| 1 |
indexing |
| 2 |
|
| 3 |
description: |
| 4 |
"Structures that may be traversed forward and backward"; |
| 5 |
|
| 6 |
status: "See notice at end of class"; |
| 7 |
names: bidirectional, traversing; |
| 8 |
access: cursor, membership; |
| 9 |
contents: generic; |
| 10 |
date: "$Date$"; |
| 11 |
revision: "$Revision$" |
| 12 |
|
| 13 |
deferred class BILINEAR [G] inherit |
| 14 |
|
| 15 |
LINEAR [G] |
| 16 |
rename |
| 17 |
search as sequential_search |
| 18 |
export |
| 19 |
{NONE} |
| 20 |
sequential_search |
| 21 |
redefine |
| 22 |
off |
| 23 |
end; |
| 24 |
|
| 25 |
LINEAR [G] |
| 26 |
redefine |
| 27 |
search, off |
| 28 |
select |
| 29 |
search |
| 30 |
end |
| 31 |
|
| 32 |
feature -- Access |
| 33 |
|
| 34 |
off: BOOLEAN is |
| 35 |
-- Is there no current item? |
| 36 |
do |
| 37 |
Result := before or after |
| 38 |
end; |
| 39 |
|
| 40 |
feature -- Cursor movement |
| 41 |
|
| 42 |
before: BOOLEAN is |
| 43 |
-- Is there no valid position to the left of current one? |
| 44 |
deferred |
| 45 |
end; |
| 46 |
|
| 47 |
back is |
| 48 |
-- Move to previous position. |
| 49 |
require |
| 50 |
not_before: not before |
| 51 |
deferred |
| 52 |
ensure then |
| 53 |
-- moved_forth_after_start: (not before) implies index = old index - 1 |
| 54 |
end; |
| 55 |
|
| 56 |
search (v: like item) is |
| 57 |
-- Move to first position (at or after current |
| 58 |
-- position) where `item' and `v' are equal. |
| 59 |
-- If structure does not include `v' ensure that |
| 60 |
-- `exhausted' will be true. |
| 61 |
-- (Reference or object equality, |
| 62 |
-- based on `object_comparison'.) |
| 63 |
do |
| 64 |
if before and not is_empty then |
| 65 |
forth |
| 66 |
end; |
| 67 |
sequential_search (v) |
| 68 |
end; |
| 69 |
|
| 70 |
invariant |
| 71 |
|
| 72 |
not_both: not (after and before) |
| 73 |
before_constraint: before implies off |
| 74 |
|
| 75 |
end -- class BILINEAR |
| 76 |
|
| 77 |
|
| 78 |
--|---------------------------------------------------------------- |
| 79 |
--| EiffelBase: Library of reusable components for Eiffel. |
| 80 |
--| Copyright (c) 1993-2006 University of Southern California and contributors. |
| 81 |
--| For ISE customers the original versions are an ISE product |
| 82 |
--| covered by the ISE Eiffel license and support agreements. |
| 83 |
--| EiffelBase may now be used by anyone as FREE SOFTWARE to |
| 84 |
--| develop any product, public-domain or commercial, without |
| 85 |
--| payment to ISE, under the terms of the ISE Free Eiffel Library |
| 86 |
--| License (IFELL) at http://eiffel.com/products/base/license.html. |
| 87 |
--| |
| 88 |
--| Interactive Software Engineering Inc. |
| 89 |
--| ISE Building, 2nd floor |
| 90 |
--| 270 Storke Road, Goleta, CA 93117 USA |
| 91 |
--| Telephone 805-685-1006, Fax 805-685-6869 |
| 92 |
--| Electronic mail <info@eiffel.com> |
| 93 |
--| Customer support e-mail <support@eiffel.com> |
| 94 |
--| For latest info see award-winning pages: http://eiffel.com |
| 95 |
--|---------------------------------------------------------------- |
| 96 |
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