%  xr.cd
%  Anders G S Svensson

%  Source: xr.nw
%          $Revision: 1.5 $
%          $Date: 1996/03/23 18:44:30 $

\usecarrot{auxfile}

\newauxfile{cxr}

\def\definexr#1#2#3{%
   \readcxr \opencxr
   \edef\@action@{%
      \noexpand\writecxr{%
         \noexpand\noexpand\noexpand\xr@definexr@
            {#1}{#2}{#3}{\noexpand\folio}}}%
   \@action@}

\def\xr@definexr@#1#2#3#4{%
   \@gdef@{xr@xr@#1}{\xr@xref@{#3}{#2}{#4}}}

\def\refxr{\relax
   \readcxr \opencxr
   \@ifnextchar@*%
      {\def\xr@xref@{\expandafter\@FirstOfTwo@\@eat@}%
       \expandafter\xr@ref@\@eat@}%
      {\let\xr@xref@\xr@tagcs@ \xr@ref@}}
\def\xr@tagcs@#1#2{%
   \@ifundefined@{#1tag}\@echo@{\@cs@{#1tag}}{#2}\@eat@}
\let\emptytag\@echo@

\def\xr@ref@#1{%
   \@ifundefined@{xr@xr@#1}%
      {\@Warning@{Undefined label: #1}[#1]}%
      {\@cs@{xr@xr@#1}}}

\def\pagexr#1{%
   \readcxr \opencxr
   \@ifundefined@{xr@xr@#1}%
      {\@Warning@{Undefined label: #1}[#1]}%
      {\def\xr@xref@{\expandafter\@SecondOfTwo@\@eat@}\@cs@{xr@xr@#1}}}

\let\pagetag\@echo@
\def\definepage#1{\definexr{#1}{\noexpand\folio}{page}}