Pair Addresses

getPair

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 authoritative onchain check for whether that factory has recorded a pair.
• Requires an on-chain lookup.

CREATE2

Ring Swap pair addresses can also be computed without any on-chain lookups because the factory uses CREATE2. In Ring Swap, this is chain-aware: use the factory for the target network and the corresponding entry in INIT_CODE_HASH_MAP.

address	The factory address
salt	keccak256(abi.encodePacked(token0, token1))
keccak256(init_code)	INIT_CODE_HASH_MAP[chainId]

• token0 must be strictly less than token1 by sort order.

• Can be computed offline.
• Requires the ability to perform keccak256.
• In Ring Swap, token0 and token1 should be the actual pair tokens, which are often FewToken addresses rather than the original ERC-20 addresses shown to users.

A CREATE2 result is only a predicted address. It does not prove that the pair is deployed, belongs to the intended factory, or contains reviewed assets. Confirm factory.getPair(token0, token1), bytecode, token0(), and token1() before use.

Examples

SDK prediction

The SDK helper computes the expected CREATE2 address:

import { ChainId, Token, WETH9 } from '@ring-protocol/sdk-core'
import { Pair, getFewTokenFromOriginalToken } from '@ring-protocol/v2-sdk'

const DAI = new Token(ChainId.MAINNET, '0x6B175474E89094C44Da98b954EedeAC495271d0F', 18, 'DAI', 'Dai Stablecoin')
const fewDAI = getFewTokenFromOriginalToken(DAI, ChainId.MAINNET)
const fewWETH = getFewTokenFromOriginalToken(WETH9[ChainId.MAINNET], ChainId.MAINNET)

const pairAddress = Pair.getAddress(fewDAI, fewWETH)

Pair.getAddress() relies on the factory and init-code constants in the installed package. The published v1.0.0 package must not be used for MegaETH. On every chain, treat the result as a candidate and require factory.getPair(fewDAI.address, fewWETH.address) to return the same address before reading reserves or moving funds.

Manual TypeScript Example

This example makes use of the Ring V2 SDK. Manual derivation has the same trust boundary as Pair.getAddress(): factory state and deployed pair code remain authoritative.

import { ChainId, Token, WETH9 } from '@ring-protocol/sdk-core'
import { FACTORY_ADDRESS_MAP, INIT_CODE_HASH_MAP, getFewTokenFromOriginalToken } from '@ring-protocol/v2-sdk'
import { pack, keccak256 } from '@ethersproject/solidity'
import { getCreate2Address } from '@ethersproject/address'

const chainId = ChainId.MAINNET
const DAI = new Token(chainId, '0x6B175474E89094C44Da98b954EedeAC495271d0F', 18, 'DAI', 'Dai Stablecoin')
const fewDAI = getFewTokenFromOriginalToken(DAI, chainId)
const fewWETH = getFewTokenFromOriginalToken(WETH9[chainId], chainId)
const [token0, token1] = fewDAI.sortsBefore(fewWETH) ? [fewDAI, fewWETH] : [fewWETH, fewDAI]

const pair = getCreate2Address(
  FACTORY_ADDRESS_MAP[chainId],
  keccak256(['bytes'], [pack(['address', 'address'], [token0.address, token1.address])]),
  INIT_CODE_HASH_MAP[chainId]
)