% visualtoks.tex, version 1.1a

% Copyright (C) 2025 plante
% This package is released under the LaTeX Project Public License (LPPL) 1.3c.

% visualtoks: typeset TeXbook-style visualisations of token lists.

% This package may be used in LaTeX by `\usepackage{visualtoks}`, or
% in plain TeX and other formats by `\input{visualtoks}`.

% See the documentation for typeset examples and caveats.



\ifdefined\visualtoks
	\expandafter\endinput
\fi
\edef\next{\catcode`\noexpand\@=\the\catcode`\@\space}
\catcode`\@=11

\input tokmap

\long\def\visualtoks@firstoftwo#1#2{#1}
\long\def\visualtoks@secondoftwo#1#2{#2}

\newdimen\visualtokssep \visualtokssep=1em

\protected\long\def\visualtoks#1{%
	\begingroup
		\leavevmode
		\ifcsname ttfamily\endcsname \ttfamily \else \tt \fi \m@th
		\hskip-\visualtokssep \tokmap\visualtoksA{#1}%
	\endgroup
}
\long\def\visualtoksA#1{%
	\hskip\visualtokssep
	\ifx\tokmap@space#1%
		\char`\ $_{10}$%
	\else\ifx\tokmap@bgroup#1%
		\char`\{$_1$%
	\else\ifx\tokmap@egroup#1%
		\char`\}$_2$%
	\else
		\escapechar`\\%
		\edef\tempa{\string#1}%
		\escapechar\m@ne
		\edef\tempb{\string#1}%
		\ifx\tempa\tempb \expandafter\visualtoks@firstoftwo \else \expandafter\visualtoks@secondoftwo \fi
			{\ifnum`\ =`#1\char`\ \else\string#1\fi$_{%
				\let~\empty
				\lccode`~=`#1\lowercase{\let~}\empty
				\ifcat$\noexpand#13\fi
				\ifcat &\noexpand#14\fi
				\ifcat##\noexpand#16\fi
				\ifcat ^\noexpand#17\fi
				\ifcat _\noexpand#18\fi
				\ifcat\space\noexpand#110\fi
				\ifcat a\noexpand#111\fi
				\ifcat !\noexpand#112\fi
				\ifcat\noexpand~\noexpand#113\fi
			}$}%
			{\visualtoksB{\string#1}%
				\long\expandafter\def\expandafter\tempa\expandafter##\expandafter1\csname\string#1\endcsname{}%
				\if\relax\detokenize\expandafter\expandafter\expandafter
					{\expandafter\tempa\expandafter#1\csname\string#1\endcsname}\relax *\fi
			}%
	\fi\fi\fi
}

\long\def\visualtoksB#1{%
	\hbox{%
		\vrule
		\vtop{%
			\vbox{%
				\hrule \kern\p@
				\hbox{\vphantom/\thinspace#1\thinspace}%
			}%
			\kern\p@ \hrule
		}%
		\vrule
	}%
}

\next

\endinput