1 files changed, 94 insertions, 0 deletions
diff --git a/src/libcore/fmt/float.rs b/src/libcore/fmt/float.rs
new file mode 100644
index 00000000000..50248fabfcd
--- /dev/null
+++ b/src/libcore/fmt/float.rs
@@ -0,0 +1,94 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use fmt::{Formatter, Result, LowerExp, UpperExp, Display, Debug};
+use num::flt2dec;
+
+// Common code of floating point Debug and Display.
+fn float_to_decimal_common<T>(fmt: &mut Formatter, num: &T, negative_zero: bool) -> Result
+    where T: flt2dec::DecodableFloat
+{
+    let force_sign = fmt.sign_plus();
+    let sign = match (force_sign, negative_zero) {
+        (false, false) => flt2dec::Sign::Minus,
+        (false, true)  => flt2dec::Sign::MinusRaw,
+        (true,  false) => flt2dec::Sign::MinusPlus,
+        (true,  true)  => flt2dec::Sign::MinusPlusRaw,
+    };
+
+    let mut buf = [0; 1024]; // enough for f32 and f64
+    let mut parts = [flt2dec::Part::Zero(0); 16];
+    let formatted = if let Some(precision) = fmt.precision {
+        flt2dec::to_exact_fixed_str(flt2dec::strategy::grisu::format_exact, *num, sign,
+                                    precision, false, &mut buf, &mut parts)
+    } else {
+        flt2dec::to_shortest_str(flt2dec::strategy::grisu::format_shortest, *num, sign,
+                                 0, false, &mut buf, &mut parts)
+    };
+    fmt.pad_formatted_parts(&formatted)
+}
+
+// Common code of floating point LowerExp and UpperExp.
+fn float_to_exponential_common<T>(fmt: &mut Formatter, num: &T, upper: bool) -> Result
+    where T: flt2dec::DecodableFloat
+{
+    let force_sign = fmt.sign_plus();
+    let sign = match force_sign {
+        false => flt2dec::Sign::Minus,
+        true  => flt2dec::Sign::MinusPlus,
+    };
+
+    let mut buf = [0; 1024]; // enough for f32 and f64
+    let mut parts = [flt2dec::Part::Zero(0); 16];
+    let formatted = if let Some(precision) = fmt.precision {
+        // 1 integral digit + `precision` fractional digits = `precision + 1` total digits
+        flt2dec::to_exact_exp_str(flt2dec::strategy::grisu::format_exact, *num, sign,
+                                  precision + 1, upper, &mut buf, &mut parts)
+    } else {
+        flt2dec::to_shortest_exp_str(flt2dec::strategy::grisu::format_shortest, *num, sign,
+                                     (0, 0), upper, &mut buf, &mut parts)
+    };
+    fmt.pad_formatted_parts(&formatted)
+}
+
+macro_rules! floating {
+    ($ty:ident) => (
+        #[stable(feature = "rust1", since = "1.0.0")]
+        impl Debug for $ty {
+            fn fmt(&self, fmt: &mut Formatter) -> Result {
+                float_to_decimal_common(fmt, self, true)
+            }
+        }
+
+        #[stable(feature = "rust1", since = "1.0.0")]
+        impl Display for $ty {
+            fn fmt(&self, fmt: &mut Formatter) -> Result {
+                float_to_decimal_common(fmt, self, false)
+            }
+        }
+
+        #[stable(feature = "rust1", since = "1.0.0")]
+        impl LowerExp for $ty {
+            fn fmt(&self, fmt: &mut Formatter) -> Result {
+                float_to_exponential_common(fmt, self, false)
+            }
+        }
+
+        #[stable(feature = "rust1", since = "1.0.0")]
+        impl UpperExp for $ty {
+            fn fmt(&self, fmt: &mut Formatter) -> Result {
+                float_to_exponential_common(fmt, self, true)
+            }
+        }
+    )
+}
+
+floating! { f32 }
+floating! { f64 }