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Here's my MWE:

% !TEX program = lualatex
\documentclass[preview,border={5mm 2.5mm 5mm 0mm},varwidth]{standalone}
\usepackage{mathtools}
\usepackage[warnings-off={mathtools-colon,mathtools-overbracket}]{unicode-math}
    \setmathfont{Latin Modern Math}
\usepackage{setspace}\setdisplayskipstretch{}

\newcommand{\testprime}[3][-2]{A' #2 x #3 ; B' #2 x #3 ; C' #2 x #3 ; P' #2 x #3 ; Q' #2 x #3 ; R' #2 x #3 ; f' #2 x #3 ; g' #2 x #3 ; h' #2 x #3}
\newcommand{\testkernedprimeleftdelimiter}[3][-2]{A' \mkern#1mu#2 x #3 ; B' \mkern#1mu#2 x #3 ; C' \mkern#1mu#2 x #3 ; P'  \mkern#1mu#2 x #3 ; Q' \mkern#1mu#2 x #3 ; R' \mkern#1mu#2 x #3 ; f' \mkern#1mu#2 x #3 ; g' \mkern#1mu#2 x #3 ; h' \mkern#1mu#2 x #3}


\begin{document}
\onehalfspacing%
[\testprime{(}{)}]
[\testkernedprimeleftdelimiter{(}{)}]


[\testprime{[}{]}]
[\testkernedprimeleftdelimiter[-0.5]{[}{]}]


[\testprime{{}{}}]
[\testkernedprimeleftdelimiter{{}{}}]


\end{document}

Minimum Working Example

I want to globally redefine ' or ^{\prime} to be kerned using \mkern only when it encounters a left delimiter (specifically -2mu for ( and \{, and -0.5mu for [) in math mode (maybe using \@ifnextchar?).

How do I achieve this?

*Related: This TeX.SX question and answer and the definition of ' in latex.ltx.

\def\active@math@prime{^\bgroup\prim@s}
{\catcode`\'=\active \global\let'\active@math@prime}
\def\prim@s{%
  \prime\futurelet\@let@token\pr@m@s}
\def\pr@m@s{%
  \ifx'\@let@token
    \expandafter\pr@@@s
  \else
    \ifx^\@let@token
      \expandafter\expandafter\expandafter\pr@@@t
    \else
      \egroup
    \fi
  \fi}
\def\pr@@@s#1{\prim@s}
\def\pr@@@t#1#2{#2\egroup}
Ingmar
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Farrel Ahmed
  • 331

1 Answers1

1

You can do it with \@ifnextchar.

\documentclass{article}

\makeatletter


\def\pr@m@s{%
  \ifx'@let@token
    \expandafter\pr@@@s
  \else
    \ifx^@let@token
      \expandafter\expandafter\expandafter\pr@@@t
    \else
      \expandafter\expandafter\expandafter\pr@@@end
    \fi
  \fi}
\def\pr@@@end{\egroup
    @ifnextchar({\mkern-2mu }{@ifnextchar{{\mkern-2mu }{@ifnextchar[{\mkern-.5mu }{}}}}


\makeatother


\begin{document}


$A'\ B''\ C''^{xy}\ f''(x)\ g'[y]\ X'''{z}$


\end{document}

output

Note that in cases like f'^x (... the space will not be added. If you do want it, you'll have to change the \egroup in\pr@@@t to \pr@@@end as well.

plante
  • 1,349
  • Thank you very much! – Farrel Ahmed Jul 02 '22 at 03:40
  • I'm sorry but it doesn't seem to be working if I add it to the preamble of my MWE. Could you help me? – Farrel Ahmed Jul 02 '22 at 03:49
  • I was testing this with plain LaTeX. In your MWE if unicode-math and \setmathfont is removed it works. Perhaps someone more familiar with those packages can fix, since the patches here are made for latex.ltx. – plante Jul 02 '22 at 04:00