Lib/wsgiref/headers.py

   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 # existence 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
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  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 #