ERC-20 智能合约：支持 TRX 和 USDT 存款，USDT 兑换 TRX 功能

以下是一个符合要求的 ERC-20 智能合约示例：

// SPDX-License-Identifier: MIT
pragma solidity 0.8.14;

import 'https://github.com/smartcontractkit/chainlink/blob/develop/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol';

contract Token {
    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;
    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor(string memory _name, string memory _symbol, uint8 _decimals, uint256 _initialSupply) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
        totalSupply = _initialSupply;
        balanceOf[msg.sender] = _initialSupply;
    }

    function transfer(address _to, uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value, 'Insufficient balance');
        balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    function approve(address _spender, uint256 _value) public returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value, 'Insufficient balance');
        require(allowance[_from][msg.sender] >= _value, 'Insufficient allowance');
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        allowance[_from][msg.sender] -= _value;
        emit Transfer(_from, _to, _value);
        return true;
    }
}

contract MyToken is Token {
    address private constant TRX_ADDRESS = 0x0000000000000000000000000000000000000000;
    address private constant USDT_ADDRESS = 0x0000000000000000000000000000000000000000;
    address private owner;
    AggregatorV3Interface internal priceFeed;

    constructor() Token('My Token', 'MYT', 18, 0) {
        owner = msg.sender;
        priceFeed = AggregatorV3Interface(0x0000000000000000000000000000000000000000); // 设置链上的 Chainlink 价格合约地址
    }

    function depositTRX() public payable {
        require(msg.value > 0, 'Invalid amount');
        balanceOf[address(this)] += msg.value;
        emit Transfer(address(0), address(this), msg.value);
    }

    function depositUSDT(uint256 _amount) public {
        require(_amount > 0, 'Invalid amount');
        // 调用 USDT 合约的转账方法将 USDT 从用户转入到合约地址
        // ...

        // 查询当前 USDT 与 TRX 的兑换价格
        int256 currentPrice = getCurrentPrice();
        require(currentPrice > 0, 'Invalid price');

        // 计算需要转出的 TRX 数量
        uint256 trxAmount = uint256(currentPrice) * _amount;

        // 转出 TRX 到转入者的地址中
        require(balanceOf[address(this)] >= trxAmount, 'Insufficient balance');
        balanceOf[address(this)] -= trxAmount;
        balanceOf[msg.sender] += trxAmount;
        emit Transfer(address(this), msg.sender, trxAmount);
    }

    function getCurrentPrice() internal view returns (int256) {
        (, int256 price, , , ) = priceFeed.latestRoundData();
        return price;
    }

    function withdrawTRX(uint256 _amount, address _to) public {
        require(msg.sender == owner, 'Only owner can call this function');
        require(_amount > 0, 'Invalid amount');
        require(balanceOf[address(this)] >= _amount, 'Insufficient balance');
        balanceOf[address(this)] -= _amount;
        payable(_to).transfer(_amount);
        emit Transfer(address(this), _to, _amount);
    }

    function withdrawUSDT(uint256 _amount, address _to) public {
        require(msg.sender == owner, 'Only owner can call this function');
        require(_amount > 0, 'Invalid amount');
        // 调用 USDT 合约的转账方法将 USDT 从合约地址转出到指定地址
        // ...
    }

    function getTRXBalance() public view returns (uint256) {
        return balanceOf[address(this)];
    }

    function getUSDTBalance() public view returns (uint256) {
        // 查询 USDT 合约当前合约地址的余额
        // ...
    }
}

请注意，上述合约中的 TRX_ADDRESS 和 USDT_ADDRESS 变量需要替换为真实的 TRX 和 USDT 合约地址。同样，priceFeed 变量需要替换为链上的 Chainlink 价格合约地址。此外，合约中的 USDT 转账方法需要根据实际情况进行实现。