boolean_algebra = { SOI ~ expression ~ EOI }
expression = { negatable_term ~ (binop ~ negatable_term)* }
negatable_term = _{ negated | term }
negated = ${ negation ~ term }
term = _{ label | "(" ~ expression ~ ")" }

negation = _{ "!" | "~" }
binop = @{ or_op | and_op }
  and_op = _{ "" }
  or_op =  _{ "+" }

label = @{ ASCII_ALPHA }