New module to support decoding multipart messages (also see mimetools).
diff --git a/Lib/multifile.py b/Lib/multifile.py
new file mode 100644
index 0000000..4dd1b52
--- /dev/null
+++ b/Lib/multifile.py
@@ -0,0 +1,118 @@
+# A class that makes each part of a multipart message "feel" like an
+# ordinary file, as long as you use fp.readline(). Allows recursive
+# use, for nested multipart messages. Probably best used together
+# with module mimetools.
+#
+# Suggested use:
+#
+# real_fp = open(...)
+# fp = MultiFile().init(real_fp)
+#
+# "read some lines from fp"
+# fp.push(separator)
+# while 1:
+# "read lines from fp until it returns an empty string" (A)
+# if not fp.next(): break
+# fp.pop()
+# "read remaining lines from fp until it returns an empty string"
+#
+# The latter sequence may be used recursively at (A).
+# It is also allowed to use multiple push()...pop() sequences.
+# Note that if a nested multipart message is terminated by a separator
+# for an outer message, this is not reported, even though it is really
+# illegal input.
+
+import sys
+import string
+
+err = sys.stderr.write
+
+Error = 'multifile.Error'
+
+class MultiFile:
+ #
+ def init(self, fp):
+ self.fp = fp
+ self.stack = [] # Grows down
+ self.level = 0
+ self.last = 0
+ self.start = self.fp.tell()
+ self.posstack = [] # Grows down
+ return self
+ #
+ def tell(self):
+ if self.level > 0:
+ return self.lastpos
+ return self.fp.tell() - self.start
+ #
+ def seek(self, pos):
+ if not 0 <= pos <= self.tell() or \
+ self.level > 0 and pos > self.lastpos:
+ raise Error, 'bad MultiFile.seek() call'
+ self.fp.seek(pos + self.start)
+ self.level = 0
+ self.last = 0
+ #
+ def readline(self):
+ if self.level > 0: return ''
+ line = self.fp.readline()
+ if not line:
+ self.level = len(self.stack)
+ self.last = (self.level > 0)
+ if self.last:
+ err('*** Sudden EOF in MultiFile.readline()\n')
+ return ''
+ if line[:2] <> '--': return line
+ n = len(line)
+ k = n
+ while k > 0 and line[k-1] in string.whitespace: k = k-1
+ mark = line[2:k]
+ if mark[-2:] == '--': mark1 = mark[:-2]
+ else: mark1 = None
+ for i in range(len(self.stack)):
+ sep = self.stack[i]
+ if sep == mark:
+ self.last = 0
+ break
+ elif mark1 <> None and sep == mark1:
+ self.last = 1
+ break
+ else:
+ return line
+ # Get here after break out of loop
+ self.lastpos = self.tell() - len(line)
+ self.level = i+1
+ if self.level > 1:
+ err('*** Missing endmarker in MultiFile.readline()\n')
+ return ''
+ #
+ def next(self):
+ while self.readline(): pass
+ if self.level > 1 or self.last:
+ return 0
+ self.level = 0
+ self.last = 0
+ self.start = self.fp.tell()
+ return 1
+ #
+ def push(self, sep):
+ if self.level > 0:
+ raise Error, 'bad MultiFile.push() call'
+ self.stack.insert(0, sep)
+ self.posstack.insert(0, self.start)
+ self.start = self.fp.tell()
+ #
+ def pop(self):
+ if self.stack == []:
+ raise Error, 'bad MultiFile.pop() call'
+ if self.level <= 1:
+ self.last = 0
+ else:
+ abslastpos = self.lastpos + self.start
+ self.level = max(0, self.level - 1)
+ del self.stack[0]
+ self.start = self.posstack[0]
+ del self.posstack[0]
+ if self.level > 0:
+ self.lastpos = abslastpos - self.start
+ #