Automated Market Maker (AMM) model sits at the heart of crypto exchange transformation, a fundamental innovation powering many centralized crypto exchange platforms and decentralized exchanges (DEXs). It is a protocol, integrated using crypto exchange development, that allows cryptocurrency trading without using traditional order books. Instead of matching buy and sell orders, AMMs rely on liquidity pools that use mathematical formulas to determine prices. Users can trade directly with the pool, and prices are adjusted based on supply and demand within the pool.
Explore | An Exhaustive Introduction to Automated Market Makers (AMM)
Steps to Implement AMM Logic in Solidity
1. Setting up the Development Environment
npx hardhat init
2. Create the Contract
Inside the contracts directory, create a new file named Amm.sol. This Solidity file will hold our Amm logic.
3. Implement the Contract
Program :
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.27;
contract TokenV2SwapAmm{
address private constant UNISWAPV2ROUTER =
0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D;
address private constant WETH_TOKEN = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
address private constant DAI_TOKEN = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
address constant USDC_TOKEN = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;
IUniswapV2Router private myrouter = IUniswapV2Router(UNISWAPV2ROUTER);
IERC20 private weth_token = IERC20(WETH_TOKEN);
IERC20 private dai_token = IERC20(DAI_TOKEN);
// Swap WETH_TOKEN to DAI_TOKEN
function swapSingleHopExactAmountIn(uint256 amount_In, uint256 amount_OutMin)
external
returns (uint256 amountOut)
{
weth_token.transferFrom(msg.sender, address(this), amount_In);
weth_token.approve(address(myrouter), amount_In);
address[] memory route;
route = new address[](2);
route[0] = WETH_TOKEN;
route[1] = DAI_TOKEN;
uint256[] memory amounts = myrouter.swapExactTokensForTokens(
amount_In, amount_OutMin, route, msg.sender, block.timestamp
);
// amounts[0] = WETH_TOKEN amount, amounts[1] = DAI_TOKEN amount
return amounts[1];
}
// Swap DAI_TOKEN -> WETH_TOKEN -> USDC_TOKEN
function swapMultiHopExactAmountIn(uint256 amount_In, uint256 amount_OutMin)
external
returns (uint256 amountOut)
{
dai_token.transferFrom(msg.sender, address(this), amount_In);
dai_token.approve(address(myrouter), amount_In);
address[] memory route;
route = new address[](3);
route[0] = DAI_TOKEN;
route[1] = WETH_TOKEN;
route[2] = USDC_TOKEN;
uint256[] memory amounts = myrouter.swapExactTokensForTokens(
amount_In, amount_OutMin, route, msg.sender, block.timestamp
);
// amounts[0] = DAI_TOKEN amount
// amounts[1] = WETH_TOKEN amount
// amounts[2] = USDC_TOKEN amount
return amounts[2];
}
// Swap WETH_TOKEN to DAI_TOKEN
function swapSingleHopExactAmountOut(
uint256 amountOutRequired,
uint256 amounttInMaxreq
) external returns (uint256 amountOut) {
weth_token.transferFrom(msg.sender, address(this), amounttInMaxreq);
weth_token.approve(address(myrouter), amounttInMaxreq);
address[] memory route;
route = new address[](2);
route[0] = WETH_TOKEN;
route[1] = DAI_TOKEN;
uint256[] memory amounts = myrouter.swapTokensForExactTokens(
amountOutRequired, amounttInMaxreq, route, msg.sender, block.timestamp
);
// Refund WETH_TOKEN to msg.sender
if (amounts[0] < amounttInMaxreq) {
weth_token.transfer(msg.sender, amounttInMaxreq - amounts[0]);
}
return amounts[1];
}
// Swap DAI_TOKEN -> WETH_TOKEN -> USDC_TOKEN
function swapMultiHopExactAmountOut(
uint256 amountOutRequired,
uint256 amounttInMaxreq
) external returns (uint256 amountOut) {
dai_token.transferFrom(msg.sender, address(this), amounttInMaxreq);
dai_token.approve(address(myrouter), amounttInMaxreq);
address[] memory route;
route = new address[](3);
route[0] = DAI_TOKEN;
route[1] = WETH_TOKEN;
route[2] = USDC_TOKEN;
uint256[] memory amounts = myrouter.swapTokensForExactTokens(
amountOutRequired, amounttInMaxreq, route, msg.sender, block.timestamp
);
// Refund DAI_TOKEN to msg.sender
if (amounts[0] < amounttInMaxreq) {
dai_token.transfer(msg.sender, amounttInMaxreq - amounts[0]);
}
return amounts[2];
}
}
interface IUniswapV2Router {
function swapExactTokensForTokens(
uint256 amount_In,
uint256 amount_OutMin,
address[] calldata route,
address to,
uint256 deadline
) external returns (uint256[] memory amounts);
function swapTokensForExactTokens(
uint256 amountOut,
uint256 amounttInMaxreq,
address[] calldata route,
address to,
uint256 deadline
) external returns (uint256[] memory amounts);
}
interface IERC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function transfer(address recipient, uint256 amount)
external
returns (bool);
function allowance(address owner, address spender)
external
view
returns (uint256);
function approve(address spender, uint256 amount) external returns (bool);
function transferFrom(address sender, address recipient, uint256 amount)
external
returns (bool);
}
interface IWETH_TOKEN is IERC20 {
function deposit() external payable;
function withdraw(uint256 amount) external;
}
Create the Contract
Inside the contracts directory, create a new file named Amm.sol. This Solidity file will contain the AMM logic for token swaps.
Implement the AMM Logic in Solidity
The following code snippet implements the AMM logic for token swaps using Uniswap's V2 router.
async function main() {
const Ammswap = await ethers.getContractFactory('TokenV2SwapAmm');
const swap = await Ammswap.deploy();
await swap.deployed();
console.log('Amm logic deployed to:', swap.address);
}
main().catch((error) => {
console.error(error);
process.exitCode = 1;
});
Testing the Contract
1. Write Tests:
- In the test directory, create a new file for the tests.
- Use Hardhat's testing framework to write tests for your contract.
2. Run Tests:
npx hardhat test
Also, Explore | Identifying Smart Contract Orchestration Patterns in Solidity
Conclusion
Congratulations on implementing Automated Market Maker (AMM) Logic in Solidity and deploying your contract on Ethereum.
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