7

Is it possible to create a key handler with the pgfkeys package that removes a key from a style?

Here's a minimal working example:

\documentclass[preview,margin=10pt,convert]{standalone}
\usepackage{pgfkeys}
\pgfkeys{/a/.code={a#1},
    /b/.code={b#1},
    /c/.code={c#1}}
\pgfkeys{/my style/.style = {/a=1, /b=2, /c=3}}
\begin{document}
\pgfkeys{/my style}\par
%\pgfkeys{/my style/.remove from style = {b}}
\pgfkeys{/my style}
\end{document}

The output is

a1b2c3a1b2c3

The desired output, if the commented line were to be uncommented, would be

a1b2c3
a1c3

Here are a couple of closely related questions. They are not duplicates of this one, but the answers to the second one might be useful in devising an answer to this question.

Unsetting a PGF/TikZ key

How to extract the value from a pgfkeys style element

Community
  • 1
Charles Staats
  • 19,514

2 Answers2

2

The following implements this with the help of expkv (as that one is expandable and fast, so I can set up the key-filtering easier).

It utilises the internal structure of a .style, parses the stored key list, and filters the values inside of that key list.

Caveat: You have to provide the key path exactly how it was defined in the style, this solution does no extensive path-parsing.

\documentclass[preview,margin=10pt]{standalone}
\usepackage{pgfkeys}

% how a style is defined (current code 2023-06-17)
\iffalse
\pgfkeys{/handlers/.style/.code=\pgfkeys{\pgfkeyscurrentpath/.code=\pgfkeysalso{#1}}}
\pgfkeysdef{/handlers/.code}{\pgfkeysdef{\pgfkeyscurrentpath}{#1}}
\long\def\pgfkeysdef#1#2{%
  \long\def\pgfkeys@temp##1\pgfeov{#2}%
  \pgfkeyslet{#1/.@cmd}{\pgfkeys@temp}%
  \pgfkeyssetvalue{#1/.@body}{#2}%
}
\long\def\pgfkeyslet#1#2{%
  \expandafter\let\csname pgfk@#1\endcsname#2%
}
\fi


\pgfkeys
  {
     /a/.code={a#1}
    ,/b/.code={b#1}
    ,/c/.code={c#1}
    ,/my style/.style = {/a=1, /b=2, /c=3}
  }


\usepackage{expkv} % yes, I use expkv to filter pgfkeys...


\makeatletter
\ExplSyntaxOn
\cs_new:Npn \mypgfkeys@checkstyle #1
  {
    \bool_lazy_and:nnF
      { \tl_if_head_eq_meaning_p:nN {#1} \pgfkeysalso }
      { \exp_args:No \tl_if_single_p:n { \use_none:n #1 } }
  }
\ExplSyntaxOff
\protected\def\mypgfkeys@not@a@style
  {%
    \PackageError{mypgfkeys}{Not a style: \pgfkeyscurrentpath}{}
    \mypgfkeys@break
  }
\def\mypgfkeys@breakpoint#1{}
\def\mypgfkeys@break#1\mypgfkeys@breakpoint#2{#2}
\pgfkeys{/handlers/.remove from style/.code=\mypgfkeysrmfromstyle{#1}}
\def\mypgfkeysrmfromstyle@mark{\mypgfkeysrmfromstyle@mark}
\protected\def\mypgfkeysrmfromstyle#1%
  {%
    \begingroup
      \ekvcsvloop\mypgfkeysrmfromstyle@makemark{#1}%
      \expandafter\let\csname mypgfkeys@@#1\endcsname\mypgfkeysrmfromstyle@mark
      \pgfkeysgetvalue{\pgfkeyscurrentpath/.@body}\mypgfkeysrmfromstyle@body
      \ifx\mypgfkeysrmfromstyle@body\relax
        \mypgfkeys@not@a@style
      \fi
      \expandafter\mypgfkeys@checkstyle\expandafter
        {\mypgfkeysrmfromstyle@body}%
        \mypgfkeys@not@a@style
      \edef\mypgfkeysrmfromstyle@body
        {%
          \expanded
            {%
              \expandafter\mypgfkeysrmfromstyle@do\expandafter
                {\mypgfkeysrmfromstyle@body}%
            }%
        }%
    \expanded{%
    \endgroup
    \unexpanded{\pgfkeys}%
      {%
        \pgfkeyscurrentpath/.style=
          {%
            \unexpanded\expandafter\expandafter\expandafter
              {\expandafter@gobble\mypgfkeysrmfromstyle@body}%
          }%
      }%
    }%
    \mypgfkeys@breakpoint\endgroup
  }
\protected\def\mypgfkeysrmfromstyle@makemark#1%
  {\expandafter\let\csname mypgfkeys@@#1\endcsname\mypgfkeysrmfromstyle@mark}
\def\mypgfkeysrmfromstyle@do#1%
  {\expandafter\mypgfkeysrmfromstyle@do@\expandafter{@secondoftwo#1}}
\def\mypgfkeysrmfromstyle@do@
  {\ekvparse\mypgfkeysrmfromstyle@do@k\mypgfkeysrmfromstyle@do@kv}
\def\mypgfkeysrmfromstyle@do@k#1%
  {%
    \expandafter\ifx\csname mypgfkeys@@#1\endcsname\mypgfkeysrmfromstyle@mark
      \expandafter@gobbletwo
    \fi
    \unexpanded{,#1}%
  }
\long\def\mypgfkeysrmfromstyle@do@kv#1#2%
  {%
    \expandafter\ifx\csname mypgfkeys@@#1\endcsname\mypgfkeysrmfromstyle@mark
      \expandafter@gobbletwo
    \fi
    \unexpanded{,#1= {#2}}%
  }
\makeatother


%\expandafter\show\csname pgfk@/my style/.@body\endcsname


\begin{document}
\pgfkeys{/my style}\par
\pgfkeys{/my style/.remove from style={/b,/c}}
\pgfkeys{/my style}
\end{document}

enter image description here

Skillmon
  • 60,462
1

Depending on your use case you can install a key filter.

This doesn't remove /b from /my style it just disables the /b style when /my style (or any other style) is used within \pgfkeysfiltered.

Code

\documentclass{article}
\usepackage{pgfkeys}
\pgfkeys{
  /a/.code={a#1},
  /b/.code={b#1},
  /c/.code={c#1},
  /my style/.style = {/a=1, /b=2, /c=3},
  /x/.style={/b=3, /c=4},
}
\begin{document}
normal: \pgfkeys{/my style}\par
\pgfkeys{
  /pgf/key filters/not/.install key filter={
    /pgf/key filters/equals=/b
  }
}
filtered: \pgfkeysfiltered{/my style}\par
Add /x \pgfkeys{/my style/.append style=/x}
and filter: \pgfkeysfiltered{/my style}\par
\end{document}

Output

normal: a1b2c3
filtered: a1c3
Add /x and filter: a1c3c4

Qrrbrbirlbel
  • 119,821