syntax for \in@ and using a macro as an argument

Question

I'm trying to have a command take in a comma separated list early in a document, and then later on test a given comma separated list to see if it contains (exactly) the same elements. Thus;

\documentclass{article}
\usepackage{etoolbox}
\makeatletter
\newcommand{\activetags}{yellow, blue, red, green}
\newif\ifis@Strict
\is@Stricttrue

\newcommand{\strictTest}[1]
    {
    \renewcommand*{\do}[1]
        {
        \in@{##1}{\activetags}
            \ifin@{}% If the element is in the second string do nothing
            \else
            \is@Strictfalse% If you find a non fitting string, mark strict as false.
            \fi
        }
    }

\newcommand{\filter}[1]{
\strictTest{#1}{\activetags}%  Check one being subset of the other
\docsvlist{#1}
\strictTest{\activetags}{#1}% Check other being subset of the one
\docsvlist{\activetags}
\ifis@Strict{The elements match!}\else{The elements don't match}\fi
\is@Stricttrue
}


\begin{document}

\filter{yellow, blue, red, green}% This should show "The elements match!"
\filter{yellow, blue, red}% This should show "The elements don't match"
\filter{yellow, blue, red, green, purple}% This should show "The elements don't match"

\ifis@Strict{It works}\else{It failed}\fi% This should show "It works"

\end{document}

I can't seem to find any info on the syntax on \in@ anywhere. As I understand it, it takes 2 arguments and tests one of them to see if it is contained as a substring in the other. This seems to be usable for what I need, but I can't seem to get macros to expand inside it.

The macro seems to work if I hardwire the \activetags command, but I can't seem to get \expandafter to work correctly, nor any of the \edef or \let commands that I know of that expand the token early...

I'm probably just missing something silly, but It's been a couple hours of trying now...

Thanks

Answer 1

\in@ doesn't perform expansion on its arguments; if you want it, you have to do it yourself.

\documentclass{article}
\usepackage{etoolbox}

\makeatletter
\newif\ifis@Strict
\is@Stricttrue

\newcommand{\strictTest}[1]{%
  \renewcommand*{\do}[1]{%
    \begingroup\edef\x{\endgroup\noexpand\in@{##1}{\activetags}}\x
    \ifin@
      % If the element is in the second string do nothing
    \else
      \is@Strictfalse% If you find a non fitting string, mark strict as false.
    \fi
  }%
}

\newcommand{\filter}[1]{%
  \strictTest{#1}{\activetags}%  Check one being subset of the other
  \docsvlist{#1} % here we want a space
  \strictTest{\activetags}{#1}% Check other being subset of the one
  \docsvlist{\activetags} % here we want a space
  \ifis@Strict
    The elements match!%
  \else
    The elements don't match%
  \fi
  \is@Stricttrue
}
\makeatother

\newcommand{\activetags}{yellow, blue, red, green}


\begin{document}

\filter{yellow, blue, red, green}% This should show "The elements match!"

\filter{yellow, blue, red}% This should show "The elements don't match"

\filter{yellow, blue, red, green, purple}% This should show "The elements don't match"

%\ifis@Strict{It works}\else{It failed}\fi% This should show "It works"

\end{document}

I have reformatted the code in order to avoid spurious spaces in the output.

However, it's not really clear what you want. The test with

\filter{green, yellow, blue, red}

would return false. There's no item by item comparison.

---

Here's an implementation with expl3 that compares both lists item by item and returns true when the items coincide even if in different order.

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn
\clist_new:N \l_jason_active_list_clist
\bool_new:N \l_jason_strict_bool

\cs_new_protected:Nn \jason_strict_test:n
 {
  \bool_set_true:N \l_jason_strict_bool
  % check whether the input items are in the fixed list
  \clist_map_inline:nn { #1 }
   {
    \clist_if_in:NnF \l_jason_active_list_clist { ##1 }
     { \bool_set_false:N \l_jason_strict_bool }
   }
  % check whether the fixed items are in the input list
  \clist_map_inline:Nn \l_jason_active_list_clist
   {
    \clist_if_in:nnF { #1 } { ##1 }
     { \bool_set_false:N \l_jason_strict_bool }
   }
 }

\NewDocumentCommand{\setactivelist}{m}
 {
  \clist_set:Nn \l_jason_active_list_clist { #1 }
 }

\NewDocumentCommand{\filter}{mmm}
 {
  \jason_strict_test:n { #1 }
  \bool_if:NTF \l_jason_strict_bool { #2 } { #3 }
 }
\ExplSyntaxOff

\setactivelist{yellow, blue, red, green}

\begin{document}

Match: \filter{yellow, blue, red, green}{The elements match}{The elements don't match}

Match: \filter{green, yellow, blue, red}{The elements match}{The elements don't match}

Not match: \filter{yellow, blue, red}{The elements match}{The elements don't match}

Not match: \filter{yellow, blue, red, green, purple}{The elements match}{The elements don't match}

\end{document}

Answer 2

If you just want to compare two strings in an unexpandable manner, you can use the \ifx primitive with both arguments stored in temporary macros with fully expanded replacement texts:

\documentclass{article}

\newcommand{\activetags}{yellow, blue, red, green}

\makeatletter
\newcommand\filter[1]{%
    \edef\tempA@{#1}%
    \edef\tempB@{\activetags}%
    \ifx\tempA@\tempB@
        The elements match\par
    \else
        The elements don't match\par
    \fi
}
\makeatother

\begin{document}

\filter{yellow, blue, red, green}% This should show "The elements match!"
\filter{yellow, blue, red}% This should show "The elements don't match"
\filter{yellow, blue, red, green, purple}% This should show "The elements don't match"

\end{document}

Your version doesn't work, as you said, because of the expansion issue. Getting the first and second argument fully expanded is a bit trickier if you want to do it in an expandably manner.