note
	description: "[
		Objects that are able to iterate over traversable structures,
		on which they can perform repeated actions and tests according
		to a number of predefined control structures such as if,
		until and others.
	]"
	library: "Free implementation of ELKS library"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	names: iterators, iteration
	date: "$Date: 2017-04-10 07:37:21 +0000 (Mon, 10 Apr 2017) $"
	revision: "$Revision: 100119 $"

deferred class 
	ITERATOR [G]

feature -- Initialization

	set (s: like target)
			-- Make s the new target of iterations.
		require
			target_exists: s /= Void
		do
			target := s
		ensure
				target = s
				target /= Void
		end
	
feature -- Access

	target: TRAVERSABLE [G]
			-- The structure to which iteration features will apply
	
feature -- Status report

	invariant_value: BOOLEAN
			-- Is the invariant satisfied?
			-- (Redefinitions of this feature will usually involve
			-- target; if so, make sure that the result is defined
			-- when target = Void.)
		do
			Result := True
		end
	
feature -- Iteration

	do_all (action: PROCEDURE [G])
			-- Apply action to every item of target.
		require
			action_exists: action /= Void
		do
			target.do_all (action)
		end

	do_if (action: PROCEDURE [G]; test: FUNCTION [G, BOOLEAN])
			-- Apply action to every item of target satisfying test.
		require
			action_exists: action /= Void
			test_exists: test /= Void
		do
			target.do_if (action, test)
		end

	do_until (action: PROCEDURE [G]; test: FUNCTION [G, BOOLEAN])
			-- Apply action to every item of target up to
			-- and including first one satisfying test.
			-- (Apply to full list if no item satisfies test).
		require
			action_exists: action /= Void
			test_exists: test /= Void
		deferred
		end

	do_while (action: PROCEDURE [G]; test: FUNCTION [G, BOOLEAN])
			-- Apply action to every item of target up to
			-- and including first one not satisfying test.
			-- (Apply to full list if all items satisfy test).
		require
			action_exists: action /= Void
			test_exists: test /= Void
		deferred
		end

	until_do (action: PROCEDURE [G]; test: FUNCTION [G, BOOLEAN])
			-- Apply action to every item of target up to
			-- but excluding first one satisfying test.
			-- (Apply to full list if no items satisfy test.)
		require
			action_exists: action /= Void
			test_exists: test /= Void
		deferred
		end

	while_do (action: PROCEDURE [G]; test: FUNCTION [G, BOOLEAN])
			-- Apply action to every item of target up to
			-- but excluding first one satisfying not test.
			-- (Apply to full list if all items satisfy test.)
		require
			action_exists: action /= Void
			test_exists: test /= Void
		deferred
		end

	there_exists (test: FUNCTION [G, BOOLEAN]): BOOLEAN
			-- Is test true for at least one item of target?
		require
			test_exists: test /= Void
		deferred
		end

	for_all (test: FUNCTION [G, BOOLEAN]): BOOLEAN
			-- Is test true for all items of target?
		require
			test_exists: test /= Void
		deferred
		end
	
invariant
	traversable_exists: target /= Void

note
	copyright: "Copyright (c) 1984-2012, 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 ITERATOR

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