Re: Checking for a macro in a string without expanding it

[Hans Hagen via ntg-context <ntg-context@ntg.nl>]

On 11/16/2021 9:09 PM, Jairo A. del Rio via ntg-context wrote:
> If I understand it correctly, you may need something like this...?
> 
> % Protection is key
> \protected\def\inner[#1]{\empty}
> % \outer is (or was) already defined in \CONTEXT
> % Please use another name
> \def\Outer{\inner[123] and \inner[some text] etc.}
> \startluacode
> local implement = interfaces.implement
> local argument = tokens.scanners.argument
> local function parseinner()
>    local r = {}
>    local str = argument()
>    str = str:gsub("\\inner%s*(%b[])",function(s)r[#r+1] = s:sub(2,#s-1)end)
>    context(table.concat(r," ")) -- Change " " by another spacer if needed
> end
> implement{name = "parseinner", public = true, actions = parseinner}
> \stopluacode
> \starttext
> \parseinner{\Outer}
> \stoptext
> 
> However, this will only work with very simple cases (no nesting, etc.). 
> Hope this helps.
well, if we start talking weird code ...

\starttext

\tolerant\def\MyInnerOuter#1\MyInner[#2]#3\MyDone\ignorearguments{#2}

\def\MyOuter#1{\MyInnerOuter#1\MyDone\ignorearguments}

whatever: \MyOuter{\MyInner[oeps]}\par
whatever: \MyOuter{\InnerMy[oeps]}\par

\edef\ItWorksA{\MyOuter{\MyInner[oeps]}}
\edef\ItWorksB{\MyOuter{\InnerMy[oeps]}}

whatever: \meaningless\ItWorksA\par
whatever: \meaningless\ItWorksB\par

\stoptext

(1) we're tolerant so no problem when no match
(2) the ignore hack quits scanning because tex will keep looking

it's pretty fast and needs no lua magic, only a twisted mind

Hans

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                                           Hans Hagen | PRAGMA ADE
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