README.md

YakSwap

Dex aggregator for EVM chains. UI available here.

About

YakSwap is a set of smart contracts for optimal path finding between two assets and execution of that path. For input&output token and input-amount optimal path should have a greatest net amount-out by considering execution gas-cost.

Search is performed by calling on-chain query-methods and can be called by anyone. However, user should avoid calling query-methods in a mutative call due to a very large gas-cost associated with a call.

Usage

Router

YakRouter is the user-facing interface to check prices and make trades. See example off-chain usage here.

Chain	Address
Avalanche	0xC4729E56b831d74bBc18797e0e17A295fA77488c

findBestPathWithGas

Finds the best path from tokenA to tokenB. Considers path's amount-out and its gas-cost.

function findBestPathWithGas(
    uint256 _amountIn,
    address _tokenIn,
    address _tokenOut,
    uint256 _maxSteps,
    uint256 _gasPrice
) external view returns (FormattedOffer memory);

Input params	Details
amountIn	Amount of tokens being sold
tokenIn	ERC20 token being sold
tokenOut	ERC20 token being bought
steps	Max number of steps for path finding (must be less than 4)
gasPrice	Gas price in gwei that will be used to estimate gasCost of each step

struct FormattedOffer {
    uint256[] amounts;
    address[] adapters;
    address[] path;
    uint256 gasEstimate;
}

Return arg	Details
amounts	Amount of token being swapped for each step. First amount is _amountIn and last amountOut.
adapters	Addresses of adapters through which trade goes.
path	Addresses of tokens through which trade goes. First token is _tokenIn and last _tokenOut.
gasEstimate	Rough estimate for gas-cost of all swaps. Gas estimates only include gas-cost of swapping and querying on adapter and not intermediate logic, nor tx-gas-cost.

swapNoSplit

Executes trades through provided path.

function swapNoSplit(
    Trade calldata _trade,
    address _to,
    uint256 _fee
) external;

Input param	Details
_trade	Arguments used for swapping
_to	Reciever address
_fee	Optional fee in bps taken before the trades

struct Trade {
    uint256 amountIn;
    uint256 amountOut;
    address[] path;
    address[] adapters;
}

Param	Details
amountIn	Amount of tokens being sold
amountOut	Amount of tokens being bought
path	Tokens being traded in respective order
adapters	Adapters through which tokens will be traded in respective order

Adapter

Adapters act as a common interface for YakRouter to interact with external contracts.

Adapters offers methods: query and swap.

function query(
    uint256 _amountIn,
    address _tokenIn,
    address _tokenOut
) external view returns (uint256);

function swap(
    uint256 _amountIn,
    uint256 _amountOut,
    address _fromToken,
    address _toToken,
    address _to
) external;

After setting up this repo call npx hardhat list-adapters --network {network-id} to get a list of live adapters and their addresses. Or see deployOptions for a list of live adapters per chain.

Local Development and testing

Install Dependencies

yarn install

Set Environmental Variables

cp .env.sample > .env

Actions

Test

Test for chain:

yarn test:{network-id}

Test individual:

npx hardhat test {path to the test/tests | empty to run all}

Deploy

yarn deploy:{network-id}

Verify

npx hardhat verify-contract --deployment-file-path {path to deployment file} --network {your network tag}

Query

npx hardhat find-best-path {fixed-amount-in} {token-in symbol/address} {token-in symbol/address}  --network {network tag}

Example:

npx hardhat find-best-path 1000 USDC yyAVAX  --network avalanche

Misc

• Static-Quoters used in KyberElastic, UniswapV3 and Quickswap adapters are published here.

Audits and Security

This project is not audited. Use at your own risk. For any questions or bug reports reach out via Telegram group YakDevs or its admins.

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Project is licensed under GPL-3, although some parts of it might be less restrictive. Copyright© 2021 Yield Yak