# Copyright (C) 2001-2006 Python Software Foundation

# Author: Barry Warsaw

# Contact: email-sig@python.org

"""Various types of useful iterators and generators."""

__all__ = [

    'body_line_iterator',

    'typed_subpart_iterator',

    'walk',

    # Do not include _structure() since it's part of the debugging API.

    ]

import sys

from cStringIO import StringIO

# This function will become a method of the Message class

def walk(self):

    """Walk over the message tree, yielding each subpart.

    The walk is performed in depth-first order.  This method is a

    generator.

    """

    yield self

    if self.is_multipart():

        for subpart in self.get_payload():

            for subsubpart in subpart.walk():

                yield subsubpart

# These two functions are imported into the Iterators.py interface module.

def body_line_iterator(msg, decode=False):

    """Iterate over the parts, returning string payloads line-by-line.

    Optional decode (default False) is passed through to .get_payload().

    """

    for subpart in msg.walk():

        payload = subpart.get_payload(decode=decode)

        if isinstance(payload, basestring):

            for line in StringIO(payload):

                yield line

def typed_subpart_iterator(msg, maintype='text', subtype=None):

    """Iterate over the subparts with a given MIME type.

    Use `maintype' as the main MIME type to match against; this defaults to

    "text".  Optional `subtype' is the MIME subtype to match against; if

    omitted, only the main type is matched.

    """

    for subpart in msg.walk():

        if subpart.get_content_maintype() == maintype:

            if subtype is None or subpart.get_content_subtype() == subtype:

                yield subpart

def _structure(msg, fp=None, level=0, include_default=False):

    """A handy debugging aid"""

    if fp is None:

        fp = sys.stdout

    tab = ' ' * (level * 4)

    print >> fp, tab + msg.get_content_type(),

    if include_default:

        print >> fp, '[%s]' % msg.get_default_type()

    else:

        print >> fp

    if msg.is_multipart():

        for subpart in msg.get_payload():

            _structure(subpart, fp, level+1, include_default)