JezK
Edit File: kill_ring.rb
class Reline::KillRing include Enumerable module State FRESH = :fresh CONTINUED = :continued PROCESSED = :processed YANK = :yank end RingPoint = Struct.new(:backward, :forward, :str) do def initialize(str) super(nil, nil, str) end def ==(other) object_id == other.object_id end end class RingBuffer attr_reader :size attr_reader :head def initialize(max = 1024) @max = max @size = 0 @head = nil # reading head of ring-shaped tape end def <<(point) if @size.zero? @head = point @head.backward = @head @head.forward = @head @size = 1 elsif @size >= @max tail = @head.forward new_tail = tail.forward @head.forward = point point.backward = @head new_tail.backward = point point.forward = new_tail @head = point else tail = @head.forward @head.forward = point point.backward = @head tail.backward = point point.forward = tail @head = point @size += 1 end end def empty? @size.zero? end end def initialize(max = 1024) @ring = RingBuffer.new(max) @ring_pointer = nil @buffer = nil @state = State::FRESH end def append(string, before_p = false) case @state when State::FRESH, State::YANK @ring << RingPoint.new(string) @state = State::CONTINUED when State::CONTINUED, State::PROCESSED if before_p @ring.head.str.prepend(string) else @ring.head.str.concat(string) end @state = State::CONTINUED end end def process case @state when State::FRESH # nothing to do when State::CONTINUED @state = State::PROCESSED when State::PROCESSED @state = State::FRESH when State::YANK # nothing to do end end def yank unless @ring.empty? @state = State::YANK @ring_pointer = @ring.head @ring_pointer.str else nil end end def yank_pop if @state == State::YANK prev_yank = @ring_pointer.str @ring_pointer = @ring_pointer.backward [@ring_pointer.str, prev_yank] else nil end end def each start = head = @ring.head loop do break if head.nil? yield head.str head = head.backward break if head == start end end end