[Zope3-checkins] CVS: Zope3/src/zope/app - batching.py:1.1

[Stephan Richter]

Update of /cvs-repository/Zope3/src/zope/app
In directory cvs.zope.org:/tmp/cvs-serv22793

Added Files:
	batching.py 
Log Message:
Added a first cut of batching support. It still does not handle orphans and
roman or alphabetic numerals, but this is just the icing on the cake. For 
now this version works really well for me in the bug tracker.


=== Added File Zope3/src/zope/app/batching.py ===
##############################################################################
#
# Copyright (c) 2003 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Batching Support

$Id: batching.py,v 1.1 2003/07/31 19:14:09 srichter Exp $
"""
from zope.interface import implements
from zope.app.interfaces.batching import IBatch

class Batch(object):
    implements(IBatch)

    def __init__(self, list, start=0, size=20):
        self.list = list
        self.start = start
        if len(list) == 0:
            self.start = -1
        elif start >= len(list):
            raise IndexError, 'start index key out of range'
        self.size = size
        self.trueSize = size
        if start+size >= len(list):
            self.trueSize = len(list)-start
        self.end = start+self.trueSize-1

    def __len__(self):
        return self.trueSize

    def __getitem__(self, key):
        if key >= self.trueSize:
            raise IndexError, 'batch index out of range'
        return self.list[self.start+key]

    def __iter__(self): 
        return iter(self.list[self.start:self.end+1])

    def __contains__(self, item):
        return item in self.__iter__()

    def nextBatch(self):
        start = self.start + self.size
        if start >= len(self.list):
            return None
        return Batch(self.list, start, self.size)
    
    def prevBatch(self):
        start = self.start - self.size
        if start < 0:
            return None
        return Batch(self.list, start, self.size)

    def first(self):
        return self.list[self.start]

    def last(self):
        return self.list[self.end]

    def total(self):
        return len(self.list)

    def startNumber(self):
        return self.start+1

    def endNumber(self):
        return self.end+1