!7

sS testCases;

p {

  testCases = loadSnippet(#1013119);

  L<S> lines = lines(testCases);

  L<Int> l = indexesOfLinesBeginningWithDoubleArrow(lines);

  int i = 0, cases = 0;

  for (int line : l) {

    S question = lines(subList(lines, i, line));

    S answer = trimDropPrefixTrim("=>", lines.get(line));

    i = line+1;

    assertContainsCodeTokensIC(answer, callAnswerFunctionVerbose(question));

    ++cases;

  }

  print("OK (" + n2(cases, 'case) + ")");

}

answer {

  // parsing

  new L<S> parts;

  L<S> l = tok_splitAtSpacedDashes_old(s);

  parts.addAll(tok_splitAtAndFromMiddle(l.get(0)));

  parts.add(l.get(1));

  // loop

  pnl(parts);

  new L<S> output;

  new Executor e;

  for (S part : parts) {

    print(part);

    e.process(part);

    L<S> out = cloneAndClearList(e.output);

    printLinesWithIndent(" => ", out);

    output.addAll(out);

  }

  try answer lines(output);

}

sclass Executor {

  int length = -1; // unknown

  new L<S> output;

  void say(S s) { output.add(s); }

  void process(S s) {

    L<S> tok = javaTok(s);

    // interpretation

    int i = findCodeTokensIC(tok, "<int>"/*, "elements"*/);

    if (i >= 0) {

      int n = parseInt(tok.get(i));

      S before = get(tok, i-2);

      if (eqic(before, "add")) ret with length += n;

      if (eqic(before, "remove")) ret with length -= n;

      ret with length = n;

    }

    if (hasCodeTokensIC(tok, "empty")) ret with length = 0;

    if (hasCodeTokensIC(tok, "add", "one")) ret with ++length;

    if (hasCodeTokensIC(tok, "remove", "one")) ret with --length;

    if (hasCodeTokensIC(tok, "how", "long"))

      say("The list is " + n2(length, "element") + " long");

  }

}