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