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Question 1

正如 @DavidCarlisle 已經在評論中指出的那樣，您可以按如下方式繼續：使用環境tabular而不是tabularx環境，使用p第二列的列類型，並使用有關第一列寬度的信息計算其寬度。此設定將允許使用\url巨集來排版長正規表示式字串，就好像它是 URL 字串一樣。

在下面的範例中，使用{and/or}是允許的，因為即使這些字元出現在正規表示式字串中，它們也會以正確的順序出現並且是平衡的。如果情況並非如此，即如果大括號不平衡，則必須使用正規表示式字串中任何地方都沒有出現的字元；例如，\url!...!和\url M...M都可以工作，因為!和都不會M出現在正規表示式字串中。

\documentclass{article}
\usepackage{booktabs}
\usepackage[spaces,hyphens]{url}

\newlength\lengtha
\newlength\lengthb
% Choose longest string in column A to calculate width
\settowidth{\lengtha}{\emph{Placeholder}}     
% Calculate width of column B as a residual
\setlength\lengthb{\dimexpr\textwidth-2\tabcolsep-\lengtha\relax} 

\begin{document}
\begin{table}
\begin{tabular}{@{} l p{\lengthb} @{}}
    \toprule
    \emph{Placeholder}&\emph{Regular~Expression}\\
    \midrule
    URL&  \url{(https?:\/\/)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,4}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)} \\
    \bottomrule
\end{tabular}
\caption{Regular Expressions}
\label{regex}\end{table}
\end{document}

Answer

正如 @DavidCarlisle 已經在評論中指出的那樣，您可以按如下方式繼續：使用環境tabular而不是tabularx環境，使用p第二列的列類型，並使用有關第一列寬度的信息計算其寬度。此設定將允許使用\url巨集來排版長正規表示式字串，就好像它是 URL 字串一樣。

在下面的範例中，使用{and/or}是允許的，因為即使這些字元出現在正規表示式字串中，它們也會以正確的順序出現並且是平衡的。如果情況並非如此，即如果大括號不平衡，則必須使用正規表示式字串中任何地方都沒有出現的字元；例如，\url!...!和\url M...M都可以工作，因為!和都不會M出現在正規表示式字串中。

\documentclass{article}
\usepackage{booktabs}
\usepackage[spaces,hyphens]{url}

\newlength\lengtha
\newlength\lengthb
% Choose longest string in column A to calculate width
\settowidth{\lengtha}{\emph{Placeholder}}     
% Calculate width of column B as a residual
\setlength\lengthb{\dimexpr\textwidth-2\tabcolsep-\lengtha\relax} 

\begin{document}
\begin{table}
\begin{tabular}{@{} l p{\lengthb} @{}}
    \toprule
    \emph{Placeholder}&\emph{Regular~Expression}\\
    \midrule
    URL&  \url{(https?:\/\/)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,4}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)} \\
    \bottomrule
\end{tabular}
\caption{Regular Expressions}
\label{regex}\end{table}
\end{document}

Question 2

由於tabularx收集其內容，直接使用是\verb行不通的。此外還\verb需要一個文字中沒有的字元來捕獲。需要\detokenize平衡的案文。

向世界宣布捕捉逐字宏

這個想法是捕獲任意字元（但是假設標準catcodes自然，否則可以設定一個循環來設定所有catcodes）並將其放入巨集中（不可能使用\verb）。語法是：

\literalset\foo<SPACE>ARBITRARY CHARACTERS<END OF LINE>

<END OF LINE> 請注意，遺囑之前的輸入中的空格不被捕獲在宏觀上\foo。開頭的<SPACE>是強制性的，在處理過程中會被刪除。不在文字輸入末尾的空格將被捕獲。

代碼：

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[margin=.5cm]{geometry}
\usepackage{tabularx}

\makeatletter
% \literalset\foo<SPACE>ARBITRARY CHARACTERS<END OF LINE>
\def\literalset #1{% assumes standard \endlinechar
    \begingroup
    \def\x{#1}%
    \catcode`\^^M 2
    \let\do\@makeother
    \dospecials
    \afterassignment\literalset@i
    \toks0=\bgroup }%
\def\literalset@i 
   {\expandafter\xdef\x{\expandafter\@gobble\the\toks0}\endgroup}
\makeatother

\begin{document}


% I have added a space between \/)? and (www compared to original.

\literalset\foo (https?:\/\/)? (www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,4}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)\\
Hello, all is fine here ? I hope so.

\typeout{I AM HERE: \meaning\foo}

\meaning\foo

\begin{table}[htbp]
\centering
\begin{tabularx}{\textwidth}{cX}
    \hline
    Placeholder&Regular Expression\\ 
    \hline
    URL&\texttt{\foo}\\
    \hline
\end{tabularx}
\caption{Regular Expressions}
\label{regex}
\end{table}

\end{document}

請注意，這種去標記化字元的很長序列的包裝是另一個問題，現在可以添加一個\printliteral命令，該命令將在每個字元後面添加斷點。

更新以新增承諾的\printliteral命令。請參閱程式碼註釋以取得解釋和上下文。

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
%\usepackage[margin=.5cm]{geometry}
\usepackage{tabularx}

\makeatletter
% \literalset\foo<SPACE>ARBITRARY CHARACTERS<END OF LINE>
\def\literalset #1{% assumes standard \endlinechar
    \begingroup
    \def\x{#1}%
    \catcode`\^^M 2
    \let\do\@makeother
    \dospecials
    \afterassignment\literalset@i
    \toks0=\bgroup }%
\def\literalset@i 
   {\expandafter\xdef\x{\expandafter\@gobble\the\toks0}\endgroup}
\makeatother

% TeX has no toggle to tell it to break long words (of random
% characters) automatically when reaching end of line: it goes
% to the right margin and beyond in absence of hyphens and
% spaces if confronted to a non-interrupted sequence of
% characters. And in a \texttt, breaking at hyphens is usually
% inihibited.

% Here is a very simple-minded macro which allows to print a
% \foo which has been declared by \literalset, with automatic
% breaks. More sophisticated treatment is possible (e.g. use
% of discretionaries to allow insertion of continuation
% symbols at breaks).

% We add a little stretch to avoid underfull/overfull boxes.

\makeatletter
\def\printliteral   #1{\expandafter\printliteral@i#1\relax }%
\def\printliteral@i #1{\if\relax #1\else\hskip\z@ \@plus .4\p@\relax
                       #1\expandafter\printliteral@i \fi}
\makeatother

\begin{document}


% I have added a space between \/)? and (www compared to original.

\literalset\foo (https?:\/\/)? (www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,4}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)\\
Hello, all is fine here ? I hope so.

\typeout{I AM HERE: \meaning\foo}

\printliteral{\meaning\foo}

\begin{table}[htbp]
\centering
%\begin{tabularx}{\textwidth}{c>{\raggedright\arraybackslash}X}
\begin{tabularx}{\textwidth}{cX}
    \hline
    Placeholder&Regular Expression\\ 
    \hline
    URL&\texttt{\printliteral\foo}\\
    \hline
\end{tabularx}
\caption{Regular Expressions}
\label{regex}
\end{table}
%\showoutput

\end{document}

Answer

由於tabularx收集其內容，直接使用是\verb行不通的。此外還\verb需要一個文字中沒有的字元來捕獲。需要\detokenize平衡的案文。

向世界宣布捕捉逐字宏

這個想法是捕獲任意字元（但是假設標準catcodes自然，否則可以設定一個循環來設定所有catcodes）並將其放入巨集中（不可能使用\verb）。語法是：

\literalset\foo<SPACE>ARBITRARY CHARACTERS<END OF LINE>

<END OF LINE> 請注意，遺囑之前的輸入中的空格不被捕獲在宏觀上\foo。開頭的<SPACE>是強制性的，在處理過程中會被刪除。不在文字輸入末尾的空格將被捕獲。

代碼：

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[margin=.5cm]{geometry}
\usepackage{tabularx}

\makeatletter
% \literalset\foo<SPACE>ARBITRARY CHARACTERS<END OF LINE>
\def\literalset #1{% assumes standard \endlinechar
    \begingroup
    \def\x{#1}%
    \catcode`\^^M 2
    \let\do\@makeother
    \dospecials
    \afterassignment\literalset@i
    \toks0=\bgroup }%
\def\literalset@i 
   {\expandafter\xdef\x{\expandafter\@gobble\the\toks0}\endgroup}
\makeatother

\begin{document}


% I have added a space between \/)? and (www compared to original.

\literalset\foo (https?:\/\/)? (www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,4}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)\\
Hello, all is fine here ? I hope so.

\typeout{I AM HERE: \meaning\foo}

\meaning\foo

\begin{table}[htbp]
\centering
\begin{tabularx}{\textwidth}{cX}
    \hline
    Placeholder&Regular Expression\\ 
    \hline
    URL&\texttt{\foo}\\
    \hline
\end{tabularx}
\caption{Regular Expressions}
\label{regex}
\end{table}

\end{document}

請注意，這種去標記化字元的很長序列的包裝是另一個問題，現在可以添加一個\printliteral命令，該命令將在每個字元後面添加斷點。

更新以新增承諾的\printliteral命令。請參閱程式碼註釋以取得解釋和上下文。

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
%\usepackage[margin=.5cm]{geometry}
\usepackage{tabularx}

\makeatletter
% \literalset\foo<SPACE>ARBITRARY CHARACTERS<END OF LINE>
\def\literalset #1{% assumes standard \endlinechar
    \begingroup
    \def\x{#1}%
    \catcode`\^^M 2
    \let\do\@makeother
    \dospecials
    \afterassignment\literalset@i
    \toks0=\bgroup }%
\def\literalset@i 
   {\expandafter\xdef\x{\expandafter\@gobble\the\toks0}\endgroup}
\makeatother

% TeX has no toggle to tell it to break long words (of random
% characters) automatically when reaching end of line: it goes
% to the right margin and beyond in absence of hyphens and
% spaces if confronted to a non-interrupted sequence of
% characters. And in a \texttt, breaking at hyphens is usually
% inihibited.

% Here is a very simple-minded macro which allows to print a
% \foo which has been declared by \literalset, with automatic
% breaks. More sophisticated treatment is possible (e.g. use
% of discretionaries to allow insertion of continuation
% symbols at breaks).

% We add a little stretch to avoid underfull/overfull boxes.

\makeatletter
\def\printliteral   #1{\expandafter\printliteral@i#1\relax }%
\def\printliteral@i #1{\if\relax #1\else\hskip\z@ \@plus .4\p@\relax
                       #1\expandafter\printliteral@i \fi}
\makeatother

\begin{document}


% I have added a space between \/)? and (www compared to original.

\literalset\foo (https?:\/\/)? (www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,4}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)\\
Hello, all is fine here ? I hope so.

\typeout{I AM HERE: \meaning\foo}

\printliteral{\meaning\foo}

\begin{table}[htbp]
\centering
%\begin{tabularx}{\textwidth}{c>{\raggedright\arraybackslash}X}
\begin{tabularx}{\textwidth}{cX}
    \hline
    Placeholder&Regular Expression\\ 
    \hline
    URL&\texttt{\printliteral\foo}\\
    \hline
\end{tabularx}
\caption{Regular Expressions}
\label{regex}
\end{table}
%\showoutput

\end{document}

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答案1

答案2

向世界宣布捕捉逐字宏

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