% Copyright 2003--2007 by Till Tantau
% Copyright 2010 by Vedran Mileti\'c
% Copyright 2011--2015 by Vedran Mileti\'c, Joseph Wright
% Copyright 2017,2018 by Louis Stuart, Joseph Wright
%
% This file may be distributed and/or modified
%
% 1. under the LaTeX Project Public License and/or
% 2. under the GNU Public License.
%
% See the file doc/licenses/LICENSE for more details.

\mode
<presentation>

\newbox\beamer@framebox
\newbox\beamer@frametitlebox
\newbox\beamer@zoombox
\newcount\beamer@zoomcount
\newcount\beamer@zoomframecount
\newdimen\beamer@frametextheight

\mode
<all>
{
  \newif\ifbeamer@inframe
  \beamer@inframefalse
% Save!
  \let\framelatex=\frame
  \def\@iframepicbox(#1,#2)[#3]#4{%
    \framelatex{\@imakepicbox(#1,#2)[#3]{#4}}%
  }%
}

\def\refcounter#1{\protected@edef\@currentlabel%
       {\csname p@#1\endcsname\csname the#1\endcsname}}%


%
% Slide Definitions
%

\newcounter{subsectionslide}[subsection]
\renewcommand\thesubsectionslide{\@arabic\c@subsectionslide}
\def\beamer@entrycode{}
\def\beamer@exitcode{}

\def\beamer@setuplinks{%
  {%
    \def\sectionentry##1##2##3##4##5{}%
    \def\slideentry##1##2##3##4##5##6{}%
    \dohead%
  }%
}

\newenvironment{beamer@frameslide}{%
  \ifbeamer@autobreak\else%
    \ifx\beamer@againname\@empty%
      {\let\@elt\beamer@restorecounter\beamer@overlaycounterresets}%
    \else%
      {\let\@elt\beamer@labelrestorecounter\beamer@overlaycounterresets}%
    \fi%
  \fi%
  \global\c@beamerpauses=1\relax%
  \expandafter\ifblank\expandafter{\beamer@framestartpage}{%
    \stepcounter{subsectionslide}%
    \xdef\beamer@framestartpage{\the\c@page}% only first time
  }{\clearpage\beamer@notesactions}% cleanup from previous slide
  \hypersetup{pdfpagetransition=R}%
  \hypersetup{pdfpageduration=}%
  \@ifundefined{thispdfpagelabel}{}{%
  \thispdfpagelabel{\insertframenumber}}%
  \xdef\beamer@frameendpage{\the\c@page}% every time
  \xdef\beamer@slidenumber{\the\numexpr\c@page-\beamer@framestartpage+1\relax}%
  \xdef\beamer@overlaynumber{\the\beamer@slideinframe}%
  \beamer@setuplinks%
  \beamer@displaybreak%
  \global\setbox\beamer@zoombox=\box\voidb@x%
  \def\beamer@zoomer{}%
  \beamer@slidehaszoomfalse%
  \gdef\insertframetitle{}%
  \gdef\insertframesubtitle{}%
  \gdef\beamer@frametitle{}%
  \gdef\beamer@shortframetitle{}%
  \gdef\beamer@framesubtitle{}%
  \let\beamer@startcomment=\beamer@startcommentinframe%
  % Start slide:
  \beamer@framenotesbegin%
    \global\setbox\beamer@framebox=\vbox\bgroup%
    \beamer@inframetrue%
    \let\frame=\framelatex% inside frames, use LaTeX's \frame command
    \begin{beamer@framepauses}%
      \refcounter{framenumber}%use frame number for  \label
      \ifbeamer@shrink%
        \hsize=\beamer@shrinkfactorinv\hsize%
        \textwidth=\beamer@shrinkfactorinv\textwidth%
        \linewidth=\beamer@shrinkfactorinv\linewidth%
      \fi%
      % Insert labels if necessary:
      \ifx\beamer@againname\@empty\else%
        \nointerlineskip\vbox to0pt{\vss%
        \label<\the\beamer@slideinframe>{\beamer@againname<\the\beamer@slideinframe>}%
        \ifnum\beamer@slideinframe=1\relax%
          \label<1>{\beamer@againname}%
        \fi%
        }\nointerlineskip%
      \fi%
      \ifx\beamer@framehypertargets\@empty\else%
        \nointerlineskip\vbox to0pt{\vss%
          \beamer@framehypertargets%
          \global\let\beamer@framehypertargets\@empty%
        }\nointerlineskip%
      \fi%
      \vskip-\parskip\vbox{}%
      \ifbeamer@plainframe\nointerlineskip\fi%
    \beamer@checkframetitle}%
    {\par
    \end{beamer@framepauses}%
  \egroup%
  \ifx\beamer@frametitle\@empty%
    \setbox\beamer@frametitlebox=\box\voidb@x%
  \else%
    \setbox\beamer@frametitlebox=\vbox{%
      \vbox{}%
      {\parskip0pt\usebeamertemplate***{frametitle}\vskip0.25em}%
    }%
  \fi%
  \ifbeamer@plainframe%
    \beamer@frametextheight=\paperheight%
  \else%
    \beamer@frametextheight=\textheight%
  \fi%
  \advance\beamer@frametextheight by-\ht\beamer@frametitlebox%
  \advance\beamer@frametextheight by-\dp\beamer@frametitlebox%
  \advance\beamer@frametextheight by-\beamer@frametopskip%
  \ifbeamer@shrink%
    \beamer@shrinkframebox%
  \fi%
  \ifx\beamer@zoomer\@empty
    \setbox\beamer@framebox=\vbox{%
      \nobreak\vbox{}\nobreak\par\nobreak\beamer@entrycode\nobreak%
      \nointerlineskip\unvbox\beamer@frametitlebox%
      \nobreak%
      \ifbeamer@autobreak%
        \vskip\beamer@frametopskipautobreak%
      \else%
        \vskip\beamer@frametopskip%
      \fi%
      \nobreak%
      \nointerlineskip\box\beamer@zoombox\nointerlineskip%
      \nobreak%
      \ifbeamer@slidehaszoom\box\beamer@framebox\else\unvbox\beamer@framebox\fi%
      % bottom skip is added in autobreakframebox
    }%
    \beamer@autobreakframebox%
  \else%
    \beamer@zoomer%
  \fi%
  \beamer@undolabels%
  \beamer@framenotesend%
  \box\beamer@framebox}


\mode
<all>
{
  \def\beamer@checkframetitle{\@ifnextchar\bgroup\beamer@inlineframetitle{}}
  \def\beamer@inlineframetitle#1{%
    \@ifnextchar\bgroup{\frametitle{#1}\framesubtitle}{\frametitle{#1}\relax}%
  }
}





%
% Resetting counters
%
\def\resetcounteronoverlays#1{%
  \@cons\beamer@overlaycounterresets{{c@#1}}%
}

\def\resetcountonoverlays#1{%
  \@cons\beamer@overlaycounterresets{{#1}}%
}

\def\beamer@overlaycounterresets{}

\resetcounteronoverlays{equation}
\resetcounteronoverlays{parentequation}
\resetcounteronoverlays{footnote}
\resetcounteronoverlays{mpfootnote}
\resetcounteronoverlays{figure}
\resetcounteronoverlays{table}
\resetcountonoverlays{beamer@zoomframecount}
\resetcounteronoverlays{ExNo}
\resetcounteronoverlays{SubExNo}
\resetcounteronoverlays{SubSubExNo}

\def\beamer@savecounter#1{%
  \@ifundefined{#1}{}%
  {\expandafter\xdef\csname saved@#1\endcsname%
    {\expandafter\the\csname #1\endcsname}}%
}
\def\beamer@restorecounter#1{%
  \@ifundefined{#1}{}%
  {\edef\temp{\csname saved@#1\endcsname}%
  \expandafter\global\csname #1\endcsname=\temp}%
}

\def\beamer@labelsavecounter#1{%
  \@ifundefined{#1}{}%
  {\expandafter\xdef\csname saved@\beamer@againname @#1\endcsname%
    {\expandafter\the\csname #1\endcsname}}%
}
\def\beamer@labelrestorecounter#1{%
  \@ifundefined{#1}{}%
  {\edef\temp{\csname saved@\beamer@againname @#1\endcsname}%
  \expandafter\global\csname #1\endcsname=\temp}%
}



%
% Skips
%
\newskip\beamer@frametopskip
\newskip\beamer@framebottomskip
\newskip\beamer@frametopskipautobreak
\newskip\beamer@framebottomskipautobreak


%
% Keys
%
\define@key{beamerframe}{label}{\def\beamer@againname{#1}%
  {\let\@elt\beamer@labelsavecounter\beamer@overlaycounterresets}%
}
\define@key{beamerframe}{relabel}{\def\beamer@againname{#1}%
  \def\beamer@undolabels{{\let\@elt\beamer@restorecounter\beamer@overlaycounterresets}}%
}
\define@key{beamerframe}{plain}[true]{%
  \beamer@plainframetrue%
  \def\beamer@frametemplate{\beamer@frametemplate@plain}}
\define@key{beamerframe}{containsverbatim}[true]{\csname beamer@containsverbatim#1\endcsname}
\define@key{beamerframe}{fragile}[true]{%
  \beamer@containsverbatimfalse%
  \beamer@isfragilefalse%
  \csname beamer@fragile#1\endcsname%
}
\def\beamer@fragilefalse{}
\def\beamer@fragiletrue{\beamer@isfragiletrue}
\def\beamer@fragilesingleslide{\beamer@containsverbatimtrue}
\define@key{beamerframe}{c}[true]{% centered
  \beamer@frametopskip=0pt plus 1fill\relax%
  \beamer@framebottomskip=0pt plus 1.5fill\relax%
  \beamer@frametopskipautobreak=0pt plus .4\paperheight\relax%
  \beamer@framebottomskipautobreak=0pt plus .6\paperheight\relax%
}
\define@key{beamerframe}{t}[true]{% top
  \beamer@frametopskip=.2cm plus .5\paperheight\relax%
  \beamer@framebottomskip=0pt plus 1fill\relax%
  \beamer@frametopskipautobreak=\beamer@frametopskip\relax%
  \beamer@framebottomskipautobreak=\beamer@framebottomskip\relax%
}
\define@key{beamerframe}{b}[true]{% bottom
  \beamer@frametopskip=0pt plus 1fill\relax%
  \beamer@framebottomskip=0pt\relax%
  \beamer@frametopskipautobreak=\beamer@frametopskip\relax%
  \beamer@framebottomskipautobreak=\beamer@framebottomskip\relax%
}

\newif\ifbeamer@noframenumbering

\define@key{beamerframe}{noframenumbering}[true]{\beamer@noframenumberingtrue}

\define@key{beamerframe}{environment}{\def\beamer@frameenvironmentsubst{#1}}

\define@key{beamerframe}{typeset second}[true]{\csname beamer@dosecondmode#1\endcsname}

\newif\ifbeamer@containsverbatim
\newif\ifbeamer@isfragile
\newif\ifbeamer@autobreak
\newif\ifbeamer@shrink
\newif\ifbeamer@plainframe
\newif\ifbeamer@slidehaszoom

\let\beamer@firstlineitemizeunskip\relax



%
% The frame environment (a trifle ugly...)
%

% Copyright notice: the following code is adapted from code from the
% amsmath package.

\newtoks\beamer@envbody
\def\beamer@frameenv{%
  \def\beamer@process@envbody{\endgroup%
    \expandafter\expandafter\expandafter\beamer@framecommand\expandafter\beamer@frameoptions\expandafter{\the\beamer@envbody}}%
  \global\beamer@envbody{}\def\beamer@begin@stack{b}%
  \begingroup
  \let\frame\beamer@collect@@body
  \def\beamer@process@envbody{\frame}%
  \beamer@process@envbody%
}

% Normally not executed; only in containsverbatim context:
\def\endframe{\egroup\begingroup\def\@currenvir{frame}}

\long\def\beamer@push@begins#1\begin#2{\ifx\end#2\else b\expandafter\beamer@push@begins\fi}
\long\def\beamer@collect@@body#1\end#2{%
  \edef\beamer@begin@stack{\beamer@push@begins#1\begin\end \expandafter\@gobble\beamer@begin@stack}%
  \ifx\@empty\beamer@begin@stack
      \global\beamer@envbody\expandafter{\the\beamer@envbody#1}%
    \def\reserved@a{#2}
    \ifx\reserved@a\beamer@frametext%
      \endgroup%
      \let\@next=\beamer@process@envbody % A little tricky! Note the grouping
      \@checkend{#2}%
    \else%
      % ok, just expand it, presumably it will generate the desired \end{frame}
      \let\@next=\beamer@process@expander%
    \fi
  \else
    \global\beamer@envbody\expandafter{\the\beamer@envbody#1\end{#2}}%
    \let\@next=\beamer@process@envbody%
  \fi
  \@next
}

\def\beamer@process@expander{%
  \def\beamer@begin@stack{b}%
  \expandafter\expandafter\expandafter\beamer@collect@@body\csname end\reserved@a\endcsname\endgroup}


\mode
<all>
{\def\beamer@frametext{frame}}

\def\frame{%
  \ifx\@currenvir\beamer@frametext%
    \gdef\beamer@frameoptions{}%
    \let\beamer@next=\beamer@copewithframeenv%
  \else%
    \let\beamer@next=\beamer@framecommand%
  \fi%
  \beamer@next}

\def\beamer@copewithframeenv{%
  \@ifnextchar<%
  {\beamer@@frameenvspec}%
  {%
    \@ifnextchar[%
    {\beamer@@frameenvopt}%
    {\expandafter\beamer@checkforverbatim\beamer@frameoptions containsverbatim\relax}}%
}
\def\beamer@@frameenvspec<#1>{%
  \expandafter\gdef\expandafter\beamer@frameoptions\expandafter{\beamer@frameoptions<#1>}%
  \beamer@copewithframeenv}
\def\beamer@@frameenvopt[#1]{%
  \expandafter\gdef\expandafter\beamer@frameoptions\expandafter{\beamer@frameoptions[#1]}%
  \beamer@copewithframeenv}

\def\beamer@checkforverbatim#1containsverbatim#2\relax{%
  \ifblank{#2}%
  {\beamer@checkforfragile#1fragile\relax}
  {% contains verbatim
    \endgroup% end environment
    \expandafter\beamer@framecommand\beamer@frameoptions\bgroup}%
}
\def\beamer@checkforfragile#1fragile#2\relax{%
  \ifblank{#2}%
  {\beamer@frameenv}% normal frame
  {% contains verbatim
    \endgroup% end environment
    \expandafter\beamer@framecommand\beamer@frameoptions\bgroup}%
}


% Check for old version:

\def\beamer@framecommand{%
  \edef\beamer@defaultospec{\beamer@gdefaultospec}%
  \@ifnextchar<\beamer@frame\beamer@checkoldframe}
\def\beamer@checkoldframe{\@ifnextchar[\beamer@@checkoldframe{\beamer@frame<*>}}
\def\beamer@@checkoldframe[{\@ifnextchar<{\beamer@frame<*>[}{\beamer@@@checkoldframe[}}
\def\beamer@@@checkoldframe[#1#2]{%
  \let\beamer@next=\beamer@newframesyntax%
  \ifcat#11% a number-like first letter in argument
    \let\beamer@next=\beamer@oldframesyntax%
  \else%
    \beamer@checkforcolon#2:.%
  \fi%
  \beamer@next{#1#2}}
\def\beamer@checkforcolon#1:#2.{%
  \ifblank{#2}{}{\let\beamer@next=\beamer@oldframesyntax}}
\def\beamer@newframesyntax#1{\beamer@@@frame<*>[#1]}
\def\beamer@oldframesyntax#1{\beamer@@@frame<#1>[]}

\def\beamer@framedefaultospec<#1>[#2]{%
  \def\beamer@defaultospec{#2}%
  \@ifnextchar[{\beamer@@@@frame<#1>}{\beamer@@@@frame<#1>[]}}

\newdimen\framewidth
\def\beamer@frame<#1>{
  \@ifnextchar[{\beamer@@@frame<#1>}{\beamer@@@frame<#1>[]}}
\def\beamer@@@frame<#1>[{\@ifnextchar<{\beamer@framedefaultospec<#1>[}{\beamer@@@@frame<#1>[}}
\def\beamer@@@@frame<#1>[#2]{%
  \framewidth\textwidth
  \beamer@savemode%
  \gdef\beamer@mode{\mode<all>}%
  \def\beamer@frametemplate{}%
  \def\beamer@againname{}%
  \def\beamer@undolabels{}%
  \def\beamer@cramped{}%
  \def\beamer@displaybreak{}%
  \setbox\beamer@footins=\box\voidb@x%
  \beamer@autobreakcount=0\relax%
  \beamer@autobreaklastheight=16000pt%
  \beamer@zoomcount=0\relax%
  \beamer@noframenumberingfalse%
  \beamer@containsverbatimfalse%
  \beamer@isfragilefalse%
  \beamer@autobreakfalse%
  \beamer@shrinkfalse%
  \beamer@plainframefalse%
  \global\advance\beamer@zoomframecount by1\relax%
  \csname beamer@dosecondmode\beamer@defaultdosecondmode\endcsname%
  \ifbeamer@centered\setkeys{beamerframe}{c}\else\setkeys{beamerframe}{t}\fi%
  \setkeys{beamerframe}{environment=frame}%
  \setkeys{beamerframe}{#2}%
  \beamer@frametemplate%
  \ifbeamer@noframenumbering%
    \ifbeamer@isfragile%Fragile frames will be processed twice
      \stepcounter{framenumber}%
    \fi%
  \else%
    \stepcounter{framenumber}%do not set \label here - it interferes with AtBegin*
  \fi%
  {\let\@elt\beamer@savecounter\beamer@overlaycounterresets}
  \gdef\beamer@framestartpage{}%
  \gdef\beamer@whichframes{#1}%
  \ifx\beamer@framerestriction\@undefined\else% restriction stuff
    \expandafter\beamer@checkifinlist\beamer@framerestriction\relax%
  \fi%
  \ifbeamer@inlecture%
  \else%
    \gdef\beamer@whichframes{all:0}%
  \fi%
  \ifx\beamer@againname\@empty%
    \beamer@slideinframe=0\relax%
    \beamer@anotherslidefalse%
    \beamer@masterdecode{\beamer@whichframes}%
    \ifbeamer@anotherslide%
        \let\beamer@howtotreatframe\beamer@doseveralframes%
      \ifbeamer@containsverbatim%
        \let\beamer@howtotreatframe\beamer@dosingleframe%
      \fi%
      \ifbeamer@autobreak%
        \let\beamer@howtotreatframe\beamer@autobreakframe%
      \fi%
      \ifbeamer@isfragile%
        \let\beamer@howtotreatframe\beamer@doexternalframe%
      \fi%
    \else% no slides in frame
      \let\beamer@howtotreatframe\beamer@donoframe%
    \fi%
  \else% again mode
    \let\beamer@howtotreatframe\beamer@doseveralframes%
    \ifbeamer@isfragile%
      \let\beamer@howtotreatframe\beamer@doexternalframe%
    \fi%
    \ifbeamer@containsverbatim
      \let\beamer@howtotreatframe\beamer@dosingleframe
    \fi
  \fi%
  \beamer@howtotreatframe}
\def\gobble@onslide{%
  \@ifstar{\gobble@onslide@aux}{%
    \@ifnextchar+{\expandafter\gobble@onslide@aux\@gobble}%
    {\gobble@onslide@aux}%
  }%
}
\def\gobble@onslide@aux{%
  \@ifnextchar<%>
    \gobble@onslide@@aux
    \@firstofone
}
\def\gobble@onslide@@aux<#1>{\@firstofone}
\def\beamer@donoframe{%
  \beamer@slideinframe=1\relax%
  \global\c@beamerpauses=1\relax%
  \setbox\beamer@tempbox\vbox\bgroup%
    \beamer@inframetrue%
    \beamer@framenotesbegin%
    \leavevmode%
    \def\pause{}%
    \let\onslide\gobble@onslide
    \afterassignment\beamer@checknoslide\let\beamer@next}
\def\beamer@checknoslide{%
  \ifcat\bgroup\noexpand\beamer@next%
    \let\beamer@do\relax%
    \aftergroup\beamer@reseteecodes%
  \else%
    \let\beamer@do\beamer@noframesingletoken%
  \fi%
  \beamer@do}
\def\beamer@noframesingletoken{\beamer@next\egroup\beamer@reseteecodes}

\long\def\beamer@doseveralframes#1{%
  \ifx\beamer@againname\@empty\else%
    % Again stuff
    \expandafter \gdef\csname beamer@again@\beamer@againname\endcsname{{#1}}%
  \fi%
  \beamer@slideinframe=1\relax%
  \loop%
  \beamer@anotherslidefalse%
  \gdef\beamer@doifnotinframe{}%
  \def\beamer@doifinframe{\begin{beamer@frameslide}%
    #1%
  \end{beamer@frameslide}}%
  \beamer@masterdecode{\beamer@whichframes}%
  \beamer@donow%
  \ifbeamer@twoscreenstext%
    \beamer@dosecondscreennow{#1}% two screen stuff
  \fi%
  \ifbeamer@anotherslide
  \advance\beamer@slideinframe by 1\relax
  \repeat%
  \beamer@writeslidentry%
  \beamer@reseteecodes}

\def\beamer@dosingleframe{%
  \beamer@slideinframe=1\relax%
  \begin{beamer@frameslide}\relax%
    \bgroup\aftergroup\beamer@endslide\afterassignment\beamer@checkslide\let\beamer@next}
\def\beamer@checkslide{%
  \ifcat\bgroup\noexpand\beamer@next%
  \let\beamer@do\beamer@checkframetitle%
  \else\let\beamer@do\beamer@singletoken\fi%
  \beamer@do}
\def\beamer@endslide{\end{beamer@frameslide}\beamer@writeslidentry\beamer@reseteecodes}
\def\beamer@singletoken{\beamer@next\egroup}

\def\beamer@doexternalframe{%
  \edef\beamer@verbfilename{\jobname\ifx\beamer@againname\@empty\else.\insertframenumber\fi.vrb}% .vrb for `verbatim'
  \beamer@setupstoppers{\beamer@frameenvironmentsubst}%
  \immediate\openout\beamer@verbatimfileout=\beamer@verbfilename%
  \expandafter\beamer@checktitleverbatim\@gobble}
\def\beamer@checktitleverbatim{\@ifnextchar\bgroup{\beamer@verbatim@frametitle}{\beamer@verbatimreadframe}}
\def\beamer@verbatim@frametitle#1{%
  \@ifnextchar\bgroup{\beamer@verbatim@framesubtitle{#1}}
  {%
    \@temptokena{#1}%
    \edef\@tempa{\string\frametitle\string{\the\@temptokena\string}}%
    \@temptokena\expandafter{\@tempa}%
    \immediate\write\beamer@verbatimfileout{\the\@temptokena}%
    \beamer@verbatimreadframe
  }%
}
\def\beamer@verbatim@framesubtitle#1#2{\beamer@verbatimreadframe\frametitle{#1}\framesubtitle{#2}}
% will return to following command with frame contents written to \beamer@verbfilename
\def\beamer@afterexternalframe{%
  \ifx\beamer@frameenvironmentsubst\beamer@frametext%
  \else%
    \immediate\write\beamer@verbatimfileout{\noexpand\beamerclosesubstitutedenvironement{\beamer@frameenvironmentsubst}}%
  \fi%
  \immediate\closeout\beamer@verbatimfileout%
  \expandafter\beamer@doframeinput\beamer@frameoptions\relax}

\def\beamer@doframeinput{\@ifnextchar<{\beamer@frameinput}{\beamer@frameinput<*>}}
\def\beamer@frameinput<#1>{\@ifnextchar[{\beamer@@frameinput<#1>}{\beamer@@frameinput<#1>[]}}
\def\beamer@@frameinput<#1>[{\@ifnextchar<{\beamer@@@@frameinput<#1>[}%
  {\edef\beamer@temp{\noexpand\beamer@@@frameinput<#1>[\beamer@defaultospec][}%
  \beamer@temp}}
\def\beamer@@@@frameinput<#1>[#2]{\@ifnextchar[{\beamer@@@frameinput<#1>[{#2}]}{\beamer@@@frameinput<#1>[{#2}][]}}
\def\beamer@@@frameinput<#1>[#2][#3]{%
  \global\advance\c@framenumber by-1\relax%
  \edef\beamer@temp{\noexpand\frame<#1>[#2][{#3,fragile=false}]%
    {\begingroup\noexpand\input{\beamer@verbfilename}\endgroup}}%
  \beamer@temp%
  \ifx\beamer@frameenvironmentsubst\beamer@frametext%
  \else%
    \expandafter\endgroup%
  \fi%
  \beamer@reseteecodes}

\def\beamerclosesubstitutedenvironement#1{
  \let\end\beamer@specialend%
  \let\endframe\relax%
  \csname end#1\endcsname}

\def\beamer@writeslidentry{%
  \expandafter\ifblank\expandafter{\beamer@framestartpage}{}% does not happen normally
  {%else
    \addtocontents{nav}%
      {\protect\headcommand{%
          \protect\slideentry{\the\c@section}{\the\c@subsection}{\the\c@subsectionslide}%
          {\beamer@framestartpage/\beamer@frameendpage}{\lastsubsection}{\the\c@part}}}%
    \addtocontents{nav}%
      {\protect\headcommand{%
        \protect\beamer@framepages{\beamer@framestartpage}{\beamer@frameendpage}}}%
    \clearpage\beamer@notesactions%
  }%
}
\def\beamer@reseteecodes{\gdef\beamer@entrycode{}\gdef\beamer@exitcode{}%
  \beamer@slideinframe=1\relax\beamer@resumemode}

\let\beamer@origend\end
\def\beamer@specialend#1{%
  \def\beamer@temp{#1}%
  \ifx\beamer@temp\beamer@frametext%
    \def\beamer@next{}%
  \else%
    \def\beamer@next{\expandafter\beamer@origend\expandafter{\beamer@temp}%
      \let\end\beamer@specialend%
      \let\endframe\relax%
    }
  \fi%
  \beamer@next}



%
% \includeonlyframes
%

\def\beamer@checkifinlist#1,#2\relax{%
  \def\beamer@temp{#1}%
  \ifx\beamer@temp\beamer@againname\else
    \def\beamer@temp{#2}%
    \ifx\beamer@temp\@empty
      \gdef\beamer@whichframes{all:0}%
    \else%
      \beamer@checkifinlist#2\relax%
    \fi%
  \fi%
}

\def\includeonlyframes#1{\def\beamer@framerestriction{#1,}}



%
% Frames in article mode
%

\mode
<article>
{
  \def\endframe{\egroup}

  \def\frame{\@ifnextchar<\beamer@frame{\beamer@frame<*>}}
  \def\beamer@frame<#1>{\@ifnextchar[{\beamer@@frame<#1>}{\beamer@@frame<#1>[]}}
  \def\beamer@@frame<#1>[{\@ifnextchar<{\beamer@framedefaultospec<#1>[}{\beamer@@@@frame<#1>[}}
  \def\beamer@framedefaultospec<#1>[#2]{%
    \@ifnextchar[{\beamer@@@@frame<#1>}{\beamer@@@@frame<#1>[]}}
  \long\def\beamer@@@@frame<#1>[#2]{%
    \global\let\insertframetitle=\@empty%
    \global\let\insertframesubtitle=\@empty%
    \beamer@slideinframe=1\relax%
    \refstepcounter{framenumber}%
    \beamer@slideinframe=0\relax%
    \beamer@anotherslidefalse%
    \beamer@masterdecode{#1}%
    \ifbeamer@anotherslide%
      \let\beamer@howtotreatframe\beamer@dosingleframe%
    \else% no slides in frame
      \let\beamer@howtotreatframe\beamer@donoframe%
    \fi%
    \beamer@slideinframe=1\relax%
    \beamer@howtotreatframe}

  \long\def\beamer@donoframe{%
    \setbox\beamer@tempbox\vbox\bgroup%
    \beamer@inframetrue%
    \let\frame=\framelatex%
    \def\@parmoderr{\let\@currbox\@tempboxa}% A trick here to gobble floats
    \usebeamertemplate{frame begin}%
    \bgroup\aftergroup\beamer@endframe%
    \beamer@article@startframe}%
  \def\beamer@dosingleframe{%
    \bgroup%
    \beamer@inframetrue%
    \let\frame=\framelatex
    \usebeamertemplate{frame begin}%
    \bgroup\aftergroup\beamer@endframe%
    \beamer@article@startframe}%
  \def\beamer@endframe{%
    \usebeamertemplate{frame end}\egroup}

  \def\beamer@article@startframe{%
    \ifx\@currenvir\beamer@frametext%
      \let\beamer@next=\beamer@checkframetitle%
    \else%
      \let\beamer@next=\beamer@article@framecmd%
    \fi%
    \beamer@next}%

  \def\beamer@article@framecmd{%
    \afterassignment\beamer@checkframetitle
    \let\beamer@next=}

  \providecommand\includeonlyframes[1]{}% no effect
}


\mode
<all>
{
  \beamer@slideinframe=1\relax%
}



%
% Frame counter
%
\mode
<all>
{
  \newcounter{framenumber}
  \def\insertframenumber{\@arabic\c@framenumber}
  \def\insertslidenumber{\beamer@slidenumber}
  \def\insertoverlaynumber{\beamer@overlaynumber}
}


%
% Pagebreak command
%
\mode
<all>
{
  \renewcommand<>{\pagebreak}[1][4]{\only#2{\beameroriginal\pagebreak[{#1}]}}
  \renewcommand<>{\nopagebreak}[1][4]{\only#2{\beameroriginal\nopagebreak[{#1}]}}
  \def\framebreak{\pagebreak<presentation>}
  \def\noframebreak{\nopagebreak<presentation>}
}


%
% Linebreak command
%
\renewcommand<>{\\}{\only#1{\beameroriginal\\}}
\renewcommand<>{\@centercr}{\only#1{\beameroriginal\@centercr}}
\renewcommand<>{\@normalcr}{\only#1{\beameroriginal\@normalcr}}

\mode
<article>
{
  \expandafter\let\expandafter\beamer@origbreak\expandafter=%
    \csname\expandafter\@gobble\string\\ \endcsname% evil trickery to add a space to the name
  \ifx\beamer@origbreak\relax
    \let\beamer@origbreak\\
  \fi
  \DeclareRobustCommand\\{\beamer@ifnextcharospec{\beamer@breaker}{\beamer@@breaker}}
  \def\beamer@breaker<#1>{\only<#1>{\beamer@origbreak}}
  \def\beamer@@breaker{\ifbeamer@inframe\else\expandafter\beamer@origbreak\fi}

  \let\beamer@origbreakcenter=\@centercr
  \def\@centercr{\beamer@ifnextcharospec{\beamer@breakercenter}{\beamer@@breakercenter}}
  \def\beamer@breakercenter<#1>{\only<#1>{\beamer@origbreakcenter}}
  \def\beamer@@breakercenter{\ifbeamer@inframe\else\expandafter\beamer@origbreakcenter\fi}
}



%
% Plain frames
%

\def\beamer@frametemplate@plain{%
  \def\beamer@entrycode{\vspace*{-\headheight}}%
  \def\beamer@exitcode{\vspace*{-\footheight}\thispagestyle{empty}}}


%
% Again frame
%

\def\againframe{\@ifnextchar<{\beamer@againframe}{\beamer@againframe<*>}}
\def\beamer@againframe<#1>{\@ifnextchar[{\beamer@@againframe<#1>}{\beamer@@againframe<#1>[]}}
\def\beamer@@againframe<#1>[{\@ifnextchar<{\beamer@@@@againframe<#1>[}{\beamer@@@againframe<#1>[<*>][}}
\def\beamer@@@@againframe<#1>[#2]{\@ifnextchar[{\beamer@@@againframe<#1>[{#2}]}{\beamer@@@againframe<#1>[{#2}][]}}
\def\beamer@@@againframe<#1>[#2][#3]#4{%
  \@ifundefined{beamer@again@#4}%
  {\ClassError{beamer}{No frame has been designated to resume under
      the name "#4"}{}}%
  {%
  \def\beamer@temp{\frame<#1>[#2][{#3,relabel=#4}]}%
  \expandafter\let\expandafter\beamer@templet\csname beamer@again@#4\endcsname%
  \expandafter\beamer@temp\beamer@templet}%
}

\mode
<article>
{
  \def\againframe{\@ifnextchar<{\beamer@againframe}{\beamer@againframe<>}}
  \def\beamer@againframe<#1>{\@ifnextchar[{\beamer@@againframe<#1>}{\beamer@@againframe<#1>[]}}
  \def\beamer@@againframe<#1>[{\@ifnextchar<{\beamer@@@@againframe<#1>[}{\beamer@@againframe<#1>[<*>][}}
  \def\beamer@@@@againframe<#1>[#2]{\@ifnextchar[{\beamer@@@againframe<#1>[{#2}]}{\beamer@@@againframe<#1>[{#2}][]}}
  \def\beamer@@@againframe<#1>[#2][#3]#4{} % do nothing
}


\mode
<all>
