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# 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(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.
#
# If seekable is given as 0, the class code will not do the bookeeping
# it normally attempts in order to make seeks relative to the beginning of the
# current file part. This may be useful when using MultiFile with a non-
# seekable stream object.
import sys
import string
Error = 'multifile.Error'
class MultiFile:
#
seekable = 0
#
def __init__(self, fp, seekable=1):
self.fp = fp
self.stack = [] # Grows down
self.level = 0
self.last = 0
if seekable:
self.seekable = 1
self.start = self.fp.tell()
self.posstack = [] # Grows down
#
def tell(self):
if self.level > 0:
return self.lastpos
return self.fp.tell() - self.start
#
def seek(self, pos, whence=0):
here = self.tell()
if whence:
if whence == 1:
pos = pos + here
elif whence == 2:
if self.level > 0:
pos = pos + self.lastpos
else:
raise Error, "can't use whence=2 yet"
if not 0 <= pos <= here 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()
# Real EOF?
if not line:
self.level = len(self.stack)
self.last = (self.level > 0)
if self.last:
raise Error, 'sudden EOF in MultiFile.readline()'
return ''
assert self.level == 0
# Fast check to see if this is just data
if self.is_data(line):
return line
else:
# Ignore trailing whitespace on marker lines
k = len(line) - 1;
while line[k] in string.whitespace:
k = k - 1
marker = line[:k+1]
# No? OK, try to match a boundary.
# Return the line (unstripped) if we don't.
for i in range(len(self.stack)):
sep = self.stack[i]
if marker == self.section_divider(sep):
self.last = 0
break
elif marker == self.end_marker(sep):
self.last = 1
break
else:
return line
# We only get here if we see a section divider or EOM line
if self.seekable:
self.lastpos = self.tell() - len(line)
self.level = i+1
if self.level > 1:
raise Error,'Missing endmarker in MultiFile.readline()'
return ''
#
def readlines(self):
list = []
while 1:
line = self.readline()
if not line: break
list.append(line)
return list
#
def read(self): # Note: no size argument -- read until EOF only!
return string.joinfields(self.readlines(), '')
#
def next(self):
while self.readline(): pass
if self.level > 1 or self.last:
return 0
self.level = 0
self.last = 0
if self.seekable:
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)
if self.seekable:
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]
if self.seekable:
self.start = self.posstack[0]
del self.posstack[0]
if self.level > 0:
self.lastpos = abslastpos - self.start
#
def is_data(self, line):
return line[:2] <> '--'
#
def section_divider(self, str):
return "--" + str
#
def end_marker(self, str):
return "--" + str + "--"
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