Tree in a growing bracket

Question

I try to enclose my syntax tree in a growing double bracket using \left \llbracket ... \right \rrbracket. However, the tree always sits in the lower half and leaving the upper half blank, which is very ugly... What's more, I cannot make the angle bracket grow with the tree...

\documentclass{article}
\usepackage{stmaryrd}
\usepackage{qtree}
\usepackage{tikz-qtree}
\begin{document}

$\left \llbracket \textbf{\Tree [.S [.S [ [.NP [.N Ann ] ] [.VP [.V smokes ] ] ] ] and [.S [ [.NP [.N John ] ] [.VP [.V drinks ] ] ] ] ]} \right \rrbracket$ \\
$\left \langle \left ( \Tree [.S [.NP [.N Ann ] ] [.VP [.V smokes ] ] ] \right ) \right \rangle$

\end{document}

Answer 1

Use the baseline option to set the baseline at the same height as the center of the picture (minus half the x height).

Code

\documentclass{article}
\usepackage{stmaryrd}
\usepackage{tikz-qtree}
\begin{document}
\[ \left \llbracket
  \tikz[font=\bfseries, baseline={([yshift=+-.5ex]current bounding box.center)}]{
    \Tree [.S [.S [ [.NP [.N Ann ] ] [.VP [.V smokes ] ] ] ] and
          [.S [ [.NP [.N John ] ] [.VP [.V drinks ] ] ] ] ]
  } \right \rrbracket\]

\[ \left\langle \left(
   \tikz[baseline={([yshift=+-.5ex]current bounding box.center)}]{
     \Tree [.S [.NP [.N Ann ] ] [.VP [.V smokes ] ] ]}
   \right) \right\rangle \]
\end{document}

Output

Answer 2

You can also either use the gathered environment of amsmath or a more low-level \vcenter{\hbox{}} construction: (but no clue for your \rangle's)

\documentclass{article}
\usepackage{stmaryrd}
%\usepackage{qtree}
\usepackage{tikz-qtree}
\usepackage{amsmath}
% \usepackage{forest}
\begin{document}

% here a construction with gathered and package forest for the tree
% $\left \llbracket
%   \begin{gathered}
%     \textbf{\begin{forest}
%       [S [S [ [NP [N [Ann] ] ] [VP [V [smokes] ] ] ] ] [and] [S [[NP [N [John]
%       ]] [VP [V [drinks] ] ]] ] ]
%     \end{forest}}
% \end{gathered}
% \right \rrbracket$ \\

$\left \llbracket \vcenter{%
      \hbox{\bfseries\Tree [.S [.S [ [.NP [.N Ann ] ] [.VP [.V smokes ] ] ] ] and [.S [ [.NP [.N John ] ] [.VP [.V drinks ] ] ] ] ]}} \right \rrbracket$ 


% with gathered:

$\left \langle \left (
    \begin{gathered}
      \Tree [.S [.NP [.N Ann ] ] [.VP [.V smokes ] ] ]
    \end{gathered}
\right ) \right \rangle$

% with \vcenter and \hbox:

$\left \langle \left (
    \vcenter{%
      \hbox{\Tree [.S [.NP [.N Ann ] ] [.VP [.V smokes ] ] ]}%
    }
\right ) \right \rangle$

\end{document}

---

If you want to have multiple trees on same line:

\documentclass{article}
\usepackage{stmaryrd}
\usepackage{tikz-qtree}
\usepackage{amsmath}

\newbox\mytreebox
\newbox\mytreeboxwithdelim

\makeatletter
\newcommand\TreeWithDelim [3]{%
   \setbox\mytreebox\hbox{{#3}}%
   \setbox\mytreeboxwithdelim\hbox{$#1\vcenter{\copy\mytreebox}#2$}%
   \dimen@=\dimexpr\ht\mytreeboxwithdelim+\dp\mytreeboxwithdelim\relax
   % in my testing, same as total height of non decorated treebox
   \leavevmode\raise\dimexpr-.5\dimen@-\fontdimen22\textfont2+\ht\mytreebox\relax\box\mytreeboxwithdelim
}
\makeatother


\begin{document}

\noindent\rlap{\rule{\linewidth}{0.4pt}}%
XX\TreeWithDelim {\left\llbracket}{\right\rrbracket}
    {\bfseries\Tree [.S [.S [ [.NP [.N Ann ] ] [.VP [.V smokes ] ] ] ] and [.S [ [.NP [.N John ] ] [.VP [.V drinks ] ] ] ] ]}\hfill
\TreeWithDelim {\left\langle\left(}{\right)\right\rangle}
    {\Tree [.S [.NP [.N Ann ] ] [.VP [.V smokes ] ] ]}XX

\end{document}

The horizontal rule is for demonstrative purposes only.

Answer 3

This combines Forest with the new coffins to create a tree style

delimit tree={<left delimiter>}{<right delimiter>}

It tries to keep the baselines correct, although I am not certain that I've got this quite right, so it may need tweaking. (It worked with minimal testing, but I don't really trust it.)

Given the definition of the new style, this allows us to write

\begin{forest}
  for tree={
    font=\bfseries,
  },
  delimit tree={\left\llbracket}{\right\rrbracket}
  [S
    [S
      [
        [NP
          [N
            [Ann]
          ]
        ]
        [VP
          [V
            [smokes]
          ]
        ]
      ]
    ]
    [and]
    [S
      [
        [NP
          [N
            [John]
          ]
        ]
        [VP
          [V
            [drinks]
          ]
        ]
      ]
    ]
  ]
\end{forest}
\begin{forest}
  delimit tree={\left\langle\left(}{\right)\right\rangle}
  [S
    [NP
      [N
        [Ann]
      ]
    ]
    [VP
      [V
        [smokes]
      ]
    ]
  ]
\end{forest}

Note that this maintains (I think!) the corrected alignment of the trees on the baseline.

Complete code:

\documentclass[border=10pt]{standalone}
\usepackage{stmaryrd,xcoffins}
\usepackage[linguistics]{forest}
\NewCoffin\OuterForestCoffin
\NewCoffin\InnerForestCoffin
\forestset{%
  delimit tree/.code n args=2{%
    \forestset{%
      draw tree stage/.style={
        for root'={
          draw tree box=0,
          draw tree,
          TeX={%
            \SetHorizontalCoffin\InnerForestCoffin{\box0}%
            \SetHorizontalCoffin\OuterForestCoffin{%
              $#1 \TypesetCoffin\InnerForestCoffin[vc,l]#2$%
            }%
            \TypesetCoffin\OuterForestCoffin[t,l](0pt,(\CoffinTotalHeight{\OuterForestCoffin}-\CoffinTotalHeight{\InnerForestCoffin})+\CoffinHeight{\InnerForestCoffin})%
          },
        },
      },
    }%
  },
}
\begin{document}
\begin{forest}
  for tree={
    font=\bfseries,
  },
  delimit tree={\left\llbracket}{\right\rrbracket}
  [S
    [S
      [
        [NP
          [N
            [Ann]
          ]
        ]
        [VP
          [V
            [smokes]
          ]
        ]
      ]
    ]
    [and]
    [S
      [
        [NP
          [N
            [John]
          ]
        ]
        [VP
          [V
            [drinks]
          ]
        ]
      ]
    ]
  ]
\end{forest}
\begin{forest}
  delimit tree={\left\langle\left(}{\right)\right\rangle}
  [S
    [NP
      [N
        [Ann]
      ]
    ]
    [VP
      [V
        [smokes]
      ]
    ]
  ]
\end{forest}
\end{document}