126 lines
2.4 KiB
Ruby
126 lines
2.4 KiB
Ruby
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
|