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import collections
from math import ceil
from django.utils import six
class InvalidPage(Exception):
pass
class PageNotAnInteger(InvalidPage):
pass
class EmptyPage(InvalidPage):
pass
class Paginator(object):
def __init__(self, object_list, per_page, orphans=0,
allow_empty_first_page=True):
self.object_list = object_list
self.per_page = int(per_page)
self.orphans = int(orphans)
self.allow_empty_first_page = allow_empty_first_page
self._num_pages = self._count = None
def validate_number(self, number):
"""
Validates the given 1-based page number.
"""
try:
number = int(number)
except (TypeError, ValueError):
raise PageNotAnInteger('That page number is not an integer')
if number < 1:
raise EmptyPage('That page number is less than 1')
if number > self.num_pages:
if number == 1 and self.allow_empty_first_page:
pass
else:
raise EmptyPage('That page contains no results')
return number
def page(self, number):
"""
Returns a Page object for the given 1-based page number.
"""
number = self.validate_number(number)
bottom = (number - 1) * self.per_page
top = bottom + self.per_page
if top + self.orphans >= self.count:
top = self.count
return self._get_page(self.object_list[bottom:top], number, self)
def _get_page(self, *args, **kwargs):
"""
Returns an instance of a single page.
This hook can be used by subclasses to use an alternative to the
standard :cls:`Page` object.
"""
return Page(*args, **kwargs)
def _get_count(self):
"""
Returns the total number of objects, across all pages.
"""
if self._count is None:
try:
self._count = self.object_list.count()
except (AttributeError, TypeError):
# AttributeError if object_list has no count() method.
# TypeError if object_list.count() requires arguments
# (i.e. is of type list).
self._count = len(self.object_list)
return self._count
count = property(_get_count)
def _get_num_pages(self):
"""
Returns the total number of pages.
"""
if self._num_pages is None:
if self.count == 0 and not self.allow_empty_first_page:
self._num_pages = 0
else:
hits = max(1, self.count - self.orphans)
self._num_pages = int(ceil(hits / float(self.per_page)))
return self._num_pages
num_pages = property(_get_num_pages)
def _get_page_range(self):
"""
Returns a 1-based range of pages for iterating through within
a template for loop.
"""
return six.moves.range(1, self.num_pages + 1)
page_range = property(_get_page_range)
QuerySetPaginator = Paginator # For backwards-compatibility.
class Page(collections.Sequence):
def __init__(self, object_list, number, paginator):
self.object_list = object_list
self.number = number
self.paginator = paginator
def __repr__(self):
return '<Page %s of %s>' % (self.number, self.paginator.num_pages)
def __len__(self):
return len(self.object_list)
def __getitem__(self, index):
if not isinstance(index, (slice,) + six.integer_types):
raise TypeError
# The object_list is converted to a list so that if it was a QuerySet
# it won't be a database hit per __getitem__.
if not isinstance(self.object_list, list):
self.object_list = list(self.object_list)
return self.object_list[index]
def has_next(self):
return self.number < self.paginator.num_pages
def has_previous(self):
return self.number > 1
def has_other_pages(self):
return self.has_previous() or self.has_next()
def next_page_number(self):
return self.paginator.validate_number(self.number + 1)
def previous_page_number(self):
return self.paginator.validate_number(self.number - 1)
def start_index(self):
"""
Returns the 1-based index of the first object on this page,
relative to total objects in the paginator.
"""
# Special case, return zero if no items.
if self.paginator.count == 0:
return 0
return (self.paginator.per_page * (self.number - 1)) + 1
def end_index(self):
"""
Returns the 1-based index of the last object on this page,
relative to total objects found (hits).
"""
# Special case for the last page because there can be orphans.
if self.number == self.paginator.num_pages:
return self.paginator.count
return self.number * self.paginator.per_page
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