Re: Multiple replacements in one regular expression?

[Urs Liska]

Am 21.01.2015 um 14:52 schrieb Urs Liska:
> Am 21.01.2015 um 14:45 schrieb Sven Axelsson:
> > On 21 January 2015 at 14:01, Urs Liska <address@hidden> wrote:>
> > > Hm, it's not as easy as that because the escaping can be quite 
> > > different,
> > > e.g.
> > >
> > > "&" -> "\&"
> > > "\" -> "\textbackslash"
> > > "[" -> "{[}"
> > >
> > > etc.
> > >
> > > So what I really need is:
> > > match (&)(\)([)
> > > and replace that with
> > > (\&)(\textbackslash )({})
> > >
> > > And I would be glad if I wouldn't have to do that with individual 
> > > runs of
> > > regexp-substitute.
> > Looks like you can use a callback function with regexp-substitute and
> > then do whatever
> > necessary there, eg. (from the Guile manual).
> >
> > (regexp-substitute/global #f "[a-z]+"  "to do and not-do"
> >    'pre (lambda (m) (string-reverse (match:substring m))) 'post)
> > ⇒ "ot od dna ton-od"
>
> That looks promising, and I think I can combine that with Johan's 
> suggestion of an association list.
>
> Thanks to both.
> Urs

It works :-)

\version "2.19.16"
#(use-modules (ice-9 regex))

str = "This should be \partcombine[or]{Apart} & match everything"

#(define escape-pairs
   '(("\\" . "\\textbackslash ")
     ("&" . "\\&")
     ("{" . "\\{")
     ("}" . "\\}")
     ("[" . "{[}")
     ("]" . "{]}")))

escape-regexp = "&|\\\\|\{|\}|\[|\]"

#(set! str
       (regexp-substitute/global #f escape-regexp str
         'pre (lambda (m)
                (assoc-ref escape-pairs (match:substring m)))
         'post))


#(ly:message "")
#(ly:message str)
#(ly:message "")

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