!7

sS input = [[
  RULE WasLAB (("was|warum")&&("ist|bedeutet|heißt|soll|meint|nenn(t|en|st)")&&("lab")||("bla"))
]];

sS rules = [[

RULE <identifier> ( <exp> ) = rule

// bracketing combines top and bottom
( <exp> ) = bracket
<bracket> = expX

// primitive expressions are also at top level
<quoted> = expX

// now come the lower levels
<expX> = exp3

<exp2> & & <exp3> = and
<exp3> = exp2
<and> = exp2

<exp1> | | <exp2> = or
<exp2> = exp1
<or> = exp1

// lowest level
<exp1> = exp
]];

p-tt {
  Explain e = explain(input, rules, "rule");
  print("Parsed as: " + structForUser(e.fullMatchClasses()));
  printExplainTree2_filterClasses(e, func(S s) { !startsWith(s, "exp") });
}

Began life as a copy of #1008809