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# This file is part of ranger, the console file manager.
# License: GNU GPL version 3, see the file "AUTHORS" for details.
# TODO: rewrite to use deque instead of list
from __future__ import (absolute_import, division, print_function)
class HistoryEmptyException(Exception):
pass
class History(object):
def __init__(self, maxlen=None, unique=True):
assert maxlen is not None, "maxlen cannot be None"
if isinstance(maxlen, History):
# pylint: disable=protected-access
self._history = list(maxlen._history)
self._index = maxlen._index
# pylint: enable=protected-access
self.maxlen = maxlen.maxlen
self.unique = maxlen.unique
else:
self._history = []
self._index = 0
self.maxlen = maxlen
self.unique = unique
def add(self, item):
# Remove everything after index
if self._index < len(self._history) - 2:
del self._history[:self._index + 1]
# Remove Duplicates
if self.unique:
try:
self._history.remove(item)
except ValueError:
pass
else:
if self._history and self._history[-1] == item:
del self._history[-1]
# Remove first if list is too long
if len(self._history) > max(self.maxlen - 1, 0):
del self._history[0]
# Append the item and fast forward
self._history.append(item)
self._index = len(self._history) - 1
def modify(self, item, unique=False):
if self._history and unique:
try:
self._history.remove(item)
except ValueError:
pass
else:
self._index -= 1
try:
self._history[self._index] = item
except IndexError:
self.add(item)
def rebase(self, other_history):
"""
Replace the past of this history by that of another.
This is used when creating a new tab to seamlessly blend in the history
of the old tab into the new one.
Example: if self is [a,b,C], the current item is uppercase, and
other_history is [x,Y,z], then self.merge(other_history) will result in
[x, y, C].
"""
assert isinstance(other_history, History)
if not self._history:
self._index = 0
future_length = 0
else:
future_length = len(self._history) - self._index - 1
self._history[:self._index] = list(
other_history._history[:other_history._index + 1]) # pylint: disable=protected-access
if len(self._history) > self.maxlen:
# pylint: disable=protected-access,invalid-unary-operand-type
self._history = self._history[-self.maxlen:]
# pylint: enable=protected-access,invalid-unary-operand-type
self._index = len(self._history) - future_length - 1
assert self._index < len(self._history)
def __len__(self):
return len(self._history)
def current(self):
if self._history:
return self._history[self._index]
else:
raise HistoryEmptyException
def top(self):
try:
return self._history[-1]
except IndexError:
raise HistoryEmptyException
def bottom(self):
try:
return self._history[0]
except IndexError:
raise HistoryEmptyException
def back(self):
self._index -= 1
if self._index < 0:
self._index = 0
return self.current()
def move(self, n):
self._index += n
if self._index > len(self._history) - 1:
self._index = len(self._history) - 1
if self._index < 0:
self._index = 0
return self.current()
def search(self, string, n):
if n != 0 and string:
step = 1 if n > 0 else -1
i = self._index
steps_left = steps_left_at_start = int(abs(n))
while steps_left:
i += step
if i >= len(self._history) or i < 0:
break
if self._history[i].startswith(string):
steps_left -= 1
if steps_left != steps_left_at_start:
self._index = i
return self.current()
def __iter__(self):
return self._history.__iter__()
def forward(self):
if self._history:
self._index += 1
if self._index > len(self._history) - 1:
self._index = len(self._history) - 1
else:
self._index = 0
return self.current()
def fast_forward(self):
if self._history:
self._index = len(self._history) - 1
else:
self._index = 0
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