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Updated section 'Two-way iteration'

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Old code for class TWO_WAY_CHAIN_ITERATOR  updated to reflect current EiffelStudio version (18,07).
Updated wikipage EiffelBase, Iteration.
	(Signed-off-by:WilliamsLima).

git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@2079 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
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2018-09-12 17:55:43 +00:00
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documentation/18.07/solutions/basic-computing/eiffelbase/eiffelbase-tutorial/eiffelbase-data-structures-overview/eiffelbase-iteration.wiki
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@@ -1,4 +1,4 @@
[[Property:modification_date|Wed, 12 Sep 2018 17:28:53 GMT]]
[[Property:modification_date|Wed, 12 Sep 2018 17:55:43 GMT]]
[[Property:publication_date|Wed, 12 Sep 2018 13:40:39 GMT]]
[[Property:title|EiffelBase, Iteration]]
[[Property:weight|6]]
@@ -260,69 +260,77 @@ An alternative design would have kept just one set of features and added two fea
Contrary to what one might at first imagine, class [[ref:libraries/base/reference/two_way_chain_iterator_chart|TWO_WAY_CHAIN_ITERATOR]] is extremely short and simple; its <code> Feature </code> clause only contains the declarations of two features, <eiffel>finish</eiffel> and <eiffel>back</eiffel>. <br/>
The trick is to use repeated inheritance. [[ref:libraries/base/reference/two_way_chain_iterator_chart|TWO_WAY_CHAIN_ITERATOR]] inherits twice from [[ref:libraries/base/reference/linear_iterator_chart|LINEAR_ITERATOR]] ; the first inheritance branch yields the forward iteration features, the second yields those for backward iteration. There is no need for any explicit declaration or redeclaration of iteration features. Here is the entire class text that yields this result:
<code>
class
TWO_WAY_CHAIN_ITERATOR [G]
class TWO_WAY_CHAIN_ITERATOR [G] inherit
inherit
LINEAR_ITERATOR [G]
redefine
target
select
start,
forth,
do_all,
until_do,
do_until,
do_if,
do_for,
search,
forall,
exists,
until_continue,
continue_until,
continue_for,
continue_search
end
LINEAR_ITERATOR [G]
redefine
target
select
start,
forth,
do_all,
until_do,
do_until,
while_do,
do_while,
do_if,
do_for,
search,
for_all,
there_exists,
until_continue,
continue_until,
while_continue,
continue_while,
continue_for,
continue_search
end
LINEAR_ITERATOR [G]
rename
start as finish,
forth as back,
do_all as do_all_back,
until_do as until_do_back,
do_until as do_until_back,
do_if as do_if_back,
do_for as do_for_back,
search as search_back,
forall as forall_back,
exists as exists_back,
until_continue as until_continue_back,
continue_until as continue_until_back,
continue_for as continue_for_back,
continue_search as continue_search_back
redefine
target
end
LINEAR_ITERATOR [G]
rename
start as finish,
forth as back,
do_all as do_all_back,
until_do as until_do_back,
do_until as do_until_back,
do_while as do_while_back,
while_do as while_do_back,
do_if as do_if_back,
do_for as do_for_back,
search as search_back,
for_all as for_all_back,
there_exists as there_exists_back,
until_continue as until_continue_back,
continue_until as continue_until_back,
while_continue as while_continue_back,
continue_while as continue_while_back,
continue_for as continue_for_back,
continue_search as continue_search_back
redefine
back, finish, target
end
feature -- Status report
create
set
target: BI_LINEAR [G]
-- The structure to which iteration features will
-- apply
feature -- Access
target: CHAIN [G]
feature -- Cursor movement
finish
-- Move cursor of target to last position.
do
target.finish
end
finish
-- Move cursor of `target' to last position.
do
target.finish
end
back
-- Move cursor of `target' backward one position.
do
target.back
end
back
-- Move cursor of target backward one position.
do
target.back
end
end
</code>