    indexing
    	description: "EiffelVision tree-item container. Implementation interface."
    	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 $"

    deferred class interface
    	EV_TREE_NODE_LIST_I

    feature -- Access

    	cursor: EV_DYNAMIC_LIST_CURSOR [EV_TREE_NODE]
    			-- Current cursor position.
    			-- (from EV_DYNAMIC_LIST_I)
    		ensure -- from EV_DYNAMIC_LIST_I
    			not_void: Result /= Void

    	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)

    	i_th (i: INTEGER_32): EV_TREE_NODE
    			-- Item at `i'-th position.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			i_within_bounds: i > 0 and then i <= count
    		ensure -- from EV_DYNAMIC_LIST_I
    			not_void: Result /= Void

    	index: INTEGER_32
    			-- Index of current position
    			-- (from EV_DYNAMIC_LIST_I)

    	index_of (v: like item; i: INTEGER_32): INTEGER_32
    			-- Index of i_th item `v', if present.
    			-- As dynamic list descendants are all sets,
    			-- Result will be zero for all values of `i'
    			-- that are not equal to one
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			positive_occurances: i > 0

    	item: EV_TREE_NODE
    			-- Current item
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			readable: index > 0 and then index <= count
    		ensure -- from EV_DYNAMIC_LIST_I
    			not_void: Result /= Void

    	item_by_data (data: ANY): like item
    			-- First item with `data'.
    			-- (from EV_ITEM_LIST_I)
    		require -- from EV_ITEM_LIST_I
    			data_not_void: data /= Void

    	off: BOOLEAN
    			-- Is there no current item?
    			-- (from EV_DYNAMIC_LIST_I)

    	retrieve_item_by_data (data: ANY; should_compare_objects: BOOLEAN): EV_TREE_NODE
    			-- `Result' is first item in `Current' with data
    			-- matching `some_data'. Compare objects if
    			-- `should_compare_objects' otherwise compare references.
    			-- (from EV_DYNAMIC_LIST_I)

    	retrieve_items_by_data (data: ANY; should_compare_objects: BOOLEAN): ARRAYED_LIST [EV_TREE_NODE]
    			-- `Result' is all items in `Current' with data
    			-- matching `some_data'. Compare objects if
    			-- `should_compare_objects' otherwise compare references.
    			-- (from EV_DYNAMIC_LIST_I)

    feature -- Measurement

    	count: INTEGER_32
    			-- Number of items.
    			-- (from EV_DYNAMIC_LIST_I)

    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

    	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

    	find_item_recursively_by_data (data: ANY): EV_TREE_NODE
    			-- If `data' contained in a tree item at any level then
    			-- assign this item to `Result'.
    		ensure
    			index_not_changed: old interface.index = interface.index

    	has (v: like item): BOOLEAN
    			-- Does structure contain `v'?
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void

    	has_recursively (an_item: like item): BOOLEAN
    			-- Does `Current' contain `an_item' at any level?
    		ensure
    			index_not_changed: old interface.index = interface.index

    	recursive_do_all (action: PROCEDURE [ANY, TUPLE [EV_TREE_NODE]])
    			-- Apply `action' to every item.
    			-- Semantics not guaranteed if `action' changes the structure;

    	retrieve_item_recursively_by_data (data: ANY; should_compare_objects: BOOLEAN): EV_TREE_NODE
    			-- If `data' contained in a tree item at any level then
    			-- assign this item to `Result'. Compare objects if
    			-- `should_compare_objects' otherwise compare references.
    		ensure
    			index_not_changed: old interface.index = interface.index

    	retrieve_items_recursively_by_data (data: ANY; should_compare_objects: BOOLEAN): ARRAYED_LIST [EV_TREE_NODE]
    			-- `Result' is all tree items contained in `Current' at any level,
    			-- with data matching `data'. Compare objects if
    			-- `should_compare_objects' otherwise compare references.
    		ensure
    			result_not_void: Result /= Void

    	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_cursor (p: CURSOR): BOOLEAN
    			-- Can the cursor be moved to position `p'?
    			-- This is True if `p' conforms to EV_DYNAMIC_LIST_CURSOR and
    			-- if it points to an item, `Current' must have it.
    			-- (from EV_DYNAMIC_LIST_I)

    feature -- Cursor movement

    	back
    			-- Move to previous item.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			not_before: index > 0

    	forth
    			-- Move cursor to next position.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			not_after: index <= count

    	go_i_th (i: INTEGER_32)
    			-- Move cursor to `i'-th position.
    			-- (from EV_DYNAMIC_LIST_I)

    	go_to (p: CURSOR)
    			-- Move cursor to position `p'.
    			-- (from EV_DYNAMIC_LIST_I)

    	move (i: INTEGER_32)
    			-- Move cursor `i' positions.
    			-- (from EV_DYNAMIC_LIST_I)

    	start
    			-- Move cursor to first position.
    			-- (from EV_DYNAMIC_LIST_I)
    		ensure -- from EV_DYNAMIC_LIST_I
    			index_on_first: index = 1

    feature -- Element change

    	append (s: SEQUENCE [EV_TREE_NODE])
    			-- Append a copy of `s'. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			sequence_not_void: s /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			count_increased: old count + s.count = count

    	extend (v: like item)
    			-- Add `v' to end. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	merge_left (other: like interface)
    			-- Merge `other' into current structure before cursor
    			-- position. Do not move cursor. Empty `other'.
    			-- (from EV_DYNAMIC_LIST_I)

    	merge_right (other: like interface)
    			-- Merge `other' into current structure after cursor
    			-- position. Do not move cursor. Empty `other'.
    			-- (from EV_DYNAMIC_LIST_I)

    	put_front (v: like item)
    			-- Add `v' at beginning. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	put_i_th (v: like item; i: INTEGER_32)
    			-- Replace item at `i'-th position by `v'.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			valid_index: i > 0 and i <= count
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	put_left (v: like item)
    			-- Add `v' to the left of cursor position. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	put_right (v: like item)
    			-- Add `v' to the right of cursor position. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	replace (v: like item)
    			-- Replace current item by `v'.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			writable: index > 0 and then index <= count
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    feature -- Removal

    	prune (v: like item)
    			-- Remove `v' if present. Do not move cursor, except if
    			-- cursor was on `v', move to right neighbor.
    			-- (from EV_DYNAMIC_LIST_I)
    		ensure -- from EV_DYNAMIC_LIST_I
    			cursor_not_moved: not old has (v) implies old interface.index = interface.index
    			cursor_not_moved: old has (v) and then old interface.index < old index_of (v, 1) implies index = old index
    			cursor_not_moved: old has (v) and then old interface.index >= old index_of (v, 1) implies index = old index - 1
    			not_has_v: not has (v)

    	remove
    			-- Remove current item. Move cursor to right neighbor
    			-- (or `after' if no right neighbor).
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			writable: not off
    		ensure -- from EV_DYNAMIC_LIST_I
    			not_has_v: not has (old item)

    	remove_left
    			-- Remove item to the left of cursor position.
    			-- Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			left_exists: index > 1
    			not_before: not (index = 0)
    		ensure then -- from EV_DYNAMIC_LIST_I
    			left_neighbor_removed: not has (old i_th (index - 1))

    	remove_right
    			-- Remove item to the right of cursor position.
    			-- Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			right_exists: index < count
    		ensure then -- from EV_DYNAMIC_LIST_I
    			right_neighbor_removed: not has (old i_th (index + 1))

    	wipe_out
    			-- Remove all items.
    			-- (from EV_DYNAMIC_LIST_I)

    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 -- Output

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

    	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)

    	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 EV_DYNAMIC_LIST_I
    	index_within_bounds: is_usable implies (index >= 0 and then index <= count + 1)

    		-- from EV_ANY_I
    	interface_coupled: is_usable implies interface /= Void and then interface.implementation = Current
    	base_make_called: base_make_called

    		-- 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 EV_TREE_NODE_LIST_I