Demo Decentralized Exchange (DEX) Implementation

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

contract DEX is ReentrancyGuard {
    struct Pool {
        uint256 reserveA;
        uint256 reserveB;
    }

    mapping(address => mapping(address => Pool)) public pools;

    event LiquidityAdded(address indexed tokenA, address indexed tokenB, uint256 amountA, uint256 amountB);
    event TokensSwapped(address indexed tokenIn, address indexed tokenOut, uint256 amountIn, uint256 amountOut);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountA,
        uint256 amountB
    ) external nonReentrant {
        require(amountA > 0 && amountB > 0, "Amounts must be greater than zero");

        IERC20(tokenA).transferFrom(msg.sender, address(this), amountA);
        IERC20(tokenB).transferFrom(msg.sender, address(this), amountB);

        pools[tokenA][tokenB].reserveA += amountA;
        pools[tokenA][tokenB].reserveB += amountB;

        emit LiquidityAdded(tokenA, tokenB, amountA, amountB);
    }

    function swapTokens(
        address tokenIn,
        address tokenOut,
        uint256 amountIn
    ) external nonReentrant {
        require(amountIn > 0, "Amount must be greater than zero");

        Pool storage pool = pools[tokenIn][tokenOut];
        require(pool.reserveA > 0 && pool.reserveB > 0, "Liquidity not available");

        // Simple swap calculation (could be improved with a more complex formula)
        uint256 amountOut = (amountIn * pool.reserveB) / pool.reserveA;

        IERC20(tokenIn).transferFrom(msg.sender, address(this), amountIn);
        IERC20(tokenOut).transfer(msg.sender, amountOut);

        // Update reserves
        pool.reserveA += amountIn;
        pool.reserveB -= amountOut;

        emit TokensSwapped(tokenIn, tokenOut, amountIn, amountOut);
    }
}

Technical Guide

2.1 Architecture

2.2 Smart Contract Breakdown

function addLiquidity(
    address tokenA,
    address tokenB,
    uint256 amountA,
    uint256 amountB
) external nonReentrant {
    require(amountA > 0 && amountB > 0, "Amounts must be greater than zero");
    ...
}

2.3 Security Measures

3. User Guide

3.1 Getting Started

3.2 Using the DEX

3.3 FAQs