% atbeginend.sty 

%

% Licensed to the Apache Software Foundation (ASF) under one or more

% contributor license agreements.  See the NOTICE file distributed with

% this work for additional information regarding copyright ownership.

% The ASF licenses this file to You under the Apache License, Version 2.0

% (the "License"); you may not use this file except in compliance with

% the License.  You may obtain a copy of the License at

%

%     http://www.apache.org/licenses/LICENSE-2.0

%

% Unless required by applicable law or agreed to in writing, software

% distributed under the License is distributed on an "AS IS" BASIS,

% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

% See the License for the specific language governing permissions and

% limitations under the License.

% defines

% \BeforeBegin{environment}{code-to-execute}

% \BeforeEnd  {environment}{code-to-execute}

% \AfterBegin {environment}{code-to-execute}

% \AfterEnd   {environment}{code-to-execute}

%

% Save \begin and \end to \BeginEnvironment and \EndEnvironment

\let\BeginEnvironment=\begin

\let\EndEnvironment=\end

\def\IfUnDef#1{\expandafter\ifx\csname#1\endcsname\relax}

% Null command needed to for \nothing{something}=.nothing.

\def\NullCom#1{}

\def\begin#1{%

%

% if defined \BeforeBeg for this environment, execute it

\IfUnDef{BeforeBeg#1}\else\csname BeforeBeg#1\endcsname\fi%

%

%

%

\IfUnDef{AfterBeg#1}% This is done to skip the command for environments

		     % which can take arguments, like multicols; YOU MUST NOT

		     % USE \AfterBegin{...}{...} for such environments!

	\let\SaveBegEng=\BeginEnvironment%

\else%

	% Start this environment

		\BeginEnvironment{#1}%

	% and execute code after \begin{environment}

		\csname AfterBeg#1\endcsname%

	% 

	\let\SaveBegEng=\NullCom%

\fi%

\SaveBegEng{#1}%

}

\def\end#1{%

%

% execute code before \end{environment}

\IfUnDef{BeforeEnd#1}\else\csname BeforeEnd#1\endcsname\fi%

%

% close this environment

\EndEnvironment{#1}%

%

% and execute code after \begin{environment}

\IfUnDef{AfterEnd#1}\else\csname AfterEnd#1\endcsname\fi%

}

%% Now, define commands

% \BeforeBegin{environment}{code-to-execute}

% \BeforeEnd  {environment}{code-to-execute}

% \AfterBegin {environment}{code-to-execute}

% \AfterEnd   {environment}{code-to-execute}

\def\BeforeBegin#1#2{\expandafter\gdef\csname BeforeBeg#1\endcsname

{#2}}

\def\BeforeEnd  #1#2{\expandafter\gdef\csname BeforeEnd#1\endcsname

{#2}}

\def\AfterBegin #1#2{\expandafter\gdef\csname AfterBeg#1\endcsname {#2}}

\def\AfterEnd   #1#2{\expandafter\gdef\csname AfterEnd#1\endcsname{#2}}