message: Add formatting options for Complex
diff: @@ -616,15 +616,49 @@ impl<T: Clone + Num> One for Complex<T> {
  }
  }
  +macro_rules! write_complex {
  + ($f:ident, $re_fmt:expr, $im_fmt:expr, $re:expr, $im:expr, $( $arg:expr ),*) => {
  + if $im < Zero::zero() {
  + write!($f, concat!($re_fmt, "-", $im_fmt), $re, T::zero() - $im.clone(), $( $arg, )*)
  + } else {
  + write!($f, concat!($re_fmt, "+", $im_fmt), $re, $im, $( $arg, )*)
  + }
  + }
  +}
  +
  /* string conversions */
  impl<T> fmt::Display for Complex<T> where
  T: fmt::Display + Num + PartialOrd + Clone
  {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  - if self.im < Zero::zero() {
  - write!(f, "{}-{}i", self.re, T::zero() - self.im.clone())
  + if let Some(precision) = f.precision() {
  + write_complex!(f, "{0:.2$}", "{1:.2$}i", self.re, self.im, precision)
  + } else {
  + write_complex!(f, "{0}", "{1}i", self.re, self.im,)
  + }
  + }
  +}
  +
  +impl<T> fmt::LowerExp for Complex<T> where
  + T: fmt::LowerExp + Num + PartialOrd + Clone
  +{
  + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  + if let Some(precision) = f.precision() {
  + write_complex!(f, "{0:.2$e}", "{1:.2$e}i", self.re, self.im, precision)
  } else {
  - write!(f, "{}+{}i", self.re, self.im)
  + write_complex!(f, "{0:e}", "{1:e}i", self.re, self.im,)
  + }
  + }
  +}
  +
  +impl<T> fmt::UpperExp for Complex<T> where
  + T: fmt::UpperExp + Num + PartialOrd + Clone
  +{
  + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  + if let Some(precision) = f.precision() {
  + write_complex!(f, "{0:.2$E}", "{1:.2$E}i", self.re, self.im, precision)
  + } else {
  + write_complex!(f, "{0:E}", "{1:E}i", self.re, self.im,)
  }
  }
  }
  @@ -1210,6 +1244,15 @@ mod test {
  test(_05_05i, "0.5+0.5i".to_string());
  }
  + #[test]
  + fn test_string_formatting() {
  + let a: Complex64 = Complex::new(1.234567, 123.4567);
  + assert_eq!(format!("{}", a), "1.234567+123.4567i");
  + assert_eq!(format!("{:.2}", a), "1.23+123.46i");
  + assert_eq!(format!("{:.2E}", a), "1.23E0+1.23E2i");
  + assert_eq!(format!("{:e}", a), "1.234567e0+1.234567e2i");
  + }
  +
  #[test]
  fn test_hash() {
  let a = Complex::new(0i32, 0i32);
  