diff options
Diffstat (limited to 'src/passwordmaker/base_conversion/iterative_conversion.rs')
| -rw-r--r-- | src/passwordmaker/base_conversion/iterative_conversion.rs | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/src/passwordmaker/base_conversion/iterative_conversion.rs b/src/passwordmaker/base_conversion/iterative_conversion.rs index 7d52e9b..710903e 100644 --- a/src/passwordmaker/base_conversion/iterative_conversion.rs +++ b/src/passwordmaker/base_conversion/iterative_conversion.rs @@ -9,7 +9,7 @@ //! If you have any great idea how to improve it: Make a merge request! use std::convert::TryInto; -use std::ops::{Mul, DivAssign}; +use std::ops::{Mul, DivAssign, MulAssign}; use std::iter::successors; pub(crate) struct IterativeBaseConversion<V,B>{ @@ -59,10 +59,10 @@ impl<V,B> IterativeBaseConversion<V,B> } impl<V,B> std::iter::Iterator for IterativeBaseConversion<V,B> - where V : for<'a> DivAssign<&'a B> + //used between steps to go to next-lower current_base_power + where V : for<'a> DivAssign<&'a B> + //used in the first iteration to ensure that MulAssign cannot overflow. RemAssignWithQuotient+ //used to get the result of each step. - TryInto<B>, //used to convert the result of each step. We _know_ this cannot fail, but requiring Into would be wrong. - for<'a> &'a V : Mul<&'a B, Output = Option<V>> + TryInto<B>+ //used to convert the result of each step. We _know_ this cannot fail, but requiring Into would be wrong. + for<'a> MulAssign<&'a B> //used instead of DivAssign after one iteration. it's faster to mul the dividend than div the divisor. { type Item = B; @@ -73,7 +73,9 @@ impl<V,B> std::iter::Iterator for IterativeBaseConversion<V,B> let result = self.current_value.rem_assign_with_quotient(&self.current_base_power); if self.switch_to_multiplication { - self.current_value = (&self.current_value * &self.base).expect("Cannot overflow."); + //mul_assign is in principle dangerous. + //Since we do two rem_assign_with_quotient calls first, we can be sure that the result is always smaller than base^max_power though. + self.current_value *= &self.base } else { self.current_base_power /= &self.base; self.switch_to_multiplication = true; @@ -128,7 +130,13 @@ mod iterative_conversion_tests{ type Output = Option<MyU128>; fn mul(self, rhs: &MyU128) -> Self::Output { self.0.checked_mul(rhs.0).map(|s| MyU128(s)) - } + } + } + + impl MulAssign<&u64> for MyU128 { + fn mul_assign(&mut self, rhs: &u64) { + self.0.mul_assign(*rhs as u128); + } } impl RemAssignWithQuotient for MyU128{ |