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116 lines
3.3 KiB
116 lines
3.3 KiB
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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#-----------------------
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# Name: pager.py List-like structure designed for handling paged results
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# Python Library
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# Author: Raymond Wagner
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#-----------------------
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from collections import Sequence, Iterator
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class PagedIterator(Iterator):
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def __init__(self, parent):
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self._parent = parent
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self._index = -1
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self._len = len(parent)
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def __iter__(self):
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return self
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def next(self):
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self._index += 1
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if self._index == self._len:
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raise StopIteration
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return self._parent[self._index]
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class UnpagedData(object):
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def copy(self):
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return self.__class__()
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def __mul__(self, other):
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return (self.copy() for a in range(other))
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def __rmul__(self, other):
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return (self.copy() for a in range(other))
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class PagedList(Sequence):
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"""
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List-like object, with support for automatically grabbing
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additional pages from a data source.
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"""
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_iter_class = None
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def __iter__(self):
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if self._iter_class is None:
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self._iter_class = type(self.__class__.__name__ + 'Iterator',
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(PagedIterator,), {})
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return self._iter_class(self)
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def __len__(self):
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try:
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return self._len
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except:
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return len(self._data)
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def __init__(self, iterable, pagesize=20):
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self._data = list(iterable)
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self._pagesize = pagesize
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def __getitem__(self, index):
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if isinstance(index, slice):
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return [self[x] for x in xrange(*index.indices(len(self)))]
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if index >= len(self):
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raise IndexError("list index outside range")
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if (index >= len(self._data)) \
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or isinstance(self._data[index], UnpagedData):
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self._populatepage(index/self._pagesize + 1)
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return self._data[index]
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def __setitem__(self, index, value):
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raise NotImplementedError
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def __delitem__(self, index):
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raise NotImplementedError
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def __contains__(self, item):
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raise NotImplementedError
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def _populatepage(self, page):
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pagestart = (page-1) * self._pagesize
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if len(self._data) < pagestart:
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self._data.extend(UnpagedData()*(pagestart-len(self._data)))
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if len(self._data) == pagestart:
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self._data.extend(self._getpage(page))
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else:
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for data in self._getpage(page):
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self._data[pagestart] = data
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pagestart += 1
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def _getpage(self, page):
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raise NotImplementedError("PagedList._getpage() must be provided " +
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"by subclass")
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class PagedRequest(PagedList):
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"""
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Derived PageList that provides a list-like object with automatic
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paging intended for use with search requests.
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"""
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def __init__(self, request, handler=None):
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self._request = request
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if handler:
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self._handler = handler
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super(PagedRequest, self).__init__(self._getpage(1), 20)
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def _getpage(self, page):
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req = self._request.new(page=page)
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res = req.readJSON()
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self._len = res['total_results']
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for item in res['results']:
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if item is None:
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yield None
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else:
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yield self._handler(item)
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