gistfile1.txt

library LinkedList {
      struct data {
        uint80 head;
        uint80 last;
        uint80 count;
        Item[] items; 
      }
      uint80 constant None = uint80(0);
      struct Item {
        uint80 prev;
        uint80 next;
        string data;
      }

  /// Appends `_data` to the end of the list self. Pushes the _data.
  function append(data storage self, string memory _data) {
    var index = uint80(self.items.push(Item({prev: self.last, next: None, data: _data,})));
    if (self.last == None)
      {
    if (self.head != None || self.count != 0) throw;
    self.head = self.last = index;
    self.count = 1;
      }
    else
      {
    self.items[self.last - 1].next = index;
    self.last = index;
    self.count++;
      }
  }

  function get_head_data(data storage self) returns (uint addr) {
    var it = iterate_start(self);
    return (iterate_get(self, it));
  }

  function get_head_iterate(data storage self) returns (uint80) {
    var it = iterate_start(self);    
    return it;
  }

  // Interface of Iterator
  function iterate_start(data storage self) returns (uint80) { return self.head; }
  function iterate_next(data storage self, uint80 _index) returns (uint80) { return self.items[_index - 1].next; }
  function iterate_get(data storage self, uint80 _index) returns (uint storageAddr){
    string s = self.items[_index - 1].data;
    uint addr;
    assembly {
        addr := s
    }
    return addr;
  }
}

contract Link {
  using LinkedList for LinkedList.data;
  LinkedList.data public list;
  function Test() {
    list.append("abcdef");
    list.append("foobar");
    list.append("qwertyuiop");
  }

  function get() returns (string) {
    uint addr = list.get_head_data();
    string s;
    assembly{
        s := addr
    }
    return (s);
  }
}