note description: "Dynamically modifiable chains" library: "Free implementation of ELKS library" legal: "See notice at end of class." status: "See notice at end of class." names: dynamic_chain, sequence access: index, cursor, membership contents: generic date: "$Date: 2018-11-14 15:15:17 +0000 (Wed, 14 Nov 2018) $" revision: "$Revision: 102463 $" deferred class DYNAMIC_CHAIN [G] inherit CHAIN [G] export {ANY} remove, prune_all, prune undefine remove, prune_all, prune end UNBOUNDED [G] feature -- Status report extendible: BOOLEAN -- May new items be added? (Answer: yes.) do Result := True end prunable: BOOLEAN -- May items be removed? (Answer: yes.) do Result := True end feature -- Element change put_front (v: like item) -- Add v at beginning. -- Do not move cursor. require extendible: extendible deferred ensure new_count: count = old count + 1 item_inserted: first = v end put_left (v: like item) -- Add v to the left of cursor position. -- Do not move cursor. require extendible: extendible not_before: not before deferred ensure new_count: count = old count + 1 new_index: index = old index + 1 end put_right (v: like item) -- Add v to the right of cursor position. -- Do not move cursor. require extendible: extendible not_after: not after deferred ensure new_count: count = old count + 1 same_index: index = old index end merge_left (other: like Current) -- Merge other into current structure before cursor -- position. Do not move cursor. Empty other. require extendible: extendible not_before: not before other_exists: other /= Void not_current: other /= Current deferred ensure new_count: count = old count + old other.count new_index: index = old index + old other.count other_is_empty: other.is_empty end merge_right (other: like Current) -- Merge other into current structure after cursor -- position. Do not move cursor. Empty other. require extendible: extendible not_after: not after other_exists: other /= Void not_current: other /= Current deferred ensure new_count: count = old count + old other.count same_index: index = old index other_is_empty: other.is_empty end feature -- Removal prune (v: like item) -- Remove first occurrence of v, if any, -- after cursor position. -- If found, move cursor to right neighbor; -- if not, make structure exhausted. do search (v) if not exhausted then remove end end remove_left -- Remove item to the left of cursor position. -- Do not move cursor. require left_exists: index > 1 deferred ensure new_count: count = old count - 1 new_index: index = old index - 1 end remove_right -- Remove item to the right of cursor position. -- Do not move cursor. require right_exists: index < count deferred ensure new_count: count = old count - 1 same_index: index = old index end prune_all (v: like item) -- Remove all occurrences of v. -- (Reference or object equality, -- based on object_comparison.) -- Leave structure exhausted. do from start search (v) until exhausted loop remove search (v) end ensure then is_exhausted: exhausted end wipe_out -- Remove all items. do from start until is_empty loop remove end end feature -- Duplication duplicate (n: INTEGER_32): like Current obsolete "[ Create a new container explicitly using `make_from_iterable` if available. Otherwise, replace a call to the feature with code that creates and initializes container. [2018-11-30] ]" -- Copy of sub-chain beginning at current position -- and having min (n, from_here) items, -- where from_here is the number of items -- at or to the right of current position. local pos: CURSOR counter: INTEGER_32 do from Result := new_chain if object_comparison then Result.compare_objects end pos := cursor until (counter = n) or else exhausted loop Result.extend (item) forth counter := counter + 1 end go_to (pos) end feature {DYNAMIC_CHAIN} -- Implementation new_chain: like Current obsolete "Use explicit creation instead. See also explanations for `duplicate`. [2018-11-30]" -- A newly created instance of the same type. -- This feature may be redefined in descendants so as to -- produce an adequately allocated and initialized object. deferred ensure result_exists: Result /= Void end note copyright: "Copyright (c) 1984-2018, 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 DYNAMIC_CHAIN
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