diff options
| -rw-r--r-- | Lib/rfc822.py | 59 |
1 files changed, 52 insertions, 7 deletions
diff --git a/Lib/rfc822.py b/Lib/rfc822.py index 9e9faee..06b372a 100644 --- a/Lib/rfc822.py +++ b/Lib/rfc822.py @@ -8,11 +8,29 @@ Directions for use: To create a Message object: first open a file, e.g.: fp = open(file, 'r') -(or use any other legal way of getting an open file object, e.g. use -sys.stdin or call os.popen()). +You can use any other legal way of getting an open file object, e.g. use +sys.stdin or call os.popen(). Then pass the open file object to the Message() constructor: m = Message(fp) +This class can work with any input object that supports read and seek +methods. The initialization method which parses the message will work +even without seek capability, but in that case the final seek to the +start of the delimiter line won't take place. However, if the input +object has an `unread' method that can push back a line of input, +Message will use that to push back the delimiter line. Thus this class +can be used to parse messages coming from a buffered stream. + +The optional `seekable' argument is provided as a workaround for +certain stdio libraries in which tell() discards buffered data before +discovering that the lseek() system call doesn't work. For maximum +portability, you should set the seekable argument to zero to prevent +that initial \code{tell} when passing in an unseekable object such as +a a file object created from a socket object. If it is 1 on entry -- +which it is by default -- the tell() method of the open file object is +called once; if this raises an exception, seekable is reset to 0. For +other nonzero values of seekable, this test is not made. + To get the text of a particular header there are several methods: str = m.getheader(name) str = m.getrawheader(name) @@ -50,6 +68,15 @@ class Message: def __init__(self, fp, seekable = 1): """Initialize the class instance and read the headers.""" + if seekable == 1: + # Exercise tell() to make sure it works + # (and then assume seek() works, too) + try: + fp.tell() + except: + seekable = 0 + else: + seekable = 1 self.fp = fp self.seekable = seekable self.startofheaders = None @@ -122,6 +149,8 @@ class Message: headerseen = string.lower(line[:i]) self.dict[headerseen] = string.strip( line[i+1:]) + elif self.iscomment(line): + pass else: # It's not a header line; stop here. if not headerseen: @@ -129,11 +158,12 @@ class Message: else: self.status = 'Bad header' # Try to undo the read. - if self.seekable: + if getattr(self.fp, 'unread'): + self.fp.unread(line) + elif self.seekable: self.fp.seek(-len(line), 1) else: - self.status = \ - self.status + '; bad seek' + self.status = self.status + '; bad seek' break def islast(self, line): @@ -146,6 +176,15 @@ class Message: line consisting of \r\n also matches. """ return line in _blanklines + + def iscomment(self, line): + """Determine whether a line should be skipped entirely. + + You may override this method in order to use Message parsing + on tagged data in RFC822-like formats that support embedded + comments or free-text data. + """ + return None def getallmatchingheaders(self, name): """Find all header lines matching a given header name. @@ -208,7 +247,7 @@ class Message: list[0] = list[0][len(name) + 1:] return string.joinfields(list, '') - def getheader(self, name): + def getheader(self, name, default=None): """Get the header value for a name. This is the normal interface: it return a stripped @@ -219,7 +258,8 @@ class Message: try: return self.dict[string.lower(name)] except KeyError: - return None + return default + get = getheader def getaddr(self, name): """Get a single address from a header, as a tuple. @@ -325,6 +365,11 @@ class Message: """ return self.dict.items() + def __str__(self): + str = '' + for hdr in self.headers: + str = str + hdr + return str # Utility functions |