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U types do not convert to each other #568

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rakanalh opened this issue Jul 13, 2021 · 2 comments · May be fixed by #691
Open

U types do not convert to each other #568

rakanalh opened this issue Jul 13, 2021 · 2 comments · May be fixed by #691

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@rakanalh
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rakanalh commented Jul 13, 2021 •
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Hello,

Is there a reason why U* types do not implement From/Into from each other? At least to be able to cast upwards.

Example,

impl From<U64> for U128 {
    fn from(num: U64) -> Self {
        num.low_u64().into() // U128 implements From<u64>
    }
}

impl From<U64> for U256 {
    fn from(num: U64) -> Self {
        num.low_u64().into() // U256 implements From<u64>
    }
}
@ordian
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ordian commented Jul 13, 2021

they do in primitive-types

parity-common/primitive-types/src/lib.rs

Lines 146 to 252 in 2d571df

impl From<U256> for U512 {
fn from(value: U256) -> U512 {
let U256(ref arr) = value;
let mut ret = [0; 8];
ret[0] = arr[0];
ret[1] = arr[1];
ret[2] = arr[2];
ret[3] = arr[3];
U512(ret)
}
}
impl TryFrom<U256> for U128 {
type Error = Error;
fn try_from(value: U256) -> Result<U128, Error> {
let U256(ref arr) = value;
if arr[2] | arr[3] != 0 {
return Err(Error::Overflow);
}
let mut ret = [0; 2];
ret[0] = arr[0];
ret[1] = arr[1];
Ok(U128(ret))
}
}
impl TryFrom<U512> for U256 {
type Error = Error;
fn try_from(value: U512) -> Result<U256, Error> {
let U512(ref arr) = value;
if arr[4] | arr[5] | arr[6] | arr[7] != 0 {
return Err(Error::Overflow);
}
let mut ret = [0; 4];
ret[0] = arr[0];
ret[1] = arr[1];
ret[2] = arr[2];
ret[3] = arr[3];
Ok(U256(ret))
}
}
impl TryFrom<U512> for U128 {
type Error = Error;
fn try_from(value: U512) -> Result<U128, Error> {
let U512(ref arr) = value;
if arr[2] | arr[3] | arr[4] | arr[5] | arr[6] | arr[7] != 0 {
return Err(Error::Overflow);
}
let mut ret = [0; 2];
ret[0] = arr[0];
ret[1] = arr[1];
Ok(U128(ret))
}
}
impl From<U128> for U512 {
fn from(value: U128) -> U512 {
let U128(ref arr) = value;
let mut ret = [0; 8];
ret[0] = arr[0];
ret[1] = arr[1];
U512(ret)
}
}
impl From<U128> for U256 {
fn from(value: U128) -> U256 {
let U128(ref arr) = value;
let mut ret = [0; 4];
ret[0] = arr[0];
ret[1] = arr[1];
U256(ret)
}
}
impl<'a> From<&'a U256> for U512 {
fn from(value: &'a U256) -> U512 {
let U256(ref arr) = *value;
let mut ret = [0; 8];
ret[0] = arr[0];
ret[1] = arr[1];
ret[2] = arr[2];
ret[3] = arr[3];
U512(ret)
}
}
impl<'a> TryFrom<&'a U512> for U256 {
type Error = Error;
fn try_from(value: &'a U512) -> Result<U256, Error> {
let U512(ref arr) = *value;
if arr[4] | arr[5] | arr[6] | arr[7] != 0 {
return Err(Error::Overflow);
}
let mut ret = [0; 4];
ret[0] = arr[0];
ret[1] = arr[1];
ret[2] = arr[2];
ret[3] = arr[3];
Ok(U256(ret))
}
}

anything missing?

@ordian
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ordian commented Jul 13, 2021

U64 is kind of legacy, see #473
but we can probably add conversions from it in ethereum-types

@halo3mic halo3mic linked a pull request Nov 7, 2022 that will close this issue
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uint: add casting from/to U64 halo3mic/parity-common
2 participants
@rakanalh @ordian