Initial revision

Demo/classes/bitvec.py

+#
+# 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
+
+error = 'bitvec.error'
+
+
+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 'FATAL', '(param, l) = ' + `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 lenght 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)'
+
+		return self
+
+
+	def _init(self, data, len):
+		self._data = data
+		self._len = len
+		return self
+
+		
+	def append(self, item):
+		#_check_value(item)
+		#self[self._len:self._len] = [item]
+		self[self._len:self._len] = \
+			  BitVec()._init(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()._init(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()._init(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' + `self._data, self._len`
+
+	def __cmp__(self, other, *rest):
+		#rprt(`self`+'.__cmp__'+`(other, ) + rest`+'\n')
+		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_lenght = 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(`self`+'.__len__()\n')
+		return self._len
+
+	def __getitem__(self, key):
+		#rprt(`self`+'.__getitem__('+`key`+')\n')
+		key = _check_key(self._len, key)
+		return self._data & (1L << key) != 0
+
+	def __setitem__(self, key, value):
+		#rprt(`self`+'.__setitem__'+`key, value`+'\n')
+		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(`self`+'.__delitem__('+`key`+')\n')
+		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(`self`+'.__getslice__'+`i, j`+'\n')
+		i, j = _check_slice(self._len, i, j)
+		if i >= j:
+			return BitVec()._init(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()._init(ndata, nlength)
+
+	def __setslice__(self, i, j, sequence, *rest):
+		#rprt(`self`+'.__setslice__'+`(i, j, sequence) + rest`+'\n')
+		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(`self`+'.__delslice__'+`i, j`+'\n')
+		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(`self`+'.__add__('+`other`+')\n')
+		retval = self.copy()
+		retval[self._len:self._len] = other
+		return retval
+
+	def __mul__(self, multiplier):
+		#rprt(`self`+'.__mul__('+`multiplier`+')\n')
+		if type(multiplier) != type(0):
+			raise TypeError, 'sequence subscript not int'
+		if multiplier <= 0:
+			return BitVec()._init(0L, 0)
+		elif multiplier == 1:
+			return self.copy()
+		#handle special cases all 0 or all 1...
+		if self._data == 0L:
+			return BitVec()._init(0L, self._len * multiplier)
+		elif (~self)._data == 0L:
+			return ~BitVec()._init(0L, self._len * multiplier)
+		#otherwise el cheapo again...
+		retval = BitVec()._init(0L, 0)
+		while multiplier:
+			retval, multiplier = retval + self, multiplier - 1
+		return retval
+
+	def __and__(self, otherseq, *rest):
+		#rprt(`self`+'.__and__'+`(otherseq, ) + rest`+'\n')
+		if type(otherseq) != type(self):
+			otherseq = apply(bitvec, (otherseq, ) + rest)
+		#sequence is now of our own type
+		return BitVec()._init(self._data & otherseq._data, \
+			  min(self._len, otherseq._len))
+
+
+	def __xor__(self, otherseq, *rest):
+		#rprt(`self`+'.__xor__'+`(otherseq, ) + rest`+'\n')
+		if type(otherseq) != type(self):
+			otherseq = apply(bitvec, (otherseq, ) + rest)
+		#sequence is now of our own type
+		return BitVec()._init(self._data ^ otherseq._data, \
+			  max(self._len, otherseq._len))
+
+
+	def __or__(self, otherseq, *rest):
+		#rprt(`self`+'.__or__'+`(otherseq, ) + rest`+'\n')
+		if type(otherseq) != type(self):
+			otherseq = apply(bitvec, (otherseq, ) + rest)
+		#sequence is now of our own type
+		return BitVec()._init(self._data | otherseq._data, \
+			  max(self._len, otherseq._len))
+
+
+	def __invert__(self):
+		#rprt(`self`+'.__invert__()\n')
+		return BitVec()._init(~self._data & ((1L << self._len) - 1), \
+			  self._len)
+
+	def __coerce__(self, otherseq, *rest):
+		#needed for *some* of the arithmetic operations
+		#rprt(`self`+'.__coerce__'+`(otherseq, ) + rest`+'\n')
+		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)
+
+
+def bitvec(params):
+	return apply(BitVec().init, params)