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authorGuido van Rossum <guido@python.org>1993-10-27 09:27:13 (GMT)
committerGuido van Rossum <guido@python.org>1993-10-27 09:27:13 (GMT)
commitb6957e434fab0b901cb2c8fafeba77f9ae7a653f (patch)
treed69890d8dd3f6442b1f8ca3a29eb12fb39a05839 /Demo/classes
parent12d12c5faf4d770160b7975b54e8f9b12694e012 (diff)
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Initial revision
Diffstat (limited to 'Demo/classes')
-rwxr-xr-xDemo/classes/bitvec.py341
1 files changed, 341 insertions, 0 deletions
diff --git a/Demo/classes/bitvec.py b/Demo/classes/bitvec.py
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+++ b/Demo/classes/bitvec.py
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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
+
+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)