Re: Regular expression converter.

[Lloyd Zusman <ljz@asfast.com>]

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Lloyd Zusman <ljz@asfast.com> writes:

> [ ... ]
>
> As an example, this proposed function/macro would convert the expression
> marked as "Perl" to the one marked "Emacs" (note that I'm writing these
> as if they would appear inside of an Elisp string, and therefore, the
> backslashes are all doubled):
>
>   Perl:   ^(.+?\\.)+(com|net|org)$
>   Emacs:  ^\\(.+?\\.\\)+\\(com\\|net\\|org\\)$
>
> [ ... ]

Well, I found something.  In case anyone is interested, I'm enclosing
it.

It's something that was originally called "rx.el", and it implements
some functions and macros that permit a less-backslash-laden regular
expression syntax.  It's by Will Mengarini <seldon@eskimo.com> and it
was written in 1998/1999.

Because its name conflicts with the current "rx.el", I have renamed it
to "xr.el" (with the package name being "xr" instead of "rx").

It implements the syntax I want, with the small exception being that it
uses the backtick (`) instead of the backslash (\) as its escape
character.  To me, that's a small price to pay for more readability.

The xr syntax for the regular expression above would be this:

  ^(.+?`.)+(com|net|org)$

It also implements a few functions that correspond to standard elisp
functions, but which use this alternate regexp syntax:

  xr=                  corresponds to `string-match'
  xr@                  corresponds to `looking-at'
  xr-search-forward    corresponds to `re-search-forward'
  xr-search-backward   corresponds to `re-search-backward'
  xr-query-replace     corresponds to `query-replace-regexp'


I've already put this package into much of my commonly used elisp code,
and it is working very nicely.



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-- 
 Lloyd Zusman
 ljz@asfast.com