python/google/appengine/_internal/django/core/paginator.py

   1 from math import ceil
   2
   3 class InvalidPage(Exception):
   4     pass
   5
   6 class PageNotAnInteger(InvalidPage):
   7     pass
   8
   9 class EmptyPage(InvalidPage):
  10     pass
  11
  12 class Paginator(object):
  13     def __init__(self, object_list, per_page, orphans=0, allow_empty_first_page=True):
  14         self.object_list = object_list
  15         self.per_page = per_page
  16         self.orphans = orphans
  17         self.allow_empty_first_page = allow_empty_first_page
  18         self._num_pages = self._count = None
  19
  20     def validate_number(self, number):
  21         "Validates the given 1-based page number."
  22         try:
  23             number = int(number)
  24         except ValueError:
  25             raise PageNotAnInteger('That page number is not an integer')
  26         if number < 1:
  27             raise EmptyPage('That page number is less than 1')
  28         if number > self.num_pages:
  29             if number == 1 and self.allow_empty_first_page:
  30                 pass
  31             else:
  32                 raise EmptyPage('That page contains no results')
  33         return number
  34
  35     def page(self, number):
  36         "Returns a Page object for the given 1-based page number."
  37         number = self.validate_number(number)
  38         bottom = (number - 1) * self.per_page
  39         top = bottom + self.per_page
  40         if top + self.orphans >= self.count:
  41             top = self.count
  42         return Page(self.object_list[bottom:top], number, self)
  43
  44     def _get_count(self):
  45         "Returns the total number of objects, across all pages."
  46         if self._count is None:
  47             try:
  48                 self._count = self.object_list.count()
  49             except (AttributeError, TypeError):
  50                 # AttributeError if object_list has no count() method.
  51                 # TypeError if object_list.count() requires arguments
  52                 # (i.e. is of type list).
  53                 self._count = len(self.object_list)
  54         return self._count
  55     count = property(_get_count)
  56
  57     def _get_num_pages(self):
  58         "Returns the total number of pages."
  59         if self._num_pages is None:
  60             if self.count == 0 and not self.allow_empty_first_page:
  61                 self._num_pages = 0
  62             else:
  63                 hits = max(1, self.count - self.orphans)
  64                 self._num_pages = int(ceil(hits / float(self.per_page)))
  65         return self._num_pages
  66     num_pages = property(_get_num_pages)
  67
  68     def _get_page_range(self):
  69         """
  70         Returns a 1-based range of pages for iterating through within
  71         a template for loop.
  72         """
  73         return range(1, self.num_pages + 1)
  74     page_range = property(_get_page_range)
  75
  76 QuerySetPaginator = Paginator # For backwards-compatibility.
  77
  78 class Page(object):
  79     def __init__(self, object_list, number, paginator):
  80         self.object_list = object_list
  81         self.number = number
  82         self.paginator = paginator
  83
  84     def __repr__(self):
  85         return '<Page %s of %s>' % (self.number, self.paginator.num_pages)
  86
  87     def has_next(self):
  88         return self.number < self.paginator.num_pages
  89
  90     def has_previous(self):
  91         return self.number > 1
  92
  93     def has_other_pages(self):
  94         return self.has_previous() or self.has_next()
  95
  96     def next_page_number(self):
  97         return self.number + 1
  98
  99     def previous_page_number(self):
 100         return self.number - 1
 101
 102     def start_index(self):
 103         """
 104         Returns the 1-based index of the first object on this page,
 105         relative to total objects in the paginator.
 106         """
 107         # Special case, return zero if no items.
 108         if self.paginator.count == 0:
 109             return 0
 110         return (self.paginator.per_page * (self.number - 1)) + 1
 111
 112     def end_index(self):
 113         """
 114         Returns the 1-based index of the last object on this page,
 115         relative to total objects found (hits).
 116         """
 117         # Special case for the last page because there can be orphans.
 118         if self.number == self.paginator.num_pages:
 119             return self.paginator.count
 120         return self.number * self.paginator.per_page