Lib/email/iterators.py

   1 # Copyright (C) 2001-2006 Python Software Foundation
   2 # Author: Barry Warsaw
   3 # Contact: email-sig@python.org
   4
   5 """Various types of useful iterators and generators."""
   6
   7 __all__ = [
   8     'body_line_iterator',
   9     'typed_subpart_iterator',
  10     'walk',
  11     # Do not include _structure() since it's part of the debugging API.
  12     ]
  13
  14 import sys
  15 from cStringIO import StringIO
  16
  17
  18 \f
  19 # This function will become a method of the Message class
  20 def walk(self):
  21     """Walk over the message tree, yielding each subpart.
  22
  23     The walk is performed in depth-first order.  This method is a
  24     generator.
  25     """
  26     yield self
  27     if self.is_multipart():
  28         for subpart in self.get_payload():
  29             for subsubpart in subpart.walk():
  30                 yield subsubpart
  31
  32
  33 \f
  34 # These two functions are imported into the Iterators.py interface module.
  35 def body_line_iterator(msg, decode=False):
  36     """Iterate over the parts, returning string payloads line-by-line.
  37
  38     Optional decode (default False) is passed through to .get_payload().
  39     """
  40     for subpart in msg.walk():
  41         payload = subpart.get_payload(decode=decode)
  42         if isinstance(payload, basestring):
  43             for line in StringIO(payload):
  44                 yield line
  45
  46
  47 def typed_subpart_iterator(msg, maintype='text', subtype=None):
  48     """Iterate over the subparts with a given MIME type.
  49
  50     Use `maintype' as the main MIME type to match against; this defaults to
  51     "text".  Optional `subtype' is the MIME subtype to match against; if
  52     omitted, only the main type is matched.
  53     """
  54     for subpart in msg.walk():
  55         if subpart.get_content_maintype() == maintype:
  56             if subtype is None or subpart.get_content_subtype() == subtype:
  57                 yield subpart
  58
  59
  60 \f
  61 def _structure(msg, fp=None, level=0, include_default=False):
  62     """A handy debugging aid"""
  63     if fp is None:
  64         fp = sys.stdout
  65     tab = ' ' * (level * 4)
  66     print >> fp, tab + msg.get_content_type(),
  67     if include_default:
  68         print >> fp, '[%s]' % msg.get_default_type()
  69     else:
  70         print >> fp
  71     if msg.is_multipart():
  72         for subpart in msg.get_payload():
  73             _structure(subpart, fp, level+1, include_default)