88 lines
2.3 KiB
Python
88 lines
2.3 KiB
Python
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def _complain_ifclosed(closed):
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if closed:
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raise ValueError, "I/O operation on closed file"
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class GeneratorFile(object):
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""" File-like object which wraps a Python generator to produce the file contents.
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Modeled on StringIO and comments on the file-like interface copied from there.
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"""
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def __init__(self, generator):
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self._generator = generator
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self._closed = False
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self._buf = ''
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self._position = 0
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def __iter__(self):
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return self
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def tell(self):
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"""Return the file's current position, like stdio's ftell()."""
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_complain_ifclosed(self._closed)
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return self._position
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def next(self):
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"""A file object is its own iterator, for example iter(f) returns f
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(unless f is closed). When a file is used as an iterator, typically
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in a for loop (for example, for line in f: print line), the next()
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method is called repeatedly. This method returns the next input line,
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or raises StopIteration when EOF is hit.
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"""
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_complain_ifclosed(self._closed)
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r = self.read()
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if not r:
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raise StopIteration
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return r
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def readable(self):
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return not self._closed
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def readline(self):
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buf = []
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while True:
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c = self.read(size=1)
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buf.append(c)
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if c == '\n' or c == '':
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return ''.join(buf)
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def flush(self):
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_complain_ifclosed(self._closed)
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def read(self, size=-1):
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"""Read at most size bytes from the file
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(less if the read hits EOF before obtaining size bytes).
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If the size argument is negative or omitted, read all data until EOF
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is reached. The bytes are returned as a string object. An empty
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string is returned when EOF is encountered immediately.
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"""
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_complain_ifclosed(self._closed)
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buf = self._buf
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while size < 0 or len(buf) < size:
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try:
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buf = buf + self._generator.next()
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except StopIteration:
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break
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returned = ''
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if size >= 1:
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self._buf = buf[size:]
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returned = buf[:size]
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else:
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self._buf = ''
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returned = buf
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self._position = self._position + len(returned)
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return returned
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def seek(self):
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raise NotImplementedError
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def close(self):
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self._closed = True
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del self._buf
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def __enter__(self):
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return self
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def __exit__(self, type, value, traceback):
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self._closed = True
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