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Re: Query replace regex with 2 alternatives
From: |
WJ |
Subject: |
Re: Query replace regex with 2 alternatives |
Date: |
8 Dec 2012 22:07:25 GMT |
User-agent: |
XanaNews/1.18.1.6 |
Jambunathan K wrote:
> Dan Espen <despen@verizon.net> writes:
>
> > Could use some help on query/replace/regex.
> >
> > I have an html file full of < and >.
> > I want to replace only some of the pairs with "[" and "]".
> >
> > I figured out the match string:
> >
> > "\\(<\\|>\\)
> >
> > (typed as)
> >
> > "\(<\|>\)
> >
> > but when it comes to the replacement, I'm not clear on how to say,
> > first match gets [ and second match gets ].
> > I believe emacs can do it but I don't see it documented.
> > I see references to \1 \2 but not in the replace string.
>
> rx-to-string is the easiest way to build such an regexp.
>
> C-h f rx
>
> Do this
>
> 1. M-x ielm RET
> 2. Copy the below regexp to the prompt
>
> (rx-to-string '(and (group-n 1 "<")
> (group-n 2 (minimal-match
> (zero-or-more anything)))
> (group-n 3 ">")))
>
> Here is a sample session.
>
> ,----
> | ELISP> (rx-to-string '(and (group-n 1 "<")
> | (group-n 2 (minimal-match
> | (zero-or-more anything)))
> | (group-n 3 ">")))
> | "\\(?:\\(?1:<\\)\\(?2:\\(?:.\\|\n\\)*?\\)\\(?3:>\\)\\)"
> `----
>
> 3. C-x b file.html
> 4. M-x reb-change-syntax RET read RET
> 5. M-x re-builder RET
> 6. Copy paste the above regexp in to *RE-Builder* buffer
> 7. You will see the various components highlighted in HTML buffer
> 8. M-x reb-change-syntax RET string RET
> 9. You will see the above regexp changed from read syntax to string
> syntax. Something like. (Yes, the regexp is on two lines)
>
> "\(?:\(?1:<\)\(?2:\(?:.\|
> \)*?\)\(?3:>\)\)"
>
> 10. C-M-%
> Copy the above regexp without surrounding double quotes RET
> <\2> RET
>
> You are done.
Where can the documentation for rx-to-string be found?