81 lines
3.3 KiB
TeX
81 lines
3.3 KiB
TeX
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\section{\module{reconvert} ---
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Convert regular expressions from regex to re form}
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\declaremodule{standard}{reconvert}
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\moduleauthor{Andrew M. Kuchling}{amk@amk.ca}
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\sectionauthor{Skip Montanaro}{skip@pobox.com}
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\modulesynopsis{Convert regex-, emacs- or sed-style regular expressions
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to re-style syntax.}
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This module provides a facility to convert regular expressions from the
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syntax used by the deprecated \module{regex} module to those used by the
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newer \module{re} module. Because of similarity between the regular
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expression syntax of \code{sed(1)} and \code{emacs(1)} and the
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\module{regex} module, it is also helpful to convert patterns written for
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those tools to \module{re} patterns.
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When used as a script, a Python string literal (or any other expression
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evaluating to a string) is read from stdin, and the translated expression is
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written to stdout as a string literal. Unless stdout is a tty, no trailing
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newline is written to stdout. This is done so that it can be used with
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Emacs \code{C-U M-|} (shell-command-on-region) which filters the region
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through the shell command.
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\begin{seealso}
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\seetitle{Mastering Regular Expressions}{Book on regular expressions
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by Jeffrey Friedl, published by O'Reilly. The second
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edition of the book no longer covers Python at all,
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but the first edition covered writing good regular expression
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patterns in great detail.}
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\end{seealso}
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\subsection{Module Contents}
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\nodename{Contents of Module reconvert}
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The module defines two functions and a handful of constants.
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\begin{funcdesc}{convert}{pattern\optional{, syntax=None}}
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Convert a \var{pattern} representing a \module{regex}-stype regular
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expression into a \module{re}-style regular expression. The optional
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\var{syntax} parameter is a bitwise-or'd set of flags that control what
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constructs are converted. See below for a description of the various
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constants.
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\end{funcdesc}
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\begin{funcdesc}{quote}{s\optional{, quote=None}}
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Convert a string object to a quoted string literal.
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This is similar to \function{repr} but will return a "raw" string (r'...'
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or r"...") when the string contains backslashes, instead of doubling all
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backslashes. The resulting string does not always evaluate to the same
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string as the original; however it will do just the right thing when passed
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into re.compile().
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The optional second argument forces the string quote; it must be a single
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character which is a valid Python string quote. Note that prior to Python
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2.5 this would not accept triple-quoted string delimiters.
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\end{funcdesc}
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\begin{datadesc}{RE_NO_BK_PARENS}
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Suppress paren conversion. This should be omitted when converting
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\code{sed}-style or \code{emacs}-style regular expressions.
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\end{datadesc}
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\begin{datadesc}{RE_NO_BK_VBAR}
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Suppress vertical bar conversion. This should be omitted when converting
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\code{sed}-style or \code{emacs}-style regular expressions.
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\end{datadesc}
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\begin{datadesc}{RE_BK_PLUS_QM}
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Enable conversion of \code{+} and \code{?} characters. This should be
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added to the \var{syntax} arg of \function{convert} when converting
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\code{sed}-style regular expressions and omitted when converting
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\code{emacs}-style regular expressions.
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\end{datadesc}
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\begin{datadesc}{RE_NEWLINE_OR}
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When set, newline characters are replaced by \code{|}.
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\end{datadesc}
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