2007-08-15 11:28:01 -03:00
|
|
|
|
|
|
|
:mod:`shlex` --- Simple lexical analysis
|
|
|
|
========================================
|
|
|
|
|
|
|
|
.. module:: shlex
|
|
|
|
:synopsis: Simple lexical analysis for Unix shell-like languages.
|
|
|
|
.. moduleauthor:: Eric S. Raymond <esr@snark.thyrsus.com>
|
|
|
|
.. moduleauthor:: Gustavo Niemeyer <niemeyer@conectiva.com>
|
|
|
|
.. sectionauthor:: Eric S. Raymond <esr@snark.thyrsus.com>
|
|
|
|
.. sectionauthor:: Gustavo Niemeyer <niemeyer@conectiva.com>
|
|
|
|
|
|
|
|
|
|
|
|
.. versionadded:: 1.5.2
|
|
|
|
|
|
|
|
The :class:`shlex` class makes it easy to write lexical analyzers for simple
|
|
|
|
syntaxes resembling that of the Unix shell. This will often be useful for
|
|
|
|
writing minilanguages, (for example, in run control files for Python
|
|
|
|
applications) or for parsing quoted strings.
|
|
|
|
|
|
|
|
.. note::
|
|
|
|
|
|
|
|
The :mod:`shlex` module currently does not support Unicode input.
|
|
|
|
|
|
|
|
The :mod:`shlex` module defines the following functions:
|
|
|
|
|
|
|
|
|
|
|
|
.. function:: split(s[, comments[, posix]])
|
|
|
|
|
|
|
|
Split the string *s* using shell-like syntax. If *comments* is :const:`False`
|
|
|
|
(the default), the parsing of comments in the given string will be disabled
|
|
|
|
(setting the :attr:`commenters` member of the :class:`shlex` instance to the
|
|
|
|
empty string). This function operates in POSIX mode by default, but uses
|
|
|
|
non-POSIX mode if the *posix* argument is false.
|
|
|
|
|
|
|
|
.. versionadded:: 2.3
|
|
|
|
|
|
|
|
.. versionchanged:: 2.6
|
|
|
|
Added the *posix* parameter.
|
|
|
|
|
|
|
|
.. note::
|
|
|
|
|
|
|
|
Since the :func:`split` function instantiates a :class:`shlex` instance, passing
|
|
|
|
``None`` for *s* will read the string to split from standard input.
|
|
|
|
|
|
|
|
The :mod:`shlex` module defines the following class:
|
|
|
|
|
|
|
|
|
|
|
|
.. class:: shlex([instream[, infile[, posix]]])
|
|
|
|
|
|
|
|
A :class:`shlex` instance or subclass instance is a lexical analyzer object.
|
|
|
|
The initialization argument, if present, specifies where to read characters
|
|
|
|
from. It must be a file-/stream-like object with :meth:`read` and
|
|
|
|
:meth:`readline` methods, or a string (strings are accepted since Python 2.3).
|
|
|
|
If no argument is given, input will be taken from ``sys.stdin``. The second
|
|
|
|
optional argument is a filename string, which sets the initial value of the
|
|
|
|
:attr:`infile` member. If the *instream* argument is omitted or equal to
|
|
|
|
``sys.stdin``, this second argument defaults to "stdin". The *posix* argument
|
|
|
|
was introduced in Python 2.3, and defines the operational mode. When *posix* is
|
|
|
|
not true (default), the :class:`shlex` instance will operate in compatibility
|
|
|
|
mode. When operating in POSIX mode, :class:`shlex` will try to be as close as
|
|
|
|
possible to the POSIX shell parsing rules.
|
|
|
|
|
|
|
|
|
|
|
|
.. seealso::
|
|
|
|
|
2008-05-25 04:25:25 -03:00
|
|
|
Module :mod:`ConfigParser`
|
2007-08-15 11:28:01 -03:00
|
|
|
Parser for configuration files similar to the Windows :file:`.ini` files.
|
|
|
|
|
|
|
|
|
|
|
|
.. _shlex-objects:
|
|
|
|
|
|
|
|
shlex Objects
|
|
|
|
-------------
|
|
|
|
|
|
|
|
A :class:`shlex` instance has the following methods:
|
|
|
|
|
|
|
|
|
|
|
|
.. method:: shlex.get_token()
|
|
|
|
|
|
|
|
Return a token. If tokens have been stacked using :meth:`push_token`, pop a
|
|
|
|
token off the stack. Otherwise, read one from the input stream. If reading
|
|
|
|
encounters an immediate end-of-file, :attr:`self.eof` is returned (the empty
|
|
|
|
string (``''``) in non-POSIX mode, and ``None`` in POSIX mode).
|
|
|
|
|
|
|
|
|
|
|
|
.. method:: shlex.push_token(str)
|
|
|
|
|
|
|
|
Push the argument onto the token stack.
|
|
|
|
|
|
|
|
|
|
|
|
.. method:: shlex.read_token()
|
|
|
|
|
|
|
|
Read a raw token. Ignore the pushback stack, and do not interpret source
|
|
|
|
requests. (This is not ordinarily a useful entry point, and is documented here
|
|
|
|
only for the sake of completeness.)
|
|
|
|
|
|
|
|
|
|
|
|
.. method:: shlex.sourcehook(filename)
|
|
|
|
|
|
|
|
When :class:`shlex` detects a source request (see :attr:`source` below) this
|
|
|
|
method is given the following token as argument, and expected to return a tuple
|
|
|
|
consisting of a filename and an open file-like object.
|
|
|
|
|
|
|
|
Normally, this method first strips any quotes off the argument. If the result
|
|
|
|
is an absolute pathname, or there was no previous source request in effect, or
|
|
|
|
the previous source was a stream (such as ``sys.stdin``), the result is left
|
|
|
|
alone. Otherwise, if the result is a relative pathname, the directory part of
|
|
|
|
the name of the file immediately before it on the source inclusion stack is
|
|
|
|
prepended (this behavior is like the way the C preprocessor handles ``#include
|
|
|
|
"file.h"``).
|
|
|
|
|
|
|
|
The result of the manipulations is treated as a filename, and returned as the
|
|
|
|
first component of the tuple, with :func:`open` called on it to yield the second
|
|
|
|
component. (Note: this is the reverse of the order of arguments in instance
|
|
|
|
initialization!)
|
|
|
|
|
|
|
|
This hook is exposed so that you can use it to implement directory search paths,
|
|
|
|
addition of file extensions, and other namespace hacks. There is no
|
|
|
|
corresponding 'close' hook, but a shlex instance will call the :meth:`close`
|
|
|
|
method of the sourced input stream when it returns EOF.
|
|
|
|
|
|
|
|
For more explicit control of source stacking, use the :meth:`push_source` and
|
|
|
|
:meth:`pop_source` methods.
|
|
|
|
|
|
|
|
|
|
|
|
.. method:: shlex.push_source(stream[, filename])
|
|
|
|
|
|
|
|
Push an input source stream onto the input stack. If the filename argument is
|
|
|
|
specified it will later be available for use in error messages. This is the
|
|
|
|
same method used internally by the :meth:`sourcehook` method.
|
|
|
|
|
|
|
|
.. versionadded:: 2.1
|
|
|
|
|
|
|
|
|
|
|
|
.. method:: shlex.pop_source()
|
|
|
|
|
|
|
|
Pop the last-pushed input source from the input stack. This is the same method
|
|
|
|
used internally when the lexer reaches EOF on a stacked input stream.
|
|
|
|
|
|
|
|
.. versionadded:: 2.1
|
|
|
|
|
|
|
|
|
|
|
|
.. method:: shlex.error_leader([file[, line]])
|
|
|
|
|
|
|
|
This method generates an error message leader in the format of a Unix C compiler
|
|
|
|
error label; the format is ``'"%s", line %d: '``, where the ``%s`` is replaced
|
|
|
|
with the name of the current source file and the ``%d`` with the current input
|
|
|
|
line number (the optional arguments can be used to override these).
|
|
|
|
|
|
|
|
This convenience is provided to encourage :mod:`shlex` users to generate error
|
|
|
|
messages in the standard, parseable format understood by Emacs and other Unix
|
|
|
|
tools.
|
|
|
|
|
|
|
|
Instances of :class:`shlex` subclasses have some public instance variables which
|
|
|
|
either control lexical analysis or can be used for debugging:
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.commenters
|
|
|
|
|
|
|
|
The string of characters that are recognized as comment beginners. All
|
|
|
|
characters from the comment beginner to end of line are ignored. Includes just
|
|
|
|
``'#'`` by default.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.wordchars
|
|
|
|
|
|
|
|
The string of characters that will accumulate into multi-character tokens. By
|
|
|
|
default, includes all ASCII alphanumerics and underscore.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.whitespace
|
|
|
|
|
|
|
|
Characters that will be considered whitespace and skipped. Whitespace bounds
|
|
|
|
tokens. By default, includes space, tab, linefeed and carriage-return.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.escape
|
|
|
|
|
|
|
|
Characters that will be considered as escape. This will be only used in POSIX
|
|
|
|
mode, and includes just ``'\'`` by default.
|
|
|
|
|
|
|
|
.. versionadded:: 2.3
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.quotes
|
|
|
|
|
|
|
|
Characters that will be considered string quotes. The token accumulates until
|
|
|
|
the same quote is encountered again (thus, different quote types protect each
|
|
|
|
other as in the shell.) By default, includes ASCII single and double quotes.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.escapedquotes
|
|
|
|
|
|
|
|
Characters in :attr:`quotes` that will interpret escape characters defined in
|
|
|
|
:attr:`escape`. This is only used in POSIX mode, and includes just ``'"'`` by
|
|
|
|
default.
|
|
|
|
|
|
|
|
.. versionadded:: 2.3
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.whitespace_split
|
|
|
|
|
|
|
|
If ``True``, tokens will only be split in whitespaces. This is useful, for
|
|
|
|
example, for parsing command lines with :class:`shlex`, getting tokens in a
|
|
|
|
similar way to shell arguments.
|
|
|
|
|
|
|
|
.. versionadded:: 2.3
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.infile
|
|
|
|
|
|
|
|
The name of the current input file, as initially set at class instantiation time
|
|
|
|
or stacked by later source requests. It may be useful to examine this when
|
|
|
|
constructing error messages.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.instream
|
|
|
|
|
|
|
|
The input stream from which this :class:`shlex` instance is reading characters.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.source
|
|
|
|
|
|
|
|
This member is ``None`` by default. If you assign a string to it, that string
|
|
|
|
will be recognized as a lexical-level inclusion request similar to the
|
|
|
|
``source`` keyword in various shells. That is, the immediately following token
|
|
|
|
will opened as a filename and input taken from that stream until EOF, at which
|
|
|
|
point the :meth:`close` method of that stream will be called and the input
|
|
|
|
source will again become the original input stream. Source requests may be
|
|
|
|
stacked any number of levels deep.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.debug
|
|
|
|
|
|
|
|
If this member is numeric and ``1`` or more, a :class:`shlex` instance will
|
|
|
|
print verbose progress output on its behavior. If you need to use this, you can
|
|
|
|
read the module source code to learn the details.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.lineno
|
|
|
|
|
|
|
|
Source line number (count of newlines seen so far plus one).
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.token
|
|
|
|
|
|
|
|
The token buffer. It may be useful to examine this when catching exceptions.
|
|
|
|
|
|
|
|
|
|
|
|
.. attribute:: shlex.eof
|
|
|
|
|
|
|
|
Token used to determine end of file. This will be set to the empty string
|
|
|
|
(``''``), in non-POSIX mode, and to ``None`` in POSIX mode.
|
|
|
|
|
|
|
|
.. versionadded:: 2.3
|
|
|
|
|
|
|
|
|
|
|
|
.. _shlex-parsing-rules:
|
|
|
|
|
|
|
|
Parsing Rules
|
|
|
|
-------------
|
|
|
|
|
|
|
|
When operating in non-POSIX mode, :class:`shlex` will try to obey to the
|
|
|
|
following rules.
|
|
|
|
|
|
|
|
* Quote characters are not recognized within words (``Do"Not"Separate`` is
|
|
|
|
parsed as the single word ``Do"Not"Separate``);
|
|
|
|
|
|
|
|
* Escape characters are not recognized;
|
|
|
|
|
|
|
|
* Enclosing characters in quotes preserve the literal value of all characters
|
|
|
|
within the quotes;
|
|
|
|
|
|
|
|
* Closing quotes separate words (``"Do"Separate`` is parsed as ``"Do"`` and
|
|
|
|
``Separate``);
|
|
|
|
|
|
|
|
* If :attr:`whitespace_split` is ``False``, any character not declared to be a
|
|
|
|
word character, whitespace, or a quote will be returned as a single-character
|
|
|
|
token. If it is ``True``, :class:`shlex` will only split words in whitespaces;
|
|
|
|
|
|
|
|
* EOF is signaled with an empty string (``''``);
|
|
|
|
|
|
|
|
* It's not possible to parse empty strings, even if quoted.
|
|
|
|
|
|
|
|
When operating in POSIX mode, :class:`shlex` will try to obey to the following
|
|
|
|
parsing rules.
|
|
|
|
|
|
|
|
* Quotes are stripped out, and do not separate words (``"Do"Not"Separate"`` is
|
|
|
|
parsed as the single word ``DoNotSeparate``);
|
|
|
|
|
|
|
|
* Non-quoted escape characters (e.g. ``'\'``) preserve the literal value of the
|
|
|
|
next character that follows;
|
|
|
|
|
|
|
|
* Enclosing characters in quotes which are not part of :attr:`escapedquotes`
|
|
|
|
(e.g. ``"'"``) preserve the literal value of all characters within the quotes;
|
|
|
|
|
|
|
|
* Enclosing characters in quotes which are part of :attr:`escapedquotes` (e.g.
|
|
|
|
``'"'``) preserves the literal value of all characters within the quotes, with
|
|
|
|
the exception of the characters mentioned in :attr:`escape`. The escape
|
|
|
|
characters retain its special meaning only when followed by the quote in use, or
|
|
|
|
the escape character itself. Otherwise the escape character will be considered a
|
|
|
|
normal character.
|
|
|
|
|
|
|
|
* EOF is signaled with a :const:`None` value;
|
|
|
|
|
|
|
|
* Quoted empty strings (``''``) are allowed;
|
|
|
|
|