From cf54a9138b672c373ce7769ad1f18518a8c17254 Mon Sep 17 00:00:00 2001
From: Xiliang Chen <xlchen1291@gmail.com>
Date: Wed, 18 Dec 2019 21:57:43 +0800
Subject: [PATCH] add helper methods to FixedU128 (#64)
---
utilities/src/fixed128.rs | 56 ++++++++++++++++++++++++++++++++++++---
1 file changed, 52 insertions(+), 4 deletions(-)
diff --git a/utilities/src/fixed128.rs b/utilities/src/fixed128.rs
index d611c11..f3cd002 100644
--- a/utilities/src/fixed128.rs
+++ b/utilities/src/fixed128.rs
@@ -2,7 +2,7 @@ use codec::{Decode, Encode};
use primitives::U256;
use rstd::convert::{Into, TryFrom, TryInto};
use sp_runtime::{
- traits::{Bounded, Saturating},
+ traits::{Bounded, Saturating, UniqueSaturatedInto},
Perbill, Percent, Permill, Perquintill,
};
@@ -38,9 +38,15 @@ impl FixedU128 {
/// Creates self from a rational number. Equal to `n/d`.
///
/// Note that this might be lossy.
- pub fn from_rational(n: u128, d: u128) -> Self {
+ pub fn from_rational<N: UniqueSaturatedInto<u128>>(n: N, d: N) -> Self {
+ // this should really be `N: Into<U256>` or else might give wrong result
+ // TODO: Should have a better way to enforce this requirement
+ let n = n.unique_saturated_into();
+ let n = U256::from(n);
+ let d = d.unique_saturated_into();
+ let d = U256::from(d);
Self(
- (U256::from(n).saturating_mul(U256::from(DIV)) / U256::from(d).max(U256::one()))
+ (n.saturating_mul(DIV.into()) / d.max(U256::one()))
.try_into()
.unwrap_or_else(|_| Bounded::max_value()),
)
@@ -117,6 +123,14 @@ impl FixedU128 {
None
}
+ /// Checked mul for int type `N`.
+ pub fn saturating_mul_int<N>(&self, other: &N) -> N
+ where
+ N: Copy + TryFrom<u128> + TryInto<u128> + Bounded,
+ {
+ self.checked_mul_int(other).unwrap_or_else(Bounded::max_value)
+ }
+
/// Checked div for int type `N`.
pub fn checked_div_int<N>(&self, other: &N) -> Option<N>
where
@@ -132,6 +146,14 @@ impl FixedU128 {
None
}
+
+ pub fn zero() -> Self {
+ Self(0)
+ }
+
+ pub fn is_zero(&self) -> bool {
+ self.0 == 0
+ }
}
impl Saturating for FixedU128 {
@@ -178,7 +200,7 @@ macro_rules! impl_perthing_into_fixed_u128 {
($perthing:ty) => {
impl Into<FixedU128> for $perthing {
fn into(self) -> FixedU128 {
- FixedU128::from_rational(self.deconstruct().into(), <$perthing>::accuracy().into())
+ FixedU128::from_rational(self.deconstruct(), <$perthing>::accuracy())
}
}
};
@@ -241,6 +263,32 @@ mod tests {
assert_eq!(a.checked_mul_int::<i32>(&b), Some(10));
}
+ #[test]
+ fn saturating_mul_int_works() {
+ let a = FixedU128::from_rational(10, 1);
+ let b = u32::max_value() / 5;
+ assert_eq!(a.saturating_mul_int(&b), u32::max_value());
+
+ let a = FixedU128::from_rational(3, 1);
+ let b = 100u8;
+ assert_eq!(a.saturating_mul_int(&b), 255u8);
+
+ let a = FixedU128::from_rational(10, 1);
+ let b = 123;
+ assert_eq!(a.saturating_mul_int(&b), 1230);
+ }
+
+ #[test]
+ fn zero_works() {
+ assert_eq!(FixedU128::zero(), FixedU128::from_natural(0));
+ }
+
+ #[test]
+ fn is_zero_works() {
+ assert!(FixedU128::zero().is_zero());
+ assert!(!FixedU128::from_natural(1).is_zero());
+ }
+
#[test]
fn checked_div_with_zero_should_be_none() {
let a = FixedU128::from_natural(1);
--
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