%%
%% This is file `undolabl.sty',
%% generated with the docstrip utility.
%%
%% The original source files were:
%%
%% undolabl.dtx  (with options: `package')
%% 
%% This is a generated file.
%% 
%% Project: undolabl
%% Version: 2011/08/08 v1.0j
%% 
%% Copyright (C) 2010, 2011 by
%%     H.-Martin M"unch <Martin dot Muench at Uni-Bonn dot de>
%% Portions of code copyrighted by other people as marked.
%% 
%% The usual disclaimer applys:
%% If it doesn't work right that's your problem.
%% (Nevertheless, send an e-mail to the maintainer
%%  when you find an error in this package.)
%% 
%% This work may be distributed and/or modified under the
%% conditions of the LaTeX Project Public License, either
%% version 1.3c of this license or (at your option) any later
%% version. This version of this license is in
%%    http://www.latex-project.org/lppl/lppl-1-3c.txt
%% and the latest version of this license is in
%%    http://www.latex-project.org/lppl.txt
%% and version 1.3c or later is part of all distributions of
%% LaTeX version 2005/12/01 or later.
%% 
%% This work has the LPPL maintenance status "maintained".
%% 
%% The Current Maintainer of this work is H.-Martin Muench.
%% 
%% The main code of this package was invented by Ulrich Diez
%% (eu_angelion AT web DOT de) and first published in the comp.text.tex
%% newsgroup at Sun, 20 Apr 2008 16:39:26 +0200, with subject:
%% Re: How to undefine/overwrite a label? (see e.g.
%% http://groups.google.de/group/comp.text.tex/msg/af6cfe93917097da?dmode=source
%% ). While Ulrich Diez neither wanted to create a package himself yet
%% nor have one published under his name, he granted the
%% publication of his code. Therefore: Thanks!
%% 
%% This work consists of the main source file undolabl.dtx
%% and the derived files
%%    undolabl.sty, undolabl.pdf, undolabl.ins, undolabl.drv,
%%    undolabl-example.tex.
%% 

\NeedsTeXFormat{LaTeX2e}[2009/09/24]
\ProvidesPackage{undolabl}[2011/08/08 v1.0j
  Overriding labels (HMM)]
%% undolabl may work with earlier versions of LaTeX2e,
%% but this was not tested. Please consider updating
%% your LaTeX2e to the most recent version
%% (if it is not already the most recent version).

\newcommand\overridelabel[1]{%
  \@bsphack
  \protected@write\@auxout{}{\string\undonewlabel{#1}}%
  \@overriddenmessage s{#1}%
  \label{#1}%
  \@esphack
  }

\newcommand\undonewlabel{\@und@newl@bel r}

\newcommand\@und@newl@bel[2]{%
  \@ifundefined{#1@#2}{%
    \PackageError{undolabl}{Label `#2' shall be overridden ^^J%
      although it does not yet exist}{%
      A label which does not exist cannot be overridden.}%
  }{%
    \expandafter\global
    \expandafter\let
    \csname #1@#2\endcsname\relax
   }%
  }

\newcommand\@overriddenmessage[2]{%
  \@ifundefined{#1@#2}{\global\@namedef{#1@#2}{i}}{%
    \expandafter\g@addto@macro\csname #1@#2\endcsname{i}%
    }%
  \PackageWarning{undolabl}{Label `#2' overridden}%
  }

\newcommand\undolabl@testdef[3]{%
  \@ifundefined{s@#2}\@secondoftwo\@firstofone{%
    \expandafter\ifx\csname s@#2\endcsname\empty
      \expandafter\@firstofone
    \else
    \expandafter\xdef\csname s@#2\endcsname{%
      \expandafter\expandafter
      \expandafter\@gobble
      \csname s@#2\endcsname
      }%
    \expandafter\@gobble
    \fi
    }{\@testdef{#1}{#2}{#3}%
     }%
  }

\protected@write\@auxout{}{\string\reset@newl@bel}

\newcommand\reset@newl@bel{%
  \ifx\@newl@bel\@testdef
    \let\@newl@bel\undolabl@testdef
    \let\undonewlabel\@gobble
  \fi
  }

\endinput
%%
%% End of file `undolabl.sty'.
