indexing
	description: "Truth values, with the boolean operations"
	external_name: "System.Boolean"
	assembly: "mscorlib"
	library: "Free implementation of ELKS library"
	copyright: "Copyright (c) 1986-2004, 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 $"

frozen expanded class interface
	BOOLEAN


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

	make_from_reference (v: BOOLEAN_REF)
			-- Initialize `Current' with `v.item'.
			-- (from BOOLEAN_REF)
		require -- from BOOLEAN_REF
			v_not_void: v /= Void
		ensure -- from BOOLEAN_REF
			item_set: item = v.item

convert
	make_from_reference ({BOOLEAN_REF})

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
			-- (from BOOLEAN_REF)
		ensure -- from HASHABLE
			good_hash_value: Result >= 0

	item: BOOLEAN
			-- Boolean value
			-- (from BOOLEAN_REF)
	
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: BOOLEAN): 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: BOOLEAN): BOOLEAN
			-- Is `other' attached to an object considered
			-- equal to current object?
			-- (from ANY)
		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

	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: BOOLEAN): 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)
	
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

	is_hashable: BOOLEAN
			-- May current object be hashed?
			-- (True by default.)
			-- (from HASHABLE)

	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 (b: BOOLEAN)
			-- Make `b' the item value.
			-- (from BOOLEAN_REF)
	
feature -- Conversion

	to_integer: INTEGER_32
			-- 1 if `True'
			-- 0 if `False'
			-- (from BOOLEAN_REF)
		ensure -- from BOOLEAN_REF
			not_item_implies_zero: not item implies Result = 0
			item_implies_one: item implies Result = 1

	to_reference: BOOLEAN_REF
			-- Associated reference of Current
			-- (from BOOLEAN_REF)
		ensure -- from BOOLEAN_REF
			to_reference_not_void: Result /= Void
			same_item: Result.item = item
	
feature -- Duplication

	copy (other: BOOLEAN)
			-- 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: BOOLEAN)
			-- 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: BOOLEAN
			-- 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: BOOLEAN)
			-- 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: BOOLEAN
			-- 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: BOOLEAN
			-- 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: BOOLEAN
			-- 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)

	infix "and" (other: BOOLEAN): BOOLEAN
			-- Boolean conjunction with `other'
		require -- from BOOLEAN_REF
			other_exists: other /= Void
		ensure -- from BOOLEAN_REF
			de_morgan: Result = not (not Current or not other)
			commutative: Result = (other and Current)
			consistent_with_semi_strict: Result implies (Current and then other)

	infix "and then" (other: BOOLEAN): BOOLEAN
			-- Boolean semi-strict conjunction with `other'
		require -- from BOOLEAN_REF
			other_exists: other /= Void
		ensure -- from BOOLEAN_REF
			de_morgan: Result = not (not Current or else not other)

	infix "implies" (other: BOOLEAN): BOOLEAN
			-- Boolean implication of `other'
			-- (semi-strict)
		require -- from BOOLEAN_REF
			other_exists: other /= Void
		ensure -- from BOOLEAN_REF
			definition: Result = (not Current or else other)

	prefix "not": BOOLEAN
			-- Negation

	infix "or" (other: BOOLEAN): BOOLEAN
			-- Boolean disjunction with `other'
		require -- from BOOLEAN_REF
			other_exists: other /= Void
		ensure -- from BOOLEAN_REF
			de_morgan: Result = not (not Current and not other)
			commutative: Result = (other or Current)
			consistent_with_semi_strict: Result implies (Current or else other)

	infix "or else" (other: BOOLEAN): BOOLEAN
			-- Boolean semi-strict disjunction with `other'
		require -- from BOOLEAN_REF
			other_exists: other /= Void
		ensure -- from BOOLEAN_REF
			de_morgan: Result = not (not Current and then not other)

	infix "xor" (other: BOOLEAN): BOOLEAN
			-- Boolean exclusive or with `other'
		require -- from BOOLEAN_REF
			other_exists: other /= Void
		ensure -- from BOOLEAN_REF
			definition: Result = ((Current or other) and not (Current and other))
	
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 boolean
			-- (from BOOLEAN_REF)
		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 BOOLEAN_REF
	involutive_negation: is_equal (not (not Current))
	non_contradiction: not (Current and (not Current))
	completeness: Current or (not Current)

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

end -- class BOOLEAN