5

Goal

I am attempting to redefine an existing command (\mintedinline) which takes a verbatim argument. I need to format this argument such that it can be passed to an outside program for processing; this requires some minor string substitution to ensure that some characters such as double quotes are properly escaped. For the substitution, I am using the xstring package.

Problem

I have discovered that the \StrSubstitute{}{}{}[] command provided by xstring does not seem to work with verbatim arguments in general, not just in my particular use case. I suspect that this is do to the verbatim text being tokenized differently/completely detokenized, but I am not enough of a LaTeXpert to fully understand the inner workings of verbatim arguments.

Minimum Working Example

\documentclass{article}
\usepackage{xstring}

% How the command needs to be formatted for my purposes
\NewDocumentCommand{\mwecmdactual}{v}{
    \StrSubstitute{#1}{a}{c}[\tmp]
    \tmp
}

% A test case showing the expected output using a mandatory argument instead of a verbatim one
\NewDocumentCommand{\mwecmdexpect}{m}{
    \StrSubstitute{#1}{a}{c}[\tmp]
    \tmp
}

\begin{document}

    Result of \verb+\mwecmdactual|abcde|+: \mwecmdactual|abcde|

    Result of \verb+\mwecmdexpect{abcde}+: \mwecmdexpect{abcde}

\end{document}

Results

The above MWE was compiled with pdflatex, and a screenshot of the output was taken:

A screenshot showing that the verbatim argument is no substituted while the normal argument is

The screenshot clearly shows the failure of \StrSubstitute to perform the substitution when it is given a verbatim argument from an encompassing command.

Request for Help

I am unfortunately bound to using the verbatim argument as I am ultimately redefining a preexisting command. Thus, any solution would need to use the verbatim argument as it is provided via the \mwecmdactual|| (in reality the \mintedinline[]{}||) command.

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2 Answers 2

Reset to default
4

Try doing it like this:

\documentclass{article}
\usepackage{xstring}

% Redefine the command to handle verbatim arguments
\NewDocumentCommand{\mwecmdactual}{v}{%
    % Detokenize the verbatim input to ensure consistent catcodes
    \edef\tmp{\detokenize{#1}}%
    % Perform substitution with detokenized patterns
    \StrSubstitute{\tmp}{\detokenize{a}}{\detokenize{c}}[\result]%
    \result% Output the result
}

% Test command for comparison
\NewDocumentCommand{\mwecmdexpect}{m}{%
    \StrSubstitute{#1}{a}{c}[\tmp]%
    \tmp%
}

\begin{document}

    Result of \verb+\mwecmdactual|abcde|+: \mwecmdactual|abcde|
    
    Result of \verb+\mwecmdexpect{abcde}+: \mwecmdexpect{abcde}

\end{document}
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1
  • This seems to have worked perfectly for both my MWE and my actual use case. Thanks! Commented Mar 22 at 14:53
4

You don't need xstring. The regular expression replacements provided in the LaTeX kernel suffice and they're category code agnostic.

\documentclass{article}
\usepackage{xstring} % for the check

% How the command needs to be formatted for my purposes
\ExplSyntaxOn
\NewDocumentCommand{\mwecmdactual}{v}
 {
  \tl_set:Nn \l_tmpa_tl {#1}
  \regex_replace_all:nnN {a}{c} \l_tmpa_tl
  \tl_use:N \l_tmpa_tl
 }
\ExplSyntaxOff

% A test case showing the expected output using a mandatory argument instead of a verbatim one
\NewDocumentCommand{\mwecmdexpect}{m}{%
    \StrSubstitute{#1}{a}{c}[\tmp]%
    \tmp
}

\begin{document}

Result of \verb+\mwecmdactual|abcde|+: \mwecmdactual|abcde|

Result of \verb+\mwecmdexpect{abcde}+: \mwecmdexpect{abcde}

\end{document}

output

More details are needed about the actual replacements you need to do.

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1
  • 1
    Hi! Thanks for your answer. I am tempted to change the accepted answer to this one as it does provide a far more robust regex experience. However, the expl3 syntax may as well have been ancient Sumerian for as well as I could understand it before finding some introduction and full reference for it. I would suggest adding some links to the relevant docs as the expl3 layer is (at first) esoteric, even by TeX standards. Commented Mar 23 at 9:58

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