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/Lib/MimeWriter.py

http://unladen-swallow.googlecode.com/
Python | 186 lines | 177 code | 1 blank | 8 comment | 2 complexity | 6a4b871453b8741976865d5626bbfb82 MD5 | raw file
  1"""Generic MIME writer.
  2
  3This module defines the class MimeWriter.  The MimeWriter class implements
  4a basic formatter for creating MIME multi-part files.  It doesn't seek around
  5the output file nor does it use large amounts of buffer space. You must write
  6the parts out in the order that they should occur in the final file.
  7MimeWriter does buffer the headers you add, allowing you to rearrange their
  8order.
  9
 10"""
 11
 12
 13import mimetools
 14
 15__all__ = ["MimeWriter"]
 16
 17import warnings
 18
 19warnings.warn("the MimeWriter module is deprecated; use the email package instead",
 20                DeprecationWarning, 2)
 21
 22class 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
185if __name__ == '__main__':
186    import test.test_MimeWriter