    indexing
    	description: "Absolute dates"
    	legal: "See notice at end of class."
    	status: "See notice at end of class."
    	date: "$Date: 2006-01-22 18:25:44 -0800 (Sun, 22 Jan 2006) $"
    	revision: "$Revision: 56675 $"
    	access: date

    class interface
    	DATE

    create
    	make (y, m, d: INTEGER_32)
    			-- Set year, month and day to `y', `m', `d' respectively.
    		require
    			correct_date: is_correct_date (y, m, d)
    		ensure
    			year_set: year = y
    			month_set: month = m
    			day_set: day = d

    	make_month_day_year (m, d, y: INTEGER_32)
    			-- Set month, day and year to `m', `d' and `y' respectively.
    		require
    			correct_date: is_correct_date (y, m, d)
    		ensure
    			year_set: year = y
    			month_set: month = m
    			day_set: day = d

    	make_day_month_year (d, m, y: INTEGER_32)
    			-- Set day, month and year to `d', `m' and `y' respectively.
    		require
    			correct_date: is_correct_date (y, m, d)
    		ensure
    			year_set: year = y
    			month_set: month = m
    			day_set: day = d

    	make_now
    			-- Set the current object to today's date.

    	make_now_utc
    			-- Set the current object to today's date in utc format.

    	make_by_days (n: INTEGER_32)
    			-- Set the current date with the number of days `n' since Origin.
    		ensure
    			days_set: days = n

    	make_from_string_default (s: STRING_8)
    			-- Initialize from a "standard" string of form
    			-- date_default_format_string.
    			-- (For 2-digit year specifications, the current century is used as
    			-- base century.)
    		require
    			s_exists: s /= Void
    			date_valid: date_valid (s, date_default_format_string)

    	make_from_string_default_with_base (s: STRING_8; base: INTEGER_32)
    			-- Initialize from a "standard" string of form
    			-- date_default_format_string with base century `base'.
    		require
    			s_exists: s /= Void
    			base_valid: base > 0 and (base \\ 100 = 0)
    			date_valid: date_valid_with_base (s, date_default_format_string, base)

    	make_from_string (s: STRING_8; code: STRING_8)
    			-- Initialize from a "standard" string of form
    			-- `code'.
    			-- (For 2-digit year specifications, the current century is used as
    			-- base century.)
    		require
    			s_exists: s /= Void
    			c_exists: code /= Void
    			date_valid: date_valid (s, code)

    	make_from_string_with_base (s: STRING_8; code: STRING_8; base: INTEGER_32)
    			-- Initialize from a "standard" string of form
    			-- `code' with base century `base'.
    		require
    			s_exists: s /= Void
    			c_exists: code /= Void
    			base_valid: base > 0 and (base \\ 100 = 0)
    			date_valid: date_valid_with_base (s, code, base)

    	make_by_compact_date (c_d: INTEGER_32)
    			-- Initialize from a compact_date.
    		require
    			c_d_valid: compact_date_valid (c_d)
    		ensure
    			compact_date_set: year | (month |<< 16) | (day |<< 24) = c_d

    	make_by_ordered_compact_date (c_d: INTEGER_32)
    			-- Initialize from a ordered_compact_date.
    		require
    			c_d_valid: ordered_compact_date_valid (c_d)
    		ensure
    			ordered_compact_date_set: ordered_compact_date = c_d

    feature -- Initialization

    	make (y, m, d: INTEGER_32)
    			-- Set year, month and day to `y', `m', `d' respectively.
    		require
    			correct_date: is_correct_date (y, m, d)
    		ensure
    			year_set: year = y
    			month_set: month = m
    			day_set: day = d

    	make_by_days (n: INTEGER_32)
    			-- Set the current date with the number of days `n' since Origin.
    		ensure
    			days_set: days = n

    	make_by_ordered_compact_date (c_d: INTEGER_32)
    			-- Initialize from a ordered_compact_date.
    		require
    			c_d_valid: ordered_compact_date_valid (c_d)
    		ensure
    			ordered_compact_date_set: ordered_compact_date = c_d

    	make_day_month_year (d, m, y: INTEGER_32)
    			-- Set day, month and year to `d', `m' and `y' respectively.
    		require
    			correct_date: is_correct_date (y, m, d)
    		ensure
    			year_set: year = y
    			month_set: month = m
    			day_set: day = d

    	make_from_string (s: STRING_8; code: STRING_8)
    			-- Initialize from a "standard" string of form
    			-- `code'.
    			-- (For 2-digit year specifications, the current century is used as
    			-- base century.)
    		require
    			s_exists: s /= Void
    			c_exists: code /= Void
    			date_valid: date_valid (s, code)

    	make_from_string_default (s: STRING_8)
    			-- Initialize from a "standard" string of form
    			-- date_default_format_string.
    			-- (For 2-digit year specifications, the current century is used as
    			-- base century.)
    		require
    			s_exists: s /= Void
    			date_valid: date_valid (s, date_default_format_string)

    	make_from_string_default_with_base (s: STRING_8; base: INTEGER_32)
    			-- Initialize from a "standard" string of form
    			-- date_default_format_string with base century `base'.
    		require
    			s_exists: s /= Void
    			base_valid: base > 0 and (base \\ 100 = 0)
    			date_valid: date_valid_with_base (s, date_default_format_string, base)

    	make_from_string_with_base (s: STRING_8; code: STRING_8; base: INTEGER_32)
    			-- Initialize from a "standard" string of form
    			-- `code' with base century `base'.
    		require
    			s_exists: s /= Void
    			c_exists: code /= Void
    			base_valid: base > 0 and (base \\ 100 = 0)
    			date_valid: date_valid_with_base (s, code, base)

    	make_month_day_year (m, d, y: INTEGER_32)
    			-- Set month, day and year to `m', `d' and `y' respectively.
    		require
    			correct_date: is_correct_date (y, m, d)
    		ensure
    			year_set: year = y
    			month_set: month = m
    			day_set: day = d

    	make_now
    			-- Set the current object to today's date.

    	make_now_utc
    			-- Set the current object to today's date in utc format.

    feature -- Access

    	date_default_format_string: STRING_8
    			-- Default output format for dates
    			-- (from DATE_CONSTANTS)

    	date_time_tools: DATE_TIME_TOOLS
    			-- Tools for outputting dates and times in different formats
    			-- (from TIME_UTILITY)

    	day: INTEGER_32
    			-- Day of the current object
    			-- (from DATE_VALUE)

    	days_in_i_th_month (i, y: INTEGER_32): INTEGER_32
    			-- Number of days in the `i' th month at year `y'
    			-- (from DATE_CONSTANTS)
    		require -- from DATE_CONSTANTS
    			i_large_enough: i >= 1
    			i_small_enough: i <= months_in_year

    	days_in_leap_year: INTEGER_32 is 366
    			-- Number of days in a leap year
    			-- (from DATE_CONSTANTS)

    	days_in_non_leap_year: INTEGER_32 is 365
    			-- Number of days in a non-leap year
    			-- (from DATE_CONSTANTS)

    	days_in_week: INTEGER_32 is 7
    			-- Number of days in a week
    			-- (from DATE_CONSTANTS)

    	days_text: ARRAY [STRING_8]
    			-- Short text representation of days
    			-- (from DATE_CONSTANTS)

    	default_format_string: STRING_8
    			-- Default output format string
    			-- (from TIME_UTILITY)

    	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)

    	long_days_text: ARRAY [STRING_8]
    			-- Long text representation of days
    			-- (from DATE_CONSTANTS)

    	long_months_text: ARRAY [STRING_8]
    			-- Long text representation of months
    			-- (from DATE_CONSTANTS)

    	max_weeks_in_year: INTEGER_32 is 53
    			-- Maximun number of weeks in a year
    			-- (from DATE_CONSTANTS)

    	month: INTEGER_32
    			-- Month of the current object
    			-- (from DATE_VALUE)

    	months_in_year: INTEGER_32 is 12
    			-- Number of months in year
    			-- (from DATE_CONSTANTS)

    	months_text: ARRAY [STRING_8]
    			-- Short text representation of months
    			-- (from DATE_CONSTANTS)

    	ordered_compact_date: INTEGER_32
    			-- Year, month, day coded for fast comparison between dates.
    			-- (from DATE_VALUE)

    	origin: DATE
    			-- Origin date
    		ensure -- from ABSOLUTE
    			result_exists: Result /= Void

    	year: INTEGER_32
    			-- Year of the current object
    			-- (from DATE_VALUE)

    feature -- Measurement

    	days: INTEGER_32
    			-- Number of days elapsed since Origin
    		ensure
    			same_duration: Result = duration.day

    	duration: DATE_DURATION
    			-- Definite duration elapsed since Origin
    		require -- from  ABSOLUTE
    			True
    		ensure then
    			definite_result: Result.definite
    			duration_set: ((Current - origin).duration).is_equal (Result)

    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 of the same type
    			-- as current object and identical to it?
    			-- (from COMPARABLE)
    		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: like Current): like Current
    			-- 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: like Current): like Current
    			-- 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: 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)

    	three_way_comparison (other: like Current): 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 the current date before `other'?
    		require -- from PART_COMPARABLE
    			other_exists: other /= Void
    		ensure then -- from COMPARABLE
    			asymmetric: Result implies not (other < Current)

    	infix "<=" (other: like Current): 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: like Current): 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: like Current): 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

    	day_of_january_1st: INTEGER_32
    			-- Day of the week of january 1st of the current year
    		ensure
    			day_of_the_week_definition: Result > 0 and then Result < 8

    	day_of_the_week: INTEGER_32
    			-- Number of day from the beginning of the week
    			-- sunday is 1, etc.., saturday is 7
    		ensure
    			day_of_the_week_range: Result > 0 and then Result < 8

    	days_at_month: INTEGER_32
    			-- Number of days from the beginning of the year
    			-- until the beginning of the current month
    		ensure
    			positive_result: Result >= 0

    	days_from (y: INTEGER_32): INTEGER_32
    			-- Days between the current year and year `y'

    	days_in_year: INTEGER_32
    			-- Number of days in the current year
    		ensure
    			valid_result: (leap_year implies Result = days_in_leap_year) and then (not leap_year implies Result = days_in_non_leap_year)

    	is_leap_year (y: INTEGER_32): BOOLEAN
    			-- Is year `y' a leap year?
    			-- (from DATE_CONSTANTS)

    	leap_year: BOOLEAN
    			-- Is the current year a leap year?

    	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))

    	week_of_year: INTEGER_32
    			-- Number of weeks from the beginning of the year
    			-- The first week of the year begins on the first sunday of the year
    			-- The week number before the first sunday of the year is 0
    		ensure
    			positive_result: Result >= 0
    			result_small_enough: Result < max_weeks_in_year

    	year_day: INTEGER_32
    			-- Number of days from the beginning of the year
    		ensure
    			result_large_enough: Result >= 1
    			result_small_enough: Result <= days_in_year

    feature -- Element change

    	set_date (y, m, d: INTEGER_32)
    			-- Set year with `y', month with `m' and day with `d'.
    			-- (from DATE_VALUE)
    		require -- from DATE_MEASUREMENT
    			d_large_enough: d >= 1
    			m_large_enough: m >= 1
    			m_small_enough: m <= months_in_year
    			d_small_enough: d <= days_in_i_th_month (m, y)
    		ensure -- from DATE_MEASUREMENT
    			day_set: day = d
    			month_set: month = m
    			year_set: year = y

    	set_day (d: INTEGER_32)
    			-- Set day to `d'.
    			-- (from DATE_VALUE)
    		require -- from DATE_MEASUREMENT
    			d_large_enough: d >= 1
    			d_small_enough: d <= days_in_month
    		ensure -- from DATE_MEASUREMENT
    			day_set: day = d

    	set_internal_ordered_compact_date (a_ordered_compact_date: like ordered_compact_date)
    			-- Set `a_ordered_compact_date' to ordered_compact_date.
    			-- (from DATE_VALUE)
    		ensure -- from DATE_VALUE
    			ordered_compact_date_set: ordered_compact_date = a_ordered_compact_date

    	set_month (m: INTEGER_32)
    			-- Set month to `m'.
    			-- (from DATE_VALUE)
    		require -- from DATE_MEASUREMENT
    			m_large_enough: m >= 1
    			m_small_enough: m <= months_in_year
    			d_small_enough: day <= days_in_i_th_month (m, year)
    		ensure -- from DATE_MEASUREMENT
    			month_set: month = m

    	set_year (y: INTEGER_32)
    			-- Set year to `y'.
    			-- (from DATE_VALUE)
    		require -- from DATE_MEASUREMENT
    			can_not_cut_29th_feb: day <= days_in_i_th_month (month, y)
    		ensure -- from DATE_MEASUREMENT
    			year_set: year = y

    feature -- Conversion

    	to_date_time: DATE_TIME
    			-- Date-time version, with a zero time component

    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

    	add (d: DATE_DURATION)
    			-- Adds `d' to the current date.
    			-- if `d' is not definite, add years and months and then days.

    	day_add (d: INTEGER_32)
    			-- Add `d' days to the current date.
    		ensure
    			days_set: days = old days + d

    	day_back
    			-- Move to previous day.
    		ensure
    			days_set: days = old days - 1

    	day_forth
    			-- Move to next day.
    			-- days is from the origin, day is current.
    		ensure
    			days_set: days = old days + 1

    	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)

    	month_add (m: INTEGER_32)
    			-- Add `m' months to the current date.
    			-- Can move days backward.

    	month_back
    			-- Move to previous month.
    			-- Can move days backward if previous month has less days than the
    			-- current month.

    	month_forth
    			-- Move to next month.
    			-- Can move days backward if next month has less days than the
    			-- current month.

    	relative_duration (other: like Current): DATE_DURATION
    			-- Duration from `other' to the current date
    		require -- from ABSOLUTE
    			other_exists: other /= Void
    		ensure -- from ABSOLUTE
    			result_exists: Result /= Void
    		ensure then
    			exact_duration: (other + Result).is_equal (Current)
    			canonical_duration: Result.canonical (other)
    			origin_date_set: equal (Result.origin_date, other)

    	year_add (y: INTEGER_32)
    			-- Add `y' years to the current date.
    			-- May cut the 29th february.
    		ensure
    			year_set: year = old year + y

    	year_back
    			-- Move to previous year.
    			-- May cut the 29th february.
    		ensure
    			year_decreased: year = old year - 1

    	year_forth
    			-- Move to next year.
    			-- May cut the 29th february.
    		ensure
    			year_increased: year = old year + 1

    	year_month_add (y, m: INTEGER_32)
    			-- Add `y' years and `m' months to the current date.
    			-- Check the number of days after.

    	infix "+" (d: DATE_DURATION): DATE
    			-- Sum to current date the duration `d'
    			-- if duration not define, add years and then months and then days.
    		ensure
    			result_exists: Result /= Void
    			definite_set: d.definite implies (Result - Current).duration.is_equal (d)

    	infix "-" (other: like Current): INTERVAL [DATE]
    			-- Interval between current object and `other'
    			-- (from ABSOLUTE)
    		require -- from ABSOLUTE
    			other_exists: other /= Void
    			other_smaller_than_current: other <= Current
    		ensure -- from ABSOLUTE
    			result_exists: Result /= Void
    			result_set: Result.start_bound.is_equal (other) and then Result.end_bound.is_equal (Current)

    feature -- Correction

    	correct_mismatch
    			-- Attempt to correct object mismatch using Mismatch_information.
    			-- (from DATE_VALUE)

    	mismatch_information: MISMATCH_INFORMATION
    			-- Original attribute values of mismatched object
    			-- (from MISMATCH_CORRECTOR)

    feature -- Output

    	formatted_out (s: STRING_8): STRING_8
    			-- Printable representation of `Current' with "standard"
    			-- Form: `s'
    		require
    			s_exists: s /= Void

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

    	out: STRING_8
    			-- Printable representation of `Current' with "standard"
    			-- Form: date_default_format_string

    	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
    			-- Was declared in ANY as synonym of out.
    			-- (from ANY)

    feature -- Platform

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

    feature -- Preconditions

    	compact_date_valid (c_d: INTEGER_32): BOOLEAN
    			-- Is compact date `c_d' valid?
    			-- (from DATE_VALIDITY_CHECKER)

    	date_valid (s: STRING_8; code_string: STRING_8): BOOLEAN
    			-- Is the code_string enough precise
    			-- To create an instance of type DATE
    			-- And does the string `s' correspond to `code_string'?
    			-- (from DATE_VALIDITY_CHECKER)
    		require -- from DATE_VALIDITY_CHECKER
    			s_exists: s /= Void
    			code_exists: code_string /= Void

    	date_valid_default (s: STRING_8): BOOLEAN
    			-- Is the code_string enough precise
    			-- To create an instance of type DATE
    			-- And does the string `s' correspond to
    			-- date_default_format_string?
    			-- (from DATE_VALIDITY_CHECKER)
    		require -- from DATE_VALIDITY_CHECKER
    			s_exists: s /= Void

    	date_valid_default_with_base (s: STRING_8; base: INTEGER_32): BOOLEAN
    			-- Is the code_string enough precise
    			-- To create an instance of type DATE
    			-- And does the string `s' correspond to
    			-- date_default_format_string?
    			-- Use base century `base'.
    			-- (from DATE_VALIDITY_CHECKER)
    		require -- from DATE_VALIDITY_CHECKER
    			s_exists: s /= Void
    			base_valid: base > 0 and (base \\ 100 = 0)

    	date_valid_with_base (s: STRING_8; code_string: STRING_8; base: INTEGER_32): BOOLEAN
    			-- Is the code_string enough precise
    			-- To create an instance of type DATE
    			-- And does the string `s' correspond to `code_string'?
    			-- Use base century `base'.
    			-- (from DATE_VALIDITY_CHECKER)
    		require -- from DATE_VALIDITY_CHECKER
    			s_exists: s /= Void
    			code_exists: code_string /= Void
    			base_valid: base > 0 and (base \\ 100 = 0)

    	is_correct_date (y, m, d: INTEGER_32): BOOLEAN
    			-- Is date specified by `y', `m', and `d' a correct date?
    			-- (from DATE_VALIDITY_CHECKER)

    	ordered_compact_date_valid (c_d: INTEGER_32): BOOLEAN
    			-- Is compact date `c_d' valid?
    			-- (from DATE_VALIDITY_CHECKER)

    feature -- Status Report

    	days_in_month: INTEGER_32
    			-- Number of days in month 'month'.
    			-- (from DATE_MEASUREMENT)
    		ensure -- from DATE_MEASUREMENT
    			positive_result: Result > 0

    invariant
    	day_large_enough: day >= 1
    	day_small_enough: day <= days_in_month
    	month_large_enough: month >= 1
    	month_small_enough: month <= months_in_year
    	year_small_enough: year <= 65535
    	year_non_negative: year >= 0

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

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

    indexing
    	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 DATE