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\tl_case:Nn(TF) 和 \str_case:nn(TF) 的好例子

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\tl_case:Nn(TF) 和 \str_case:nn(TF) 的好例子

在學習過程中expl3，我很難使用\str_case:nn(TF)and \tl_case:Nn(TF)。我在網路上找不到好的例子。 （例如，那些在unravel\tl_case:Nn(TF)對我來說太複雜了\str_case:nn(TF)。讓我們來解決

  1. \tl_case:NnTF
  2. \str_case:nnTF
  3. \str_case_e:nnTF

第一的。我從那裡得到它們http://mirrors.ctan.org/macros/latex/contrib/l3kernel/interface3.pdf。如果您希望提供其他後綴的範例，例如 :cnTF、:Nn 等，請隨時提供。

答案1

這只是應用的演示\str_case:nnTF，\str_case_e:nn並且\tl_case:nnTF。

等的情況:cnTF已經在對該問題的評論中進行了解釋。

\str_case_e和之間的差異\str_case在於論證的擴展。 a\tl..和之間的差異\str..在於，對於字串，字元的 catcode 全部相等 (12)，但空格字元除外，其代碼仍然為 10，而在標記列表中，catcode 被保留。

這些\foo:nnTF版本只是將條件分支輸入到輸入流中 - 可以使用匹配的括號{foobar}{...}進行進一步處理或設定（或“排版”）或將其轉移到 TF- 分支。

我個人使用\foo:nn唯一的並且不記得\foo:nnTF到目前為止我需要的，但這當然取決於實際的用例。

\documentclass{article}

\usepackage{expl3}

\ExplSyntaxOn

\newcommand{\strcase}[1]{%
  \str_case:nn {#1} {
    {TeX} {\use:c{#1}\space is\space the\space predecessor\space of\space \LaTeX}
    {LaTeX} {\use:c{#1}\space is\space the\space successor\space of\space \TeX}
  }
}

\newcommand{\strcasetf}[3]{%
  \str_case:nnTF {#1} {
    {TeX} {\use:c{#1}\space is\space the\space predecessor\space of\space \LaTeX}
    {LaTeX} {\use:c{#1}\space is\space the\space successor\space of\space \TeX}
    {Word} {#1\space is\space a\space 'typesetter'}
  }{
    \space#2
  }{
    \space#3
  }
}

\newcommand{\genericstrcase}[3]{%
  \str_case:nn {#3} {
    {#1} {It was the first argument}
    {#2} {It was the second argument}
    {Other} {#1 it was 'other'}
  }
}


\newcommand{\strcasextf}[3]{%
  \str_case_e:nnTF {#1} {
    {TeX} {\use:c{#1}\space is\space the\space predecessor\space of\space \LaTeX}
    {LaTeX} {\use:c{#1}\space is\space the\space successor\space of\space \TeX}
    {Word} {#1\space is\space a\space 'typesetter'}
  }{
    \space#2
  }{
    \space#3
  }
}

\tl_new:N \l_tl_one
\tl_new:N \l_tl_two

\newcommand{\tlcase}[3]{%
  \tl_set:Nn \l_tl_one {#1}
  \tl_set:Nn \l_tl_two {#2}

\tl_set:Nn \l_tmpa_tl {#3}

\tl_case:Nn \l_tmpa_tl {
  {\l_tl_one} {Yes,\space it\space was\space #1}
  {\l_tl_two}  {Yes,\space it\space was\space #2}
}
}

\ExplSyntaxOff

\newcommand{\LaTeXStr}{LaTeX}
\newcommand{\WordPressString}{WordPress}
\newcommand{\WordString}{Word}


\begin{document}

\strcase{TeX}

\strcase{LaTeX}

\strcasetf{LaTeX}{-- the strings match}{-- the strings does not match!}

\strcasetf{Word}{-- the strings match}{-- the strings does not match!}

\strcasetf{WordPress}{-- the strings match}{-- the strings does not match!}

\textbf{Compare}

\strcasetf{\LaTeXStr}{-- the strings match}{-- the strings does not match!}

\strcasextf{\LaTeXStr}{-- the strings match}{-- the strings does not match!}

\tlcase{LaTeX}{TeX}{LaTeX}
\tlcase{LaTeX}{TeX}{\LaTeX} % Does nothing, since \LaTeX is not expanded

\textbf{Comparing command tokens}

\tlcase{\LaTeX}{TeX}{\LaTeX}% Compares again

\tlcase{LaTeX is very nice}{TeX}{LaTeX is very nice} 
\tlcase{TeX is nice}{TeX is not outdated}{TeX is very nice} % Does not match

\textbf{Comparing strings}

\genericstrcase{LaTeX}{TeX}{LaTeX}

\genericstrcase{ #LaTeX}{ #TeX}{ #TeX}

\genericstrcase{\LaTeX}{TeX}{\LaTeX}

\end{document}

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