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During the process of text editing it may become necessary for regions of text to be manipulated non-sequentially. The kill ring and its surrounding protocol offers both a temporary location for data to be stored, as well as methods for stored data to be accessed.
Conceptually, the kill ring is a stack of bounded depth, so that when elements are pushed beyond that depth, the oldest element is removed. All newly added data is attached to a single point at the “start of ring position” or SORP.
This protocol provides two methods which govern how data is to be attached to the SORP. The first method moves the current SORP to a new position, on to which a new object is attached. The second conserves the current position and replaces its contents with a sequence constructed of new and pre-existing SORP objects. This latter method is refered to as a “concatenating push”.
For data retrievial the kill ring class provides a “yank point” which allows focus to be shifted from the SORP to other positions within the kill ring. The yank point is limited to two types of motition, one being a rotation away from the SORP and the other being an immediate return or “reset” to the start position. When the kill ring is modified, for example by a push, the yank point will be reset to the start position.