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