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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 io 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            yield from subpart.walk()
30
31
32
33# These two functions are imported into the Iterators.py interface module.
34def body_line_iterator(msg, decode=False):
35    """Iterate over the parts, returning string payloads line-by-line.
36
37    Optional decode (default False) is passed through to .get_payload().
38    """
39    for subpart in msg.walk():
40        payload = subpart.get_payload(decode=decode)
41        if isinstance(payload, str):
42            yield from StringIO(payload)
43
44
45def typed_subpart_iterator(msg, maintype='text', subtype=None):
46    """Iterate over the subparts with a given MIME type.
47
48    Use `maintype' as the main MIME type to match against; this defaults to
49    "text".  Optional `subtype' is the MIME subtype to match against; if
50    omitted, only the main type is matched.
51    """
52    for subpart in msg.walk():
53        if subpart.get_content_maintype() == maintype:
54            if subtype is None or subpart.get_content_subtype() == subtype:
55                yield subpart
56
57
58
59def _structure(msg, fp=None, level=0, include_default=False):
60    """A handy debugging aid"""
61    if fp is None:
62        fp = sys.stdout
63    tab = ' ' * (level * 4)
64    print(tab + msg.get_content_type(), end='', file=fp)
65    if include_default:
66        print(' [%s]' % msg.get_default_type(), file=fp)
67    else:
68        print(file=fp)
69    if msg.is_multipart():
70        for subpart in msg.get_payload():
71            _structure(subpart, fp, level+1, include_default)
72