expl3 调用函数时使用字符串变量

Question

我正在尝试实现一个根据输入的预定义字符串计算索引的函数。基本上，它以 2 个字母作为输入，然后计算索引。

我先逐块构建，先编写了计算函数，现在尝试添加字符串提取。我想输入一个字符串，从中提取字母，然后计算索引。

事实上，这没有多大意义，但这是一个更大项目的一部分；）

输入字符串为N和N。计算出的索引为8。计算此索引有效。

失败之处从输入字符串中提取这些字母AV:N/AC:N，并调用函数计算索引。

如果我使用静态字母调用该函数，则不会出现任何问题

\exp_args:Ne \__XXXX_choose_mapping:nn
   { \fp_eval:n { \__XXXX_compute_value:n {N} } } % N is static
   { \fp_eval:n { \__XXXX_factor_scaling:n {N} } } % N is static

我可以从输入字符串中提取 2 N（并将它们存储在字符串变量中，但像这样调用函数会失败

\exp_args:Ne \__XXXX_choose_mapping:nn
   { \fp_eval:n { \__XXXX_compute_value:n { \l_XXXXXAV_str } } }
   { \fp_eval:n { \__XXXX_factor_scaling:n { \l_XXXXXAC_str } } }
    

我应该怎么做才能使这个带有变量的函数调用起作用？

这是我的（失败的）MWE

\documentclass{article}
\usepackage{expl3}

\ExplSyntaxOn
\cs_new:Npn \__XXXX_parse_value:n #1
{
    \str_case:nnF {#1}
    {
        { N } { 0.85 } % This value will be selected
        { A } { 0.62 } % This will not
    }
    {
        \msg_expandable_error:nnn { XXXX } { wrong-case } {#1}
        1.00 % default value
    }
}{}

\cs_new:Npn \__XXXX_compute_value:n #1 { 1 - (1 - \__XXXX_parse_value:n {#1} ) }

\cs_new:Npn \__XXXX_factor_scaling:n #1 { 8.22 * (\__XXXX_parse_value:n {#1} ) }

\NewExpandableDocumentCommand \basicMacro { m }
{
    \exp_args:Ne \__XXXX_choose_mapping:nn
    { \fp_eval:n { \__XXXX_compute_value:n {#1} } }
    { \fp_eval:n { \__XXXX_factor_scaling:n {#1} } }
}

\cs_new:Npn \__XXXX_choose_mapping:nn #1 #2
{
    \fp_compare:nTF { #1 <= 0 }
    { 0.0 }
    { \fp_eval:n { round( min( 1.08 * (#1 + #2), 10) ) } }
}

%%%%%%%%%%%%%%%%%%%%%%%%%%
% These are the thresholds
\def\scoreCrit{9.0}
\def\scoreLow{5.0}

\NewExpandableDocumentCommand \category { m }{%
    %\newcommand{\category}[1]{
    \fp_compare:nNnTF {#1}<{\scoreLow}{Info}
    {
        \fp_compare:nNnTF{#1}<{\scoreCrit}{High}
        {Critical}
    }%
}%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% ADDITIONS
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\NewExpandableDocumentCommand \computeXXXXX { m }{%
    
    \str_new:N \l_XXXXXAV_str
    \str_new:N \l_XXXXXAC_str
    % A group allows nesting
    \group_begin:
    % Split into parts (separated by "/")
    \seq_set_split:Nnn \l__tnscalc_splittab_seq { / } { #1 }
    % Check that there are 2 items
    \int_compare:nNnTF {(\seq_count:N \l__tnscalc_splittab_seq)} = {2}{}{FALSE}
    % Get the 1st item out of the list : AV:N
    \seq_pop_left:NN \l__tnscalc_splittab_seq \l__tnscalc_tempAV_tl

    % Check item's value
    \str_case_e:nnF {\l__tnscalc_tempAV_tl}
    {
        {AV:N} { \str_set:Nn \l_XXXXXAV_str {N} }
        {AV:H} { \str_set:Nn \l_XXXXXAV_str {H} }
    }
    { \PackageError{XXXXX}{"\l__tnscalc_tempAV_tl"~is~not~a~XXXXX~AV~value}{<help>}}
    % Get the 2nd item out of the list : AC:N
    \seq_pop_left:NN \l__tnscalc_splittab_seq \l__tnscalc_tempAC_tl
    \str_case_e:nnF {\l__tnscalc_tempAC_tl}
    {
        {AC:N} { \str_set:Nn \l_XXXXXAC_str {N} }
        {AC:H} { \str_set:Nn \l_XXXXXAC_str {H} }
    }
    { \PackageError{XXXXX}{"\l__tnscalc_tempAC_tl"~is~not~a~XXXXX~AC~value}{<help>}}
    
%   \str_show:N \l_XXXXXAV_str
%   \str_show:N \l_XXXXXAC_str

%   % THIS WORKS BUT IS STATIC
%   \exp_args:Ne \__XXXX_choose_mapping:nn
%   { \fp_eval:n { \__XXXX_compute_value:n {N} } }
%   { \fp_eval:n { \__XXXX_factor_scaling:n {N} } }
    
    % THIS DOES NOT WORK    
    \exp_args:Ne \__XXXX_choose_mapping:nn
    { \fp_eval:n { \__XXXX_compute_value:n { \l_XXXXXAV_str } } }
    { \fp_eval:n { \__XXXX_factor_scaling:n { \l_XXXXXAC_str } } }
    
    \group_end:
}%




\ExplSyntaxOff

\begin{document}
    
    \edef\x{\basicMacro{N}}
    
    \texttt{\meaning\x}
    
    \category{\x}
    
    \category{\basicMacro{N}}
    
    ------
    
    \computeXXXXX{AV:N/AC:N} % FAILING LINE
    
    \category{\computeXXXXX{AV:N/AC:N}} % FAILING LINE
    
\end{document}