Auto merge of serde-rs#170 - DonSheddow:complex-fmt, r=cuviper

Add formatting options for Complex

This adds LowerExp and UpperExp traits for Complex, taking precision into account. Fixes serde-rs#148

complex/src/lib.rs

@@ -616,16 +616,102 @@ impl<T: Clone + Num> One for Complex<T> {
     }
 }
 
+macro_rules! write_complex {
+    ($f:ident, $t:expr, $prefix:expr, $re:expr, $im:expr, $T:ident) => {{
+        let abs_re = if $re < Zero::zero() { $T::zero() - $re.clone() } else { $re.clone() };
+        let abs_im = if $im < Zero::zero() { $T::zero() - $im.clone() } else { $im.clone() };
+
+        let real: String;
+        let imag: String;
+
+        if let Some(prec) = $f.precision() {
+            real = format!(concat!("{:.1$", $t, "}"), abs_re, prec);
+            imag = format!(concat!("{:.1$", $t, "}"), abs_im, prec);
+        }
+        else {
+            real = format!(concat!("{:", $t, "}"), abs_re);
+            imag = format!(concat!("{:", $t, "}"), abs_im);
+        }
+
+        let prefix = if $f.alternate() { $prefix } else { "" };
+        let sign = if $re < Zero::zero() {
+            "-"
+        } else if $f.sign_plus() {
+            "+"
+        } else {
+            ""
+        };
+
+        let complex = if $im < Zero::zero() {
+            format!("{}{pre}{re}-{pre}{im}i", sign, re=real, im=imag, pre=prefix)
+        }
+        else {
+            format!("{}{pre}{re}+{pre}{im}i", sign, re=real, im=imag, pre=prefix)
+        };
+
+        if let Some(width) = $f.width() {
+            write!($f, "{0: >1$}", complex, width)
+        }
+        else {
+            write!($f, "{}", complex)
+        }
+    }}
+}
+
 /* 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())
-        } else {
-            write!(f, "{}+{}i", self.re, self.im)
-        }
+        write_complex!(f, "", "", self.re, self.im, T)
+    }
+}
+
+impl<T> fmt::LowerExp for Complex<T> where
+    T: fmt::LowerExp + Num + PartialOrd + Clone
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write_complex!(f, "e", "", self.re, self.im, T)
+    }
+}
+
+impl<T> fmt::UpperExp for Complex<T> where
+    T: fmt::UpperExp + Num + PartialOrd + Clone
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write_complex!(f, "E", "", self.re, self.im, T)
+    }
+}
+
+impl<T> fmt::LowerHex for Complex<T> where
+    T: fmt::LowerHex + Num + PartialOrd + Clone
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write_complex!(f, "x", "0x", self.re, self.im, T)
+    }
+}
+
+impl<T> fmt::UpperHex for Complex<T> where
+    T: fmt::UpperHex + Num + PartialOrd + Clone
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write_complex!(f, "X", "0x", self.re, self.im, T)
+    }
+}
+
+impl<T> fmt::Octal for Complex<T> where
+    T: fmt::Octal + Num + PartialOrd + Clone
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write_complex!(f, "o", "0o", self.re, self.im, T)
+    }
+}
+
+impl<T> fmt::Binary for Complex<T> where
+    T: fmt::Binary + Num + PartialOrd + Clone
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write_complex!(f, "b", "0b", self.re, self.im, T)
     }
 }
 
@@ -1210,6 +1296,25 @@ mod test {
         test(_05_05i, "0.5+0.5i".to_string());
     }
 
+    #[test]
+    fn test_string_formatting() {
+        let a = Complex::new(1.23456, 123.456);
+        assert_eq!(format!("{}", a), "1.23456+123.456i");
+        assert_eq!(format!("{:.2}", a), "1.23+123.46i");
+        assert_eq!(format!("{:.2e}", a), "1.23e0+1.23e2i");
+        assert_eq!(format!("{:+20.2E}", a), "     +1.23E0+1.23E2i");
+
+        let b = Complex::new(0x80, 0xff);
+        assert_eq!(format!("{:X}", b), "80+FFi");
+        assert_eq!(format!("{:#x}", b), "0x80+0xffi");
+        assert_eq!(format!("{:+#b}", b), "+0b10000000+0b11111111i");
+        assert_eq!(format!("{:+#16o}", b), "   +0o200+0o377i");
+
+        let c = Complex::new(-10, -10000);
+        assert_eq!(format!("{}", c), "-10-10000i");
+        assert_eq!(format!("{:16}", c), "      -10-10000i");
+    }
+
     #[test]
     fn test_hash() {
         let a = Complex::new(0i32, 0i32);