indexing
	description: "Bit sequences of length `count%', with binary operations"

class interface
	BIT_REF

feature -- Access

	conforms_to (other: BIT_REF): BOOLEAN
			-- Is dynamic type of current object a descendant of
			-- dynamic type of other?
		require -- from GENERAL
			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 item and @.
		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 and @.
		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-bi boolean disjunction with other
		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
	
feature -- Output

	out: STRING
			-- Tagged printable representation.
	
invariant

		-- from GENERAL
	reflexive_equality: standard_is_equal (Current);
	reflexive_conformance: conforms_to (Current);

end -- class BIT_REF