note

	description: "[
		Data structures of the most general kind,
		used to hold zero or more items.
		]"
	legal: "See notice at end of class."

	status: "See notice at end of class."
	names: access;
	access: membership;
	contents: generic;
	date: "$Date$"
	revision: "$Revision$"

deferred class
	CONTAINER [G]

feature -- Access

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

feature -- Status report

	is_empty: BOOLEAN
			-- Is there no element?
		deferred
		end

	empty: BOOLEAN
			-- Is there no element?
		obsolete
			"ELKS 2000: Use `is_empty' instead"
		do
			Result := is_empty
		end

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

	changeable_comparison_criterion: BOOLEAN
			-- May `object_comparison' be changed?
			-- (Answer: yes by default.)
		do
			Result := True
		end

feature -- Status setting

	compare_objects
			-- Ensure that future search operations will use `equal'
			-- rather than `=' for comparing references.
		require
			changeable_comparison_criterion: changeable_comparison_criterion
		do
			object_comparison := True
		ensure
			object_comparison
		end

	compare_references
			-- Ensure that future search operations will use `='
			-- rather than `equal' for comparing references.
		require
			changeable_comparison_criterion: changeable_comparison_criterion
		do
			object_comparison := False
		ensure
			reference_comparison: not object_comparison
		end

feature -- Conversion

	linear_representation: LINEAR [G]
			-- Representation as a linear structure
		deferred
		end

note
	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 CONTAINER