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Question 1

正如@DavidCarlisle 在评论中指出的那样，您可以按如下方式进行：使用环境tabular而不是tabularx环境，使用p第二列的列类型，并使用有关第一列宽度的信息计算其宽度。此设置允许使用宏\url来排版长正则表达式字符串，就像它是 URL 字符串一样。

在下面的例子中，使用{and/or}是允许的，因为即使这些字符出现在正则表达式字符串中，它们也会以正确的顺序出现并且是平衡的。如果不是这种情况，即如果花括号不平衡，则必须使用在正则表达式字符串中任何地方都没有出现的字符；例如，\url!...!和\url M...M都可以工作，因为!nor 都不M出现在正则表达式字符串中。

\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 在评论中指出的那样，您可以按如下方式进行：使用环境tabular而不是tabularx环境，使用p第二列的列类型，并使用有关第一列宽度的信息计算其宽度。此设置允许使用宏\url来排版长正则表达式字符串，就像它是 URL 字符串一样。

在下面的例子中，使用{and/or}是允许的，因为即使这些字符出现在正则表达式字符串中，它们也会以正确的顺序出现并且是平衡的。如果不是这种情况，即如果花括号不平衡，则必须使用在正则表达式字符串中任何地方都没有出现的字符；例如，\url!...!和\url M...M都可以工作，因为!nor 都不M出现在正则表达式字符串中。

\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

由于tabularx收集了其内容，直接使用是\verb行不通的。此外，还\verb需要一个不在文本中的字符来捕获。\detokenize需要平衡的文本。

向世界宣布一个逐字捕获宏

这个想法是捕获任意字符（但是假设标准 catcode 自然，否则可以设置一个循环来设置所有 catcode）并将其放入宏中（用无法实现\verb）。语法是：

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

请注意，输入中的空格在<END OF LINE> 请注意，在will不被捕获在宏中\foo。<SPACE>开头的是必需的，并在处理过程中被删除。文字输入末尾以外的空格将被捕获。

代码：

\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}

请注意，这种去标记字符的非常长的序列的换行是另一个问题，现在可以添加一个\printliteral命令，在每个字符后添加断点。

更新以添加承诺的\printliteral命令。请参阅代码注释以了解解释和上下文。

\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

由于tabularx收集了其内容，直接使用是\verb行不通的。此外，还\verb需要一个不在文本中的字符来捕获。\detokenize需要平衡的文本。

向世界宣布一个逐字捕获宏

这个想法是捕获任意字符（但是假设标准 catcode 自然，否则可以设置一个循环来设置所有 catcode）并将其放入宏中（用无法实现\verb）。语法是：

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

请注意，输入中的空格在<END OF LINE> 请注意，在will不被捕获在宏中\foo。<SPACE>开头的是必需的，并在处理过程中被删除。文字输入末尾以外的空格将被捕获。

代码：

\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}

请注意，这种去标记字符的非常长的序列的换行是另一个问题，现在可以添加一个\printliteral命令，在每个字符后添加断点。

更新以添加承诺的\printliteral命令。请参阅代码注释以了解解释和上下文。

\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

向世界宣布一个逐字捕获宏

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