是否可以在森林树周围放置支架？

Question

我想使用forest大号\llbracket和\rrbracket围绕它的树（语义解释括号）来创建一棵树。schemabox看起来很有希望，但似乎不起作用。

我该怎么做呢？

（或者，是否有另一个我可以使用来执行此操作的树包？）

\documentclass[a4paper]{article}
\usepackage{graphicx}
\usepackage{forest}
\begin{document}

% big open double-bracket here
\begin{forest}
 [A tree] 
\end{forest}
% big close double-bracket here

\end{document}

Answer 1

\documentclass[a4paper]{article}
\usepackage{graphicx}
\usepackage{forest,stmaryrd}
\begin{document}

$\left\llbracket
\begin{forest}
 [A tree] 
\end{forest}
\right\rrbracket$

\end{document}

执行此操作的宏，垂直居中：

\newcommand{\brr}[1]{
\left\llbracket\raisebox{-.5\height}{ #1 }
\right\rrbracket}

使用：

\begin{equation}
\brr{\begin{forest}[X]\end{forest}}
\end{equation}

Answer 2

由于forest用途，tikz您可以简单地进行绘图tikz：

代码：

\documentclass[a4paper]{article}
\usepackage{graphicx}
\usepackage{forest}

\newcommand{\StubSize}{0.5em}%
\newcommand{\BraceForest}[1][]{%
    \begin{scope}[overlay]
        \coordinate (Left Start)  at ($(current bounding box.south west)+(\StubSize,0ex)$);
        \coordinate (Left End)    at ($(current bounding box.north west)+(\StubSize,0ex)$);
        \coordinate (Right Start) at ($(current bounding box.south east)-(\StubSize,0ex)$);
        \coordinate (Right End)   at ($(current bounding box.north east)-(\StubSize,0ex)$);
        \draw [#1] (Left Start) 
                -- (current bounding box.south west)
                -- (current bounding box.north west)
                -- (Left End);
        \draw [#1] (Right Start) 
                -- (current bounding box.south east)
                -- (current bounding box.north east)
                -- (Right End);
    \end{scope}
}


\begin{document}

\begin{forest}
 [A tree] 
 \BraceForest[red,ultra thick]%
\end{forest}

\end{document}