%  Boolean --- Boolean expressions
%
%  Copyright (C) 2006 Didier Rémy
%
%  Author         : Didier Remy 
%  Version        : 0.1
%  Bug Reports    : to author
%  Web Site       : http://pauillac.inria.fr/~remy/latex/
% 
%  Boolean is free software; you can redistribute it and/or modify
%  it under the terms of the GNU General Public License as published by
%  the Free Software Foundation; either version 2, or (at your option)
%  any later version.
%  
%  Boolean is distributed in the hope that it will be useful,
%  but WITHOUT ANY WARRANTY; without even the implied warranty of
%  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%  GNU General Public License for more details 
%  (http://pauillac.inria.fr/~remy/license/GPL).
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%  File boolean.sty (LaTeX macros)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{boolean}
    [2006/10/05 version 0.1  Boolean expressions]

%% This package  provides LaTeX with boolean expressions 

%% Identification
%% Preliminary declaratitons

\newcommand {\True}[2]{#1}
\newcommand {\False}[2]{#2}

\let \bln@true \True
\let \bln@false \False

%% Options

\let \bln@withstring \bln@false
\DeclareOption {string}{\let \bln@withstring \bln@true}
\ProcessOptions

%% Public commands (also given inner hidden names)

\newcommand {\And}[2]{#1{#2}{\bln@false}}
\newcommand {\Or}[2]{#1{\bln@true}{#2}}
\newcommand {\Not}[1]{#1{\bln@false}{\bln@true}}
\newcommand {\IfThenElse}[3]{#1{#2}{#3}}

\let \bln@and \And
\let \bln@or  \Or
\let \bln@not \Not
\let \bln@ifthenelse  \IfThenElse


%% To convert if.. macros into Booleans: 

\newcommand {\texbool}[1]
    {#1\let \bln@do \bln@true \else \let \bln@do \bln@false\fi \bln@do}
\newcommand {\nottexbool}[1]
    {#1\let \bln@do \bln@false \else \let \bln@do \bln@true\fi \bln@do}
%% Does not work
\let \bln@tex \texbool
\let \bln@nottex \nottexbool

\newcommand {\ifxbool}[2]
    {\ifx #1#2\let \bln@do \bln@true \else \let \bln@do \bln@false \fi \bln@do}
\let \bln@ifx \ifxbool

\newcommand {\ifybool}[2]
    {\def \bln@testa{#1}\ifxbool{\bln@testa}{#2}}
\let \bln@ify \ifybool

\newcommand {\ifequalbool}[2]
    {\def \bln@testa{#1}\def \bln@testb{#2}\ifxbool{\bln@testa}{\bln@testb}}
\let \bln@ifequal \ifequalbool

\def \bln@empty {}
\newcommand {\IsEmpty}[1]
    {\ifybool{#1}{\bln@empty}}
\newcommand {\IsxEmpty}[1]
    {\ifxbool{#1}{\bln@empty}}
\let \bln@isempty \IsEmpty
\let \bln@isxempty \IsxEmpty

%% To force evaluation, e.g. if a blnlean expression is to be used several
%% times. This takes a Boolean expression and returns a Boolean value, i.e. 
%% \True or \False.

\newcommand* {\LetBoolVal}[2]
        {#2{\let #1\bln@true}{\let #1\bln@false}}
\newcommand* {\NewBoolVal}[2]
        {\@ifdefinable #1{\letboolval{#1}{#2}}}

%% We provide comman separated list versions of And and Or

\def \bln@scan #1,#2\bln@to#3#4{%
    \bln@isempty{#2}{#3{#4}{#1}}
          {\bln@scan #2\bln@to {#3}{#3{#4}{#1}}}%
}
\def \bln@eval #1#2#3{%
    \bln@isempty{#1}{#3}%
          {\bln@scan #1,\bln@to {#2}{#3}}%
}

\newcommand*{\AndList}[1]{\bln@eval {#1}{\bln@and}{\bln@true}}
\newcommand*{\OrList} [1]{\bln@eval {#1}{\bln@or}{\bln@false}}

%% %% In some contexts, shorter names may be more convenient

%% \newcommand*{\ShorterBooleanNames}{%
%%   \let \true  \bln@true
%%   \let \false \bln@true
%%   \let \or    \bln@or
%%   \let \and   \bln@and
%%   \let \not   \bln@not
%%   \let \orl   \bln@orl
%%   \let \andl  \bln@andl
%% }

%% Useful tests macros

\newcommand {\IsDefined}[1]
        {\bln@nottex {\expandafter \ifx \csname #1\endcsname \relax}}
\newcommand {\IsUndefined}[1]
        {\bln@tex {\expandafter \ifx \csname #1\endcsname \relax}}

%% Comparisson between strings (optional)
%% If not required, we stop here 

\bln@withstring {}{\endinput}

\RequirePackage{substr}

\newcommand{\StringMatch}[4]{%
  \IfSubStringInString{#2}{#1}
     {#3{\BeforeSubString{#2}{#1}}{\BehindSubString{#2}{#1}}}
     {#4}%
}

\def \str@infix  #1#2{\bln@true}
\def \str@prefix #1#2{\IsEmpty{#1}}
\def \str@suffix #1#2{\IsEmpty{#2}}

\newcommand {\StringInfix}   {\StringMatch {\str@infix}{\bln@false}}
\newcommand {\StringSuffix}  {\stringmatch {\str@suffix}{\bln@false}}
\newcommand {\ifstringprefix}{\stringmatch {\str@prefix}{\bln@false}}

{}


\endinput