The tinyexpr library I use to evaluate expressions does not support boolean operations. I would have to switch to the newer 
tineyexpr-plusplus version, which also has much richer functionality:

https://github.com/Blake-Madden/tinyexpr-plusplus/blob/tinyexpr%2B%2B/TinyExprChanges.md

Unfortunately it requires C++17, and at the moment we limit MIDAS to C++11, meaning we would break this requirement. I 
believe at the moment there are still some experiments (mainly at TRIUMF) which are stuck to older OS and therefore cannot 
switch to C++17, but hopefully this will change over time.

Stefan