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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
14import sys
15from cStringIO import StringIO
16
17
18
19# This function will become a method of the Message class
20def 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
34# These two functions are imported into the Iterators.py interface module.
35def 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
47def 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
61def _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)
74