cpython/Lib/fileinput.py at 3.15 · python/cpython · GitHub

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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(encoding="utf-8"):

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 and the optional arguments mode and

openhook are ignored. 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 by default, you can override this by

setting the mode parameter to input() or FileInput.__init__().

If an I/O error occurs during opening or reading a file, the OSError

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=True 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.

"""

import io

import sys, os

from types import GenericAlias

__all__ = ["input", "close", "nextfile", "filename", "lineno", "filelineno",

"fileno", "isfirstline", "isstdin", "FileInput", "hook_compressed",

"hook_encoded"]

_state = None

def input(files=None, inplace=False, backup="", *, mode="r", openhook=None,

encoding=None, errors=None):

"""Return an instance of the FileInput class, which can be iterated.

The parameters are passed to the constructor of the FileInput class.

The returned instance, in addition to being an iterator,

keeps global state for the functions of this module,.

"""

global _state

if _state and _state._file:

raise RuntimeError("input() already active")

_state = FileInput(files, inplace, backup, mode=mode, openhook=openhook,

encoding=encoding, errors=errors)

return _state

def close():

"""Close the sequence."""

global _state

state = _state

_state = None

if state:

state.close()

def nextfile():

"""

Close 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.

Before the first line has been read, this function has no effect;

it cannot be used to skip the first file. After the last line of the

last file has been read, this function has no effect.

"""

if not _state:

raise RuntimeError("no active input()")

return _state.nextfile()

def filename():

"""

Return the name of the file currently being read.

Before the first line has been read, returns None.

"""

if not _state:

raise RuntimeError("no active input()")

return _state.filename()

def lineno():

"""

Return the cumulative line number of the line that has just been read.

Before the first line has been read, returns 0. After the last line

of the last file has been read, returns the line number of that line.

"""

if not _state:

raise RuntimeError("no active input()")

return _state.lineno()

def filelineno():

"""

Return the line number in the current file. Before the first line

has been read, returns 0. After the last line of the last file has

been read, returns the line number of that line within the file.

"""

if not _state:

raise RuntimeError("no active input()")

return _state.filelineno()

def fileno():

"""

Return the file number of the current file. When no file is currently

opened, returns -1.

"""

if not _state:

raise RuntimeError("no active input()")

return _state.fileno()

def isfirstline():

"""

Returns true the line just read is the first line of its file,

otherwise returns false.

"""

if not _state:

raise RuntimeError("no active input()")

return _state.isfirstline()

def isstdin():

"""

Returns true if the last line was read from sys.stdin,

otherwise returns false.

"""

if not _state:

raise RuntimeError("no active input()")

return _state.isstdin()

class FileInput:

"""FileInput([files[, inplace[, backup]]], *, mode=None, openhook=None)

Class FileInput is the implementation of the module; its methods

filename(), lineno(), fileline(), isfirstline(), isstdin(), fileno(),

nextfile() and close() correspond to the functions of the same name

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; random access and readline() cannot be mixed.

"""

def __init__(self, files=None, inplace=False, backup="", *,

mode="r", openhook=None, encoding=None, errors=None):

if isinstance(files, str):

files = (files,)

elif isinstance(files, os.PathLike):

files = (os.fspath(files), )

else:

if files is None:

files = sys.argv[1:]

if not files:

files = ('-',)

else:

files = tuple(files)

self._files = files

self._inplace = inplace

self._backup = backup

self._savestdout = None

self._output = None

self._filename = None

self._startlineno = 0

self._filelineno = 0

self._file = None

self._isstdin = False

self._backupfilename = None

self._encoding = encoding

self._errors = errors

# We can not use io.text_encoding() here because old openhook doesn't

# take encoding parameter.

if (sys.flags.warn_default_encoding and

"b" not in mode and encoding is None and openhook is None):

import warnings

warnings.warn("'encoding' argument not specified.",

EncodingWarning, 2)

# restrict mode argument to reading modes

if mode not in ('r', 'rb'):

raise ValueError("FileInput opening mode must be 'r' or 'rb'")

self._mode = mode

self._write_mode = mode.replace('r', 'w')

if openhook:

if inplace:

raise ValueError("FileInput cannot use an opening hook in inplace mode")

if not callable(openhook):

raise ValueError("FileInput openhook must be callable")

self._openhook = openhook

def __del__(self):

self.close()

def close(self):

try:

self.nextfile()

finally:

self._files = ()

def __enter__(self):

return self

def __exit__(self, type, value, traceback):

self.close()

def __iter__(self):

return self

def __next__(self):

while True:

line = self._readline()

if line:

self._filelineno += 1

return line

if not self._file:

raise StopIteration

self.nextfile()

# repeat with next file

def nextfile(self):

savestdout = self._savestdout

self._savestdout = None

if savestdout:

sys.stdout = savestdout

output = self._output

self._output = None

try:

if output:

output.close()

finally:

file = self._file

self._file = None

try:

del self._readline # restore FileInput._readline

except AttributeError:

pass

try:

if file and not self._isstdin:

file.close()

finally:

backupfilename = self._backupfilename

self._backupfilename = None

if backupfilename and not self._backup:

try: os.unlink(backupfilename)

except OSError: pass

self._isstdin = False

def readline(self):

while True:

line = self._readline()

if line:

self._filelineno += 1

return line

if not self._file:

return line

self.nextfile()

# repeat with next file

def _readline(self):

if not self._files:

if 'b' in self._mode:

return b''

else:

return ''

self._filename = self._files[0]

self._files = self._files[1:]

self._startlineno = self.lineno()

self._filelineno = 0

self._file = None

self._isstdin = False

self._backupfilename = 0

# EncodingWarning is emitted in __init__() already

if "b" not in self._mode:

encoding = self._encoding or "locale"

else:

encoding = None

if self._filename == '-':

self._filename = '<stdin>'

if 'b' in self._mode:

self._file = getattr(sys.stdin, 'buffer', sys.stdin)

else:

self._file = sys.stdin

self._isstdin = True

else:

if self._inplace:

self._backupfilename = (

os.fspath(self._filename) + (self._backup or ".bak"))

try:

os.unlink(self._backupfilename)

except OSError:

pass

# The next few lines may raise OSError

os.rename(self._filename, self._backupfilename)

self._file = open(self._backupfilename, self._mode,

encoding=encoding, errors=self._errors)

try:

perm = os.fstat(self._file.fileno()).st_mode

except OSError:

self._output = open(self._filename, self._write_mode,

encoding=encoding, errors=self._errors)

else:

mode = os.O_CREAT | os.O_WRONLY | os.O_TRUNC

if hasattr(os, 'O_BINARY'):

mode |= os.O_BINARY

fd = os.open(self._filename, mode, perm)

self._output = os.fdopen(fd, self._write_mode,

encoding=encoding, errors=self._errors)

try:

os.chmod(self._filename, perm)

except OSError:

pass

self._savestdout = sys.stdout

sys.stdout = self._output

else:

# This may raise OSError

if self._openhook:

# Custom hooks made previous to Python 3.10 didn't have

# encoding argument

if self._encoding is None:

self._file = self._openhook(self._filename, self._mode)

else:

self._file = self._openhook(

self._filename, self._mode, encoding=self._encoding, errors=self._errors)

else:

self._file = open(self._filename, self._mode, encoding=encoding, errors=self._errors)

self._readline = self._file.readline # hide FileInput._readline

return self._readline()

def filename(self):

return self._filename

def lineno(self):

return self._startlineno + self._filelineno

def filelineno(self):

return self._filelineno

def fileno(self):

if self._file:

try:

return self._file.fileno()

except ValueError:

return -1

else:

return -1

def isfirstline(self):

return self._filelineno == 1

def isstdin(self):

return self._isstdin

__class_getitem__ = classmethod(GenericAlias)

def hook_compressed(filename, mode, *, encoding=None, errors=None):

if encoding is None and "b" not in mode: # EncodingWarning is emitted in FileInput() already.

encoding = "locale"

ext = os.path.splitext(filename)[1]

if ext == '.gz':

import gzip

stream = gzip.open(filename, mode)

elif ext == '.bz2':

import bz2

stream = bz2.BZ2File(filename, mode)

else:

return open(filename, mode, encoding=encoding, errors=errors)

# gzip and bz2 are binary mode by default.

if "b" not in mode:

stream = io.TextIOWrapper(stream, encoding=encoding, errors=errors)

return stream

def hook_encoded(encoding, errors=None):

def openhook(filename, mode):

return open(filename, mode, encoding=encoding, errors=errors)

return openhook

def _test():

import getopt

inplace = False

backup = False

opts, args = getopt.getopt(sys.argv[1:], "ib:")

for o, a in opts:

if o == '-i': inplace = True

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()

cpython/Lib/fileinput.py at 3.15 · python/cpython · GitHub

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