PloneMisc.py

   1 ##
   2 ## The following code comes from Plone project http://plone.org
   3 ##
   4 """ Useful utilities function from the Plone project like Batch.
   5
   6 $Id: PloneMisc.py 1502 2009-05-31 17:33:32Z pin $
   7 $URL: http://svn.cri.ensmp.fr/svn/Plinn/branches/CMF-2.1/PloneMisc.py $
   8 """
   9
  10
  11 from __future__ import nested_scopes
  12
  13 from ZTUtils.Batch import Batch as ZTUBatch
  14 from ZTUtils import make_query
  15 from ExtensionClass import Base
  16
  17 # These have to be duplicated from ZTUtils.Batch to use the correct Batch
  18 # class, otherwise orphans will come out wrong in the 'show x next messages'.
  19 class LazyPrevBatch(Base):
  20         def __of__(self, parent):
  21                 return Batch(parent._sequence, parent._size,
  22                                          parent.first - parent._size + parent.overlap, 0,
  23                                          parent.orphan, parent.overlap)
  24
  25 class LazyNextBatch(Base):
  26         def __of__(self, parent):
  27                 try: parent._sequence[parent.end]
  28                 except IndexError: return None
  29                 return Batch(parent._sequence, parent._size,
  30                                          parent.end - parent.overlap, 0,
  31                                          parent.orphan, parent.overlap)
  32
  33 class LazySequenceLength(Base):
  34         def __of__(self, parent):
  35                 parent.sequence_length = l = len(parent._sequence)
  36                 return l
  37
  38 class Batch(ZTUBatch):
  39         """Create a sequence batch"""
  40         __allow_access_to_unprotected_subobjects__ = 1
  41
  42         previous = LazyPrevBatch()
  43         next = LazyNextBatch()
  44         sequence_length = LazySequenceLength()
  45
  46         size = first= start = end = orphan = overlap = navlist = None
  47         numpages = pagenumber = pagerange = pagerangeend = pagerangestart = pagenumber = quantumleap = None
  48
  49         def __init__( self
  50                                 , sequence
  51                                 , size
  52                                 , start=0
  53                                 , end=0
  54                                 , orphan=0
  55                                 , overlap=0
  56                                 , pagerange=7
  57                                 , quantumleap=0
  58                                 , b_start_str='b_start'
  59                                 , before_getitem=lambda item: item
  60                                 , ):
  61                 """ Encapsulate sequence in batches of size
  62                 sequence                - the data to batch.
  63                 size                    - the number of items in each batch. This will be computed if left out.
  64                 start                   - the first element of sequence to include in batch (0-index)
  65                 end                             - the last element of sequence to include in batch (0-index, optional)
  66                 orphan                  - the next page will be combined with the current page if it does not contain more than orphan elements
  67                 overlap                 - the number of overlapping elements in each batch
  68                 pagerange               - the number of pages to display in the navigation
  69                 quantumleap             - 0 or 1 to indicate if bigger increments should be used in the navigation list for big results.
  70                 b_start_str             - the request variable used for start, default 'b_start'
  71                 before_getitem  - function that compute the item before getting it
  72                 """
  73                 start = start + 1
  74
  75                 start,end,sz = opt(start,end,size,orphan,sequence)
  76
  77                 self._sequence = sequence
  78                 self.size = sz
  79                 self._size = size
  80                 self.start = start
  81                 self.end = end
  82                 self.orphan = orphan
  83                 self.overlap = overlap
  84                 self.first = max(start - 1, 0)
  85                 self.length = self.end - self.first
  86
  87                 self.b_start_str = b_start_str
  88
  89                 self.last = self.sequence_length - size
  90
  91                 # Set up next and previous
  92                 if self.first == 0:
  93                         self.previous = None
  94
  95                 # Set up the total number of pages
  96                 self.numpages = calculate_pagenumber(self.sequence_length - self.orphan, self.size, self.overlap)
  97
  98                 # Set up the current page number
  99                 self.pagenumber = calculate_pagenumber(self.start, self.size, self.overlap)
 100
 101                 # Set up pagerange for the navigation quick links
 102                 self.pagerange, self.pagerangestart, self.pagerangeend = calculate_pagerange(self.pagenumber,self.numpages,pagerange)
 103
 104                 # Set up the lists for the navigation: 4 5 [6] 7 8
 105                 #  navlist is the complete list, including pagenumber
 106                 #  prevlist is the 4 5 in the example above
 107                 #  nextlist is 7 8 in the example above
 108                 self.navlist = self.prevlist = self.nextlist = []
 109                 if self.pagerange and self.numpages >= 1:
 110                         self.navlist  = range(self.pagerangestart, self.pagerangeend)
 111                         self.prevlist = range(self.pagerangestart, self.pagenumber)
 112                         self.nextlist = range(self.pagenumber + 1, self.pagerangeend)
 113
 114                 # QuantumLeap - faster navigation for big result sets
 115                 self.quantumleap = quantumleap
 116                 self.leapback = self.leapforward = []
 117                 if self.quantumleap:
 118                         self.leapback = calculate_leapback(self.pagenumber, self.numpages, self.pagerange)
 119                         self.leapforward = calculate_leapforward(self.pagenumber, self.numpages, self.pagerange)
 120
 121                 # comptute item before getting it
 122                 self.before_getitem = before_getitem
 123
 124         def __getitem__(self, index):
 125                 if index < 0:
 126                         if index + self.end < self.first: raise IndexError, index
 127                         item = self._sequence[index + self.end]
 128                         return self.before_getitem(item)
 129
 130                 if index >= self.length: raise IndexError, index
 131                 item = self._sequence[index+self.first]
 132                 return self.before_getitem(item)
 133
 134         def pageurl(self, formvariables, pagenumber=-1):
 135                 """ Makes the url for a given page """
 136                 if pagenumber == -1:
 137                         pagenumber = self.pagenumber
 138                 b_start = pagenumber * (self.size - self.overlap) - self.size
 139                 return make_query(formvariables, {self.b_start_str:b_start})
 140
 141         def navurls(self, formvariables, navlist=[]):
 142                 """ Returns the page number and url for the navigation quick links """
 143                 if not navlist: navlist = self.navlist
 144                 return map(lambda x, formvariables = formvariables: (x, self.pageurl(formvariables, x)), navlist)
 145
 146         def prevurls(self, formvariables):
 147                 """ Helper method to get prev navigation list from templates """
 148                 return self.navurls(formvariables, self.prevlist)
 149
 150         def nexturls(self, formvariables):
 151                 """ Helper method to get next navigation list from templates """
 152                 return self.navurls(formvariables, self.nextlist)
 153
 154 # Calculate start, end, batchsize
 155 # This is copied from ZTUtils.Batch.py because orphans were not correct there.
 156 # 04/16/04 modified by Danny Bloemendaal (_ender_). Removed try/except structs because
 157 # in some situations they cause some unexpected problems. Also fixed some problems with the orphan stuff. Seems to work now.
 158 def opt(start,end,size,orphan,sequence):
 159         length = len(sequence)
 160         if size < 1:
 161                 if start > 0 and end > 0 and end >= start:
 162                         size = end + 1 - start
 163                 else: size = 25
 164         if start > 0:
 165                 if start>length:
 166                         start = length
 167                 if end > 0:
 168                         if end < start: end = start
 169                 else:
 170                         end = start + size - 1
 171                         if (end+orphan)>=length:
 172                                 end = length
 173         elif end > 0:
 174                 if (end)>length:
 175                         end = length
 176                 start = end + 1 - size
 177                 if start - 1 < orphan: start = 1
 178         else:
 179                 start = 1
 180                 end = start + size - 1
 181                 if (end+orphan)>=length:
 182                         end = length
 183         return start,end,size
 184
 185 def calculate_pagenumber(elementnumber, batchsize, overlap=0):
 186         """ Calculate the pagenumber for the navigation """
 187         # To find first element in a page,
 188         # elementnumber = pagenumber * (size - overlap) - size (- orphan?)
 189         try:
 190                 pagenumber,remainder = divmod(elementnumber, batchsize - overlap)
 191         except ZeroDivisionError:
 192                 pagenumber, remainder = divmod(elementnumber, 1)
 193         if remainder > overlap:
 194                 pagenumber = pagenumber + 1
 195         pagenumber = max(pagenumber, 1)
 196         return pagenumber
 197
 198 def calculate_pagerange(pagenumber, numpages, pagerange):
 199         """ Calculate the pagerange for the navigation quicklinks """
 200         # Pagerange is the number of pages linked to in the navigation, odd number
 201         pagerange = max(0 , pagerange + pagerange % 2 - 1)
 202         # Making sure the list will not start with negative values
 203         pagerangestart = max ( 1, pagenumber - (pagerange - 1 ) / 2 )
 204         # Making sure the list does not expand beyond the last page
 205         pagerangeend = min ( pagenumber + (pagerange - 1 ) / 2, numpages) + 1
 206         return pagerange, pagerangestart, pagerangeend
 207
 208 def calculate_quantum_leap_gap(numpages, pagerange):
 209         """ Find the QuantumLeap gap. Current width of list is 6 clicks (30/5) """
 210         return int(max(1,round(float(numpages - pagerange)/30))*5)
 211
 212 def calculate_leapback(pagenumber, numpages, pagerange):
 213         """ Check the distance between start and 0 and add links as necessary """
 214         leapback = []
 215         quantum_leap_gap = calculate_quantum_leap_gap(numpages, pagerange)
 216         num_back_leaps = max(0,min(3, int(round(float(pagenumber - pagerange)/quantum_leap_gap) - 0.3)))
 217         if num_back_leaps:
 218                 pagerange, pagerangestart, pagerangeend = calculate_pagerange( pagenumber, numpages, pagerange)
 219                 leapback = range(pagerangestart - num_back_leaps * quantum_leap_gap, pagerangestart, quantum_leap_gap)
 220         return leapback
 221
 222 def calculate_leapforward(pagenumber, numpages, pagerange):
 223         """ Check the distance between end and length and add links as necessary """
 224         leapforward = []
 225         quantum_leap_gap = calculate_quantum_leap_gap(numpages, pagerange)
 226         num_forward_leaps = max(0,min(3, int(round(float(numpages - pagenumber - pagerange)/quantum_leap_gap) - 0.3)))
 227         if num_forward_leaps:
 228                 pagerange, pagerangestart, pagerangeend = calculate_pagerange( pagenumber, numpages, pagerange)
 229                 leapforward = range(pagerangeend-1 + quantum_leap_gap, pagerangeend-1 + (num_forward_leaps+1) * quantum_leap_gap, quantum_leap_gap)
 230         return leapforward
 231
 232
 233 class IndexIterator:
 234         __allow_access_to_unprotected_subobjects__ = 1
 235
 236         def __init__(self, upper=100000, pos=0):
 237                 self.upper=upper
 238                 self.pos=pos
 239
 240         def next(self):
 241                 if self.pos <= self.upper:
 242                         self.pos += 1
 243                         return self.pos
 244                 raise KeyError, 'Reached upper bounds'