/Demo/classes/bitvec.py

http://unladen-swallow.googlecode.com/ · Python · 333 lines · 231 code · 57 blank · 45 comment · 63 complexity · ecddbc26916927cdc4b9384cdf2c80c2 MD5 · raw file

  1. #
  2. # this is a rather strict implementation of a bit vector class
  3. # it is accessed the same way as an array of python-ints, except
  4. # the value must be 0 or 1
  5. #
  6. import sys; rprt = sys.stderr.write #for debugging
  7. class error(Exception):
  8. pass
  9. def _check_value(value):
  10. if type(value) != type(0) or not 0 <= value < 2:
  11. raise error, 'bitvec() items must have int value 0 or 1'
  12. import math
  13. def _compute_len(param):
  14. mant, l = math.frexp(float(param))
  15. bitmask = 1L << l
  16. if bitmask <= param:
  17. raise RuntimeError('(param, l) = %r' % ((param, l),))
  18. while l:
  19. bitmask = bitmask >> 1
  20. if param & bitmask:
  21. break
  22. l = l - 1
  23. return l
  24. def _check_key(len, key):
  25. if type(key) != type(0):
  26. raise TypeError, 'sequence subscript not int'
  27. if key < 0:
  28. key = key + len
  29. if not 0 <= key < len:
  30. raise IndexError, 'list index out of range'
  31. return key
  32. def _check_slice(len, i, j):
  33. #the type is ok, Python already checked that
  34. i, j = max(i, 0), min(len, j)
  35. if i > j:
  36. i = j
  37. return i, j
  38. class BitVec:
  39. def __init__(self, *params):
  40. self._data = 0L
  41. self._len = 0
  42. if not len(params):
  43. pass
  44. elif len(params) == 1:
  45. param, = params
  46. if type(param) == type([]):
  47. value = 0L
  48. bit_mask = 1L
  49. for item in param:
  50. # strict check
  51. #_check_value(item)
  52. if item:
  53. value = value | bit_mask
  54. bit_mask = bit_mask << 1
  55. self._data = value
  56. self._len = len(param)
  57. elif type(param) == type(0L):
  58. if param < 0:
  59. raise error, 'bitvec() can\'t handle negative longs'
  60. self._data = param
  61. self._len = _compute_len(param)
  62. else:
  63. raise error, 'bitvec() requires array or long parameter'
  64. elif len(params) == 2:
  65. param, length = params
  66. if type(param) == type(0L):
  67. if param < 0:
  68. raise error, \
  69. 'can\'t handle negative longs'
  70. self._data = param
  71. if type(length) != type(0):
  72. raise error, 'bitvec()\'s 2nd parameter must be int'
  73. computed_length = _compute_len(param)
  74. if computed_length > length:
  75. print 'warning: bitvec() value is longer than the length indicates, truncating value'
  76. self._data = self._data & \
  77. ((1L << length) - 1)
  78. self._len = length
  79. else:
  80. raise error, 'bitvec() requires array or long parameter'
  81. else:
  82. raise error, 'bitvec() requires 0 -- 2 parameter(s)'
  83. def append(self, item):
  84. #_check_value(item)
  85. #self[self._len:self._len] = [item]
  86. self[self._len:self._len] = \
  87. BitVec(long(not not item), 1)
  88. def count(self, value):
  89. #_check_value(value)
  90. if value:
  91. data = self._data
  92. else:
  93. data = (~self)._data
  94. count = 0
  95. while data:
  96. data, count = data >> 1, count + (data & 1 != 0)
  97. return count
  98. def index(self, value):
  99. #_check_value(value):
  100. if value:
  101. data = self._data
  102. else:
  103. data = (~self)._data
  104. index = 0
  105. if not data:
  106. raise ValueError, 'list.index(x): x not in list'
  107. while not (data & 1):
  108. data, index = data >> 1, index + 1
  109. return index
  110. def insert(self, index, item):
  111. #_check_value(item)
  112. #self[index:index] = [item]
  113. self[index:index] = BitVec(long(not not item), 1)
  114. def remove(self, value):
  115. del self[self.index(value)]
  116. def reverse(self):
  117. #ouch, this one is expensive!
  118. #for i in self._len>>1: self[i], self[l-i] = self[l-i], self[i]
  119. data, result = self._data, 0L
  120. for i in range(self._len):
  121. if not data:
  122. result = result << (self._len - i)
  123. break
  124. result, data = (result << 1) | (data & 1), data >> 1
  125. self._data = result
  126. def sort(self):
  127. c = self.count(1)
  128. self._data = ((1L << c) - 1) << (self._len - c)
  129. def copy(self):
  130. return BitVec(self._data, self._len)
  131. def seq(self):
  132. result = []
  133. for i in self:
  134. result.append(i)
  135. return result
  136. def __repr__(self):
  137. ##rprt('<bitvec class instance object>.' + '__repr__()\n')
  138. return 'bitvec(%r, %r)' % (self._data, self._len)
  139. def __cmp__(self, other, *rest):
  140. #rprt('%r.__cmp__%r\n' % (self, (other,) + rest))
  141. if type(other) != type(self):
  142. other = apply(bitvec, (other, ) + rest)
  143. #expensive solution... recursive binary, with slicing
  144. length = self._len
  145. if length == 0 or other._len == 0:
  146. return cmp(length, other._len)
  147. if length != other._len:
  148. min_length = min(length, other._len)
  149. return cmp(self[:min_length], other[:min_length]) or \
  150. cmp(self[min_length:], other[min_length:])
  151. #the lengths are the same now...
  152. if self._data == other._data:
  153. return 0
  154. if length == 1:
  155. return cmp(self[0], other[0])
  156. else:
  157. length = length >> 1
  158. return cmp(self[:length], other[:length]) or \
  159. cmp(self[length:], other[length:])
  160. def __len__(self):
  161. #rprt('%r.__len__()\n' % (self,))
  162. return self._len
  163. def __getitem__(self, key):
  164. #rprt('%r.__getitem__(%r)\n' % (self, key))
  165. key = _check_key(self._len, key)
  166. return self._data & (1L << key) != 0
  167. def __setitem__(self, key, value):
  168. #rprt('%r.__setitem__(%r, %r)\n' % (self, key, value))
  169. key = _check_key(self._len, key)
  170. #_check_value(value)
  171. if value:
  172. self._data = self._data | (1L << key)
  173. else:
  174. self._data = self._data & ~(1L << key)
  175. def __delitem__(self, key):
  176. #rprt('%r.__delitem__(%r)\n' % (self, key))
  177. key = _check_key(self._len, key)
  178. #el cheapo solution...
  179. self._data = self[:key]._data | self[key+1:]._data >> key
  180. self._len = self._len - 1
  181. def __getslice__(self, i, j):
  182. #rprt('%r.__getslice__(%r, %r)\n' % (self, i, j))
  183. i, j = _check_slice(self._len, i, j)
  184. if i >= j:
  185. return BitVec(0L, 0)
  186. if i:
  187. ndata = self._data >> i
  188. else:
  189. ndata = self._data
  190. nlength = j - i
  191. if j != self._len:
  192. #we'll have to invent faster variants here
  193. #e.g. mod_2exp
  194. ndata = ndata & ((1L << nlength) - 1)
  195. return BitVec(ndata, nlength)
  196. def __setslice__(self, i, j, sequence, *rest):
  197. #rprt('%s.__setslice__%r\n' % (self, (i, j, sequence) + rest))
  198. i, j = _check_slice(self._len, i, j)
  199. if type(sequence) != type(self):
  200. sequence = apply(bitvec, (sequence, ) + rest)
  201. #sequence is now of our own type
  202. ls_part = self[:i]
  203. ms_part = self[j:]
  204. self._data = ls_part._data | \
  205. ((sequence._data | \
  206. (ms_part._data << sequence._len)) << ls_part._len)
  207. self._len = self._len - j + i + sequence._len
  208. def __delslice__(self, i, j):
  209. #rprt('%r.__delslice__(%r, %r)\n' % (self, i, j))
  210. i, j = _check_slice(self._len, i, j)
  211. if i == 0 and j == self._len:
  212. self._data, self._len = 0L, 0
  213. elif i < j:
  214. self._data = self[:i]._data | (self[j:]._data >> i)
  215. self._len = self._len - j + i
  216. def __add__(self, other):
  217. #rprt('%r.__add__(%r)\n' % (self, other))
  218. retval = self.copy()
  219. retval[self._len:self._len] = other
  220. return retval
  221. def __mul__(self, multiplier):
  222. #rprt('%r.__mul__(%r)\n' % (self, multiplier))
  223. if type(multiplier) != type(0):
  224. raise TypeError, 'sequence subscript not int'
  225. if multiplier <= 0:
  226. return BitVec(0L, 0)
  227. elif multiplier == 1:
  228. return self.copy()
  229. #handle special cases all 0 or all 1...
  230. if self._data == 0L:
  231. return BitVec(0L, self._len * multiplier)
  232. elif (~self)._data == 0L:
  233. return ~BitVec(0L, self._len * multiplier)
  234. #otherwise el cheapo again...
  235. retval = BitVec(0L, 0)
  236. while multiplier:
  237. retval, multiplier = retval + self, multiplier - 1
  238. return retval
  239. def __and__(self, otherseq, *rest):
  240. #rprt('%r.__and__%r\n' % (self, (otherseq,) + rest))
  241. if type(otherseq) != type(self):
  242. otherseq = apply(bitvec, (otherseq, ) + rest)
  243. #sequence is now of our own type
  244. return BitVec(self._data & otherseq._data, \
  245. min(self._len, otherseq._len))
  246. def __xor__(self, otherseq, *rest):
  247. #rprt('%r.__xor__%r\n' % (self, (otherseq,) + rest))
  248. if type(otherseq) != type(self):
  249. otherseq = apply(bitvec, (otherseq, ) + rest)
  250. #sequence is now of our own type
  251. return BitVec(self._data ^ otherseq._data, \
  252. max(self._len, otherseq._len))
  253. def __or__(self, otherseq, *rest):
  254. #rprt('%r.__or__%r\n' % (self, (otherseq,) + rest))
  255. if type(otherseq) != type(self):
  256. otherseq = apply(bitvec, (otherseq, ) + rest)
  257. #sequence is now of our own type
  258. return BitVec(self._data | otherseq._data, \
  259. max(self._len, otherseq._len))
  260. def __invert__(self):
  261. #rprt('%r.__invert__()\n' % (self,))
  262. return BitVec(~self._data & ((1L << self._len) - 1), \
  263. self._len)
  264. def __coerce__(self, otherseq, *rest):
  265. #needed for *some* of the arithmetic operations
  266. #rprt('%r.__coerce__%r\n' % (self, (otherseq,) + rest))
  267. if type(otherseq) != type(self):
  268. otherseq = apply(bitvec, (otherseq, ) + rest)
  269. return self, otherseq
  270. def __int__(self):
  271. return int(self._data)
  272. def __long__(self):
  273. return long(self._data)
  274. def __float__(self):
  275. return float(self._data)
  276. bitvec = BitVec