1 """Manage HTTP Response Headers

     2 

     3 Much of this module is red-handedly pilfered from email.Message in the stdlib,

     4 so portions are Copyright (C) 2001,2002 Python Software Foundation, and were

     5 written by Barry Warsaw.

     6 """

     7 

     8 from types import ListType, TupleType

     9 

    10 # Regular expression that matches `special' characters in parameters, the

    11 # existance of which force quoting of the parameter value.

    12 import re

    13 tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]')

    14 

    15 def _formatparam(param, value=None, quote=1):

    16     """Convenience function to format and return a key=value pair.

    17 

    18     This will quote the value if needed or if quote is true.

    19     """

    20     if value is not None and len(value) > 0:

    21         if quote or tspecials.search(value):

    22             value = value.replace('\\', '\\\\').replace('"', r'\"')

    23             return '%s="%s"' % (param, value)

    24         else:

    25             return '%s=%s' % (param, value)

    26     else:

    27         return param

    28 

    29 

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    39 

    40 

    41 

    42 class Headers:

    43 

    44     """Manage a collection of HTTP response headers"""

    45 

    46     def __init__(self,headers):

    47         if type(headers) is not ListType:

    48             raise TypeError("Headers must be a list of name/value tuples")

    49         self._headers = headers

    50 

    51     def __len__(self):

    52         """Return the total number of headers, including duplicates."""

    53         return len(self._headers)

    54 

    55     def __setitem__(self, name, val):

    56         """Set the value of a header."""

    57         del self[name]

    58         self._headers.append((name, val))

    59 

    60     def __delitem__(self,name):

    61         """Delete all occurrences of a header, if present.

    62 

    63         Does *not* raise an exception if the header is missing.

    64         """

    65         name = name.lower()

    66         self._headers[:] = [kv for kv in self._headers if kv[0].lower() != name]

    67 

    68     def __getitem__(self,name):

    69         """Get the first header value for 'name'

    70 

    71         Return None if the header is missing instead of raising an exception.

    72 

    73         Note that if the header appeared multiple times, the first exactly which

    74         occurrance gets returned is undefined.  Use getall() to get all

    75         the values matching a header field name.

    76         """

    77         return self.get(name)

    78 

    79 

    80 

    81 

    82 

    83     def has_key(self, name):

    84         """Return true if the message contains the header."""

    85         return self.get(name) is not None

    86 

    87     __contains__ = has_key

    88 

    89 

    90     def get_all(self, name):

    91         """Return a list of all the values for the named field.

    92 

    93         These will be sorted in the order they appeared in the original header

    94         list or were added to this instance, and may contain duplicates.  Any

    95         fields deleted and re-inserted are always appended to the header list.

    96         If no fields exist with the given name, returns an empty list.

    97         """

    98         name = name.lower()

    99         return [kv[1] for kv in self._headers if kv[0].lower()==name]

   100 

   101 

   102     def get(self,name,default=None):

   103         """Get the first header value for 'name', or return 'default'"""

   104         name = name.lower()

   105         for k,v in self._headers:

   106             if k.lower()==name:

   107                 return v

   108         return default

   109 

   110 

   111     def keys(self):

   112         """Return a list of all the header field names.

   113 

   114         These will be sorted in the order they appeared in the original header

   115         list, or were added to this instance, and may contain duplicates.

   116         Any fields deleted and re-inserted are always appended to the header

   117         list.

   118         """

   119         return [k for k, v in self._headers]

   120 

   121 

   122 

   123 

   124     def values(self):

   125         """Return a list of all header values.

   126 

   127         These will be sorted in the order they appeared in the original header

   128         list, or were added to this instance, and may contain duplicates.

   129         Any fields deleted and re-inserted are always appended to the header

   130         list.

   131         """

   132         return [v for k, v in self._headers]

   133 

   134     def items(self):

   135         """Get all the header fields and values.

   136 

   137         These will be sorted in the order they were in the original header

   138         list, or were added to this instance, and may contain duplicates.

   139         Any fields deleted and re-inserted are always appended to the header

   140         list.

   141         """

   142         return self._headers[:]

   143 

   144     def __repr__(self):

   145         return "Headers(%r)" % self._headers

   146 

   147     def __str__(self):

   148         """str() returns the formatted headers, complete with end line,

   149         suitable for direct HTTP transmission."""

   150         return '\r\n'.join(["%s: %s" % kv for kv in self._headers]+['',''])

   151 

   152     def setdefault(self,name,value):

   153         """Return first matching header value for 'name', or 'value'

   154 

   155         If there is no header named 'name', add a new header with name 'name'

   156         and value 'value'."""

   157         result = self.get(name)

   158         if result is None:

   159             self._headers.append((name,value))

   160             return value

   161         else:

   162             return result

   163 

   164 

   165     def add_header(self, _name, _value, **_params):

   166         """Extended header setting.

   167 

   168         _name is the header field to add.  keyword arguments can be used to set

   169         additional parameters for the header field, with underscores converted

   170         to dashes.  Normally the parameter will be added as key="value" unless

   171         value is None, in which case only the key will be added.

   172 

   173         Example:

   174 

   175         h.add_header('content-disposition', 'attachment', filename='bud.gif')

   176 

   177         Note that unlike the corresponding 'email.Message' method, this does

   178         *not* handle '(charset, language, value)' tuples: all values must be

   179         strings or None.

   180         """

   181         parts = []

   182         if _value is not None:

   183             parts.append(_value)

   184         for k, v in _params.items():

   185             if v is None:

   186                 parts.append(k.replace('_', '-'))

   187             else:

   188                 parts.append(_formatparam(k.replace('_', '-'), v))

   189         self._headers.append((_name, "; ".join(parts)))

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   205 #