Source

WRAPPED ERC20 TOKEN

wrappedToken use for all ERC20 token, example: WETH for ETH.

deploy

• copy ERC20 address (for example deploy erc20 Mock)
• paste address as value in Wrapped contract constructor + name + symbol
• before anything: approve wrapped contract as/is spender from base erc20 token
• deposit : make wrapped token and locked base token
• withdraw : burn wrapped and return locked token to the life cycle
• other functions same an ERC20

develop

• using IWrapped interface is custom/optional : if using this intrface, then inherit erc165 & inherite Wrapped contract. need to register

libraries

in this example use @openzeppelin/contracts --> sub --> erc20

if you like to use flat version, use this

ready/deployed

• ERC20 Token

• Wrapped Token

• mock token here

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Review

• Deposit

function deposit(uint256 amount) external returns (bool success) { 
    SafeERC20.safeTransferFrom(token, _msgSender(), address(this), amount);
    mint(amount);
    balances += amount;
    require(isBalanced(), "check not pass");
    emit Transfer(address(this), _msgSender(), amount);
    success = true;
}

• Withdraw

function withdraw(uint256 amount) external returns (bool success) {
    require(amount <= balances, "fund is low");
    SafeERC20.safeTransfer(token, _msgSender(), amount);
    burn(amount);
    balances -= amount;
    require(isBalanced(), "check not pass");
    emit Transfer(address(this), _msgSender(), amount);
    success = true;
}

function withdraw(address to, uint256 amount) external returns (bool success) { 
    require(amount <= balances, "fund is low");
    SafeERC20.safeTransfer(token, to, amount);
    burn(amount);
    balances -= amount;
    require(isBalanced(), "check not pass");
    emit Transfer(address(this), to, amount);
    success = true;
}

• Refund

function refund() external returns (bool success) {
    // require(_terminate() == 0, "refund denied");
    _terminate();
    require(deposited[_msgSender()] == 0, "refund denied");
    success = true;
}

function _terminate() internal returns (uint256) {
    uint256 value = deposited[_msgSender()];
    require(value <= balances, "fund is low");
    require(value > 0, "gas spend for 0!");
    _burn(_msgSender(), value);
    deposited[_msgSender()] -= value;
    balances -= value;
    require(isBalanced(), "check not pass");
    emit Transfer(address(this), _msgSender(), value);
    return value;
}

• Mint

function mint(uint256 amount) internal {
    uint256 tmp = deposited[_msgSender()];
    _mint(_msgSender(), amount);
    deposited[_msgSender()] += amount;
    require(deposited[_msgSender()] > tmp, "amount can not be 0");
}

• Burn

function burn(uint256 amount) internal {
    uint256 tmp = deposited[_msgSender()];
    _burn(_msgSender(), amount);
    deposited[_msgSender()] -= amount;
    require(deposited[_msgSender()] < tmp, "amount can not be 0");
}