Lib/MimeWriter.py

   1 """Generic MIME writer.
   2
   3 This module defines the class MimeWriter.  The MimeWriter class implements
   4 a basic formatter for creating MIME multi-part files.  It doesn't seek around
   5 the output file nor does it use large amounts of buffer space. You must write
   6 the parts out in the order that they should occur in the final file.
   7 MimeWriter does buffer the headers you add, allowing you to rearrange their
   8 order.
   9
  10 """
  11
  12
  13 import mimetools
  14
  15 __all__ = ["MimeWriter"]
  16
  17 import warnings
  18
  19 warnings.warn("the MimeWriter module is deprecated; use the email package instead",
  20                 DeprecationWarning, 2)
  21
  22 class MimeWriter:
  23
  24     """Generic MIME writer.
  25
  26     Methods:
  27
  28     __init__()
  29     addheader()
  30     flushheaders()
  31     startbody()
  32     startmultipartbody()
  33     nextpart()
  34     lastpart()
  35
  36     A MIME writer is much more primitive than a MIME parser.  It
  37     doesn't seek around on the output file, and it doesn't use large
  38     amounts of buffer space, so you have to write the parts in the
  39     order they should occur on the output file.  It does buffer the
  40     headers you add, allowing you to rearrange their order.
  41
  42     General usage is:
  43
  44     f = <open the output file>
  45     w = MimeWriter(f)
  46     ...call w.addheader(key, value) 0 or more times...
  47
  48     followed by either:
  49
  50     f = w.startbody(content_type)
  51     ...call f.write(data) for body data...
  52
  53     or:
  54
  55     w.startmultipartbody(subtype)
  56     for each part:
  57         subwriter = w.nextpart()
  58         ...use the subwriter's methods to create the subpart...
  59     w.lastpart()
  60
  61     The subwriter is another MimeWriter instance, and should be
  62     treated in the same way as the toplevel MimeWriter.  This way,
  63     writing recursive body parts is easy.
  64
  65     Warning: don't forget to call lastpart()!
  66
  67     XXX There should be more state so calls made in the wrong order
  68     are detected.
  69
  70     Some special cases:
  71
  72     - startbody() just returns the file passed to the constructor;
  73       but don't use this knowledge, as it may be changed.
  74
  75     - startmultipartbody() actually returns a file as well;
  76       this can be used to write the initial 'if you can read this your
  77       mailer is not MIME-aware' message.
  78
  79     - If you call flushheaders(), the headers accumulated so far are
  80       written out (and forgotten); this is useful if you don't need a
  81       body part at all, e.g. for a subpart of type message/rfc822
  82       that's (mis)used to store some header-like information.
  83
  84     - Passing a keyword argument 'prefix=<flag>' to addheader(),
  85       start*body() affects where the header is inserted; 0 means
  86       append at the end, 1 means insert at the start; default is
  87       append for addheader(), but insert for start*body(), which use
  88       it to determine where the Content-Type header goes.
  89
  90     """
  91
  92     def __init__(self, fp):
  93         self._fp = fp
  94         self._headers = []
  95
  96     def addheader(self, key, value, prefix=0):
  97         """Add a header line to the MIME message.
  98
  99         The key is the name of the header, where the value obviously provides
 100         the value of the header. The optional argument prefix determines
 101         where the header is inserted; 0 means append at the end, 1 means
 102         insert at the start. The default is to append.
 103
 104         """
 105         lines = value.split("\n")
 106         while lines and not lines[-1]: del lines[-1]
 107         while lines and not lines[0]: del lines[0]
 108         for i in range(1, len(lines)):
 109             lines[i] = "    " + lines[i].strip()
 110         value = "\n".join(lines) + "\n"
 111         line = key + ": " + value
 112         if prefix:
 113             self._headers.insert(0, line)
 114         else:
 115             self._headers.append(line)
 116
 117     def flushheaders(self):
 118         """Writes out and forgets all headers accumulated so far.
 119
 120         This is useful if you don't need a body part at all; for example,
 121         for a subpart of type message/rfc822 that's (mis)used to store some
 122         header-like information.
 123
 124         """
 125         self._fp.writelines(self._headers)
 126         self._headers = []
 127
 128     def startbody(self, ctype, plist=[], prefix=1):
 129         """Returns a file-like object for writing the body of the message.
 130
 131         The content-type is set to the provided ctype, and the optional
 132         parameter, plist, provides additional parameters for the
 133         content-type declaration.  The optional argument prefix determines
 134         where the header is inserted; 0 means append at the end, 1 means
 135         insert at the start. The default is to insert at the start.
 136
 137         """
 138         for name, value in plist:
 139             ctype = ctype + ';\n %s=\"%s\"' % (name, value)
 140         self.addheader("Content-Type", ctype, prefix=prefix)
 141         self.flushheaders()
 142         self._fp.write("\n")
 143         return self._fp
 144
 145     def startmultipartbody(self, subtype, boundary=None, plist=[], prefix=1):
 146         """Returns a file-like object for writing the body of the message.
 147
 148         Additionally, this method initializes the multi-part code, where the
 149         subtype parameter provides the multipart subtype, the boundary
 150         parameter may provide a user-defined boundary specification, and the
 151         plist parameter provides optional parameters for the subtype.  The
 152         optional argument, prefix, determines where the header is inserted;
 153         0 means append at the end, 1 means insert at the start. The default
 154         is to insert at the start.  Subparts should be created using the
 155         nextpart() method.
 156
 157         """
 158         self._boundary = boundary or mimetools.choose_boundary()
 159         return self.startbody("multipart/" + subtype,
 160                               [("boundary", self._boundary)] + plist,
 161                               prefix=prefix)
 162
 163     def nextpart(self):
 164         """Returns a new instance of MimeWriter which represents an
 165         individual part in a multipart message.
 166
 167         This may be used to write the part as well as used for creating
 168         recursively complex multipart messages. The message must first be
 169         initialized with the startmultipartbody() method before using the
 170         nextpart() method.
 171
 172         """
 173         self._fp.write("\n--" + self._boundary + "\n")
 174         return self.__class__(self._fp)
 175
 176     def lastpart(self):
 177         """This is used to designate the last part of a multipart message.
 178
 179         It should always be used when writing multipart messages.
 180
 181         """
 182         self._fp.write("\n--" + self._boundary + "--\n")
 183
 184
 185 if __name__ == '__main__':
 186     import test.test_MimeWriter