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!7

sclass Token {
  S text;
  CNC group;
  int index;
  
  toString { ret text; }
}

sclass CNC {
  S text; // if known
  new L<Token> tokens;
}

p-exp {
  S s = "There are 6 chess pieces. How many chess pieces do you know?";
  CNC in1 = makeCNC("There are 6 chess pieces. How many chess pieces do you know?");
  CNC out1 = makeCNC("6");
  CNC in2 = makeCNC("There are 16 chess pieces. How many chess pieces do you know?");
  
  LPair<Token> l = zipCNC(in1, in2);
  if (l == null) ret;
  l = antiFilter(l, func(Pair<Token> p) -> Bool { eqic(p.a.text, p.b.text) });
  print("Remaining differences:");
  pnl(l);
  printStruct(pairsToMap(pairListMap(func(Token t) -> S { t.text }, l)));
}

static CNC makeCNC(S s) {
  CNC cnc = nu(CNC, text := s);
  L<S> tok = javaTokWithAngleBrackets(s);
  for i over tok:
    cnc.tokens.add(nu(Token, text := tok.get(i), group := cnc, index := i);
  ret cnc;
}

// may return null (no match)
static LPair<Token> zipCNC(CNC cnc1, CNC cnc2) {
  ret zipTwoListsToPairs_ifSameLength(cnc1.tokens, cnc2.tokens);
}

static LPair<Token> dropSame(LPair<Token> l) {
  ret antiFilter(l, func(Pair<Token> p) -> Bool { eqic(p.a.text, p.b.text) });
}