In(de)finite number of Boolean arguments

Question

I would like to know if it is possible to program a function that would accept a given symbol an infinite number of times. The application I have in mind is the following. I would like, if possible, a command \spac which would take two booleans and by default be defined as \vspace*{0.5ex}.

It would take two symbols.

• The * says if there is a line break or not; thus, \spac* is defined as \\[0.5ex].

• The presence of one + means that there will be a 0.5ex \vspace increment.

• The specificity here, is that we should be able to add as many + as we want, or, if not possible (this is part of the question, to determine whether it is possible or not), a reasonably high number of them such as 5 or 6.

To sum up, each + will add 0.5ex to the total vertical space. The vertical space will thus always be equal to 0.5*(n+1)ex, n symbolizing the number of +s.

I would like the +(s) to be written directly without separators, just like a t+ argument type.

Examples:

• \spac+++++ will produce a vspace of 0.5*6 = 3ex, without a line break.
• \spac*++ will produce a line break and a vspace of 0.5*3 = 1.5ex.

Context

\documentclass{article}
\usepackage{linguex}
\usepackage{etoolbox}
\NewDocumentCommand{\tslt}{m}{`#1'}
  \makeatletter


\patchcmd{\a}{\ifnum\theExDepth=2\topsep .3\Extopsep\else\topsep 0pt\fi 
    \parsep\z@\itemsep\z@}
{\ifnum\theExDepth>1\topsep\csname pxtop\roman{ExDepth}\endcsname
    \itemsep\csname pxitem\roman{ExDepth}\endcsname\else\topsep\z@\itemsep\z@\fi
    \parsep\z@}{}{}
  \makeatother


\newlength{\pxtopii}
\newlength{\pxtopiii}
\newlength{\pxitemii}
\newlength{\pxitemiii}
\newcommand{\spaceab}[1]{\setlength{\pxitemii}{#1}}
\newcommand{\spaceii}[1]{\setlength{\pxitemiii}{#1}}
\newcommand{\spacebefa}[1]{\setlength{\pxtopii}{#1}}
\newcommand{\spacebefi}[1]{\setlength{\pxtopiii}{#1}}
\newcommand{\alignright}{\hspace{1em}\raggedright\hspace*{\fill}}
\NewDocumentCommand{\web}{o}{%
    \begingroup\alignright%
        (\textsc{web}\IfValueT{#1}{,~#1})\endgroup\par}
\begin{document}
\spaceab{1ex}
\spacebefa{2ex}


\ex. Example 1\label{ex1}
\a. Sublevel1a\label{ex1a}\
\tslt{translation 1a}
\b. Sublevel1b\label{ex1b}\
\tslt{translation 1b}
\spaceab{2ex}
\spaceii{1ex}
\ex. Example 2\label{ex2}\
    \a. sublevel2a
        \a. sublevel 2ai\
            \tslt{translation 2ai}
        \b. sublevel 2aii
            \tslt{translation 2aii}
    \z.
    \b. \a. sublevel 2bi\
            \tslt{translation 2bi}
        \b. sublevel 2bii\
            \tslt{translation 2biii}
        \b. sublevel 2biii
            \tslt{translation 2biii}
    \z.
    \b. sublevel2c\
        \tslt{translation 2c}
\ex. Example XXXXX
\tslt{translation}\web\vspace*{1ex}
\end{document}

Depending on how heavy the sentences and translations are, and how the overall look feels, I adjust the spacings. The space before a translation is given with some \vspace*{} value. But the line break sometimes is already given by the previous command (such as \web), so i do not want to systematically integrate it.

Answer 1

Because I don't understand why do you want to insert vertical spaces in horizontal mode (i.e. \spac without*), I show you only the principle of the unlimited + arguments. And, of course, the \par at the beginning of the macro means that we will insert the space in vertical mode only.

Or do you mean \vadjust usage? This is TeX primitive (used in LaTeX \vspace) which is a source of many confusions of LaTeX users, so I don't use it in the \spac macro.

\def\spac{\par \spacA+}
\def\spacA+{\vskip.5ex \futurelet\next\spacB}
\def\spacB{\ifx\next+\expandafter\spacA \fi}
% testing:
\hrule width1cm
\spac
\hrule
\spac+
\hrule
\spac++
\hrule
\spac++++++
\hrule
\bye

Answer 2

The following logs

adding 2.15277pt
adding 4.30554pt
adding 75.34698pt

and produces

I didn't use the * form at all as you need to be in vertical mode to add vertical space.

\documentclass{article}
\newlength\spaclen
\NewDocumentCommand\spac{}{\par\setlength\spaclen{0.5ex}\innerspac}
\NewDocumentCommand\innerspac{t{+}}{%
  \IfBooleanTF{#1}%
  {\addtolength\spaclen{.5ex}\innerspac}%
  {\typeout{adding \the\spaclen}\addvspace\spaclen}}
\begin{document}
aaa\spac b
aaa\spac+ b
aaa\spac++++++++++++++++++++++++++++++++++ b
\end{document}

Answer 3

Count the number of + following \spac or \spac*.

I achieve this by doing a regex search and replace. A space following the last + or the single * is ignored.

\documentclass{article}
\usepackage{indentfirst}% just for alignment after \subsubsection
\ExplSyntaxOn
\NewDocumentCommand\spac{s}
 {
  \IfBooleanTF { #1 }
   {
    \peek_regex_replace_once:nn { (+)\s } { \c{krebs_spac_break:n}{\1} }
   }
   {
    \peek_regex_replace_once:nn { (+)\s } { \c{krebs_spac_nobreak:n}{\1} }
   }
 }
\cs_new_protected:Nn \krebs_spac_break:n
 {
  \typeout{Adding~\inteval{\tl_count:n{#1}+1}ex}
  \[\inteval{\tl_count:n{#1}+1}ex]
 }
\cs_new_protected:Nn \krebs_spac_nobreak:n
 {
  \typeout{Adding~\inteval{\tl_count:n{#1}+1}ex}
  \vspace{\inteval{\tl_count:n{#1}+1}ex}
 }
\ExplSyntaxOff
\begin{document}
\subsubsection*{zero}
aaa\spac b
aaa\spac* b
\subsubsection*{one}
aaa\spac+ b
aaa\spac*+ b
\subsubsection*{two}
aaa\spac++ b
aaa\spac*++ b
\subsubsection*{three}
aaa\spac+++ b
aaa\spac*+++ b
\end{document}

Console output (the \typeout instructions are just for this)

Adding 1ex
Adding 1ex
Adding 2ex
Adding 2ex
Adding 3ex
Adding 3ex
Adding 4ex
Adding 4ex

Answer 4

David Carlisle's command \innerspac can be slightly modified in order to support the minus sign -.

All we have to do is check for a - sign after checking for a +. As long as one of the two symbols is found, the loop goes on. It stops when both boolean values are False.

% !TEX TS-program = lualatex
\documentclass{article}
\newlength\spaclen
\NewDocumentCommand\spac{}{\par\setlength\spaclen{.5ex}\innerspac}
\NewDocumentCommand\innerspac{t{+}t{-}}{%
    \IfBooleanTF{#1}{%
        \addtolength\spaclen{.5ex}%
        \IfBooleanTF{#2}{%
            \addtolength\spaclen{-.5ex}}{}%
        \innerspac}{%
        \IfBooleanTF{#2}{%
            \addtolength\spaclen{-.5ex}\innerspac}{%
            \typeout{adding \the\spaclen}\addvspace\spaclen}}}
\begin{document}
aaa\spac b

aaa\spac+ b

aaa\spac- b

aaa\spac-- b

aaa\spac--- b

aaa\spac++++++++++++++++++++++++++++++++++ b

aaa\spac++--- b

aaa\spac+-+-+-+- b


\end{document}

Logs (with LuaTeX engine):

• adding 2.155pt
• adding 4.31pt
• adding 0.0pt
• adding -2.155pt
• adding -4.31pt
• adding 75.42496pt
• adding 0.0pt
• adding 2.155pt