!7

p-exp {
  S input = "Stell dir vor die Hütte brennt";
  L<S> tok = javaTok(input);
  Parser parser = FixedTokenIC("Stell", func -> Parser {
    FixedTokenIC("dir", func -> Parser {
      FixedTokenIC("vor", func -> Parser {
        RestParser(voidfunc(S s) {
          print("Got sentence: " + s)
        })
      })
    })
  });
  tok.add("<over>");
  for i over tok: {
    parser = parser.consumeToken(tok.get(i), i);
    if (parser == null && i < l(tok)-1)
      print("No parse after " + joinSubList(tok, 0, i+1));
  }
}

abstract sclass Parser {
  abstract Parser consumeToken(S t, int idx);
}

srecord FixedTokenIC(S token, F0<Parser> nextParser) extends Parser {
  Parser consumeToken(S t, int idx) {
    if (even(idx)) this; // N token
    if (!eqic(token, t)) null;
    ret nextParser!;
  }
}

srecord RestParser(VF1<S> onParse) > Parser {
  new L<S> consumed;
  
  Parser consumeToken(S t, int idx) {
    if (eq(t, "<over>")) {
      callF(onParse, join(consumed));
      null;
    } else {
      consumed.add(t);
      this;
    }
  }
}