EiffelBase class
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Eiffel Class
indexing
description: "Structures that may be traversed forward and backward";
status: "See notice at end of class";
names: bidirectional, traversing;
access: cursor, membership;
contents: generic;
date: "$Date: 2007-03-30 11:10:11 -0800 (Fri, 30 Mar 2007) $";
revision: "$Revision: 95354 $"
deferred class BILINEAR [G]
inherit
LINEAR [G]
rename
search as sequential_search
export
{NONE} sequential_search
redefine
off
end;
LINEAR [G]
redefine
search, off
select
search
end
feature -- Access
off: BOOLEAN is
-- Is there no current item?
do
Result := before or after
end;
feature -- Cursor movement
before: BOOLEAN is
-- Is there no valid position to the left of current one?
deferred
end;
back is
-- Move to previous position.
require
not_before: notbefore
deferred
ensure
moved_back: index = old index - 1
end;
search (v: like item) is
-- Move to first position (at or after current
-- position) where item and v are equal.
-- If structure does not include v ensure that
-- exhausted will be true.
-- (Reference or object equality,
-- based on object_comparison.)
do
if before and notempty then
forth
end;
sequential_search (v)
end;
invariant
not_both: not(after and before);
empty_property: empty implies (after or before);
before_constraint: before implies off;
end -- class BILINEAR
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