The \boolexpr macro evaluates boolean expressions in a purely expandable way.

\boolexpr{ A \OR B \AND C } expands to 0 if the logical expression is TRUE. A, B, C may be: numeric expressions such as: x=y, x<>y, x>y or x<y; – boolean switches: \iftrue 0\else 1\fi;
– conditionals: \ifcsname whatsit\endcsname 0\else 1\fi;
– another \boolexpr: \boolexpr{ D \OR E \AND F }:

\boolexpr may be used with \ifcase:
\ifcase\boolexpr{ A \OR B \AND C }

The \switch command (which is also expandable) has the form:
\switch

The author is Florent Chervet. The package is Copyright © 2009 Florent Chervet.