latex-examples/bnf-syntax-pkg.tex at master · weidongzhou1994/latex-examples · GitHub

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% ref: https://tex.stackexchange.com/a/24934/79060
\documentclass{article}
\usepackage{syntax}
\input code-with-output
\ifx\example\undefined
  \newenvironment{example}{}{}
\fi

\begin{document}

\setcounter{tcb@cnt@example}{3}
\begin{example}[]{\texttt{syntax} pkg, default settings}
  % \usepackage{syntax}

  \begin{grammar}
    <statement> ::= <ident> `=' <expr>
    \alt `for' <ident> `=' <expr> `to' <expr> `do' <statement>
    \alt `{' <stat-list> `}'
    \alt <empty>

    <stat-list> ::= <statement> `;' <stat-list> | <statement>
  \end{grammar}
\end{example}
\paragraph{}

\begin{example}{\texttt{syntax} pkg, modified settings}
  % \usepackage{syntax}

  \makeatletter
  \setlength{\grammarparsep}{10pt plus 1pt minus 1pt}
  \settowidth{\@tempdima}{\textit{<statement>}}
  \addtolength{\grammarindent}{\@tempdima}
  \makeatother

  \begin{grammar}
    <statement> ::= <ident> `=' <expr>
                \alt `for' <ident> `=' <expr> `to' <expr> `do' <statement>
                \alt `{' <stat-list> `}'
                \alt <empty>

    <stat-list> ::= <statement> `;' <stat-list> | <statement>
  \end{grammar}
\end{example}

\end{document}