AppPkg/Applications/Python/Python-2.7.2/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
  28
  29
  30 class Headers:
  31
  32     """Manage a collection of HTTP response headers"""
  33
  34     def __init__(self,headers):
  35         if type(headers) is not ListType:
  36             raise TypeError("Headers must be a list of name/value tuples")
  37         self._headers = headers
  38
  39     def __len__(self):
  40         """Return the total number of headers, including duplicates."""
  41         return len(self._headers)
  42
  43     def __setitem__(self, name, val):
  44         """Set the value of a header."""
  45         del self[name]
  46         self._headers.append((name, val))
  47
  48     def __delitem__(self,name):
  49         """Delete all occurrences of a header, if present.
  50
  51         Does *not* raise an exception if the header is missing.
  52         """
  53         name = name.lower()
  54         self._headers[:] = [kv for kv in self._headers if kv[0].lower() != name]
  55
  56     def __getitem__(self,name):
  57         """Get the first header value for 'name'
  58
  59         Return None if the header is missing instead of raising an exception.
  60
  61         Note that if the header appeared multiple times, the first exactly which
  62         occurrance gets returned is undefined.  Use getall() to get all
  63         the values matching a header field name.
  64         """
  65         return self.get(name)
  66
  67     def has_key(self, name):
  68         """Return true if the message contains the header."""
  69         return self.get(name) is not None
  70
  71     __contains__ = has_key
  72
  73
  74     def get_all(self, name):
  75         """Return a list of all the values for the named field.
  76
  77         These will be sorted in the order they appeared in the original header
  78         list or were added to this instance, and may contain duplicates.  Any
  79         fields deleted and re-inserted are always appended to the header list.
  80         If no fields exist with the given name, returns an empty list.
  81         """
  82         name = name.lower()
  83         return [kv[1] for kv in self._headers if kv[0].lower()==name]
  84
  85
  86     def get(self,name,default=None):
  87         """Get the first header value for 'name', or return 'default'"""
  88         name = name.lower()
  89         for k,v in self._headers:
  90             if k.lower()==name:
  91                 return v
  92         return default
  93
  94
  95     def keys(self):
  96         """Return a list of all the header field names.
  97
  98         These will be sorted in the order they appeared in the original header
  99         list, or were added to this instance, and may contain duplicates.
 100         Any fields deleted and re-inserted are always appended to the header
 101         list.
 102         """
 103         return [k for k, v in self._headers]
 104
 105     def values(self):
 106         """Return a list of all header values.
 107
 108         These will be sorted in the order they appeared in the original header
 109         list, or were added to this instance, and may contain duplicates.
 110         Any fields deleted and re-inserted are always appended to the header
 111         list.
 112         """
 113         return [v for k, v in self._headers]
 114
 115     def items(self):
 116         """Get all the header fields and values.
 117
 118         These will be sorted in the order they were in the original header
 119         list, or were added to this instance, and may contain duplicates.
 120         Any fields deleted and re-inserted are always appended to the header
 121         list.
 122         """
 123         return self._headers[:]
 124
 125     def __repr__(self):
 126         return "Headers(%r)" % self._headers
 127
 128     def __str__(self):
 129         """str() returns the formatted headers, complete with end line,
 130         suitable for direct HTTP transmission."""
 131         return '\r\n'.join(["%s: %s" % kv for kv in self._headers]+['',''])
 132
 133     def setdefault(self,name,value):
 134         """Return first matching header value for 'name', or 'value'
 135
 136         If there is no header named 'name', add a new header with name 'name'
 137         and value 'value'."""
 138         result = self.get(name)
 139         if result is None:
 140             self._headers.append((name,value))
 141             return value
 142         else:
 143             return result
 144
 145     def add_header(self, _name, _value, **_params):
 146         """Extended header setting.
 147
 148         _name is the header field to add.  keyword arguments can be used to set
 149         additional parameters for the header field, with underscores converted
 150         to dashes.  Normally the parameter will be added as key="value" unless
 151         value is None, in which case only the key will be added.
 152
 153         Example:
 154
 155         h.add_header('content-disposition', 'attachment', filename='bud.gif')
 156
 157         Note that unlike the corresponding 'email.message' method, this does
 158         *not* handle '(charset, language, value)' tuples: all values must be
 159         strings or None.
 160         """
 161         parts = []
 162         if _value is not None:
 163             parts.append(_value)
 164         for k, v in _params.items():
 165             if v is None:
 166                 parts.append(k.replace('_', '-'))
 167             else:
 168                 parts.append(_formatparam(k.replace('_', '-'), v))
 169         self._headers.append((_name, "; ".join(parts)))