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Mini Shell
"""Manage HTTP Response Headers
Much of this module is red-handedly pilfered from email.message in the
stdlib,
so portions are Copyright (C) 2001,2002 Python Software Foundation, and
were
written by Barry Warsaw.
"""
from types import ListType, TupleType
# Regular expression that matches `special' characters in parameters,
the
# existence of which force quoting of the parameter value.
import re
tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]')
def _formatparam(param, value=None, quote=1):
"""Convenience function to format and return a key=value
pair.
This will quote the value if needed or if quote is true.
"""
if value is not None and len(value) > 0:
if quote or tspecials.search(value):
value = value.replace('\\',
'\\\\').replace('"', r'\"')
return '%s="%s"' % (param, value)
else:
return '%s=%s' % (param, value)
else:
return param
class Headers:
"""Manage a collection of HTTP response
headers"""
def __init__(self,headers):
if type(headers) is not ListType:
raise TypeError("Headers must be a list of name/value
tuples")
self._headers = headers
def __len__(self):
"""Return the total number of headers, including
duplicates."""
return len(self._headers)
def __setitem__(self, name, val):
"""Set the value of a header."""
del self[name]
self._headers.append((name, val))
def __delitem__(self,name):
"""Delete all occurrences of a header, if present.
Does *not* raise an exception if the header is missing.
"""
name = name.lower()
self._headers[:] = [kv for kv in self._headers if kv[0].lower() !=
name]
def __getitem__(self,name):
"""Get the first header value for 'name'
Return None if the header is missing instead of raising an
exception.
Note that if the header appeared multiple times, the first exactly
which
occurrance gets returned is undefined. Use getall() to get all
the values matching a header field name.
"""
return self.get(name)
def has_key(self, name):
"""Return true if the message contains the
header."""
return self.get(name) is not None
__contains__ = has_key
def get_all(self, name):
"""Return a list of all the values for the named
field.
These will be sorted in the order they appeared in the original
header
list or were added to this instance, and may contain duplicates.
Any
fields deleted and re-inserted are always appended to the header
list.
If no fields exist with the given name, returns an empty list.
"""
name = name.lower()
return [kv[1] for kv in self._headers if kv[0].lower()==name]
def get(self,name,default=None):
"""Get the first header value for 'name',
or return 'default'"""
name = name.lower()
for k,v in self._headers:
if k.lower()==name:
return v
return default
def keys(self):
"""Return a list of all the header field names.
These will be sorted in the order they appeared in the original
header
list, or were added to this instance, and may contain duplicates.
Any fields deleted and re-inserted are always appended to the
header
list.
"""
return [k for k, v in self._headers]
def values(self):
"""Return a list of all header values.
These will be sorted in the order they appeared in the original
header
list, or were added to this instance, and may contain duplicates.
Any fields deleted and re-inserted are always appended to the
header
list.
"""
return [v for k, v in self._headers]
def items(self):
"""Get all the header fields and values.
These will be sorted in the order they were in the original header
list, or were added to this instance, and may contain duplicates.
Any fields deleted and re-inserted are always appended to the
header
list.
"""
return self._headers[:]
def __repr__(self):
return "Headers(%r)" % self._headers
def __str__(self):
"""str() returns the formatted headers, complete
with end line,
suitable for direct HTTP transmission."""
return '\r\n'.join(["%s: %s" % kv for kv in
self._headers]+['',''])
def setdefault(self,name,value):
"""Return first matching header value for
'name', or 'value'
If there is no header named 'name', add a new header with
name 'name'
and value 'value'."""
result = self.get(name)
if result is None:
self._headers.append((name,value))
return value
else:
return result
def add_header(self, _name, _value, **_params):
"""Extended header setting.
_name is the header field to add. keyword arguments can be used to
set
additional parameters for the header field, with underscores
converted
to dashes. Normally the parameter will be added as
key="value" unless
value is None, in which case only the key will be added.
Example:
h.add_header('content-disposition',
'attachment', filename='bud.gif')
Note that unlike the corresponding 'email.message'
method, this does
*not* handle '(charset, language, value)' tuples: all
values must be
strings or None.
"""
parts = []
if _value is not None:
parts.append(_value)
for k, v in _params.items():
if v is None:
parts.append(k.replace('_', '-'))
else:
parts.append(_formatparam(k.replace('_',
'-'), v))
self._headers.append((_name, "; ".join(parts)))