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- import collections.abc
- import warnings
- from math import ceil
-
- from django.utils.functional import cached_property
- from django.utils.translation import gettext_lazy as _
-
-
- class UnorderedObjectListWarning(RuntimeWarning):
- pass
-
-
- class InvalidPage(Exception):
- pass
-
-
- class PageNotAnInteger(InvalidPage):
- pass
-
-
- class EmptyPage(InvalidPage):
- pass
-
-
- class Paginator:
-
- def __init__(self, object_list, per_page, orphans=0,
- allow_empty_first_page=True):
- self.object_list = object_list
- self._check_object_list_is_ordered()
- self.per_page = int(per_page)
- self.orphans = int(orphans)
- self.allow_empty_first_page = allow_empty_first_page
-
- def validate_number(self, number):
- """Validate the given 1-based page number."""
- try:
- if isinstance(number, float) and not number.is_integer():
- raise ValueError
- 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 get_page(self, number):
- """
- Return a valid page, even if the page argument isn't a number or isn't
- in range.
- """
- try:
- number = self.validate_number(number)
- except PageNotAnInteger:
- number = 1
- except EmptyPage:
- number = self.num_pages
- return self.page(number)
-
- def page(self, number):
- """Return 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):
- """
- Return 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)
-
- @cached_property
- def count(self):
- """Return the total number of objects, across all pages."""
- try:
- return 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).
- return len(self.object_list)
-
- @cached_property
- def num_pages(self):
- """Return the total number of pages."""
- if self.count == 0 and not self.allow_empty_first_page:
- return 0
- hits = max(1, self.count - self.orphans)
- return ceil(hits / self.per_page)
-
- @property
- def page_range(self):
- """
- Return a 1-based range of pages for iterating through within
- a template for loop.
- """
- return range(1, self.num_pages + 1)
-
- def _check_object_list_is_ordered(self):
- """
- Warn if self.object_list is unordered (typically a QuerySet).
- """
- ordered = getattr(self.object_list, 'ordered', None)
- if ordered is not None and not ordered:
- obj_list_repr = (
- '{} {}'.format(self.object_list.model, self.object_list.__class__.__name__)
- if hasattr(self.object_list, 'model')
- else '{!r}'.format(self.object_list)
- )
- warnings.warn(
- 'Pagination may yield inconsistent results with an unordered '
- 'object_list: {}.'.format(obj_list_repr),
- UnorderedObjectListWarning,
- stacklevel=3
- )
-
-
- QuerySetPaginator = Paginator # For backwards-compatibility.
-
-
- class Page(collections.abc.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, (int, slice)):
- 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):
- """
- Return 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):
- """
- Return 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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