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/Lib/wsgiref/headers.py

http://unladen-swallow.googlecode.com/
Python | 205 lines | 163 code | 23 blank | 19 comment | 10 complexity | 84c3e83d2fe8e5bfb42ed6600d785f1c MD5 | raw file
  1"""Manage HTTP Response Headers
  2
  3Much of this module is red-handedly pilfered from email.message in the stdlib,
  4so portions are Copyright (C) 2001,2002 Python Software Foundation, and were
  5written by Barry Warsaw.
  6"""
  7
  8from 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.
 12import re
 13tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]')
 14
 15def _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
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 40
 41
 42class 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#