    indexing
    	description: "Any medium that can perform input and/or output"
    	legal: "See notice at end of class."
    	status: "See notice at end of class."
    	date: "$Date: 2006-07-24 16:05:42 -0700 (Mon, 24 Jul 2006) $"
    	revision: "$Revision: 61601 $"

    deferred class interface
    	IO_MEDIUM

    feature -- Access

    	generating_type: STRING_8
    			-- Name of current object's generating type
    			-- (type of which it is a direct instance)
    			-- (from ANY)

    	generator: STRING_8
    			-- Name of current object's generating class
    			-- (base class of the type of which it is a direct instance)
    			-- (from ANY)

    	name: STRING_8
    			-- Medium name

    	retrieved: ANY
    			-- Retrieved object structure
    			-- To access resulting object under correct type,
    			-- use assignment attempt.
    			-- Will raise an exception (code `Retrieve_exception')
    			-- if content is not a stored Eiffel structure.
    		require
    			is_readable: readable
    			support_storable: support_storable
    		ensure
    			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 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))

    	is_equal (other: like Current): 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: like Current): 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

    	bytes_read: INTEGER_32
    			-- Last number of bytes read by read_to_managed_pointer.

    	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

    	exists: BOOLEAN
    			-- Does medium exist?

    	extendible: BOOLEAN
    			-- May new items be added?

    	handle: INTEGER_32
    			-- Handle to medium
    		require
    			valid_handle: handle_available

    	handle_available: BOOLEAN
    			-- Is the handle available after class has been
    			-- created?

    	is_closed: BOOLEAN
    			-- Is the I/O medium open

    	is_executable: BOOLEAN
    			-- Is medium executable?
    		require
    			handle_exists: exists

    	is_open_read: BOOLEAN
    			-- Is this medium opened for input

    	is_open_write: BOOLEAN
    			-- Is this medium opened for output

    	is_plain_text: BOOLEAN
    			-- Is file reserved for text (character sequences)?

    	is_readable: BOOLEAN
    			-- Is medium readable?
    		require
    			handle_exists: exists

    	is_writable: BOOLEAN
    			-- Is medium writable?
    		require
    			handle_exists: exists

    	last_character: CHARACTER_8
    			-- Last character read by read_character

    	last_double: REAL_64
    			-- Last double read by read_double

    	last_integer: INTEGER_32
    			-- Last integer read by read_integer

    	last_integer_16: INTEGER_16
    			-- Last 16-bit integer read by read_integer_16

    	last_integer_32: INTEGER_32
    			-- Synonymy of last_integer

    	last_integer_64: INTEGER_64
    			-- Last 64-bit integer read by read_integer_64

    	last_integer_8: INTEGER_8
    			-- Last 8-bit integer read by read_integer_8

    	last_natural: NATURAL_32
    			-- Last 32-bit natural read by read_natural

    	last_natural_16: NATURAL_16
    			-- Last 16-bit natural read by read_natural_16

    	last_natural_32: NATURAL_32
    			-- Synonymy of last_natural

    	last_natural_64: NATURAL_64
    			-- Last 64-bit natural read by read_natural_64

    	last_natural_8: NATURAL_8
    			-- Last 8-bit natural read by read_natural_8

    	last_real: REAL_32
    			-- Last real read by read_real

    	last_string: STRING_8
    			-- Last string read

    	readable: BOOLEAN
    			-- Is there a current item that may be read?
    		require
    			handle_exists: exists

    	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))

    	support_storable: BOOLEAN
    			-- Can medium be used to store an Eiffel object?

    feature -- Status setting

    	close
    			-- Close medium.
    		require
    			medium_is_open: not is_closed

    feature -- Element change

    	basic_store (object: ANY)
    			-- Produce an external representation of the
    			-- entire object structure reachable from `object'.
    			-- Retrievable within current system only.
    		require
    			object_not_void: object /= Void
    			extendible: extendible
    			support_storable: support_storable

    	general_store (object: ANY)
    			-- Produce an external representation of the
    			-- entire object structure reachable from `object'.
    			-- Retrievable from other systems for same platform
    			-- (machine architecture).
    		require
    			object_not_void: object /= Void
    			extendible: extendible
    			support_storable: support_storable

    	independent_store (object: ANY)
    			-- Produce an external representation of the
    			-- entire object structure reachable from `object'.
    			-- Retrievable from other systems for the same or other
    			-- platform (machine architecture).
    		require
    			object_not_void: object /= Void
    			extendible: extendible
    			support_storable: support_storable

    feature -- Removal

    	dispose
    			-- Ensure this medium is closed when garbage collected.

    feature -- Duplication

    	copy (other: like Current)
    			-- 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: like Current)
    			-- 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: like Current
    			-- New object structure recursively duplicated from Current.
    			-- (from ANY)
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, Result)

    	frozen standard_copy (other: like Current)
    			-- 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: like Current
    			-- 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: like Current
    			-- 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: like Current
    			-- 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)

    feature -- Obsolete

    	lastchar: CHARACTER_8
    			-- Last character read by read_character

    	lastdouble: REAL_64
    			-- Last double read by read_double

    	lastint: INTEGER_32
    			-- Last integer read by read_integer

    	lastreal: REAL_32
    			-- Last real read by read_real

    	laststring: STRING_8
    			-- Last string read

    feature -- Input

    	read_character
    			-- Read a new character.
    			-- Make result available in last_character.
    			-- Was declared in IO_MEDIUM as synonym of readchar.
    		require
    			is_readable: readable

    	read_double
    			-- Read a new double.
    			-- Make result available in last_double.
    			-- Was declared in IO_MEDIUM as synonym of readdouble.
    		require
    			is_readable: readable

    	read_integer
    			-- Read a new 32-bit integer.
    			-- Make result available in last_integer.
    			-- Was declared in IO_MEDIUM as synonym of readint and read_integer_32.
    		require
    			is_readable: readable

    	read_integer_16
    			-- Read a new 16-bit integer.
    			-- Make result available in last_integer_16.
    		require
    			is_readable: readable

    	read_integer_32
    			-- Read a new 32-bit integer.
    			-- Make result available in last_integer.
    			-- Was declared in IO_MEDIUM as synonym of read_integer and readint.
    		require
    			is_readable: readable

    	read_integer_64
    			-- Read a new 64-bit integer.
    			-- Make result available in last_integer_64.
    		require
    			is_readable: readable

    	read_integer_8
    			-- Read a new 8-bit integer.
    			-- Make result available in last_integer_8.
    		require
    			is_readable: readable

    	read_line
    			-- Read characters until a new line or
    			-- end of medium.
    			-- Make result available in last_string.
    			-- Was declared in IO_MEDIUM as synonym of readline.
    		require
    			is_readable: readable
    		ensure
    			last_string_not_void: last_string /= Void

    	read_natural
    			-- Read a new 32-bit natural.
    			-- Make result available in last_natural.
    			-- Was declared in IO_MEDIUM as synonym of read_natural_32.
    		require
    			is_readable: readable

    	read_natural_16
    			-- Read a new 16-bit natural.
    			-- Make result available in last_natural_16.
    		require
    			is_readable: readable

    	read_natural_32
    			-- Read a new 32-bit natural.
    			-- Make result available in last_natural.
    			-- Was declared in IO_MEDIUM as synonym of read_natural.
    		require
    			is_readable: readable

    	read_natural_64
    			-- Read a new 64-bit natural.
    			-- Make result available in last_natural_64.
    		require
    			is_readable: readable

    	read_natural_8
    			-- Read a new 8-bit natural.
    			-- Make result available in last_natural_8.
    		require
    			is_readable: readable

    	read_real
    			-- Read a new real.
    			-- Make result available in last_real.
    			-- Was declared in IO_MEDIUM as synonym of readreal.
    		require
    			is_readable: readable

    	read_stream (nb_char: INTEGER_32)
    			-- Read a string of at most `nb_char' bound characters
    			-- or until end of medium is encountered.
    			-- Make result available in last_string.
    			-- Was declared in IO_MEDIUM as synonym of readstream.
    		require
    			is_readable: readable
    		ensure
    			last_string_not_void: last_string /= Void

    	read_to_managed_pointer (p: MANAGED_POINTER; start_pos, nb_bytes: INTEGER_32)
    			-- Read at most `nb_bytes' bound bytes and make result
    			-- available in `p' at position `start_pos'.
    		require
    			p_not_void: p /= Void
    			p_large_enough: p.count >= nb_bytes + start_pos
    			nb_bytes_non_negative: nb_bytes >= 0
    			is_readable: readable
    		ensure
    			bytes_read_non_negative: bytes_read >= 0
    			bytes_read_not_too_big: bytes_read <= nb_bytes

    	readchar
    			-- Read a new character.
    			-- Make result available in last_character.
    			-- Was declared in IO_MEDIUM as synonym of read_character.
    		require
    			is_readable: readable

    	readdouble
    			-- Read a new double.
    			-- Make result available in last_double.
    			-- Was declared in IO_MEDIUM as synonym of read_double.
    		require
    			is_readable: readable

    	readint
    			-- Read a new 32-bit integer.
    			-- Make result available in last_integer.
    			-- Was declared in IO_MEDIUM as synonym of read_integer and read_integer_32.
    		require
    			is_readable: readable

    	readline
    			-- Read characters until a new line or
    			-- end of medium.
    			-- Make result available in last_string.
    			-- Was declared in IO_MEDIUM as synonym of read_line.
    		require
    			is_readable: readable
    		ensure
    			last_string_not_void: last_string /= Void

    	readreal
    			-- Read a new real.
    			-- Make result available in last_real.
    			-- Was declared in IO_MEDIUM as synonym of read_real.
    		require
    			is_readable: readable

    	readstream (nb_char: INTEGER_32)
    			-- Read a string of at most `nb_char' bound characters
    			-- or until end of medium is encountered.
    			-- Make result available in last_string.
    			-- Was declared in IO_MEDIUM as synonym of read_stream.
    		require
    			is_readable: readable
    		ensure
    			last_string_not_void: last_string /= Void

    feature -- Output

    	io: STD_FILES
    			-- Handle to standard file setup
    			-- (from ANY)

    	new_line
    			-- Write a new line character to medium
    			-- Was declared in IO_MEDIUM as synonym of put_new_line.
    		require
    			extendible: extendible

    	out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of tagged_out.
    			-- (from ANY)

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

    	put_boolean (b: BOOLEAN)
    			-- Write `b' to medium.
    			-- Was declared in IO_MEDIUM as synonym of putbool.
    		require
    			extendible: extendible

    	put_character (c: CHARACTER_8)
    			-- Write `c' to medium.
    			-- Was declared in IO_MEDIUM as synonym of putchar.
    		require
    			extendible: extendible

    	put_double (d: REAL_64)
    			-- Write `d' to medium.
    			-- Was declared in IO_MEDIUM as synonym of putdouble.
    		require
    			extendible: extendible

    	put_integer (i: INTEGER_32)
    			-- Write `i' to medium.
    			-- Was declared in IO_MEDIUM as synonym of putint and put_integer_32.
    		require
    			extendible: extendible

    	put_integer_16 (i: INTEGER_16)
    			-- Write `i' to medium.
    		require
    			extendible: extendible

    	put_integer_32 (i: INTEGER_32)
    			-- Write `i' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_integer and putint.
    		require
    			extendible: extendible

    	put_integer_64 (i: INTEGER_64)
    			-- Write `i' to medium.
    		require
    			extendible: extendible

    	put_integer_8 (i: INTEGER_8)
    			-- Write `i' to medium.
    		require
    			extendible: extendible

    	put_managed_pointer (p: MANAGED_POINTER; start_pos, nb_bytes: INTEGER_32)
    			-- Put data of length `nb_bytes' pointed by `start_pos' index in `p' at
    			-- current position.
    		require
    			p_not_void: p /= Void
    			p_large_enough: p.count >= nb_bytes + start_pos
    			nb_bytes_non_negative: nb_bytes >= 0
    			extendible: extendible

    	put_natural (i: NATURAL_32)
    			-- Write `i' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_natural_32.
    		require
    			extendible: extendible

    	put_natural_16 (i: NATURAL_16)
    			-- Write `i' to medium.
    		require
    			extendible: extendible

    	put_natural_32 (i: NATURAL_32)
    			-- Write `i' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_natural.
    		require
    			extendible: extendible

    	put_natural_64 (i: NATURAL_64)
    			-- Write `i' to medium.
    		require
    			extendible: extendible

    	put_natural_8 (i: NATURAL_8)
    			-- Write `i' to medium.
    		require
    			extendible: extendible

    	put_new_line
    			-- Write a new line character to medium
    			-- Was declared in IO_MEDIUM as synonym of new_line.
    		require
    			extendible: extendible

    	put_real (r: REAL_32)
    			-- Write `r' to medium.
    			-- Was declared in IO_MEDIUM as synonym of putreal.
    		require
    			extendible: extendible

    	put_string (s: STRING_8)
    			-- Write `s' to medium.
    			-- Was declared in IO_MEDIUM as synonym of putstring.
    		require
    			extendible: extendible
    			non_void: s /= Void

    	putbool (b: BOOLEAN)
    			-- Write `b' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_boolean.
    		require
    			extendible: extendible

    	putchar (c: CHARACTER_8)
    			-- Write `c' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_character.
    		require
    			extendible: extendible

    	putdouble (d: REAL_64)
    			-- Write `d' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_double.
    		require
    			extendible: extendible

    	putint (i: INTEGER_32)
    			-- Write `i' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_integer and put_integer_32.
    		require
    			extendible: extendible

    	putreal (r: REAL_32)
    			-- Write `r' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_real.
    		require
    			extendible: extendible

    	putstring (s: STRING_8)
    			-- Write `s' to medium.
    			-- Was declared in IO_MEDIUM as synonym of put_string.
    		require
    			extendible: extendible
    			non_void: s /= Void

    	frozen tagged_out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of out.
    			-- (from ANY)

    feature -- Platform

    	operating_environment: OPERATING_ENVIRONMENT
    			-- Objects available from the operating system
    			-- (from ANY)

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

    indexing
    	library: "EiffelBase: Library of reusable components for Eiffel."
    	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
    	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
    	source: "[
    		Eiffel Software
    		356 Storke Road, Goleta, CA 93117 USA
    		Telephone 805-685-1006, Fax 805-685-6869
    		Website http://www.eiffel.com
    		Customer support http://support.eiffel.com
    	]"

    end -- class IO_MEDIUM