Pair Addresses
The most obvious way to get the address for a pair is to call getPair on the factory. If the pair exists, this function will return its address, else
address(0) (0x0000000000000000000000000000000000000000).- The “canonical” way to determine whether or not a pair exists.
- Requires an on-chain lookup.
Thanks to some fancy footwork in the factory, we can also compute pair addresses without any on-chain lookups because of CREATE2. The following values are required for this technique:
| |
address | |
salt | keccak256(abi.encodePacked(token0, token1)) |
keccak256(init_code) | 0x96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f |
token0must be strictly less thantoken1by sort order.- Can be computed offline.
- Requires the ability to perform
keccak256.
This example makes use of the WhiteSwap SDK. In reality, the SDK computes pair addresses behind the scenes, obviating the need to compute them manually like this.
import { FACTORY_ADDRESS, INIT_CODE_HASH } from '@whiteswap/sdk'
import { pack, keccak256 } from '@ethersproject/solidity'
import { getCreate2Address } from '@ethersproject/address'
const token0 = '0xCAFE000000000000000000000000000000000000' // change me!
const token1 = '0xF00D000000000000000000000000000000000000' // change me!
const pair = getCreate2Address(
FACTORY_ADDRESS,
keccak256(['bytes'], [pack(['address', 'address'], [token0, token1])]),
INIT_CODE_HASH'
)
Last modified 2yr ago