How to select a command based on the expansion of \Cref*?

Question

(This is a somewhat of a continuation of this question of mine, which @egreg provided an easy solution to.)

In the following (slight variation of egreg's) MWE, three commands are defined. \mylabel creates \label (to be used by \Cref in the next two commands) and a \RecordProperties that will be used to record other info. Then there are \mychapref and \mysecref that produce the "conditional"/"relative" references.

\documentclass{book}
\usepackage{hyperref}
\usepackage{cleveref}
\NewProperty{chapter}{now}{\bfseries??}{\Roman{chapter}}
\NewProperty{section}{now}{\bfseries??}{\arabic{section}}
\NewDocumentCommand{\mylabel}{m}{%
    \label{#1}%
    \RecordProperties{#1@recProp}{chapter,section,target}%
}
\ExplSyntaxOn
\NewDocumentCommand{\myref}{m}{
    % If \Cref{#1} begins with "Chapter", then execute \mychapref{#1}.
    % If \Cref{#1} begins with "Section", then execute \mysecref{#1}.
}
\NewDocumentCommand{\mychapref}{m}{
    \str_if_eq:eeTF { \RefProperty{#1@recProp}{chapter} } { \Roman{chapter} } {
        % we are in the same chap
        this~chapter
    } {
        % in a diff chap
        \Cref{#1}
    }
}
\NewDocumentCommand{\mysecref}{m}{
    \str_if_eq:eeTF { \RefProperty{#1@recProp}{chapter} } { \Roman{chapter} } {
        % we are in the same chap
        \str_if_eq:eeTF{ \RefProperty{#1@recProp}{section} } { \arabic{section}} {
            % in the same sec
            this~section
            } {
            %same chap diff sec
            \Cref{#1}
            }
        }
{
    % in a diff chap
    \Cref{#1},\nobreakspace Chapter\nobreakspace\RefProperty{#1@recProp}{chapter}
}

}
\ExplSyntaxOff
\begin{document}
    \chapter{First chapter}\mylabel{CHAP: I}
    \mychapref{CHAP: I}
\section{abc}\mylabel{SEC: I.1}

\mysecref{SEC: I.1}

\section{efg}

\mysecref{SEC: I.1}


\chapter{Second chapter}

\mychapref{CHAP: I}

\mysecref{SEC: I.1}


\end{document}

What is wanted: I want to "combine" \mychapref and \mysecref in a command \myref as described in the comment above. However, I came across the fact that \Cref* is not expandable and hence I can't assign it to string variables using \str_set:Ne, or try \exp_args:Ne, and then procees with the logic.

Is there a way to implement what is intended here?

---

Edit:

So, I tried to define \myref via \mycreftype that @gusbrs defines here, like so:

\NewDocumentCommand{\myref}{m}{
    \str_if_eq:eeTF { \mychapref{#1} } { chapter } { \mychapref{#1} } {}
    \str_if_eq:eeTF { \mycreftype{#1} } { section } { \mysecref{#1} } {}
}

However, running the MWE (with just the above and @gusbrs' definition of \mycreftype added to the preamble, along with replacing \mychapref{CHAP: I} with \myref{CHAP: I}), I get error messages, the first being

Argument of \@firstoftwo has an extra }. \myref{CHAP: I}

Any help?

Answer 1

You can use the procedure at https://tex.stackexchange.com/a/692754/105447 to retrieve the reference type, and than compare that.

\documentclass{book}
\usepackage{hyperref}
\usepackage{cleveref}
\NewProperty{chapter}{now}{\textbf{??}}{\Roman{chapter}}
\NewProperty{section}{now}{\textbf{??}}{\arabic{section}}
\AddToHookWithArguments{label}{%
  \RecordProperties{#1@recProp}{chapter,section,target}%
}
\ExplSyntaxOn
\makeatletter
\tl_new:N \l_mytempvar_tl
\NewDocumentCommand{\myref}{m}{
  \cref@gettype {#1} { \l_mytempvar_tl }
  \str_case:VnF \l_mytempvar_tl
    {
      % If type is "chapter", then execute \mychapref{#1}.
      { chapter } { \mychapref{#1} }
      % If type is "section", then execute \mysecref{#1}.
      { section } { \mysecref{#1} }
    }
    {
      % Anything else, just \Cref
      \Cref {#1}
    }
}
\makeatother
\NewDocumentCommand{\mychapref}{m}{
  \str_if_eq:eeTF { \RefProperty { #1 @recProp } { chapter } } { \Roman{chapter} }
    {
      % we are in the same chap
      this~chapter
    }
    {
      % in a diff chap
      \Cref {#1}
    }
}
\NewDocumentCommand{\mysecref}{m}{
  \str_if_eq:eeTF { \RefProperty { #1@recProp } { chapter } } { \Roman{chapter} }
    {
      % we are in the same chap
      \str_if_eq:eeTF{ \RefProperty { #1 @recProp } { section } } { \arabic{section} }
        {
          % in the same sec
          this~section
        }
        {
          %same chap diff sec
          \Cref {#1}
        }
    }
    {
      % in a diff chap
      \Cref {#1},\nobreakspace Chapter\nobreakspace
      \RefProperty { #1 @recProp } { chapter }
    }
}
\ExplSyntaxOff
\begin{document}
\chapter{First chapter}
\label{CHAP:I}
\mychapref{CHAP:I}\par
\myref{CHAP:I}
\section{abc}
\label{SEC:I.1}
\mysecref{SEC:I.1}\par
\myref{SEC:I.1}
\section{efg}
\mysecref{SEC:I.1}\par
\myref{SEC:I.1}
\chapter{Second chapter}
\mychapref{CHAP:I}\par
\myref{CHAP:I}\par
\mysecref{SEC:I.1}\par
\myref{SEC:I.1}
\end{document}