Equivalent for abi.encodePacked

Question

I am using ethers-rs to write a defi app. I need to calculate the CREATE2 address in rust. I couldn't find the equivalent of abi.encodePacked(token0, token1) in rust.

The code used in Uniswap's library ( https://vomtom.at/how-to-use-uniswap-v2-as-a-developer ):

    // calculates the CREATE2 address for a pair without making any external calls
    function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
        (address token0, address token1) = sortTokens(tokenA, tokenB);
        pair = address(uint(keccak256(abi.encodePacked(
                hex'ff',
                factory,
                keccak256(abi.encodePacked(token0, token1)),
                hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
            ))));
    }

Unfortunately I didn't get much help from the internet.

What's the equivalent for abi.encodePacked in rust.

Regards.

Answer 1

abi.encodePacked simply concatenates the bytes of the serialised parameters - in this case two addresses.

Usually EVM pads data items to uint256 word boundaries, but encodePacked is special .

Address is 160 bits (20 bytes) so the result of encodePacked should be 40 bytes, bytes of two addresses concatenated.