note
	description: "[
		Subsets that are traversable linearly without commitment to a concrete
		implementation.
	]"
	library: "Free implementation of ELKS library"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	names: linear_subset, subset, set
	access: membership
	contents: generic
	date: "$Date: 2017-03-23 19:18:26 +0000 (Thu, 23 Mar 2017) $"
	revision: "$Revision: 100033 $"

deferred class interface
	LINEAR_SUBSET [G]

feature -- Access

	generating_type: TYPE [detachable LINEAR_SUBSET [G]]
			-- Type of current object
			-- (type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generating_type_not_void: Result /= Void

	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

	has (v: G): BOOLEAN
			-- Does structure include v?
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from CONTAINER)
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not is_empty

	index: INTEGER_32
			-- Current index

	item: G
			-- Current item
			-- (from TRAVERSABLE_SUBSET)
		require -- from TRAVERSABLE_SUBSET
			not_off: not off

	new_cursor: ITERATION_CURSOR [G]
			-- Fresh cursor associated with current structure
			-- (from ITERABLE)
		ensure -- from ITERABLE
			result_attached: Result /= Void
	
feature -- Measurement

	count: INTEGER_32
			-- Number of items
			-- (from TRAVERSABLE_SUBSET)
	
feature -- Comparison

	frozen deep_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			shallow_implies_deep: standard_equal (a, b) implies Result
			both_or_none_void: (a = Void) implies (Result = (b = Void))
			same_type: (Result and (a /= Void)) implies (b /= Void and then a.same_type (b))
			symmetric: Result implies deep_equal (b, a)

	disjoint (other: TRAVERSABLE_SUBSET [G]): BOOLEAN
			-- Do current set and other have no
			-- items in common?
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison

	frozen equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.is_equal (b))

	frozen is_deep_equal alias "≡≡≡" (other: LINEAR_SUBSET [G]): 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: LINEAR_SUBSET [G]): 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 ~ Current
			consistent: standard_is_equal (other) implies Result

	is_subset alias "⊆" (other: TRAVERSABLE_SUBSET [G]): BOOLEAN
			-- Is current set a subset of other?
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison

	is_superset alias "⊇" (other: SUBSET [G]): BOOLEAN
			-- Is current set a superset of other?
			-- (from SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison

	frozen standard_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b 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
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.standard_is_equal (b))

	frozen standard_is_equal alias "≜" (other: LINEAR_SUBSET [G]): 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

	after: BOOLEAN
			-- Is cursor behind last item?
			-- (from TRAVERSABLE_SUBSET)

	before: BOOLEAN
			-- Is cursor at left from first item?

	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

	extendible: BOOLEAN
			-- May new items be added?
			-- (from COLLECTION)

	is_empty: BOOLEAN
			-- Is container empty?
			-- (from TRAVERSABLE_SUBSET)

	is_inserted (v: G): BOOLEAN
			-- Has v been inserted by the most recent insertion?
			-- (By default, the value returned is equivalent to calling 
			-- has (v). However, descendants might be able to provide more
			-- efficient implementations.)
			-- (from COLLECTION)

	islast: BOOLEAN
			-- Is cursor at last item?

	object_comparison: BOOLEAN
			-- Must search operations use equal rather than =
			-- for comparing references? (Default: no, use =.)
			-- (from CONTAINER)

	off: BOOLEAN
			-- Is cursor off the active items?
			-- (from TRAVERSABLE_SUBSET)

	prunable: BOOLEAN
			-- May items be removed?
			-- (from COLLECTION)

	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))

	valid_index (n: INTEGER_32): BOOLEAN
			-- Is n a valid index?
		ensure
			index_valid: 0 <= n and n <= count + 1
	
feature -- Status setting

	compare_objects
			-- Ensure that future search operations will use equal
			-- rather than = for comparing references.
			-- (from CONTAINER)
		require -- from CONTAINER
			changeable_comparison_criterion: changeable_comparison_criterion
		ensure -- from CONTAINER
				object_comparison

	compare_references
			-- Ensure that future search operations will use =
			-- rather than equal for comparing references.
			-- (from CONTAINER)
		require -- from CONTAINER
			changeable_comparison_criterion: changeable_comparison_criterion
		ensure -- from CONTAINER
			reference_comparison: not object_comparison
	
feature -- Cursor movement

	forth
			-- Move cursor to next element.
			-- (from TRAVERSABLE_SUBSET)
		require -- from TRAVERSABLE_SUBSET
			not_after: not after

	go_i_th (i: INTEGER_32)
			-- Move cursor to i-th item.
		require
			valid_index: valid_index (i)
		ensure
			cursor_moved: index = i

	start
			-- Move cursor to first item.
			-- (from TRAVERSABLE_SUBSET)
	
feature -- Element change

	extend (v: G)
			-- Ensure that set includes v.
			-- Was declared in SET as synonym of put.
			-- (from SET)
		require -- from COLLECTION
			extendible: extendible
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
		ensure then -- from SET
			in_set_already: old has (v) implies (count = old count)
			added_to_set: not old has (v) implies (count = old count + 1)

	fill (other: CONTAINER [G])
			-- Fill with as many items of other as possible.
			-- The representations of other and current structure
			-- need not be the same.
			-- (from COLLECTION)
		require -- from COLLECTION
			other_not_void: other /= Void
			extendible: extendible

	merge (other: CONTAINER [G])
			-- Add all items of other.
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison

	move_item (v: G)
			-- Move v to the left of cursor.
		require
			item_exists: v /= Void
			item_in_set: has (v)

	put (v: G)
			-- Ensure that set includes v.
			-- Was declared in SET as synonym of extend.
			-- (from SET)
		require -- from COLLECTION
			extendible: extendible
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
		ensure then -- from SET
			in_set_already: old has (v) implies (count = old count)
			added_to_set: not old has (v) implies (count = old count + 1)

	put_left (v: G)
			-- Insert v before the cursor.
		require
			item_exists: v /= Void
			not_before: not before
		ensure
			cursor_position_unchanged: index = old index + 1
	
feature -- Removal

	changeable_comparison_criterion: BOOLEAN
			-- May object_comparison be changed?
			-- (Answer: only if set empty; otherwise insertions might
			-- introduce duplicates, destroying the set property.)
			-- (from SET)
		require -- from  CONTAINER
			True
		ensure then -- from SET
			only_on_empty: Result = is_empty

	prune (v: G)
			-- Remove v if present.
			-- (from SET)
		require -- from COLLECTION
			prunable: prunable
		ensure then -- from SET
			removed_count_change: old has (v) implies (count = old count - 1)
			not_removed_no_count_change: not old has (v) implies (count = old count)
			item_deleted: not has (v)

	prune_all (v: G)
			-- Remove all occurrences of v.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from COLLECTION)
		require -- from COLLECTION
			prunable: prunable
		ensure -- from COLLECTION
			no_more_occurrences: not has (v)

	remove
			-- Remove current item.
			-- (from TRAVERSABLE_SUBSET)
		require -- from TRAVERSABLE_SUBSET
			not_off: not off

	wipe_out
			-- Remove all items.
			-- (from COLLECTION)
		require -- from COLLECTION
			prunable: prunable
		ensure -- from COLLECTION
			wiped_out: is_empty
	
feature -- Conversion

	linear_representation: LINEAR [G]
			-- Representation as a linear structure
			-- (from CONTAINER)
	
feature -- Duplication

	copy (other: LINEAR_SUBSET [G])
			-- 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: Current ~ other

	frozen deep_copy (other: LINEAR_SUBSET [G])
			-- 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: LINEAR_SUBSET [G]
			-- 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: LINEAR_SUBSET [G])
			-- 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: LINEAR_SUBSET [G]
			-- 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: LINEAR_SUBSET [G]
			-- New object equal to Current
			-- twin calls copy; to change copying/twinning semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result ~ Current
	
feature -- Basic operations

	frozen default: detachable LINEAR_SUBSET [G]
			-- 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)
		ensure -- from ANY
			instance_free: class

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
		ensure -- from ANY
			instance_free: class

	intersect (other: TRAVERSABLE_SUBSET [G])
			-- Remove all items not in other.
			-- No effect if other is_empty.
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		ensure -- from SUBSET
			is_subset_other: is_subset (other)

	subtract (other: TRAVERSABLE_SUBSET [G])
			-- Remove all items also in other.
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
		ensure -- from SUBSET
			is_disjoint: disjoint (other)

	symdif (other: TRAVERSABLE_SUBSET [G])
			-- Remove all items also in other, and add all
			-- items of other not already present.
			-- (from TRAVERSABLE_SUBSET)
		require -- from SUBSET
			set_exists: other /= Void
			same_rule: object_comparison = other.object_comparison
	
feature -- Output

	Io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			io_not_void: Result /= Void

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		ensure -- from ANY
			out_not_void: Result /= Void

	print (o: detachable ANY)
			-- Write terse external representation of o
			-- on standard output.
			-- (from ANY)
		ensure -- from ANY
			instance_free: class

	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
			instance_free: class
			operating_environment_not_void: Result /= Void
	
invariant
	before_definition: before = (index = 0)

		-- from TRAVERSABLE_SUBSET
	empty_definition: is_empty = (count = 0)
	count_range: count >= 0

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

note
	copyright: "Copyright (c) 1984-2017, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		5949 Hollister Ave., 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 LINEAR_SUBSET

Generated by ISE EiffelStudio