static Object unstructure(String text) {
  ret unstructure(text, false);
}

static Object unstructure(String text, final boolean allDynamic) {
  ret unstructure(text, allDynamic, null);
}

static int structure_internStringsLongerThan = 50;

// classFinder: func(name) -> class (optional)
static Object unstructure(String text, final boolean allDynamic,
  final O classFinder) {
  if (text == null) ret null;
  final L<S> tok = javaTokC(text);
  final boolean debug = unstructure_debug;

  class X {
    int i = 0;
    new HashMap<Integer, O> refs;
    new HashMap<Integer, O> tokrefs;
    new HashSet<S> concepts;
    new HashMap<S, Class> classesMap;
    new L<Runnable> stack;

    Object parse() {
      String t = tok.get(i);
      
      int refID = 0;
      if (structure_isMarker(t, 0, l(t))) {
        refID = parseInt(t.substring(1));
        i++;
      }
      
      // if (debug) print("parse: " + quote(t));
      
      int tokIndex = i;  
      O o = parse_inner(refID, tokIndex);
      if (refID != 0)
        refs.put(refID, o);
      if (o != null)
        tokrefs.put(tokIndex, o);
      ret o;
    }
    
    O parse_inner(int refID, int tokIndex) {
      String t = tok.get(i);
      
      // if (debug) print("parse_inner: " + quote(t));
      
      Class c = classesMap.get(t);
      if (c == null) {
        if (t.startsWith("\"")) {
          String s = internIfLongerThan(unquote(tok.get(i)), structure_internStringsLongerThan);
          i++;
          return s;
        }
        
        if (t.startsWith("'"))
          ret unquoteCharacter(tok.get(i++));
        if (t.equals("bigint"))
          return parseBigInt();
        if (t.equals("d"))
          return parseDouble();
        if (t.equals("fl"))
          return parseFloat();
        if (t.equals("false") || t.equals("f")) {
          i++; return false;
        }
        if (t.equals("true") || t.equals("t")) {
          i++; return true;
        }
        if (t.equals("-")) {
          t = tok.get(i+1);
          i += 2;
          ret isLongConstant(t) ? (O) (-parseLong(t)) : (O) (-parseInt(t));
        }
        if (isInteger(t) || isLongConstant(t)) {
          i++;
          //if (debug) print("isLongConstant " + quote(t) + " => " + isLongConstant(t));
          if (isLongConstant(t)) ret parseLong(t);
          long l = parseLong(t);
          bool isInt = l == (int) l;
          if (debug)
            print("l=" + l + ", isInt: " + isInt);
          ret isInt ? (O) new Integer((int) l) : (O) new Long(l);
        }
        
        if (t.equals("File")) {
          File f = new File(unquote(tok.get(i+1)));
          i += 2;
          ret f;
        }
        
        if (t.startsWith("r") && isInteger(t.substring(1))) {
          i++;
          int ref = Integer.parseInt(t.substring(1));
          O o = refs.get(ref);
          if (o == null)
            print("Warning: unsatisfied back reference " + ref);
          ret o;
        }
      
        if (t.startsWith("t") && isInteger(t.substring(1))) {
          i++;
          int ref = Integer.parseInt(t.substring(1));
          O o = tokrefs.get(ref);
          if (o == null)
            print("Warning: unsatisfied token reference " + ref);
          ret o;
        }
        
        if (t.equals("hashset"))
          return parseHashSet();
        if (t.equals("treeset"))
          return parseTreeSet();
        if (eqOneOf(t, "hashmap", "hm"))
          return parseHashMap();
        if (t.equals("{"))
          return parseMap();
        if (t.equals("["))
          return parseList();
        if (t.equals("bitset"))
          return parseBitSet();
        if (t.equals("array") || t.equals("intarray"))
          return parseArray();
        if (t.equals("ba")) {
          S hex = unquote(tok.get(i+1));
          i += 2;
          ret hexToBytes(hex);
        }
        if (t.equals("boolarray")) {
          int n = parseInt(tok.get(i+1));
          S hex = unquote(tok.get(i+2));
          i += 6;
          ret boolArrayFromBytes(hexToBytes(hex), n);
        }
        if (t.equals("class"))
          return parseClass();
        if (t.equals("l"))
          return parseLisp();
        if (t.equals("null")) {
          i++; return null;
        }
        
        /* in dev.
        if (!allDynamic && t.equals("run")) {
          S snippetID = unquote(t.get(i+1));
          i += 2;
          run(
        }
        */
        
        if (eq(t, "c")) {
          consume("c");
          t = tok.get(i);
          assertTrue(isJavaIdentifier(t));
          concepts.add(t);
        }
      }
      
      if (c == null && !isJavaIdentifier(t))
        throw new RuntimeException("Unknown token " + (i+1) + ": " + t);

      // any other class name
      if (c == null) {
        // First, find class
        if (allDynamic) c = null;
        else if (classFinder != null)
          c = (Class) callF(classFinder, t);
        else
          c = findClass(t);
        if (c != null)
          classesMap.put(t, c);
      }
          
      // Check if it has an outer reference
      i++;
      bool hasOuter = eq(get(tok, i), "(") && eq(get(tok, i+1), "this$1");
      
      DynamicObject dO = null;
      O o = null;
      if (c != null)
        o = hasOuter ? nuStubInnerObject(c) : nuEmptyObject(c);
      else {
        if (concepts.contains(t) && (c = findClass("Concept")) != null)
          o = dO = (DynamicObject) nuEmptyObject(c);
        else
          dO = new DynamicObject;
        dO.className = t;
        if (debug) print("Made dynamic object " + t + " " + shortClassName(dO));
      }
      
      // Save in references list early because contents of object
      // might link back to main object
      
      if (refID != 0)
        refs.put(refID, o != null ? o : dO);
      tokrefs.put(tokIndex, o != null ? o : dO);
      
      // NOW parse the fields!
      
      final new HashMap<S, O> fields;
      final O _o = o;
      final DynamicObject _dO = dO;
      if (i < tok.size() && tok.get(i).equals("(")) {
        consume("(");
        stack.add(r {
          if (tok.get(i).equals(")")) {
            consume(")");
            objRead(_o, _dO, fields);
          } else {
            S key = unquote(tok.get(i++));
            consume("=");
            stack.add(this);
            O value = parse();
            fields.put(key, value);
            if (tok.get(i).equals(",")) i++;
          }
        });
      } else
        objRead(o, dO, fields);

      return o != null ? o : dO;
    }
    
    void objRead(O o, DynamicObject dO, Map<S, O> fields) {
      if (o != null)
        if (dO != null) {
          if (debug)
            printStructure("setOptAllDyn", fields);
          setOptAllDyn(dO, fields);
        } else
          setOptAll(o, fields);
      else for (S field : keys(fields))
        dO.fieldValues.put(field.intern(), fields.get(field));

      if (o != null)
        pcallOpt_noArgs(o, "_doneLoading");
    }
    
    Object parseSet(Set set) {
      set.addAll((L) parseList());
      return set;
    }
    
    Object parseLisp() {
      consume("l");
      consume("(");
      new ArrayList list;
      stack.add(r {
        if (tok.get(i).equals(")"))
          consume(")");
        else {
          stack.add(this);
          list.add(parse());
          if (tok.get(i).equals(",")) i++;
        }
      });
      return newObject("main$Lisp", (S) list.get(0), subList(list, 1));
    }
    
    Object parseBitSet() {
      consume("bitset");
      consume("{");
      new BitSet bs;
      stack.add(r {
        if (tok.get(i).equals("}"))
          consume("}");
        else {
          stack.add(this);
          bs.set((Integer) parse());
          if (tok.get(i).equals(",")) i++;
        }
      });
      return bs;
    }
    
    Object parseList() {
      consume("[");
      new ArrayList list;
      stack.add(r {
        if (tok.get(i).equals("]"))
          consume("]");
        else {
          stack.add(this);
          O o = parse();
          //if (debug) print("List element type: " + getClassName(o));
          list.add(o);
          if (tok.get(i).equals(",")) i++;
        }
      });
      return list;
    }
    
    Object parseArray() {
      S type = tok.get(i);
      i++;
      consume("{");
      final List list = new ArrayList;
      
      // TODO!!
      
      stack.add(r {
        if (tok.get(i).equals("}"))
          consume("}");
        else {
          stack.add(this);
          list.add(parse());
          if (tok.get(i).equals(",")) i++;
        }
      });
      if (type.equals("intarray"))
        return toIntArray(list);
      return list.toArray();
    }
    
    Object parseClass() {
      consume("class");
      consume("(");
      S name = tok.get(i);
      i++;
      consume(")");
      Class c = allDynamic ? null : findClass(name);
      if (c != null) ret c;
      new DynamicObject dO;
      dO.className = "java.lang.Class";
      dO.fieldValues.put("name", name);
      ret dO;
    }
    
    Object parseBigInt() {
      consume("bigint");
      consume("(");
      S val = tok.get(i);
      i++;
      if (eq(val, "-")) {
        val = "-" + tok.get(i);
        i++;
      }
      consume(")");
      ret new BigInteger(val);
    }
    
    Object parseDouble() {
      consume("d");
      consume("(");
      S val = unquote(tok.get(i));
      i++;
      consume(")");
      ret Double.parseDouble(val);
    }
    
    Object parseFloat() {
      consume("fl");
      S val;
      if (eq(tok.get(i), "(")) {
        consume("(");
        val = unquote(tok.get(i));
        i++;
        consume(")");
      } else {
        val = unquote(tok.get(i));
        i++;
      }
      ret Float.parseFloat(val);
    }
    
    Object parseHashMap() {
      i++;
      return parseMap(new HashMap);
    }
    
    Object parseHashSet() {
      consume("hashset");
      return parseSet(new HashSet);
    }
    
    Object parseTreeSet() {
      consume("treeset");
      return parseSet(new TreeSet);
    }
    
    Object parseMap() {
      return parseMap(new TreeMap);
    }
    
    Object parseMap(Map map) {
      consume("{");
      while (!tok.get(i).equals("}")) {
        O key = parse();
        consume("=");
        Object value = parse();
        map.put(key, value);
        if (tok.get(i).equals(",")) i++;
      }
      consume("}");
      return map;
    }
    
    void consume(String s) {
      if (!tok.get(i).equals(s)) {
        S prevToken = i-1 >= 0 ? tok.get(i-1) : "";
        S nextTokens = join(tok.subList(i, Math.min(i+2, tok.size())));
        fail(quote(s) + " expected: " + prevToken + " " + nextTokens + " (" + i + "/" + tok.size() + ")");
      }
      i++;
    }
    
    O parse_x() {
      O o = parse();
      while (nempty(stack))
        popLast(stack).run();
      ret o;
    }
  }
  
  ret new X().parse_x();
}

static boolean unstructure_debug;

Began life as a copy of #1005604