Reading in a conf file as a property list

Question

I'm not worried about supporting sections, although a bounty would be given for doing so :)

Here's what I have so far, but it produces strange output for #2:

\begin{filecontents}{test}
\Property this property = some value
\Property k = v
\end{filecontents}
\documentclass{article}
\usepackage{expl3}
\ExplSyntaxOn

\cs_new:Npn \Property #1=#2^^M
  {
    1:#1\par
    2:#2\par
  }

\ExplSyntaxOff
\begin{document}
\input{test}
\end{document}

Ideally, I would like to have a syntax like

\begin{filecontents*}{test.conf}
this property = some value
k = v

# bounty
[section]
property=value
\end{filecontents*}
\documentclass{article}
\usepackage{xparse}
\ExplSyntaxOn

\begin{document}
\conf_load:Nn \l_tmpa_prop { test.conf }

% outputs {some value} (brace groups irrelevant)
\conf_get:Nn \l_tmpa_prop { this ~ property }

% bounty; outputs {value} (brace groups irrelevant)
\conf_get:Nnn \l_tmpa_prop { section } { property }

\end{document}

How can this be accomplished? I should note that the details of the interface / naming is just a suggestion.

Ideas

(a work-in-progress list)

• Reading in the file and mapping a macro over each line; doesn't support sections
• Making necessary characters active for the read and practicing dark magic

Answer 1

Is this what you have in mind?

I define a toplevel property list and a section one; add the plists you need.

\begin{filecontents*}{test.conf}
this property = some value
k = v

# bounty
[section]
property=value
\end{filecontents*}
\documentclass{article}
\usepackage{xparse}
\ExplSyntaxOn
\NewDocumentCommand{\confload}{m}
 {
  \allred_conf_load:n { #1 }
 }

\prop_new:N \g_allred_conf_toplevel_prop
\prop_new:N \g_allred_conf_section_prop
\tl_new:N \l__allred_level_tl
\ior_new:N \g_allred_read_conf_stream

\cs_new_protected:Npn \allred_conf_load:n #1
 {
  \group_begin:
  \tex_endlinechar:D \c_minus_one % Ugly! Complain with the team!
  \char_set_catcode_comment:n { `\# }
  \ior_open:Nn \g_allred_read_conf_stream { #1 }
  \tl_set:Nn \l__allred_level_tl { toplevel }
  \ior_map_inline:Nn \g_allread_read_conf_stream
   {
    \tl_if_blank:nF { ##1 }
     {
      \__allred_process_line:x { \tl_trim_spaces:n { ##1 } }
     }
   }
  \ior_close:N \g_allred_read_conf_stream { #1 }
  \group_end:
 }

\cs_new_protected:Npn \__allred_process_line:n #1
 {
  \str_case_x:nnF { \tl_item:nn { #1 } { 1 } }
   {
    { [ } { \__allred_process_newlevel:n { #1 } }
   }
   {
    \__allred_process_property:n { #1 }
   }
 }
\cs_generate_variant:Nn \__allred_process_line:n { x }

\cs_new_protected:Npn \__allred_process_newlevel:n #1
 {
  \__allred_process_newlevel:w #1
 }
\cs_new_protected:Npn \__allred_process_newlevel:w [ #1 ]
 {
  \tl_set:Nn \l__allred_level_tl { #1 }
 }
\cs_new_protected:Npn \__allred_process_property:n #1
 {
  \__allred_process_property_aux:www #1 ==\q_stop
 }
\cs_new_protected:Npn \__allred_process_property_aux:www #1 = #2 = #3 \q_stop
 {
  \prop_gput:cxx { g__allred_conf_ \l__allred_level_tl _prop }
   { \tl_trim_spaces:n { #1 } }
   { \tl_trim_spaces:n { #2 } }
 }
\cs_generate_variant:Nn \prop_gput:cnn { cxx }

\ExplSyntaxOff


\begin{document}
\confload{test.conf}

\ExplSyntaxOn
\prop_show:N \g__allred_conf_toplevel_prop
\prop_show:N \g__allred_conf_section_prop
\ExplSyntaxOff


\end{document}

This is the output on the terminal

The property list \g__allred_conf_toplevel_prop contains the pairs (without
outer braces):
>  {this property}  =>  {some value}
>  {k}  =>  {v}.
<recently read> }

l.78 \prop_show:N \g__allred_conf_toplevel_prop

? 
The property list \g__allred_conf_section_prop contains the pairs (without
outer braces):
>  {property}  =>  {value}.
<recently read> }

l.79 \prop_show:N \g__allred_conf_section_prop

Answer 2

My solution uses no expl3, no special latex macros, only TeX primitives. Just for comparison. The coding of this task begins from line 11 (first ten lines are copied as universal macros from OPmac).

\bgroup \catcode`!=3 \catcode`?=3 % \replacestrings, \addto, \sxdef from OPmac
\gdef\replacestrings#1#2{%
   \long\def\tmp##1#1##2!{\ifx!##2!\addto\tmpb{##1}\else\addto\tmpb{##1#2}\tmp##2!\fi}%
   \edef\tmpb{\expandafter}\expandafter\tmp\tmpb?#1!%
   \def\tmp##1?{\def\tmpb{##1}}\expandafter\tmp\tmpb
}
\egroup
\long\def\addto#1#2{\expandafter\def\expandafter#1\expandafter{#1#2}}
\def\sxdef#1{\expandafter\xdef\csname#1\endcsname}

% \readconf config_file 
\newread\infile
\def\readconf #1 {\bgroup \catcode`\#=14 \endlinechar=-1
   \def\sectionconf{global}\openin\infile=#1 \readconfA
}
\def\readconfA{\ifeof\infile \egroup \else
   \read\infile to\tmp 
   \expandafter\readconfB\tmp\par
   \expandafter \readconfA\fi
}
\def\readconfB#1\par{\ifx\par#1\par \else \readconfC#1\par \fi}
\def\readconfC#1#2\par{\ifx[#1\expandafter\readconfD \else\expandafter\readconfE\fi#1#2\par}
\def\readconfD[#1]#2\par{\def\sectionconf{#1}}
\def\readconfE#1\par{\def\tmpb{#1}\replacestrings{= }{=}\replacestrings{ =}{=}%
   \expandafter\readconfF\tmpb\par}
\def\readconfF#1=#2\par{\setkeyval{#1}{#2}}

\def\setkeyval#1#2{\expandafter\ifx\csname conf:\sectionconf\endcsname\relax
   \sxdef{conf:\sectionconf}{}\fi
   \sxdef{conf:\sectionconf}{\csname conf:\sectionconf\endcsname{#1}}%
   \sxdef{key:\sectionconf:#1}{#2}%
}

% \showconf[section]
\def\showconf[#1]{\def\sectionconf{#1}\message{SECTION [#1]:}%
   \expandafter\expandafter\expandafter \showconfA \csname conf:#1\endcsname \relax
}
\def\showconfA#1{\ifx\relax#1\else \showconfB{#1}\expandafter\showconfA\fi}
\def\showconfB#1{\message{{#1} => {\csname key:\sectionconf:#1\endcsname}}}

\readconf test.conf

\showconf [global]  % SECTION [global]: {this property} => {some value} {k} => {v}
\showconf [section] % SECTION [section]: {property} => {value}

\end