and_not_void: Result /= Void

	frozen infix "|" (i: like Current): like Current
			-- Bitwise or between Current' and `i'.
		require
			i_not_void: i /= Void
		ensure
			bitwise_or_not_void: Result /= Void

	frozen infix "|<<" (n: INTEGER_32): like Current
			-- Shift Current from `n' position to left.
		require
			n_nonnegative: n >= 0
			n_less_or_equal_to_8: n <= 8
		ensure
			bit_shift_left_not_void: Result /= Void

	frozen infix "|>>" (n: INTEGER_32): like Current
			-- Shift Current from `n' position to right.
		require
			n_nonnegative: n >= 0
			n_less_or_equal_to_8: n <= 8
		ensure
			bit_shift_right_not_void: Result /= Void
	
feature -- Output

	io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)
		ensure -- from ANY
			io_not_void: Result /= Void

	out: STRING_8
			-- Printable representation of integer value
		require -- from  DEBUG_OUTPUT
			True
		require -- from  ANY
			True
		ensure -- from DEBUG_OUTPUT
			result_not_void: Result /= Void
		ensure -- from ANY
			out_not_void: Result /= Void

	print (some: ?ANY)
			-- Write terse external representation of `some'
			-- on standard output.
			-- (from ANY)

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

	operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
		ensure -- from ANY
			operating_environment_not_void: Result /= Void
	
invariant
		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

		-- from COMPARABLE
	irreflexive_comparison: not (Current < Current)

end -- class NATURAL_8_REF