An implementation of the Uniswap v2 protocol running on top of =nil;

• [Overview]

This project showcases the migration of Uniswap V2 to the =nil; cluster. It adapts Uniswap’s core contracts (Factory, Pair and Router) to work seamlessly with the unique architecture of =nil;. The project can be used as an example of migrating a dApp from Ethereum compatible networks to =nil; while benefitting from improved scalability offered by zkSharding:

1. Multi-Token Support: =nil; natively supports multiple custom tokens without having to rely on the ERC20 standard
2. Async/Sync Calls: =nil; supports async execution of transactions within one shard or across multiple shards
3. Load Distribution: =nil; spreads execution of transactions across shards without fragmenting its state

Clone the repository:

git clone https://github.com/NilFoundation/nil.git
cd ./nil/uniswap

Install dependencies:

npm install

Create a new .env file structured similarly to ./.env.example.

Nil.js is the recommended way for interacting with =nil;. To install Nil.js:

npm install @nilfoundation/niljs

Create a new smart account:

const client = new PublicClient({
  transport: new HttpTransport({
    endpoint: RPC_ENDPOINT,
  }),
  shardId: 1,
});

const smartAccount = await generateSmartAccount({
  shardId: 1,
  rpcEndpoint: RPC_ENDPOINT,
  faucetEndpoint: FAUCET_ENDPOINT,
});

The SmartAccount instance can deploy contracts or create contract instances attached to already deployed smart contracts:

// deployment
const {contract, address} = await deployNilContract(
  smartAccount,
  FactoryJson.abi,
  FactoryJsn.bytecode,
  [], // constructor arguments
  smartAccount.shardId,
  ["callExternalMethod"], // external methods
);

// attach to an existing contract
const contract2 = getContract({
   abi: TokenJson.abi,
   address: tokenAddress,
   client: smartAccount.client,
   smartAccount: smartAccount, // optional for write methods
   externalInterface: { // optional for external methods
      signer: smartAccount.signer,
      methods: ["callExternalMethod"],
   }
});

Call Uniswap contracts after deploying all contracts:

// read method
const balance = await contract.read.getTokenBalanceOf([smartAccount.address]);

// write method with tokens
const hash = await pair.write.swap([0, expectedOutputAmount, smartAccount.address], {
   tokens: [{
      id: token0Address,
      amount: swapAmount,
   }]
});

// external methods
const hash1 = await contract.external.mintToken([mintAmount]);

The project also provides two Hardhat tasks that showcase the full full lifecycle from deployment to execution. These tasks cover deploying and initializing all necessary contracts as well as minting, swapping, and burning

1. Using Factory, Pair, and Router Contracts This demo includes an additional layer by utilizing the Router contract along with Factory and Pair View the demo-router task

Note that:

• The UniswapV2Factory is used for creating new pairs. UniswapV2Router01 calls already deployed pair contracts.
• UniswapV2Router01 can be deployed on a different shard.
• Vulnerability: no checks are performed during adding/removing liquidity and swaps.
• Rates and output amounts are entirely calculated on the user side.

2. Using Router with Sync Calls (1 shard) This demo task shows how to deploy the UniswapV2Router01 contract and use it as a proxy for adding/removing liquidity and swaps via sync calls. It allows for checking amounts before pair calls and maintains token rates. View the demo-router task

Note that:

• UniswapV2Router01 should be deployed on the same shard as the pair contract.
• It maintains the token exchange rate when adding/removing liquidity.
• It supports limit checks for token amounts.

1. Compile the project

npx hardhat compile

2. Run the demo tasks:

• For the demo with Router (Factory, Pair, and Router):

npx hardhat demo-router

• For the demo with Router (Sync calls):

npx hardhat demo-router-sync

Contributions are always welcome! Feel free to submit pull requests or open issues to discuss potential changes or improvements.

This project is licensed under the GPL-3.0 License. See the LICENSE file for more details. Portions of this project are derived from Uniswap V2 and are also subject to the GPL-3.0 License.