summary refs log tree commit diff stats
path: root/ranger/container/history.py
blob: 355c7c7222daac6b75da8c268475ce6994e6d7cd (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
pre { line-height: 125%; }
td.linenos .normal { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
span.linenos { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
td.linen
class HistoryEmptyException(Exception):
	pass

class History(object):
	def __init__(self, maxlen = None):
		from collections import deque
		self.history = deque(maxlen = maxlen)
		self.history_forward = deque(maxlen = maxlen)
	
	def add(self, item):
		if len(self.history) == 0 or self.history[-1] != item:
			self.history.append(item)
			self.history_forward.clear()
	
	def modify(self, item):
		try:
			self.history[-1] = item
		except IndexError:
			raise HistoryEmptyException

	def __len__(self):
		return len(self.history)

	def current(self):
		try:
			return self.history[-1]
		except IndexError:
			raise HistoryEmptyException()

	def top(self):
		try:
			return self.history_forward[0]
		except IndexError:
			try:
				return self.history[-1]
			except IndexError:
				raise HistoryEmptyException()

	def bottom(self):
		try:
			return self.history[0]
		except IndexError:
			raise HistoryEmptyException()

	def back(self):
		if len(self.history) > 1:
			self.history_forward.append( self.history.pop() )
		return self.current()

	def move(self, n):
		if n > 0:
			return self.forward()
		if n < 0:
			return self.back()

	def __iter__(self):
		return self.history.__iter__()

	def next(self):
		return self.history.next()

	def forward(self):
		if len(self.history_forward) > 0:
			self.history.append( self.history_forward.pop() )
		return self.current()

	def fast_forward(self):
		if self.history_forward:
			self.history.extend(self.history_forward)
			self.history_forward.clear()