如果參數包含許多以 {} 分隔的標記，則吞噬該參數

Question

如何實現\mymacro具有一個參數和以下行為的巨集：我想傳遞以下形式的參數\mymacro{some text}或兩個巢狀參數，例如\mymacro{{Text 1}{Text2}}.期望的輸出是這樣的：

\mymacro{Some text}        ->   Some text 
\mymacro{{Some text}}      ->   Some text 
\mymacro{{Text 1}{Text 2}} ->   1: Text 1 / 2: Text 2

那麼，如何測試是否給出了一個字串或兩個以 {} 分隔的標記？

Answer 1

這可以透過功能來完成\def...#{...}，以測試參數是否以內部開始{。

\def\mymacro#1{\mymacroA#1{\end}{\end}\end}
\def\mymacroA#1#{%
   \ifx\end#1\end          % parameter begins by {
      \expandafter\mymacroB \else #1\expandafter\mymacroC
   \fi
}
\def\mymacroB#1#2#3\end{%
   \ifx\end#1\empty        % paremeter is empty
   \else\ifx\end#2\empty   % parameter has only one {}
      #1\else 1: #1 / 2: #2%
   \fi\fi
}
\def\mymacroC#1\end{}

A) \mymacro{Some text}        =   Some text 

B) \mymacro{{Some text}}      =   Some text 

C) \mymacro{{Text 1}{Text 2}} =   1: Text 1 / 2: Text 2

\bye

Answer 2

這是針對您的問題的完全可擴展的解決方案。我不知道你是否願意經歷這一切地獄。

\documentclass{article}

\makeatletter

\begingroup
  \catcode`{=12
  \global\let\bracetwelve={
\endgroup

\def\firsttoken#1#2\endfirsttoken{#1}

\def\ifelsefirstcharbrace#1{%
  \if\bracetwelve\expandafter\firsttoken\detokenize{#1}\relax\relax\endfirsttoken
    \expandafter\@firstoftwo
  \else
    \expandafter\@secondoftwo
  \fi
}

\def\stripbracesrelax#1\relax{#1}

\makeatother

\def\mymacro#1{%
  \ifelsefirstcharbrace{#1}%
    {\domymacrotwo#1\relax\enddomymacrotwo}%
    {\domymacroone{#1}}}

\def\domymacroone#1{#1}

\def\domymacrotwo#1#2\enddomymacrotwo{%
  \ifx#2\relax
    \domymacroone{#1}%
  \else
    1: #1 / 2: \stripbracesrelax#2
  \fi}

\begin{document}
\ttfamily

\edef\x{\mymacro{}} \meaning\x

\edef\x{\mymacro{Some text}} \meaning\x

\edef\x{\mymacro{{Some text}}} \meaning\x

\edef\x{\mymacro{{Text 1}{Text 2}}} \meaning\x

\edef\x{\mymacro{{}{}}} \meaning\x
\end{document}

---

您可能想改用xparse。

\documentclass{article}
\usepackage{xparse}

\DeclareDocumentCommand \mymacro { g g }
{%
  \IfValueT{#1}{\IfValueTF{#2}{1: #1 / 2: #2}{#1}}%
}

\begin{document}
\mymacro

\mymacro{Some text}

\mymacro{Some text}

\mymacro{Text 1}{Text 2}

\mymacro{}{}
\end{document}