Merge pull request #1866 from CosmWasm/checked-multiply-ratio

Add missing checked_multiply_ratio implementations
CosmWasm · Sep 7, 2023 · 7b2e753 · 7b2e753
2 parents 4e5b2bf + 06fa3d4
commit 7b2e753
Show file tree

Hide file tree

Showing 4 changed files with 299 additions and 4 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -14,10 +14,13 @@ and this project adheres to
   `TryFrom<Int{128,256,512}>` for `Int64`, `TryFrom<Int{256,512}>` for `Int128`,
   `TryFrom<Int512>` for `Int256` and `Int256::from_i128` for const contexts
   ([#1861]).
+- cosmwasm-std: Add `Int{64,128,256}::{checked_multiply_ratio, full_mul}`
+  ([#1866])
 - cosmwasm-std: Add `is_negative` for `Int{64,128,256,512}` ([#1867]).
 
 [#1854]: https://github.com/CosmWasm/cosmwasm/pull/1854
 [#1861]: https://github.com/CosmWasm/cosmwasm/pull/1861
+[#1866]: https://github.com/CosmWasm/cosmwasm/pull/1866
 [#1867]: https://github.com/CosmWasm/cosmwasm/pull/1867
 
 ## [1.4.0] - 2023-09-04

diff --git a/packages/std/src/math/int128.rs b/packages/std/src/math/int128.rs
@@ -10,7 +10,8 @@ use serde::{de, ser, Deserialize, Deserializer, Serialize};
 
 use crate::errors::{DivideByZeroError, DivisionError, OverflowError, OverflowOperation, StdError};
 use crate::{
-    forward_ref_partial_eq, ConversionOverflowError, Int256, Int512, Int64, Uint128, Uint64,
+    forward_ref_partial_eq, CheckedMultiplyRatioError, ConversionOverflowError, Int256, Int512,
+    Int64, Uint128, Uint64,
 };
 
 use super::conversion::shrink_be_int;
@@ -99,6 +100,45 @@ impl Int128 {
         Self(self.0.pow(exp))
     }
 
+    /// Returns `self * numerator / denominator`.
+    ///
+    /// Due to the nature of the integer division involved, the result is always floored.
+    /// E.g. 5 * 99/100 = 4.
+    pub fn checked_multiply_ratio<A: Into<Self>, B: Into<Self>>(
+        &self,
+        numerator: A,
+        denominator: B,
+    ) -> Result<Self, CheckedMultiplyRatioError> {
+        let numerator = numerator.into();
+        let denominator = denominator.into();
+        if denominator.is_zero() {
+            return Err(CheckedMultiplyRatioError::DivideByZero);
+        }
+        match (self.full_mul(numerator) / Int256::from(denominator)).try_into() {
+            Ok(ratio) => Ok(ratio),
+            Err(_) => Err(CheckedMultiplyRatioError::Overflow),
+        }
+    }
+
+    /// Multiplies two [`Int128`] values without overflow, producing an
+    /// [`Int256`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use cosmwasm_std::Int128;
+    ///
+    /// let a = Int128::MAX;
+    /// let result = a.full_mul(2i32);
+    /// assert_eq!(result.to_string(), "340282366920938463463374607431768211454");
+    /// ```
+    #[must_use = "this returns the result of the operation, without modifying the original"]
+    pub fn full_mul(self, rhs: impl Into<Self>) -> Int256 {
+        Int256::from(self.i128())
+            .checked_mul(Int256::from(rhs.into()))
+            .unwrap()
+    }
+
     pub fn checked_add(self, other: Self) -> Result<Self, OverflowError> {
         self.0
             .checked_add(other.0)
@@ -912,6 +952,65 @@ mod tests {
         _ = Int128::MAX.pow(2u32);
     }
 
+    #[test]
+    fn int128_checked_multiply_ratio_works() {
+        let base = Int128(500);
+
+        // factor 1/1
+        assert_eq!(base.checked_multiply_ratio(1i128, 1i128).unwrap(), base);
+        assert_eq!(base.checked_multiply_ratio(3i128, 3i128).unwrap(), base);
+        assert_eq!(
+            base.checked_multiply_ratio(654321i128, 654321i128).unwrap(),
+            base
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(i128::MAX, i128::MAX).unwrap(),
+            base
+        );
+
+        // factor 3/2
+        assert_eq!(
+            base.checked_multiply_ratio(3i128, 2i128).unwrap(),
+            Int128(750)
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(333333i128, 222222i128).unwrap(),
+            Int128(750)
+        );
+
+        // factor 2/3 (integer devision always floors the result)
+        assert_eq!(
+            base.checked_multiply_ratio(2i128, 3i128).unwrap(),
+            Int128(333)
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(222222i128, 333333i128).unwrap(),
+            Int128(333)
+        );
+
+        // factor 5/6 (integer devision always floors the result)
+        assert_eq!(
+            base.checked_multiply_ratio(5i128, 6i128).unwrap(),
+            Int128(416)
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(100i128, 120i128).unwrap(),
+            Int128(416)
+        );
+    }
+
+    #[test]
+    fn int128_checked_multiply_ratio_does_not_panic() {
+        assert_eq!(
+            Int128(500i128).checked_multiply_ratio(1i128, 0i128),
+            Err(CheckedMultiplyRatioError::DivideByZero),
+        );
+        assert_eq!(
+            Int128(500i128).checked_multiply_ratio(i128::MAX, 1i128),
+            Err(CheckedMultiplyRatioError::Overflow),
+        );
+    }
+
     #[test]
     fn int128_shr_works() {
         let original = Int128::from_be_bytes([

diff --git a/packages/std/src/math/int256.rs b/packages/std/src/math/int256.rs
@@ -10,8 +10,8 @@ use serde::{de, ser, Deserialize, Deserializer, Serialize};
 
 use crate::errors::{DivideByZeroError, DivisionError, OverflowError, OverflowOperation, StdError};
 use crate::{
-    forward_ref_partial_eq, ConversionOverflowError, Int128, Int512, Int64, Uint128, Uint256,
-    Uint64,
+    forward_ref_partial_eq, CheckedMultiplyRatioError, ConversionOverflowError, Int128, Int512,
+    Int64, Uint128, Uint256, Uint64,
 };
 
 /// Used internally - we don't want to leak this type since we might change
@@ -155,6 +155,48 @@ impl Int256 {
         Self(self.0.pow(exp))
     }
 
+    /// Returns `self * numerator / denominator`.
+    ///
+    /// Due to the nature of the integer division involved, the result is always floored.
+    /// E.g. 5 * 99/100 = 4.
+    pub fn checked_multiply_ratio<A: Into<Self>, B: Into<Self>>(
+        &self,
+        numerator: A,
+        denominator: B,
+    ) -> Result<Self, CheckedMultiplyRatioError> {
+        let numerator = numerator.into();
+        let denominator = denominator.into();
+        if denominator.is_zero() {
+            return Err(CheckedMultiplyRatioError::DivideByZero);
+        }
+        match (self.full_mul(numerator) / Int512::from(denominator)).try_into() {
+            Ok(ratio) => Ok(ratio),
+            Err(_) => Err(CheckedMultiplyRatioError::Overflow),
+        }
+    }
+
+    /// Multiplies two [`Int256`] values without overflow, producing an
+    /// [`Int512`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use cosmwasm_std::Int256;
+    ///
+    /// let a = Int256::MAX;
+    /// let result = a.full_mul(2i32);
+    /// assert_eq!(
+    ///     result.to_string(),
+    ///     "115792089237316195423570985008687907853269984665640564039457584007913129639934"
+    /// );
+    /// ```
+    #[must_use = "this returns the result of the operation, without modifying the original"]
+    pub fn full_mul(self, rhs: impl Into<Self>) -> Int512 {
+        Int512::from(self)
+            .checked_mul(Int512::from(rhs.into()))
+            .unwrap()
+    }
+
     pub fn checked_add(self, other: Self) -> Result<Self, OverflowError> {
         self.0
             .checked_add(other.0)
@@ -1009,6 +1051,65 @@ mod tests {
         _ = Int256::MAX.pow(2u32);
     }
 
+    #[test]
+    fn int256_checked_multiply_ratio_works() {
+        let base = Int256::from_i128(500);
+
+        // factor 1/1
+        assert_eq!(base.checked_multiply_ratio(1i128, 1i128).unwrap(), base);
+        assert_eq!(base.checked_multiply_ratio(3i128, 3i128).unwrap(), base);
+        assert_eq!(
+            base.checked_multiply_ratio(654321i128, 654321i128).unwrap(),
+            base
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(i128::MAX, i128::MAX).unwrap(),
+            base
+        );
+
+        // factor 3/2
+        assert_eq!(
+            base.checked_multiply_ratio(3i128, 2i128).unwrap(),
+            Int256::from_i128(750)
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(333333i128, 222222i128).unwrap(),
+            Int256::from_i128(750)
+        );
+
+        // factor 2/3 (integer devision always floors the result)
+        assert_eq!(
+            base.checked_multiply_ratio(2i128, 3i128).unwrap(),
+            Int256::from_i128(333)
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(222222i128, 333333i128).unwrap(),
+            Int256::from_i128(333)
+        );
+
+        // factor 5/6 (integer devision always floors the result)
+        assert_eq!(
+            base.checked_multiply_ratio(5i128, 6i128).unwrap(),
+            Int256::from_i128(416)
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(100i128, 120i128).unwrap(),
+            Int256::from_i128(416)
+        );
+    }
+
+    #[test]
+    fn int256_checked_multiply_ratio_does_not_panic() {
+        assert_eq!(
+            Int256::from_i128(500i128).checked_multiply_ratio(1i128, 0i128),
+            Err(CheckedMultiplyRatioError::DivideByZero),
+        );
+        assert_eq!(
+            Int256::MAX.checked_multiply_ratio(Int256::MAX, 1i128),
+            Err(CheckedMultiplyRatioError::Overflow),
+        );
+    }
+
     #[test]
     fn int256_shr_works() {
         let original = Int256::new([

diff --git a/packages/std/src/math/int64.rs b/packages/std/src/math/int64.rs
@@ -9,7 +9,10 @@ use schemars::JsonSchema;
 use serde::{de, ser, Deserialize, Deserializer, Serialize};
 
 use crate::errors::{DivideByZeroError, DivisionError, OverflowError, OverflowOperation, StdError};
-use crate::{forward_ref_partial_eq, ConversionOverflowError, Int128, Int256, Int512, Uint64};
+use crate::{
+    forward_ref_partial_eq, CheckedMultiplyRatioError, ConversionOverflowError, Int128, Int256,
+    Int512, Uint64,
+};
 
 use super::conversion::shrink_be_int;
 
@@ -97,6 +100,45 @@ impl Int64 {
         Self(self.0.pow(exp))
     }
 
+    /// Returns `self * numerator / denominator`.
+    ///
+    /// Due to the nature of the integer division involved, the result is always floored.
+    /// E.g. 5 * 99/100 = 4.
+    pub fn checked_multiply_ratio<A: Into<Self>, B: Into<Self>>(
+        &self,
+        numerator: A,
+        denominator: B,
+    ) -> Result<Self, CheckedMultiplyRatioError> {
+        let numerator = numerator.into();
+        let denominator = denominator.into();
+        if denominator.is_zero() {
+            return Err(CheckedMultiplyRatioError::DivideByZero);
+        }
+        match (self.full_mul(numerator) / Int128::from(denominator)).try_into() {
+            Ok(ratio) => Ok(ratio),
+            Err(_) => Err(CheckedMultiplyRatioError::Overflow),
+        }
+    }
+
+    /// Multiplies two [`Int64`] values without overflow, producing an
+    /// [`Int128`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use cosmwasm_std::Int64;
+    ///
+    /// let a = Int64::MAX;
+    /// let result = a.full_mul(2i32);
+    /// assert_eq!(result.to_string(), "18446744073709551614");
+    /// ```
+    #[must_use = "this returns the result of the operation, without modifying the original"]
+    pub fn full_mul(self, rhs: impl Into<Self>) -> Int128 {
+        Int128::from(self)
+            .checked_mul(Int128::from(rhs.into()))
+            .unwrap()
+    }
+
     pub fn checked_add(self, other: Self) -> Result<Self, OverflowError> {
         self.0
             .checked_add(other.0)
@@ -888,6 +930,56 @@ mod tests {
         _ = Int64::MAX.pow(2u32);
     }
 
+    #[test]
+    fn int64_checked_multiply_ratio_works() {
+        let base = Int64(500);
+
+        // factor 1/1
+        assert_eq!(base.checked_multiply_ratio(1i64, 1i64).unwrap(), base);
+        assert_eq!(base.checked_multiply_ratio(3i64, 3i64).unwrap(), base);
+        assert_eq!(
+            base.checked_multiply_ratio(654321i64, 654321i64).unwrap(),
+            base
+        );
+        assert_eq!(
+            base.checked_multiply_ratio(i64::MAX, i64::MAX).unwrap(),
+            base
+        );
+
+        // factor 3/2
+        assert_eq!(base.checked_multiply_ratio(3i64, 2i64).unwrap(), Int64(750));
+        assert_eq!(
+            base.checked_multiply_ratio(333333i64, 222222i64).unwrap(),
+            Int64(750)
+        );
+
+        // factor 2/3 (integer devision always floors the result)
+        assert_eq!(base.checked_multiply_ratio(2i64, 3i64).unwrap(), Int64(333));
+        assert_eq!(
+            base.checked_multiply_ratio(222222i64, 333333i64).unwrap(),
+            Int64(333)
+        );
+
+        // factor 5/6 (integer devision always floors the result)
+        assert_eq!(base.checked_multiply_ratio(5i64, 6i64).unwrap(), Int64(416));
+        assert_eq!(
+            base.checked_multiply_ratio(100i64, 120i64).unwrap(),
+            Int64(416)
+        );
+    }
+
+    #[test]
+    fn int64_checked_multiply_ratio_does_not_panic() {
+        assert_eq!(
+            Int64(500i64).checked_multiply_ratio(1i64, 0i64),
+            Err(CheckedMultiplyRatioError::DivideByZero),
+        );
+        assert_eq!(
+            Int64(500i64).checked_multiply_ratio(i64::MAX, 1i64),
+            Err(CheckedMultiplyRatioError::Overflow),
+        );
+    }
+
     #[test]
     fn int64_shr_works() {
         let original = Int64::from_be_bytes([0u8, 0u8, 0u8, 0u8, 2u8, 0u8, 4u8, 2u8]);