python/Demo/classes/bitvec.py at master · pylee/python · GitHub

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# this is a rather strict implementation of a bit vector class

# it is accessed the same way as an array of python-ints, except

# the value must be 0 or 1

import sys; rprt = sys.stderr.write #for debugging

class error(Exception):

pass

def _check_value(value):

if type(value) != type(0) or not 0 <= value < 2:

raise error, 'bitvec() items must have int value 0 or 1'

import math

def _compute_len(param):

mant, l = math.frexp(float(param))

bitmask = 1L << l

if bitmask <= param:

raise RuntimeError('(param, l) = %r' % ((param, l),))

while l:

bitmask = bitmask >> 1

if param & bitmask:

break

l = l - 1

return l

def _check_key(len, key):

if type(key) != type(0):

raise TypeError, 'sequence subscript not int'

if key < 0:

key = key + len

if not 0 <= key < len:

raise IndexError, 'list index out of range'

return key

def _check_slice(len, i, j):

#the type is ok, Python already checked that

i, j = max(i, 0), min(len, j)

if i > j:

i = j

return i, j

class BitVec:

def __init__(self, *params):

self._data = 0L

self._len = 0

if not len(params):

pass

elif len(params) == 1:

param, = params

if type(param) == type([]):

value = 0L

bit_mask = 1L

for item in param:

# strict check

#_check_value(item)

if item:

value = value | bit_mask

bit_mask = bit_mask << 1

self._data = value

self._len = len(param)

elif type(param) == type(0L):

if param < 0:

raise error, 'bitvec() can\'t handle negative longs'

self._data = param

self._len = _compute_len(param)

else:

raise error, 'bitvec() requires array or long parameter'

elif len(params) == 2:

param, length = params

if type(param) == type(0L):

if param < 0:

raise error, \

'can\'t handle negative longs'

self._data = param

if type(length) != type(0):

raise error, 'bitvec()\'s 2nd parameter must be int'

computed_length = _compute_len(param)

if computed_length > length:

print 'warning: bitvec() value is longer than the length indicates, truncating value'

self._data = self._data & \

((1L << length) - 1)

self._len = length

else:

raise error, 'bitvec() requires array or long parameter'

else:

raise error, 'bitvec() requires 0 -- 2 parameter(s)'

def append(self, item):

#_check_value(item)

#self[self._len:self._len] = [item]

self[self._len:self._len] = \

BitVec(long(not not item), 1)

def count(self, value):

#_check_value(value)

if value:

data = self._data

else:

data = (~self)._data

count = 0

while data:

data, count = data >> 1, count + (data & 1 != 0)

return count

def index(self, value):

#_check_value(value):

if value:

data = self._data

else:

data = (~self)._data

index = 0

if not data:

raise ValueError, 'list.index(x): x not in list'

while not (data & 1):

data, index = data >> 1, index + 1

return index

def insert(self, index, item):

#_check_value(item)

#self[index:index] = [item]

self[index:index] = BitVec(long(not not item), 1)

def remove(self, value):

del self[self.index(value)]

def reverse(self):

#ouch, this one is expensive!

#for i in self._len>>1: self[i], self[l-i] = self[l-i], self[i]

data, result = self._data, 0L

for i in range(self._len):

if not data:

result = result << (self._len - i)

break

result, data = (result << 1) | (data & 1), data >> 1

self._data = result

def sort(self):

c = self.count(1)

self._data = ((1L << c) - 1) << (self._len - c)

def copy(self):

return BitVec(self._data, self._len)

def seq(self):

result = []

for i in self:

result.append(i)

return result

def __repr__(self):

##rprt('<bitvec class instance object>.' + '__repr__()\n')

return 'bitvec(%r, %r)' % (self._data, self._len)

def __cmp__(self, other, *rest):

#rprt('%r.__cmp__%r\n' % (self, (other,) + rest))

if type(other) != type(self):

other = apply(bitvec, (other, ) + rest)

#expensive solution... recursive binary, with slicing

length = self._len

if length == 0 or other._len == 0:

return cmp(length, other._len)

if length != other._len:

min_length = min(length, other._len)

return cmp(self[:min_length], other[:min_length]) or \

cmp(self[min_length:], other[min_length:])

#the lengths are the same now...

if self._data == other._data:

return 0

if length == 1:

return cmp(self[0], other[0])

else:

length = length >> 1

return cmp(self[:length], other[:length]) or \

cmp(self[length:], other[length:])

def __len__(self):

#rprt('%r.__len__()\n' % (self,))

return self._len

def __getitem__(self, key):

#rprt('%r.__getitem__(%r)\n' % (self, key))

key = _check_key(self._len, key)

return self._data & (1L << key) != 0

def __setitem__(self, key, value):

#rprt('%r.__setitem__(%r, %r)\n' % (self, key, value))

key = _check_key(self._len, key)

#_check_value(value)

if value:

self._data = self._data | (1L << key)

else:

self._data = self._data & ~(1L << key)

def __delitem__(self, key):

#rprt('%r.__delitem__(%r)\n' % (self, key))

key = _check_key(self._len, key)

#el cheapo solution...

self._data = self[:key]._data | self[key+1:]._data >> key

self._len = self._len - 1

def __getslice__(self, i, j):

#rprt('%r.__getslice__(%r, %r)\n' % (self, i, j))

i, j = _check_slice(self._len, i, j)

if i >= j:

return BitVec(0L, 0)

if i:

ndata = self._data >> i

else:

ndata = self._data

nlength = j - i

if j != self._len:

#we'll have to invent faster variants here

#e.g. mod_2exp

ndata = ndata & ((1L << nlength) - 1)

return BitVec(ndata, nlength)

def __setslice__(self, i, j, sequence, *rest):

#rprt('%s.__setslice__%r\n' % (self, (i, j, sequence) + rest))

i, j = _check_slice(self._len, i, j)

if type(sequence) != type(self):

sequence = apply(bitvec, (sequence, ) + rest)

#sequence is now of our own type

ls_part = self[:i]

ms_part = self[j:]

self._data = ls_part._data | \

((sequence._data | \

(ms_part._data << sequence._len)) << ls_part._len)

self._len = self._len - j + i + sequence._len

def __delslice__(self, i, j):

#rprt('%r.__delslice__(%r, %r)\n' % (self, i, j))

i, j = _check_slice(self._len, i, j)

if i == 0 and j == self._len:

self._data, self._len = 0L, 0

elif i < j:

self._data = self[:i]._data | (self[j:]._data >> i)

self._len = self._len - j + i

def __add__(self, other):

#rprt('%r.__add__(%r)\n' % (self, other))

retval = self.copy()

retval[self._len:self._len] = other

return retval

def __mul__(self, multiplier):

#rprt('%r.__mul__(%r)\n' % (self, multiplier))

if type(multiplier) != type(0):

raise TypeError, 'sequence subscript not int'

if multiplier <= 0:

return BitVec(0L, 0)

elif multiplier == 1:

return self.copy()

#handle special cases all 0 or all 1...

if self._data == 0L:

return BitVec(0L, self._len * multiplier)

elif (~self)._data == 0L:

return ~BitVec(0L, self._len * multiplier)

#otherwise el cheapo again...

retval = BitVec(0L, 0)

while multiplier:

retval, multiplier = retval + self, multiplier - 1

return retval

def __and__(self, otherseq, *rest):

#rprt('%r.__and__%r\n' % (self, (otherseq,) + rest))

if type(otherseq) != type(self):

otherseq = apply(bitvec, (otherseq, ) + rest)

#sequence is now of our own type

return BitVec(self._data & otherseq._data, \

min(self._len, otherseq._len))

def __xor__(self, otherseq, *rest):

#rprt('%r.__xor__%r\n' % (self, (otherseq,) + rest))

if type(otherseq) != type(self):

otherseq = apply(bitvec, (otherseq, ) + rest)

#sequence is now of our own type

return BitVec(self._data ^ otherseq._data, \

max(self._len, otherseq._len))

def __or__(self, otherseq, *rest):

#rprt('%r.__or__%r\n' % (self, (otherseq,) + rest))

if type(otherseq) != type(self):

otherseq = apply(bitvec, (otherseq, ) + rest)

#sequence is now of our own type

return BitVec(self._data | otherseq._data, \

max(self._len, otherseq._len))

def __invert__(self):

#rprt('%r.__invert__()\n' % (self,))

return BitVec(~self._data & ((1L << self._len) - 1), \

self._len)

def __coerce__(self, otherseq, *rest):

#needed for *some* of the arithmetic operations

#rprt('%r.__coerce__%r\n' % (self, (otherseq,) + rest))

if type(otherseq) != type(self):

otherseq = apply(bitvec, (otherseq, ) + rest)

return self, otherseq

def __int__(self):

return int(self._data)

def __long__(self):

return long(self._data)

def __float__(self):

return float(self._data)

bitvec = BitVec

python/Demo/classes/bitvec.py at master · pylee/python · GitHub

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