[106] | 1 | """Response classes.
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| 2 |
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| 3 | The seek_wrapper code is not used if you're using UserAgent with
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| 4 | .set_seekable_responses(False), or if you're using the urllib2-level interface
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| 5 | without SeekableProcessor or HTTPEquivProcessor. Class closeable_response is
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| 6 | instantiated by some handlers (AbstractHTTPHandler), but the closeable_response
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| 7 | interface is only depended upon by Browser-level code. Function
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| 8 | upgrade_response is only used if you're using Browser or
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| 9 | ResponseUpgradeProcessor.
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| 10 |
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| 11 |
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| 12 | Copyright 2006 John J. Lee <jjl@pobox.com>
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| 13 |
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| 14 | This code is free software; you can redistribute it and/or modify it
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| 15 | under the terms of the BSD or ZPL 2.1 licenses (see the file COPYING.txt
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| 16 | included with the distribution).
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| 17 |
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| 18 | """
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| 19 |
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| 20 | import copy, mimetools
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| 21 | from cStringIO import StringIO
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| 22 | import urllib2
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| 23 |
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| 24 |
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| 25 | def len_of_seekable(file_):
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| 26 | # this function exists because evaluation of len(file_.getvalue()) on every
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| 27 | # .read() from seek_wrapper would be O(N**2) in number of .read()s
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| 28 | pos = file_.tell()
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| 29 | file_.seek(0, 2) # to end
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| 30 | try:
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| 31 | return file_.tell()
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| 32 | finally:
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| 33 | file_.seek(pos)
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| 34 |
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| 35 |
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| 36 | # XXX Andrew Dalke kindly sent me a similar class in response to my request on
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| 37 | # comp.lang.python, which I then proceeded to lose. I wrote this class
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| 38 | # instead, but I think he's released his code publicly since, could pinch the
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| 39 | # tests from it, at least...
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| 40 |
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| 41 | # For testing seek_wrapper invariant (note that
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| 42 | # test_urllib2.HandlerTest.test_seekable is expected to fail when this
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| 43 | # invariant checking is turned on). The invariant checking is done by module
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| 44 | # ipdc, which is available here:
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| 45 | # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/436834
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| 46 | ## from ipdbc import ContractBase
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| 47 | ## class seek_wrapper(ContractBase):
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| 48 | class seek_wrapper:
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| 49 | """Adds a seek method to a file object.
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| 50 |
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| 51 | This is only designed for seeking on readonly file-like objects.
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| 52 |
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| 53 | Wrapped file-like object must have a read method. The readline method is
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| 54 | only supported if that method is present on the wrapped object. The
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| 55 | readlines method is always supported. xreadlines and iteration are
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| 56 | supported only for Python 2.2 and above.
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| 57 |
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| 58 | Public attributes:
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| 59 |
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| 60 | wrapped: the wrapped file object
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| 61 | is_closed: true iff .close() has been called
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| 62 |
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| 63 | WARNING: All other attributes of the wrapped object (ie. those that are not
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| 64 | one of wrapped, read, readline, readlines, xreadlines, __iter__ and next)
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| 65 | are passed through unaltered, which may or may not make sense for your
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| 66 | particular file object.
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| 67 |
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| 68 | """
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| 69 | # General strategy is to check that cache is full enough, then delegate to
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| 70 | # the cache (self.__cache, which is a cStringIO.StringIO instance). A seek
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| 71 | # position (self.__pos) is maintained independently of the cache, in order
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| 72 | # that a single cache may be shared between multiple seek_wrapper objects.
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| 73 | # Copying using module copy shares the cache in this way.
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| 74 |
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| 75 | def __init__(self, wrapped):
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| 76 | self.wrapped = wrapped
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| 77 | self.__read_complete_state = [False]
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| 78 | self.__is_closed_state = [False]
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| 79 | self.__have_readline = hasattr(self.wrapped, "readline")
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| 80 | self.__cache = StringIO()
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| 81 | self.__pos = 0 # seek position
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| 82 |
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| 83 | def invariant(self):
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| 84 | # The end of the cache is always at the same place as the end of the
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| 85 | # wrapped file (though the .tell() method is not required to be present
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| 86 | # on wrapped file).
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| 87 | return self.wrapped.tell() == len(self.__cache.getvalue())
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| 88 |
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| 89 | def close(self):
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| 90 | self.wrapped.close()
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| 91 | self.is_closed = True
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| 92 |
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| 93 | def __getattr__(self, name):
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| 94 | if name == "is_closed":
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| 95 | return self.__is_closed_state[0]
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| 96 | elif name == "read_complete":
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| 97 | return self.__read_complete_state[0]
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| 98 |
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| 99 | wrapped = self.__dict__.get("wrapped")
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| 100 | if wrapped:
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| 101 | return getattr(wrapped, name)
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| 102 |
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| 103 | return getattr(self.__class__, name)
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| 104 |
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| 105 | def __setattr__(self, name, value):
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| 106 | if name == "is_closed":
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| 107 | self.__is_closed_state[0] = bool(value)
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| 108 | elif name == "read_complete":
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| 109 | if not self.is_closed:
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| 110 | self.__read_complete_state[0] = bool(value)
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| 111 | else:
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| 112 | self.__dict__[name] = value
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| 113 |
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| 114 | def seek(self, offset, whence=0):
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| 115 | assert whence in [0, 1, 2]
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| 116 |
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| 117 | # how much data, if any, do we need to read?
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| 118 | if whence == 2: # 2: relative to end of *wrapped* file
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| 119 | if offset < 0: raise ValueError("negative seek offset")
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| 120 | # since we don't know yet where the end of that file is, we must
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| 121 | # read everything
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| 122 | to_read = None
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| 123 | else:
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| 124 | if whence == 0: # 0: absolute
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| 125 | if offset < 0: raise ValueError("negative seek offset")
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| 126 | dest = offset
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| 127 | else: # 1: relative to current position
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| 128 | pos = self.__pos
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| 129 | if pos < offset:
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| 130 | raise ValueError("seek to before start of file")
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| 131 | dest = pos + offset
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| 132 | end = len_of_seekable(self.__cache)
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| 133 | to_read = dest - end
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| 134 | if to_read < 0:
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| 135 | to_read = 0
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| 136 |
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| 137 | if to_read != 0:
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| 138 | self.__cache.seek(0, 2)
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| 139 | if to_read is None:
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| 140 | assert whence == 2
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| 141 | self.__cache.write(self.wrapped.read())
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| 142 | self.read_complete = True
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| 143 | self.__pos = self.__cache.tell() - offset
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| 144 | else:
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| 145 | data = self.wrapped.read(to_read)
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| 146 | if not data:
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| 147 | self.read_complete = True
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| 148 | else:
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| 149 | self.__cache.write(data)
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| 150 | # Don't raise an exception even if we've seek()ed past the end
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| 151 | # of .wrapped, since fseek() doesn't complain in that case.
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| 152 | # Also like fseek(), pretend we have seek()ed past the end,
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| 153 | # i.e. not:
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| 154 | #self.__pos = self.__cache.tell()
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| 155 | # but rather:
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| 156 | self.__pos = dest
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| 157 | else:
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| 158 | self.__pos = dest
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| 159 |
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| 160 | def tell(self):
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| 161 | return self.__pos
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| 162 |
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| 163 | def __copy__(self):
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| 164 | cpy = self.__class__(self.wrapped)
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| 165 | cpy.__cache = self.__cache
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| 166 | cpy.__read_complete_state = self.__read_complete_state
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| 167 | cpy.__is_closed_state = self.__is_closed_state
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| 168 | return cpy
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| 169 |
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| 170 | def get_data(self):
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| 171 | pos = self.__pos
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| 172 | try:
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| 173 | self.seek(0)
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| 174 | return self.read(-1)
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| 175 | finally:
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| 176 | self.__pos = pos
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| 177 |
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| 178 | def read(self, size= -1):
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| 179 | pos = self.__pos
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| 180 | end = len_of_seekable(self.__cache)
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| 181 | available = end - pos
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| 182 |
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| 183 | # enough data already cached?
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| 184 | if size <= available and size != -1:
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| 185 | self.__cache.seek(pos)
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| 186 | self.__pos = pos + size
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| 187 | return self.__cache.read(size)
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| 188 |
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| 189 | # no, so read sufficient data from wrapped file and cache it
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| 190 | self.__cache.seek(0, 2)
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| 191 | if size == -1:
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| 192 | self.__cache.write(self.wrapped.read())
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| 193 | self.read_complete = True
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| 194 | else:
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| 195 | to_read = size - available
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| 196 | assert to_read > 0
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| 197 | data = self.wrapped.read(to_read)
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| 198 | if not data:
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| 199 | self.read_complete = True
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| 200 | else:
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| 201 | self.__cache.write(data)
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| 202 | self.__cache.seek(pos)
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| 203 |
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| 204 | data = self.__cache.read(size)
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| 205 | self.__pos = self.__cache.tell()
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| 206 | assert self.__pos == pos + len(data)
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| 207 | return data
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| 208 |
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| 209 | def readline(self, size= -1):
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| 210 | if not self.__have_readline:
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| 211 | raise NotImplementedError("no readline method on wrapped object")
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| 212 |
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| 213 | # line we're about to read might not be complete in the cache, so
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| 214 | # read another line first
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| 215 | pos = self.__pos
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| 216 | self.__cache.seek(0, 2)
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| 217 | data = self.wrapped.readline()
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| 218 | if not data:
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| 219 | self.read_complete = True
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| 220 | else:
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| 221 | self.__cache.write(data)
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| 222 | self.__cache.seek(pos)
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| 223 |
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| 224 | data = self.__cache.readline()
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| 225 | if size != -1:
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| 226 | r = data[:size]
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| 227 | self.__pos = pos + size
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| 228 | else:
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| 229 | r = data
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| 230 | self.__pos = pos + len(data)
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| 231 | return r
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| 232 |
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| 233 | def readlines(self, sizehint= -1):
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| 234 | pos = self.__pos
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| 235 | self.__cache.seek(0, 2)
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| 236 | self.__cache.write(self.wrapped.read())
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| 237 | self.read_complete = True
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| 238 | self.__cache.seek(pos)
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| 239 | data = self.__cache.readlines(sizehint)
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| 240 | self.__pos = self.__cache.tell()
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| 241 | return data
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| 242 |
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| 243 | def __iter__(self): return self
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| 244 | def next(self):
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| 245 | line = self.readline()
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| 246 | if line == "": raise StopIteration
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| 247 | return line
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| 248 |
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| 249 | xreadlines = __iter__
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| 250 |
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| 251 | def __repr__(self):
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| 252 | return ("<%s at %s whose wrapped object = %r>" %
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| 253 | (self.__class__.__name__, hex(abs(id(self))), self.wrapped))
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| 254 |
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| 255 |
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| 256 | class response_seek_wrapper(seek_wrapper):
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| 257 |
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| 258 | """
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| 259 | Supports copying response objects and setting response body data.
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| 260 |
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| 261 | """
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| 262 |
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| 263 | def __init__(self, wrapped):
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| 264 | seek_wrapper.__init__(self, wrapped)
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| 265 | self._headers = self.wrapped.info()
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| 266 |
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| 267 | def __copy__(self):
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| 268 | cpy = seek_wrapper.__copy__(self)
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| 269 | # copy headers from delegate
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| 270 | cpy._headers = copy.copy(self.info())
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| 271 | return cpy
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| 272 |
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| 273 | # Note that .info() and .geturl() (the only two urllib2 response methods
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| 274 | # that are not implemented by seek_wrapper) must be here explicitly rather
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| 275 | # than by seek_wrapper's __getattr__ delegation) so that the nasty
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| 276 | # dynamically-created HTTPError classes in get_seek_wrapper_class() get the
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| 277 | # wrapped object's implementation, and not HTTPError's.
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| 278 |
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| 279 | def info(self):
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| 280 | return self._headers
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| 281 |
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| 282 | def geturl(self):
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| 283 | return self.wrapped.geturl()
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| 284 |
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| 285 | def set_data(self, data):
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| 286 | self.seek(0)
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| 287 | self.read()
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| 288 | self.close()
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| 289 | cache = self._seek_wrapper__cache = StringIO()
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| 290 | cache.write(data)
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| 291 | self.seek(0)
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| 292 |
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| 293 |
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| 294 | class eoffile:
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| 295 | # file-like object that always claims to be at end-of-file...
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| 296 | def read(self, size= -1): return ""
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| 297 | def readline(self, size= -1): return ""
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| 298 | def __iter__(self): return self
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| 299 | def next(self): return ""
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| 300 | def close(self): pass
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| 301 |
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| 302 | class eofresponse(eoffile):
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| 303 | def __init__(self, url, headers, code, msg):
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| 304 | self._url = url
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| 305 | self._headers = headers
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| 306 | self.code = code
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| 307 | self.msg = msg
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| 308 | def geturl(self): return self._url
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| 309 | def info(self): return self._headers
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| 310 |
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| 311 |
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| 312 | class closeable_response:
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| 313 | """Avoids unnecessarily clobbering urllib.addinfourl methods on .close().
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| 314 |
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| 315 | Only supports responses returned by mechanize.HTTPHandler.
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| 316 |
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| 317 | After .close(), the following methods are supported:
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| 318 |
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| 319 | .read()
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| 320 | .readline()
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| 321 | .info()
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| 322 | .geturl()
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| 323 | .__iter__()
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| 324 | .next()
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| 325 | .close()
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| 326 |
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| 327 | and the following attributes are supported:
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| 328 |
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| 329 | .code
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| 330 | .msg
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| 331 |
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| 332 | Also supports pickling (but the stdlib currently does something to prevent
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| 333 | it: http://python.org/sf/1144636).
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| 334 |
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| 335 | """
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| 336 | # presence of this attr indicates is useable after .close()
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| 337 | closeable_response = None
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| 338 |
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| 339 | def __init__(self, fp, headers, url, code, msg):
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| 340 | self._set_fp(fp)
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| 341 | self._headers = headers
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| 342 | self._url = url
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| 343 | self.code = code
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| 344 | self.msg = msg
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| 345 |
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| 346 | def _set_fp(self, fp):
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| 347 | self.fp = fp
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| 348 | self.read = self.fp.read
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| 349 | self.readline = self.fp.readline
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| 350 | if hasattr(self.fp, "readlines"): self.readlines = self.fp.readlines
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| 351 | if hasattr(self.fp, "fileno"):
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| 352 | self.fileno = self.fp.fileno
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| 353 | else:
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| 354 | self.fileno = lambda: None
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| 355 | self.__iter__ = self.fp.__iter__
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| 356 | self.next = self.fp.next
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| 357 |
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| 358 | def __repr__(self):
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| 359 | return '<%s at %s whose fp = %r>' % (
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| 360 | self.__class__.__name__, hex(abs(id(self))), self.fp)
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| 361 |
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| 362 | def info(self):
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| 363 | return self._headers
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| 364 |
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| 365 | def geturl(self):
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| 366 | return self._url
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| 367 |
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| 368 | def close(self):
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| 369 | wrapped = self.fp
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| 370 | wrapped.close()
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| 371 | new_wrapped = eofresponse(
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| 372 | self._url, self._headers, self.code, self.msg)
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| 373 | self._set_fp(new_wrapped)
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| 374 |
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| 375 | def __getstate__(self):
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| 376 | # There are three obvious options here:
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| 377 | # 1. truncate
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| 378 | # 2. read to end
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| 379 | # 3. close socket, pickle state including read position, then open
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| 380 | # again on unpickle and use Range header
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| 381 | # XXXX um, 4. refuse to pickle unless .close()d. This is better,
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| 382 | # actually ("errors should never pass silently"). Pickling doesn't
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| 383 | # work anyway ATM, because of http://python.org/sf/1144636 so fix
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| 384 | # this later
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| 385 |
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| 386 | # 2 breaks pickle protocol, because one expects the original object
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| 387 | # to be left unscathed by pickling. 3 is too complicated and
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| 388 | # surprising (and too much work ;-) to happen in a sane __getstate__.
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| 389 | # So we do 1.
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| 390 |
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| 391 | state = self.__dict__.copy()
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| 392 | new_wrapped = eofresponse(
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| 393 | self._url, self._headers, self.code, self.msg)
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| 394 | state["wrapped"] = new_wrapped
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| 395 | return state
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| 396 |
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| 397 | def test_response(data='test data', headers=[],
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| 398 | url="http://example.com/", code=200, msg="OK"):
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| 399 | return make_response(data, headers, url, code, msg)
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| 400 |
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| 401 | def test_html_response(data='test data', headers=[],
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| 402 | url="http://example.com/", code=200, msg="OK"):
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| 403 | headers += [("Content-type", "text/html")]
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| 404 | return make_response(data, headers, url, code, msg)
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| 405 |
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| 406 | def make_response(data, headers, url, code, msg):
|
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| 407 | """Convenient factory for objects implementing response interface.
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| 408 |
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| 409 | data: string containing response body data
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| 410 | headers: sequence of (name, value) pairs
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| 411 | url: URL of response
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| 412 | code: integer response code (e.g. 200)
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| 413 | msg: string response code message (e.g. "OK")
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| 414 |
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| 415 | """
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| 416 | mime_headers = make_headers(headers)
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| 417 | r = closeable_response(StringIO(data), mime_headers, url, code, msg)
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| 418 | return response_seek_wrapper(r)
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| 419 |
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| 420 |
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| 421 | def make_headers(headers):
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| 422 | """
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| 423 | headers: sequence of (name, value) pairs
|
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| 424 | """
|
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| 425 | hdr_text = []
|
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| 426 | for name_value in headers:
|
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| 427 | hdr_text.append("%s: %s" % name_value)
|
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| 428 | return mimetools.Message(StringIO("\n".join(hdr_text)))
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| 429 |
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| 430 |
|
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| 431 | # Rest of this module is especially horrible, but needed, at least until fork
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| 432 | # urllib2. Even then, may want to preseve urllib2 compatibility.
|
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| 433 |
|
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| 434 | def get_seek_wrapper_class(response):
|
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| 435 | # in order to wrap response objects that are also exceptions, we must
|
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| 436 | # dynamically subclass the exception :-(((
|
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| 437 | if (isinstance(response, urllib2.HTTPError) and
|
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| 438 | not hasattr(response, "seek")):
|
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| 439 | if response.__class__.__module__ == "__builtin__":
|
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| 440 | exc_class_name = response.__class__.__name__
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| 441 | else:
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| 442 | exc_class_name = "%s.%s" % (
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| 443 | response.__class__.__module__, response.__class__.__name__)
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| 444 |
|
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| 445 | class httperror_seek_wrapper(response_seek_wrapper, response.__class__):
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| 446 | # this only derives from HTTPError in order to be a subclass --
|
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| 447 | # the HTTPError behaviour comes from delegation
|
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| 448 |
|
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| 449 | _exc_class_name = exc_class_name
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| 450 |
|
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| 451 | def __init__(self, wrapped):
|
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| 452 | response_seek_wrapper.__init__(self, wrapped)
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| 453 | # be compatible with undocumented HTTPError attributes :-(
|
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| 454 | self.hdrs = wrapped.info()
|
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| 455 | self.filename = wrapped.geturl()
|
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| 456 |
|
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| 457 | def __repr__(self):
|
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| 458 | return (
|
---|
| 459 | "<%s (%s instance) at %s "
|
---|
| 460 | "whose wrapped object = %r>" % (
|
---|
| 461 | self.__class__.__name__, self._exc_class_name,
|
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| 462 | hex(abs(id(self))), self.wrapped)
|
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| 463 | )
|
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| 464 | wrapper_class = httperror_seek_wrapper
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| 465 | else:
|
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| 466 | wrapper_class = response_seek_wrapper
|
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| 467 | return wrapper_class
|
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| 468 |
|
---|
| 469 | def seek_wrapped_response(response):
|
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| 470 | """Return a copy of response that supports seekable response interface.
|
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| 471 |
|
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| 472 | Accepts responses from both mechanize and urllib2 handlers.
|
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| 473 |
|
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| 474 | Copes with both oridinary response instances and HTTPError instances (which
|
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| 475 | can't be simply wrapped due to the requirement of preserving the exception
|
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| 476 | base class).
|
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| 477 | """
|
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| 478 | if not hasattr(response, "seek"):
|
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| 479 | wrapper_class = get_seek_wrapper_class(response)
|
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| 480 | response = wrapper_class(response)
|
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| 481 | assert hasattr(response, "get_data")
|
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| 482 | return response
|
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| 483 |
|
---|
| 484 | def upgrade_response(response):
|
---|
| 485 | """Return a copy of response that supports Browser response interface.
|
---|
| 486 |
|
---|
| 487 | Browser response interface is that of "seekable responses"
|
---|
| 488 | (response_seek_wrapper), plus the requirement that responses must be
|
---|
| 489 | useable after .close() (closeable_response).
|
---|
| 490 |
|
---|
| 491 | Accepts responses from both mechanize and urllib2 handlers.
|
---|
| 492 |
|
---|
| 493 | Copes with both ordinary response instances and HTTPError instances (which
|
---|
| 494 | can't be simply wrapped due to the requirement of preserving the exception
|
---|
| 495 | base class).
|
---|
| 496 | """
|
---|
| 497 | wrapper_class = get_seek_wrapper_class(response)
|
---|
| 498 | if hasattr(response, "closeable_response"):
|
---|
| 499 | if not hasattr(response, "seek"):
|
---|
| 500 | response = wrapper_class(response)
|
---|
| 501 | assert hasattr(response, "get_data")
|
---|
| 502 | return copy.copy(response)
|
---|
| 503 |
|
---|
| 504 | # a urllib2 handler constructed the response, i.e. the response is an
|
---|
| 505 | # urllib.addinfourl or a urllib2.HTTPError, instead of a
|
---|
| 506 | # _Util.closeable_response as returned by e.g. mechanize.HTTPHandler
|
---|
| 507 | try:
|
---|
| 508 | code = response.code
|
---|
| 509 | except AttributeError:
|
---|
| 510 | code = None
|
---|
| 511 | try:
|
---|
| 512 | msg = response.msg
|
---|
| 513 | except AttributeError:
|
---|
| 514 | msg = None
|
---|
| 515 |
|
---|
| 516 | # may have already-.read() data from .seek() cache
|
---|
| 517 | data = None
|
---|
| 518 | get_data = getattr(response, "get_data", None)
|
---|
| 519 | if get_data:
|
---|
| 520 | data = get_data()
|
---|
| 521 |
|
---|
| 522 | response = closeable_response(
|
---|
| 523 | response.fp, response.info(), response.geturl(), code, msg)
|
---|
| 524 | response = wrapper_class(response)
|
---|
| 525 | if data:
|
---|
| 526 | response.set_data(data)
|
---|
| 527 | return response
|
---|