symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/multifile.rst
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+:mod:`multifile` --- Support for files containing distinct parts
+================================================================
+
+.. module:: multifile
+   :synopsis: Support for reading files which contain distinct parts, such as some MIME data.
+   :deprecated:
+.. sectionauthor:: Eric S. Raymond <esr@snark.thyrsus.com>
+
+
+.. deprecated:: 2.5
+   The :mod:`email` package should be used in preference to the :mod:`multifile`
+   module. This module is present only to maintain backward compatibility.
+
+The :class:`MultiFile` object enables you to treat sections of a text file as
+file-like input objects, with ``''`` being returned by :meth:`readline` when a
+given delimiter pattern is encountered.  The defaults of this class are designed
+to make it useful for parsing MIME multipart messages, but by subclassing it and
+overriding methods  it can be easily adapted for more general use.
+
+
+.. class:: MultiFile(fp[, seekable])
+
+   Create a multi-file.  You must instantiate this class with an input object
+   argument for the :class:`MultiFile` instance to get lines from, such as a file
+   object returned by :func:`open`.
+
+   :class:`MultiFile` only ever looks at the input object's :meth:`readline`,
+   :meth:`seek` and :meth:`tell` methods, and the latter two are only needed if you
+   want random access to the individual MIME parts. To use :class:`MultiFile` on a
+   non-seekable stream object, set the optional *seekable* argument to false; this
+   will prevent using the input object's :meth:`seek` and :meth:`tell` methods.
+
+It will be useful to know that in :class:`MultiFile`'s view of the world, text
+is composed of three kinds of lines: data, section-dividers, and end-markers.
+MultiFile is designed to support parsing of messages that may have multiple
+nested message parts, each with its own pattern for section-divider and
+end-marker lines.
+
+
+.. seealso::
+
+   Module :mod:`email`
+      Comprehensive email handling package; supersedes the :mod:`multifile` module.
+
+
+.. _multifile-objects:
+
+MultiFile Objects
+-----------------
+
+A :class:`MultiFile` instance has the following methods:
+
+
+.. method:: MultiFile.readline(str)
+
+   Read a line.  If the line is data (not a section-divider or end-marker or real
+   EOF) return it.  If the line matches the most-recently-stacked boundary, return
+   ``''`` and set ``self.last`` to 1 or 0 according as the match is or is not an
+   end-marker.  If the line matches any other stacked boundary, raise an error.  On
+   encountering end-of-file on the underlying stream object, the method raises
+   :exc:`Error` unless all boundaries have been popped.
+
+
+.. method:: MultiFile.readlines(str)
+
+   Return all lines remaining in this part as a list of strings.
+
+
+.. method:: MultiFile.read()
+
+   Read all lines, up to the next section.  Return them as a single (multiline)
+   string.  Note that this doesn't take a size argument!
+
+
+.. method:: MultiFile.seek(pos[, whence])
+
+   Seek.  Seek indices are relative to the start of the current section. The *pos*
+   and *whence* arguments are interpreted as for a file seek.
+
+
+.. method:: MultiFile.tell()
+
+   Return the file position relative to the start of the current section.
+
+
+.. method:: MultiFile.next()
+
+   Skip lines to the next section (that is, read lines until a section-divider or
+   end-marker has been consumed).  Return true if there is such a section, false if
+   an end-marker is seen.  Re-enable the most-recently-pushed boundary.
+
+
+.. method:: MultiFile.is_data(str)
+
+   Return true if *str* is data and false if it might be a section boundary.  As
+   written, it tests for a prefix other than ``'-``\ ``-'`` at start of line (which
+   all MIME boundaries have) but it is declared so it can be overridden in derived
+   classes.
+
+   Note that this test is used intended as a fast guard for the real boundary
+   tests; if it always returns false it will merely slow processing, not cause it
+   to fail.
+
+
+.. method:: MultiFile.push(str)
+
+   Push a boundary string.  When a decorated version of this boundary  is found as
+   an input line, it will be interpreted as a section-divider  or end-marker
+   (depending on the decoration, see :rfc:`2045`).  All subsequent reads will
+   return the empty string to indicate end-of-file, until a call to :meth:`pop`
+   removes the boundary a or :meth:`next` call reenables it.
+
+   It is possible to push more than one boundary.  Encountering the
+   most-recently-pushed boundary will return EOF; encountering any other
+   boundary will raise an error.
+
+
+.. method:: MultiFile.pop()
+
+   Pop a section boundary.  This boundary will no longer be interpreted as EOF.
+
+
+.. method:: MultiFile.section_divider(str)
+
+   Turn a boundary into a section-divider line.  By default, this method
+   prepends ``'--'`` (which MIME section boundaries have) but it is declared so
+   it can be overridden in derived classes.  This method need not append LF or
+   CR-LF, as comparison with the result ignores trailing whitespace.
+
+
+.. method:: MultiFile.end_marker(str)
+
+   Turn a boundary string into an end-marker line.  By default, this method
+   prepends ``'--'`` and appends ``'--'`` (like a MIME-multipart end-of-message
+   marker) but it is declared so it can be overridden in derived classes.  This
+   method need not append LF or CR-LF, as comparison with the result ignores
+   trailing whitespace.
+
+Finally, :class:`MultiFile` instances have two public instance variables:
+
+
+.. attribute:: MultiFile.level
+
+   Nesting depth of the current part.
+
+
+.. attribute:: MultiFile.last
+
+   True if the last end-of-file was for an end-of-message marker.
+
+
+.. _multifile-example:
+
+:class:`MultiFile` Example
+--------------------------
+
+.. sectionauthor:: Skip Montanaro <skip@pobox.com>
+
+
+::
+
+   import mimetools
+   import multifile
+   import StringIO
+
+   def extract_mime_part_matching(stream, mimetype):
+       """Return the first element in a multipart MIME message on stream
+       matching mimetype."""
+
+       msg = mimetools.Message(stream)
+       msgtype = msg.gettype()
+       params = msg.getplist()
+
+       data = StringIO.StringIO()
+       if msgtype[:10] == "multipart/":
+
+           file = multifile.MultiFile(stream)
+           file.push(msg.getparam("boundary"))
+           while file.next():
+               submsg = mimetools.Message(file)
+               try:
+                   data = StringIO.StringIO()
+                   mimetools.decode(file, data, submsg.getencoding())
+               except ValueError:
+                   continue
+               if submsg.gettype() == mimetype:
+                   break
+           file.pop()
+       return data.getvalue()
+