import copy
import sys
# Public domain
class ListMixin(object):
"""
Defines all list operations from a small subset of methods.
Subclasses should define _get_element(i), _set_element(i, value),
__len__(), _resize_region(start, end, new_size) and
_constructor(iterable). Define __iter__() for extra speed.
The _get_element() and _set_element() methods are given indices with
0 <= i < len(self).
The _resize_region() method should resize the slice self[start:end]
so that it has size new_size. It is given indices such that
start <= end, 0 <= start <= len(self) and 0 <= end <= len(self).
The resulting elements in self[start:start+new_size] can be set to
None or arbitrary Python values.
The _constructor() method accepts an iterable and should return a
new instance of the same class as self, populated with the elements
of the given iterable.
"""
def __cmp__(self, other):
return cmp(list(self), list(other))
def __hash__(self):
raise TypeError('list objects are unhashable')
def __iter__(self):
for i in xrange(len(self)):
yield self._get_element(i)
def _tuple_from_slice(self, i):
"""
Get (start, end, step) tuple from slice object.
"""
(start, end, step) = i.indices(len(self))
# Replace (0, -1, 1) with (0, 0, 1) (misfeature in .indices()).
if step == 1:
if end < start:
end = start
step = None
if i.step == None:
step = None
return (start, end, step)
def _fix_index(self, i):
if i < 0:
i += len(self)
if i < 0 or i >= len(self):
raise IndexError('list index out of range')
return i
def __getitem__(self, i):
if isinstance(i, slice):
(start, end, step) = self._tuple_from_slice(i)
if step == None:
indices = xrange(start, end)
else:
indices = xrange(start, end, step)
return self._constructor([self._get_element(i) for i in indices])
else:
return self._get_element(self._fix_index(i))
def __setitem__(self, i, value):
if isinstance(i, slice):
(start, end, step) = self._tuple_from_slice(i)
if step != None:
# Extended slice
indices = range(start, end, step)
if len(value) != len(indices):
raise ValueError(('attempt to assign sequence of size %d' +
' to extended slice of size %d') %
(len(value), len(indices)))
for (j, assign_val) in enumerate(value):
self._set_element(indices[j], assign_val)
else:
# Normal slice
if len(value) != (end - start):
self._resize_region(start, end, len(value))
for (j, assign_val) in enumerate(value):
self._set_element(start + j, assign_val)
else:
# Single element
self._set_element(self._fix_index(i), value)
def __delitem__(self, i):
if isinstance(i, slice):
(start, end, step) = self._tuple_from_slice(i)
if step != None:
# Extended slice
indices = range(start, end, step)
# Sort indices descending
if len(indices) > 0 and indices[0] < indices[-1]:
indices.reverse()
for j in indices:
del self[j]
else:
# Normal slice
self._resize_region(start, end, 0)
else:
# Single element
i = self._fix_index(i)
self._resize_region(i, i + 1, 0)
def __add__(self, other):
if isinstance(other, self.__class__):
ans = self._constructor(self)
ans += other
return ans
return list(self) + other
def __mul__(self, other):
ans = self._constructor(self)
ans *= other
return ans
def __radd__(self, other):
if isinstance(other, self.__class__):
ans = other._constructor(self)
ans += self
return ans
return other + list(self)
def __rmul__(self, other):
return self * other
def __iadd__(self, other):
self[len(self):len(self)] = other
return self
def __imul__(self, other):
if other <= 0:
self[:] = []
elif other > 1:
aux = list(self)
for i in xrange(other-1):
self.extend(aux)
return self
def append(self, other):
self[len(self):len(self)] = [other]
def extend(self, other):
self[len(self):len(self)] = other
def count(self, other):
ans = 0
for item in self:
if item == other:
ans += 1
return ans
def reverse(self):
for i in xrange(len(self)//2):
j = len(self) - 1 - i
(self[i], self[j]) = (self[j], self[i])
def index(self, x, i=0, j=None):
if i != 0 or j is not None:
(i, j, ignore) = self._tuple_from_slice(slice(i, j))
if j is None:
j = len(self)
for k in xrange(i, j):
if self._get_element(k) == x:
return k
raise ValueError('index(x): x not in list')
def insert(self, i, x):
self[i:i] = [x]
def pop(self, i=None):
if i == None:
i = len(self)-1
ans = self[i]
del self[i]
return ans
def remove(self, x):
for i in xrange(len(self)):
if self._get_element(i) == x:
del self[i]
return
raise ValueError('remove(x): x not in list')
# Define sort() as appropriate for the Python version.
if sys.version_info[:3] < (2, 4, 0):
def sort(self, cmpfunc=None):
ans = list(self)
ans.sort(cmpfunc)
self[:] = ans
else:
def sort(self, cmpfunc=None, key=None, reverse=False):
ans = list(self)
if reverse == True:
ans.sort(cmpfunc, key, reverse)
elif key != None:
ans.sort(cmpfunc, key)
else:
ans.sort(cmpfunc)
self[:] = ans
def __copy__(self):
return self._constructor(self)
def __deepcopy__(self, memo={}):
ans = self._constructor([])
memo[id(self)] = ans
ans[:] = copy.deepcopy(tuple(self), memo)
return ans
# Tracking idea from R. Hettinger's deque class. It's not
# multithread safe, but does work with the builtin Python classes.
def __str__(self, track=[]):
if id(self) in track:
return '...'
track.append(id(self))
ans = '%r' % (list(self),)
track.remove(id(self))
return ans
def __repr__(self):
return self.__class__.__name__ + '(' + str(self) + ')'
# Example usage:
class TestList(ListMixin):
def __init__(self, L=[]):
self.L = list(L)
def _constructor(self, iterable):
return TestList(iterable)
def __len__(self):
return len(self.L)
def _get_element(self, i):
assert 0 <= i < len(self)
return self.L[i]
def _set_element(self, i, x):
assert 0 <= i < len(self)
self.L[i] = x
def _resize_region(self, start, end, new_size):
assert 0 <= start <= len(self)
assert 0 <= end <= len(self)
assert start <= end
self.L[start:end] = [None] * new_size
# Now TestList() has behavior identical to that of list().
