summaryrefslogtreecommitdiffstats
path: root/Lib/fileinput.py
blob: 81a7545dd87a5d5d2f6bceb0c2c92450e9398603 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
"""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 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=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.

Performance: this module is unfortunately one of the slower ways of
processing large numbers of input lines.  Nevertheless, a significant
speed-up has been obtained by using readlines(bufsize) instead of
readline().  A new keyword argument, bufsize=N, is present on the
input() function and the FileInput() class to override the default
buffer size.

XXX Possible additions:

- optional getopt argument processing
- isatty()
- read(), read(size), even readlines()

"""

import sys, os

__all__ = ["input", "close", "nextfile", "filename", "lineno", "filelineno",
           "isfirstline", "isstdin", "FileInput"]

_state = None

DEFAULT_BUFSIZE = 8*1024

def input(files=None, inplace=False, backup="", bufsize=0,
          mode="r", openhook=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, bufsize, mode, openhook)
    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[, bufsize, [, mode[, openhook]]]]]])

    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="", bufsize=0,
                 mode="r", openhook=None):
        if isinstance(files, str):
            files = (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._bufsize = bufsize or DEFAULT_BUFSIZE
        self._savestdout = None
        self._output = None
        self._filename = None
        self._lineno = 0
        self._filelineno = 0
        self._file = None
        self._isstdin = False
        self._backupfilename = None
        self._buffer = []
        self._bufindex = 0
        # restrict mode argument to reading modes
        if mode not in ('r', 'rU', 'U', 'rb'):
            raise ValueError("FileInput opening mode must be one of "
                             "'r', 'rU', 'U' and 'rb'")
        if 'U' in mode:
            import warnings
            warnings.warn("'U' mode is deprecated",
                          DeprecationWarning, 2)
        self._mode = mode
        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):
        try:
            line = self._buffer[self._bufindex]
        except IndexError:
            pass
        else:
            self._bufindex += 1
            self._lineno += 1
            self._filelineno += 1
            return line
        line = self.readline()
        if not line:
            raise StopIteration
        return line

    def __getitem__(self, i):
        if i != self._lineno:
            raise RuntimeError("accessing lines out of order")
        try:
            return self.__next__()
        except StopIteration:
            raise IndexError("end of input reached")

    def nextfile(self):
        savestdout = self._savestdout
        self._savestdout = 0
        if savestdout:
            sys.stdout = savestdout

        output = self._output
        self._output = 0
        try:
            if output:
                output.close()
        finally:
            file = self._file
            self._file = 0
            try:
                if file and not self._isstdin:
                    file.close()
            finally:
                backupfilename = self._backupfilename
                self._backupfilename = 0
                if backupfilename and not self._backup:
                    try: os.unlink(backupfilename)
                    except OSError: pass

                self._isstdin = False
                self._buffer = []
                self._bufindex = 0

    def readline(self):
        try:
            line = self._buffer[self._bufindex]
        except IndexError:
            pass
        else:
            self._bufindex += 1
            self._lineno += 1
            self._filelineno += 1
            return line
        if not self._file:
            if not self._files:
                if 'b' in self._mode:
                    return b''
                else:
                    return ''
            self._filename = self._files[0]
            self._files = self._files[1:]
            self._filelineno = 0
            self._file = None
            self._isstdin = False
            self._backupfilename = 0
            if self._filename == '-':
                self._filename = '<stdin>'
                if 'b' in self._mode:
                    self._file = sys.stdin.buffer
                else:
                    self._file = sys.stdin
                self._isstdin = True
            else:
                if self._inplace:
                    self._backupfilename = (
                        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)
                    try:
                        perm = os.fstat(self._file.fileno()).st_mode
                    except OSError:
                        self._output = open(self._filename, "w")
                    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, "w")
                        try:
                            if hasattr(os, 'chmod'):
                                os.chmod(self._filename, perm)
                        except OSError:
                            pass
                    self._savestdout = sys.stdout
                    sys.stdout = self._output
                else:
                    # This may raise OSError
                    if self._openhook:
                        self._file = self._openhook(self._filename, self._mode)
                    else:
                        self._file = open(self._filename, self._mode)
        self._buffer = self._file.readlines(self._bufsize)
        self._bufindex = 0
        if not self._buffer:
            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 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


def hook_compressed(filename, mode):
    ext = os.path.splitext(filename)[1]
    if ext == '.gz':
        import gzip
        return gzip.open(filename, mode)
    elif ext == '.bz2':
        import bz2
        return bz2.BZ2File(filename, mode)
    else:
        return open(filename, mode)


def hook_encoded(encoding):
    def openhook(filename, mode):
        return open(filename, mode, encoding=encoding)
    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()