indexing
	description: "Bit sequences of length `count', with binary operations"
	status: "See notice at end of class"
	date: "$Date$"
	revision: "$Revision$"

class interface
	BIT_REF

create

feature -- Access

	conforms_to (other: BIT_REF): BOOLEAN
			-- Is dynamic type of current object a descendant of
			-- dynamic type of other?
		require -- from ANY
			other_not_void: other /= void

	generator: STRING
			-- Name of the current object's generating class.

	item (i: INTEGER): BOOLEAN
			-- i-th bit
			-- Was declared in BIT_REF as synonym of @.
		require
			index_large_enough: i >= 1
			index_small_enough: i <= count

	infix "@" (i: INTEGER): BOOLEAN
			-- i-th bit
			-- Was declared in BIT_REF as synonym of item.
		require
			index_large_enough: i >= 1
			index_small_enough: i <= count
	
feature -- Measurement

	count: INTEGER
			-- Size of the current bit object
	
feature -- Element change

	put (value: BOOLEAN; i: INTEGER)
			-- Set the i-th bit to 1 if value is True, 0 if False
		require
			index_large_enough: i >= 1
			index_small_enough: i <= count
		ensure
			value_inserted: item (i) = value
	
feature -- Basic operations

	infix "#" (s: INTEGER): like Current
			-- Result of rotating bit sequence by s positions
			-- (Positive s rotates right, negative s rotates left.)

	infix "^" (s: INTEGER): like Current
			-- Result of shifting bit sequence by s positions
			-- (Positive s shifts right, negative s shifts left;
			-- bits falling off the sequence's bounds are lost.)

	infix "and" (other: BIT_REF): BIT_REF
			-- Bit-by-bit boolean conjunction with other
		require
			other_exists: other /= void
			conformance: other.count <= count

	infix "implies" (other: BIT_REF): BIT_REF
			-- Bit-by-bit boolean implication of other
		require
			other_exists: other /= void
			conformance: other.count <= count

	prefix "not": like Current
			-- Bit-by-bit negation

	infix "or" (other: BIT_REF): BIT_REF
			-- Bit-by-bit boolean disjunction with other
			-- Was declared in BIT_REF as synonym of |.
		require
			other_exists: other /= void
			conformance: other.count <= count

	infix "xor" (other: BIT_REF): BIT_REF
			-- Bit-by-bit exclusive or with other
		require
			other_exists: other /= void
			conformance: other.count <= count

	infix "|" (other: BIT_REF): BIT_REF
			-- Bit-by-bit boolean disjunction with other
			-- Was declared in BIT_REF as synonym of or.
		require
			other_exists: other /= void
			conformance: other.count <= count
	
feature -- Output

	out: STRING
			-- Tagged printable representation.
	
invariant

	valid_count: count > 0
		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

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 BIT_REF