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+
+: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::
+
+ Module :mod:`ConfigParser`
+ 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;
+