% \iffalse meta comment
% File: fnbreak.dtx Copyright (C) 2003, 2004 Harald Harders
% \fi
%
% \iffalse
%
%<*driver>
\documentclass{ltxdoc}
\title{The \texttt{fnbreak} package}
\author{Harald Harders\\\texttt{h.harders@tu-bs.de}}
\date{Version \fileversion, \filedate, Printed \today}
\EnableCrossrefs
\CodelineIndex
\DoNotIndex{\def,\edef,\let,\newcommand,\newenvironment,\newcounter}
\DoNotIndex{\setcounter,\space}
\CodelineNumbered
\RecordChanges
\CheckSum{132}
\IfFileExists{fnbreak-v.tex}{%
  \input{fnbreak-v.tex}
  \GetFileInfo{fnbreak-v.tex}
}{%
  \PackageError{fnbreak}{File fnbreak-v.tex not found,
    please\MessageBreak 
    run `latex fnbreak.ins' first}{No additional help}%
  \def\fileversion{\textbf{??}}%
  \def\filedate{\textbf{??}}%
}
\begin{document}
 \DocInput{fnbreak.dtx}
\end{document}
%</driver>
% \fi
%
% \changes{0.01}{2003/04/03}{First version}
%
% \maketitle
% \begin{abstract}
% \noindent This package detects footnotes that are split over several
% pages. It writes a warning into the log file.
% \end{abstract}
%
% \tableofcontents
%
% \section*{Copyright}
% Copyright 2003, 2004 Harald Harders.
%
% This program can be redistributed and/or modified under the terms
% of the LaTeX Project Public License Distributed from CTAN
% archives in directory macros/latex/base/lppl.txt; either
% version 1.3 of the License, or any later version.
%
% \section{The user interface}
%
% To use this package place
%\begin{verbatim}
%\usepackage{fnbreak}
%\end{verbatim}
% in the preamble of your document.
%
% If a footnote is split over a page break, a warning like the
% following is put into the log:
%\begin{verbatim}
%Package fnbreak Warning: Footnote number 1 (label `a')
%(fnbreak)                has been split over different pages:
%(fnbreak)                page 1 to page 2.
%\end{verbatim}
% Sometimes, complicated footnote labels are used (for example, when
% using symbols):
%\begin{verbatim}
%Package fnbreak Warning: Footnote number 1 (label `\ensuremath {*}')
%(fnbreak)                has been split over different pages:
%(fnbreak)                page 1 to page 2.
%\end{verbatim}
% In some cases may this even break the function.
% To avoid these problems, you may give the package option |nolabel|:
%\begin{verbatim}
%\usepackage[nolabel]{fnbreak}
%\end{verbatim}
% Then the label is omitted in the warning:
%\begin{verbatim}
%Package fnbreak Warning: Footnote number 1 
%(fnbreak)                has been split over different pages:
%(fnbreak)                page 1 to page 2.
%\end{verbatim}
%
% When using the package option |verbose| the fnbreak package writes a
% message for every footnote, even if it is completely on one page.
%
% \StopEventually{\PrintChanges \PrintIndex}
%
% \section{The implementation}
%
% The approach of this package is very simple:
% At the begin and the end of each footnote text, the footnote number
% and current page are written to the aux file. Then, it is tested if
% both pages are the same for each footnote.
%
% Heading of the package:
%    \begin{macrocode}
%<package>\ProvidesPackage{fnbreak}
%<version>\ProvidesFile{fnbreak-v.tex}
%<package|version>  [2004/04/06  v1.10  Warning for pagebreak in footnote (HH)]
%<*package>
%    \end{macrocode}
% Declare an option to show not only the footnote number but also the
% label.
% \changes{1.10}{2004/04/06}{Add option `verbose'}%
%    \begin{macrocode}
\newif\iffnb@showlabel
\fnb@showlabeltrue
\newif\iffnb@verbose
\DeclareOption{nolabel}{\fnb@showlabelfalse}
\DeclareOption{verbose}{\fnb@verbosetrue}
\ProcessOptions\relax
%    \end{macrocode}
% Define default values in order to avoid possible problems:
% \changes{1.00}{2004/04/01}{Correct some internal macro names}%
%    \begin{macrocode}
\xdef\fnb@@footnotestartnum{0}
\xdef\fnb@@footnotestartpage{0}
%    \end{macrocode}
% When the aux file is read the first time (before \cs{begin\{document\}},
% do nothing:
%    \begin{macrocode}
\def\fnb@footnotestart#1#2#3{}
\def\fnb@footnoteend#1#2#3{}
%    \end{macrocode}
% Define the working commands at \cs{begin\{document\}} in order to
% activate them when the aux file is read at the end of the document:
%    \begin{macrocode}
\AtBeginDocument{%
%    \end{macrocode}
% If the start of a footnote has been found, just define commands
% containing the footnote number (only for debugging) and the start page:
%    \begin{macrocode}
  \def\fnb@footnotestart#1#2#3{%
    \xdef\fnb@@footnotestartnum{#1}%
    \xdef\fnb@@footnotestartpage{#3}%
  }%
%    \end{macrocode}
% \changes{1.00}{2004/04/01}{No need to have numerical page numbers
%   anymore}%
% \changes{1.00}{2004/04/01}{Use the footnote number instead of the
%   label, show both in the warning}%
% If the end of a footnote has been found, test wheather the footnote
% numbers fit and wheather the start and end pages are the same. If
% one of the tests fails, generate a warning:\footnote{Thanks to
%   Bastien Roucaries for pointing at a problem with symbol footnote
%   marks.}
%    \begin{macrocode}
  \def\fnb@footnoteend#1#2#3{%
    \xdef\fnb@@footnoteendnum{#1}%
    \xdef\fnb@@footnoteendpage{#3}%
%    \end{macrocode}
% Test if start and end refer to the same footnote.
%    \begin{macrocode}
    \ifx\fnb@@footnotestartnum\fnb@@footnoteendnum
%    \end{macrocode}
% Test if the footnote ends on the same page it has started.
%    \begin{macrocode}
      \ifx\fnb@@footnotestartpage\fnb@@footnoteendpage
%    \end{macrocode}
% Yes, the footnote is completely on one page.
% Print a message if |verbose| mode is requested.
%    \begin{macrocode}
        \iffnb@verbose
          \message{Package fnbreak: Footnote number #1
            \iffnb@showlabel(label `#2') \fi^^J%
            \space\space\space\space\space\space
            \space\space\space\space\space\space
            \space\space\space\space\space
            completely on page #3.}%
        \fi
      \else
%    \end{macrocode}
% No, the footnote contains a pagebreak.
% Print a warning.
%    \begin{macrocode}
        \PackageWarningNoLine{fnbreak}{Footnote number #1
          \iffnb@showlabel(label `#2')\fi
          \MessageBreak
          has been split over different pages:\MessageBreak
          page \fnb@@footnotestartpage\space to page #3}%
%    \end{macrocode}
% Redefine the \cs{fnb@globalwarning} to print a warning at the end of
% the log file.
%    \begin{macrocode}
        \def\fnb@globalwarning{%
          \PackageWarningNoLine{fnbreak}{There are footnotes with a
            pagebreak.\MessageBreak
            Check if they are acceptable}%
        }%
      \fi
    \else
%    \end{macrocode}
% This macro trys to handle different footnotes.
% This may not happen and is an internal error.
%    \begin{macrocode}
      \PackageError{fnbreak}{Internal problem:\MessageBreak
        Start and stop marker of footnote do not fit:\MessageBreak
        start: \fnb@@footnotestartnum, page \fnb@@footnotestartpage,
        end: #1, page #3}{%
        This error may not happen.
        Please try to make a short example which shows this behaviour
        and send a bug report to h.harders@tu-bs.de.}%
    \fi
    }%
  }
%    \end{macrocode}
% Define command that writes the footnote start marker to the aux
% file:
%    \begin{macrocode}
  \def\fnb@fnstart{\@bsphack
    \protected@write\@auxout{}{%
      \string\fnb@footnotestart{\the\c@footnote}{\thefootnote}{\thepage}%
    }%
    \@esphack
  }
%    \end{macrocode}
% Define command that writes the footnote end marker to the aux file:
%    \begin{macrocode}
  \def\fnb@fnend{\@bsphack
    \protected@write\@auxout{}{%
      \string\fnb@footnoteend{\the\c@footnote}{\thefootnote}{\thepage}%
    }%
    \@esphack
  }
%    \end{macrocode}
% \changes{1.00}{2004/04/01}{Patch \cs{@footnotetext} instead of
%   re-writing it}%
% Redefine \cs{@footnotetext} by patching the calls \cs{fnb@fnstart}
% and \cs{fnb@fnend} after all other packages have been
% loaded.\footnote{Thanks to Bastien Roucaries for that patch}
%    \begin{macrocode}
\AtBeginDocument{%
  \newcommand\fnb@orig@footnotetext{}%
  \let\fnb@orig@footnotetext\@footnotetext
  \long\def\@footnotetext#1{\fnb@orig@footnotetext{\fnb@fnstart#1\fnb@fnend}}%
%    \end{macrocode}
% \changes{1.10}{2004/04/06}{Write a warning at the end of the log
%   file}%
% Append \cs{fnb@globalwarning} to \cs{@dofilelist} in order to print
% the global warning \cs{fnb@globalwarning} after all other messages,
% e.g., the \cs{listfiles} list.
%    \begin{macrocode}
  \newcommand\fnb@dofilelist{}%
  \let\fnb@dofilelist\@dofilelist
  \def\@dofilelist{\fnb@dofilelist\fnb@globalwarning}%
}
%    \end{macrocode}
% Initialise \cs{fnb@globalwarning} to print no warning by default.
%    \begin{macrocode}
\newcommand\fnb@globalwarning{}%
\let\fnb@globalwarning\relax
%</package>
%    \end{macrocode}
%
% \Finale