158 lines
4.6 KiB
Python
158 lines
4.6 KiB
Python
"""A readline()-style interface to the parts of a multipart message.
|
|
|
|
The MultiFile class 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 bookkeeping
|
|
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.
|
|
"""
|
|
|
|
__all__ = ["MultiFile","Error"]
|
|
|
|
class Error(Exception):
|
|
pass
|
|
|
|
class MultiFile:
|
|
|
|
seekable = 0
|
|
|
|
def __init__(self, fp, seekable=1):
|
|
self.fp = fp
|
|
self.stack = []
|
|
self.level = 0
|
|
self.last = 0
|
|
if seekable:
|
|
self.seekable = 1
|
|
self.start = self.fp.tell()
|
|
self.posstack = []
|
|
|
|
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
|
|
marker = line.rstrip()
|
|
# No? OK, try to match a boundary.
|
|
# Return the line (unstripped) if we don't.
|
|
for i, sep in enumerate(reversed(self.stack)):
|
|
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 ''.join(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.append(sep)
|
|
if self.seekable:
|
|
self.posstack.append(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)
|
|
self.stack.pop()
|
|
if self.seekable:
|
|
self.start = self.posstack.pop()
|
|
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 + "--"
|