Any help appreciated!

errors

string_builder.rs:11:35: 11:40 error: assigning to dereference of mutable & pointer prohibited due to outstanding loan
string_builder.rs:11       PartialContent(ref vec) => { *self = FullContent(str::from_chars(*vec)); },
                                                        ^~~~~
string_builder.rs:9:10: 9:15 note: loan of dereference of mutable & pointer granted here
string_builder.rs:9     match *self {
                              ^~~~~
string_builder.rs:23:8: 23:13 error: assigning to dereference of mutable & pointer prohibited due to outstanding loan
string_builder.rs:23         *self = PartialContent(*vec);
                             ^~~~~
string_builder.rs:17:10: 17:15 note: loan of dereference of mutable & pointer granted here
string_builder.rs:17     match *self {
                               ^~~~~
string_builder.rs:23:31: 23:35 error: moving out of dereference of mutable & pointer
string_builder.rs:23         *self = PartialContent(*vec);
                                                    ^~~~
error: aborting due to 3 previous errors

string_builder.rs

enum StringBuilder {
  NoContent,
  PartialContent(~[char]),
  FullContent(~str),
}

impl StringBuilder {
  fn finalize(&mut self) {
    match *self {
      NoContent => { },
      PartialContent(ref vec) => { *self = FullContent(str::from_chars(*vec)); },
      FullContent(_) => { },
    }
  }

  fn push(&mut self, c: char) {
    match *self {
      NoContent => {
        *self = PartialContent(~[c]);
      },
      PartialContent(ref mut vec) => {
        vec.push(c);
        *self = PartialContent(*vec);
      },
      FullContent(_) => {  },
    }
  }

  fn to_str(&self) -> ~str {
    match *self {
      NoContent => { ~"" },
      PartialContent(ref vec) => { str::from_chars(*vec) },
      FullContent(ref string) => { copy *string },
    }
  }
}

fn main() {
  let mut string_builder = NoContent;
  string_builder.push('h');
  string_builder.push('e');
  string_builder.push('l');
  string_builder.push('l');
  string_builder.push('o');
  string_builder.finalize();

  io::println(string_builder.to_str());
}