Mercurial > p > roundup > code
comparison roundup/cgi/ZTUtils/Batch.py @ 1049:b9988e118055
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| author | Richard Jones <richard@users.sourceforge.net> |
|---|---|
| date | Thu, 05 Sep 2002 00:37:09 +0000 |
| parents | |
| children | c26471971d18 |
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| 1048:1250251f2793 | 1049:b9988e118055 |
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| 1 ############################################################################## | |
| 2 # | |
| 3 # Copyright (c) 2001 Zope Corporation and Contributors. All Rights Reserved. | |
| 4 # | |
| 5 # This software is subject to the provisions of the Zope Public License, | |
| 6 # Version 2.0 (ZPL). A copy of the ZPL should accompany this distribution. | |
| 7 # THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED | |
| 8 # WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED | |
| 9 # WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS | |
| 10 # FOR A PARTICULAR PURPOSE | |
| 11 # | |
| 12 ############################################################################## | |
| 13 __doc__='''Batch class, for iterating over a sequence in batches | |
| 14 | |
| 15 $Id: Batch.py,v 1.1 2002-09-05 00:37:09 richard Exp $''' | |
| 16 __version__='$Revision: 1.1 $'[11:-2] | |
| 17 | |
| 18 class LazyPrevBatch: | |
| 19 def __of__(self, parent): | |
| 20 return Batch(parent._sequence, parent._size, | |
| 21 parent.first - parent._size + parent.overlap, 0, | |
| 22 parent.orphan, parent.overlap) | |
| 23 | |
| 24 class LazyNextBatch: | |
| 25 def __of__(self, parent): | |
| 26 try: parent._sequence[parent.end] | |
| 27 except IndexError: return None | |
| 28 return Batch(parent._sequence, parent._size, | |
| 29 parent.end - parent.overlap, 0, | |
| 30 parent.orphan, parent.overlap) | |
| 31 | |
| 32 class LazySequenceLength: | |
| 33 def __of__(self, parent): | |
| 34 parent.sequence_length = l = len(parent._sequence) | |
| 35 return l | |
| 36 | |
| 37 class Batch: | |
| 38 """Create a sequence batch""" | |
| 39 __allow_access_to_unprotected_subobjects__ = 1 | |
| 40 | |
| 41 previous = LazyPrevBatch() | |
| 42 next = LazyNextBatch() | |
| 43 sequence_length = LazySequenceLength() | |
| 44 | |
| 45 def __init__(self, sequence, size, start=0, end=0, | |
| 46 orphan=0, overlap=0): | |
| 47 '''Encapsulate "sequence" in batches of "size". | |
| 48 | |
| 49 Arguments: "start" and "end" are 0-based indexes into the | |
| 50 sequence. If the next batch would contain no more than | |
| 51 "orphan" elements, it is combined with the current batch. | |
| 52 "overlap" is the number of elements shared by adjacent | |
| 53 batches. If "size" is not specified, it is computed from | |
| 54 "start" and "end". Failing that, it is 7. | |
| 55 | |
| 56 Attributes: Note that the "start" attribute, unlike the | |
| 57 argument, is a 1-based index (I know, lame). "first" is the | |
| 58 0-based index. "length" is the actual number of elements in | |
| 59 the batch. | |
| 60 | |
| 61 "sequence_length" is the length of the original, unbatched, sequence | |
| 62 ''' | |
| 63 | |
| 64 start = start + 1 | |
| 65 | |
| 66 start,end,sz = opt(start,end,size,orphan,sequence) | |
| 67 | |
| 68 self._sequence = sequence | |
| 69 self.size = sz | |
| 70 self._size = size | |
| 71 self.start = start | |
| 72 self.end = end | |
| 73 self.orphan = orphan | |
| 74 self.overlap = overlap | |
| 75 self.first = max(start - 1, 0) | |
| 76 self.length = self.end - self.first | |
| 77 if self.first == 0: | |
| 78 self.previous = None | |
| 79 | |
| 80 | |
| 81 def __getitem__(self, index): | |
| 82 if index < 0: | |
| 83 if index + self.end < self.first: raise IndexError, index | |
| 84 return self._sequence[index + self.end] | |
| 85 | |
| 86 if index >= self.length: raise IndexError, index | |
| 87 return self._sequence[index+self.first] | |
| 88 | |
| 89 def __len__(self): | |
| 90 return self.length | |
| 91 | |
| 92 def opt(start,end,size,orphan,sequence): | |
| 93 if size < 1: | |
| 94 if start > 0 and end > 0 and end >= start: | |
| 95 size=end+1-start | |
| 96 else: size=7 | |
| 97 | |
| 98 if start > 0: | |
| 99 | |
| 100 try: sequence[start-1] | |
| 101 except IndexError: start=len(sequence) | |
| 102 | |
| 103 if end > 0: | |
| 104 if end < start: end=start | |
| 105 else: | |
| 106 end=start+size-1 | |
| 107 try: sequence[end+orphan-1] | |
| 108 except IndexError: end=len(sequence) | |
| 109 elif end > 0: | |
| 110 try: sequence[end-1] | |
| 111 except IndexError: end=len(sequence) | |
| 112 start=end+1-size | |
| 113 if start - 1 < orphan: start=1 | |
| 114 else: | |
| 115 start=1 | |
| 116 end=start+size-1 | |
| 117 try: sequence[end+orphan-1] | |
| 118 except IndexError: end=len(sequence) | |
| 119 return start,end,size |