rdfref-query.sty

\ProvidesPackage{rdfref-query}
\RequirePackage{rdfref-core}
\def\Var#1{Variable: #1}
\def\Value#1{Value: #1}

\newcommand\BindVal[2]{%
\IfBeginWith{#2}{?}{%
\ifcsdef{rdfquery@#2}{\def#1{\Value{\csuse{rdfquery@#2}}}}{\def#1{\Var{#2}}}%
}{\def#1{\Value{#2}}}%
}

\newcommand\SaveVal[2]{%
\csedef{rdfquery@#1}{#2}%
}

\newcommand\GetValProperty[2]{%
 \expandafter\GetProperty\expandafter{\GetVal{#1}}{#2}%
}


\newcommand\GetVal[1]{%
\csuse{rdfquery@#1}%
}


\newcommand\QueryType[3]{%
\bgroup%
\def\Var##1{v}%
\def\Value##1{l}%
\xdef\qtype{#1#2#3}%
\egroup%
}
\newcommand\DeclareQueryProcessor[2]{%
\long\csgdef{rdfquery@proc@#1}##1{%
\long\def\continue{##1}%
#2}%
}

% v means variable to be looked up, l is searched literal
\DeclareQueryProcessor{vlv}{%
% why we redefine \Value and \Var? I should write comments next time
\def\Value##1{##1}%
\def\Var##1{##1}%
\MapPropertyList\predicate{%
\SaveVal\subject{\ifx\\##1\\\else\First##1\fi}%
\SaveVal\object{\ifx\\##1\\\else\Second##1\fi}%
\continue
}%
}

\DeclareQueryProcessor{vll}{%
	% this is first querry processor after two years, I have no idea what 
	% needs to be done
\def\Value##1{##1}%
\def\Var##1{##1}%
\MapPropertyList\predicate{%
	% only do action if searched \object is equal to current objeect
	\IfStrEq{\object}{\ifx\\##1\\\else\Second##1\fi}{%
	% ##1 is variable passed by \do, two tokens are here:
	  \SaveVal\subject{\ifx\\##1\\\else\First##1\fi}%
	  % \SaveVal\predicate{\ifx\\##1\\\else\Second##1\fi}% no need to save predicate, as we are looking only for subject in this query processor
    \continue}{}%
 }%
}


\DeclareQueryProcessor{llv}{%
  \def\Value##1{##1}%
  \def\Var##1{##1}%
  % Subject can have multiple values of property, so we need to loop over them
  \MapPropertyList\predicate{%
    \IfStrEq\subject{\ifx\\##1\\\else\First##1\fi}{%
      \SaveVal\object{\ifx\\##1\\\else\Second##1\fi}%
    \continue}{}%
  }%
}%


\DeclareQueryProcessor{lvv}{%
 \def\Value##1{##1}%
 \def\Var##1{##1}%
 \MapSubjectList\subject{%
  \SaveVal\predicate{\ifx\\##1\\\else\First##1\fi}%
  \SaveVal\object{\ifx\\##1\\\else\Second##1\fi}%
  \continue%
 }%
}

\DeclareQueryProcessor{lvl}{%
 \def\Value##1{##1}%
 \def\Var##1{##1}%
 \MapSubjectList\subject{%
   % \IfStrEq{\GetProperty{\subject}{##1}}{\object}{%
   \IfStrEq{\ifx\\##1\\\else\Second##1\fi}{\object}{%
    \SaveVal\predicate{\ifx\\##1\\\else\First##1\fi}% 
    \continue%
   }{}%
 }% 
}

\DeclareQueryProcessor{lll}{%
\def\Value##1{##1}%
\def\Var##1{##1}%
\IfStrEq{\GetPropertyNoCheck{\subject}{\predicate}}{\object}{\continue}{}%
}



\newcommand\Bind[4]{%
\bgroup%
\BindVal\subject{#1}%
\BindVal\predicate{#2}%
\BindVal\object{#3}%
\QueryType\subject\predicate\object%
\ifcsdef{rdfquery@proc@\qtype}{\csuse{rdfquery@proc@\qtype}{#4}}{\typeout{\detokenize{Unknown RDF query processor:} \qtype}}%
\egroup%
}

% what is the purpose of this command?
\newcommand\OptionalBind[3]{%
%\bgroup%
\BindVal\subject{#1}%
\BindVal\predicate{#2}%
\BindVal\object{#3}%
\QueryType\subject\predicate\object%
\ifcsdef{rdfquery@proc@\qtype}{\csuse{rdfquery@proc@\qtype}{}}{\typeout{\detokenize{Unknown RDF query processor:} \qtype}}%
%#4
%\egroup%  
}

\endinput