360 lines
12 KiB
Python
360 lines
12 KiB
Python
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"""Helper class to quickly write a loop over all standard input files.
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Typical use is:
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import fileinput
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for line in fileinput.input():
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process(line)
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This iterates over the lines of all files listed in sys.argv[1:],
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defaulting to sys.stdin if the list is empty. If a filename is '-' it
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is also replaced by sys.stdin. To specify an alternative list of
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filenames, pass it as the argument to input(). A single file name is
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also allowed.
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Functions filename(), lineno() return the filename and cumulative line
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number of the line that has just been read; filelineno() returns its
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line number in the current file; isfirstline() returns true iff the
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line just read is the first line of its file; isstdin() returns true
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iff the line was read from sys.stdin. Function nextfile() closes the
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current file so that the next iteration will read the first line from
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the next file (if any); lines not read from the file will not count
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towards the cumulative line count; the filename is not changed until
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after the first line of the next file has been read. Function close()
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closes the sequence.
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Before any lines have been read, filename() returns None and both line
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numbers are zero; nextfile() has no effect. After all lines have been
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read, filename() and the line number functions return the values
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pertaining to the last line read; nextfile() has no effect.
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All files are opened in text mode. If an I/O error occurs during
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opening or reading a file, the IOError exception is raised.
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If sys.stdin is used more than once, the second and further use will
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return no lines, except perhaps for interactive use, or if it has been
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explicitly reset (e.g. using sys.stdin.seek(0)).
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Empty files are opened and immediately closed; the only time their
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presence in the list of filenames is noticeable at all is when the
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last file opened is empty.
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It is possible that the last line of a file doesn't end in a newline
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character; otherwise lines are returned including the trailing
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newline.
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Class FileInput is the implementation; its methods filename(),
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lineno(), fileline(), isfirstline(), isstdin(), nextfile() and close()
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correspond to the functions in the module. In addition it has a
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readline() method which returns the next input line, and a
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__getitem__() method which implements the sequence behavior. The
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sequence must be accessed in strictly sequential order; sequence
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access and readline() cannot be mixed.
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Optional in-place filtering: if the keyword argument inplace=1 is
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passed to input() or to the FileInput constructor, the file is moved
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to a backup file and standard output is directed to the input file.
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This makes it possible to write a filter that rewrites its input file
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in place. If the keyword argument backup=".<some extension>" is also
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given, it specifies the extension for the backup file, and the backup
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file remains around; by default, the extension is ".bak" and it is
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deleted when the output file is closed. In-place filtering is
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disabled when standard input is read. XXX The current implementation
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does not work for MS-DOS 8+3 filesystems.
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Performance: this module is unfortunately one of the slower ways of
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processing large numbers of input lines. Nevertheless, a significant
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speed-up has been obtained by using readlines(bufsize) instead of
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readline(). A new keyword argument, bufsize=N, is present on the
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input() function and the FileInput() class to override the default
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buffer size.
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XXX Possible additions:
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- optional getopt argument processing
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- specify open mode ('r' or 'rb')
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- fileno()
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- isatty()
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- read(), read(size), even readlines()
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"""
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import sys, os
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__all__ = ["input","close","nextfile","filename","lineno","filelineno",
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"isfirstline","isstdin","FileInput"]
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_state = None
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DEFAULT_BUFSIZE = 8*1024
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def input(files=None, inplace=0, backup="", bufsize=0):
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"""input([files[, inplace[, backup]]])
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Create an instance of the FileInput class. The instance will be used
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as global state for the functions of this module, and is also returned
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to use during iteration. The parameters to this function will be passed
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along to the constructor of the FileInput class.
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"""
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global _state
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if _state and _state._file:
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raise RuntimeError, "input() already active"
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_state = FileInput(files, inplace, backup, bufsize)
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return _state
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def close():
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"""Close the sequence."""
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global _state
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state = _state
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_state = None
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if state:
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state.close()
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def nextfile():
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"""
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Close the current file so that the next iteration will read the first
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line from the next file (if any); lines not read from the file will
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not count towards the cumulative line count. The filename is not
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changed until after the first line of the next file has been read.
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Before the first line has been read, this function has no effect;
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it cannot be used to skip the first file. After the last line of the
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last file has been read, this function has no effect.
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"""
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if not _state:
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raise RuntimeError, "no active input()"
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return _state.nextfile()
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def filename():
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"""
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Return the name of the file currently being read.
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Before the first line has been read, returns None.
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"""
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if not _state:
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raise RuntimeError, "no active input()"
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return _state.filename()
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def lineno():
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"""
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Return the cumulative line number of the line that has just been read.
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Before the first line has been read, returns 0. After the last line
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of the last file has been read, returns the line number of that line.
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"""
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if not _state:
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raise RuntimeError, "no active input()"
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return _state.lineno()
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def filelineno():
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"""
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Return the line number in the current file. Before the first line
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has been read, returns 0. After the last line of the last file has
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been read, returns the line number of that line within the file.
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"""
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if not _state:
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raise RuntimeError, "no active input()"
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return _state.filelineno()
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def isfirstline():
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"""
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Returns true the line just read is the first line of its file,
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otherwise returns false.
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"""
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if not _state:
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raise RuntimeError, "no active input()"
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return _state.isfirstline()
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def isstdin():
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"""
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Returns true if the last line was read from sys.stdin,
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otherwise returns false.
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"""
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if not _state:
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raise RuntimeError, "no active input()"
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return _state.isstdin()
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class FileInput:
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"""class FileInput([files[, inplace[, backup]]])
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Class FileInput is the implementation of the module; its methods
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filename(), lineno(), fileline(), isfirstline(), isstdin(), nextfile()
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and close() correspond to the functions of the same name in the module.
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In addition it has a readline() method which returns the next
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input line, and a __getitem__() method which implements the
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sequence behavior. The sequence must be accessed in strictly
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sequential order; random access and readline() cannot be mixed.
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"""
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def __init__(self, files=None, inplace=0, backup="", bufsize=0):
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if isinstance(files, basestring):
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files = (files,)
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else:
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if files is None:
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files = sys.argv[1:]
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if not files:
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files = ('-',)
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else:
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files = tuple(files)
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self._files = files
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self._inplace = inplace
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self._backup = backup
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self._bufsize = bufsize or DEFAULT_BUFSIZE
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self._savestdout = None
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self._output = None
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self._filename = None
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self._lineno = 0
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self._filelineno = 0
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self._file = None
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self._isstdin = False
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self._backupfilename = None
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self._buffer = []
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self._bufindex = 0
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def __del__(self):
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self.close()
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def close(self):
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self.nextfile()
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self._files = ()
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def __iter__(self):
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return self
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def next(self):
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try:
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line = self._buffer[self._bufindex]
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except IndexError:
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pass
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else:
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self._bufindex += 1
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self._lineno += 1
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self._filelineno += 1
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return line
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line = self.readline()
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if not line:
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raise StopIteration
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return line
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def __getitem__(self, i):
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if i != self._lineno:
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raise RuntimeError, "accessing lines out of order"
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try:
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return self.next()
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except StopIteration:
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raise IndexError, "end of input reached"
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def nextfile(self):
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savestdout = self._savestdout
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self._savestdout = 0
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if savestdout:
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sys.stdout = savestdout
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output = self._output
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self._output = 0
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if output:
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output.close()
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file = self._file
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self._file = 0
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if file and not self._isstdin:
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file.close()
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backupfilename = self._backupfilename
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self._backupfilename = 0
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if backupfilename and not self._backup:
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try: os.unlink(backupfilename)
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except OSError: pass
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self._isstdin = False
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self._buffer = []
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self._bufindex = 0
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def readline(self):
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try:
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line = self._buffer[self._bufindex]
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except IndexError:
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pass
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else:
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self._bufindex += 1
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self._lineno += 1
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self._filelineno += 1
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return line
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if not self._file:
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if not self._files:
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return ""
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self._filename = self._files[0]
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self._files = self._files[1:]
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self._filelineno = 0
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self._file = None
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self._isstdin = False
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self._backupfilename = 0
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if self._filename == '-':
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self._filename = '<stdin>'
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self._file = sys.stdin
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self._isstdin = True
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else:
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if self._inplace:
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self._backupfilename = (
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self._filename + (self._backup or os.extsep+"bak"))
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try: os.unlink(self._backupfilename)
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except os.error: pass
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# The next few lines may raise IOError
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os.rename(self._filename, self._backupfilename)
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self._file = open(self._backupfilename, "r")
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try:
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perm = os.fstat(self._file.fileno()).st_mode
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except OSError:
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self._output = open(self._filename, "w")
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else:
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fd = os.open(self._filename,
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os.O_CREAT | os.O_WRONLY | os.O_TRUNC,
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perm)
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self._output = os.fdopen(fd, "w")
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try:
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if hasattr(os, 'chmod'):
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os.chmod(self._filename, perm)
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except OSError:
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pass
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self._savestdout = sys.stdout
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sys.stdout = self._output
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else:
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# This may raise IOError
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self._file = open(self._filename, "r")
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self._buffer = self._file.readlines(self._bufsize)
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self._bufindex = 0
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if not self._buffer:
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self.nextfile()
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# Recursive call
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return self.readline()
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def filename(self):
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return self._filename
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def lineno(self):
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return self._lineno
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def filelineno(self):
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return self._filelineno
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def isfirstline(self):
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return self._filelineno == 1
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def isstdin(self):
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return self._isstdin
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def _test():
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import getopt
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inplace = 0
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backup = 0
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opts, args = getopt.getopt(sys.argv[1:], "ib:")
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for o, a in opts:
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if o == '-i': inplace = 1
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if o == '-b': backup = a
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for line in input(args, inplace=inplace, backup=backup):
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if line[-1:] == '\n': line = line[:-1]
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if line[-1:] == '\r': line = line[:-1]
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print "%d: %s[%d]%s %s" % (lineno(), filename(), filelineno(),
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isfirstline() and "*" or "", line)
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print "%d: %s[%d]" % (lineno(), filename(), filelineno())
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if __name__ == '__main__':
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_test()
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