Token Wrapping

Token_wrapper.sol

contract ERC20Wrapper is ERC20, ERC1155Receiver {
    uint256 public tokenId;
    IShareToken public shareToken;
    IERC20 public cash;
    address public augurFoundry;

    /**
     * @dev sets values for
     * @param _augurFoundry A trusted factory contract so that users can wrap multiple tokens in one
     * transaction without giving individual approvals
     * @param _shareToken address of shareToken for which this wrapper is for
     * @param _cash DAI
     * @param _tokenId id of market outcome this wrapper is for
     * @param _name a descriptive name mentioning market and outcome
     * @param _symbol symbol
     * @param _decimals decimals
     */
    constructor(
        address _augurFoundry,
        IShareToken _shareToken,
        IERC20 _cash,
        uint256 _tokenId,
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) public ERC20(_name, _symbol) {
        _setupDecimals(_decimals);
        augurFoundry = _augurFoundry;
        tokenId = _tokenId;
        shareToken = _shareToken;
        cash = _cash;
    }

    /**@dev A function that gets ERC1155s and mints ERC20s
     * Requirements:
     *
     * - if the msg.sender is not augurFoundry then it needs to have given setApprovalForAll
     *  to this contract (if the msg.sender is augur foundry then we trust it and know that
     *  it would have transferred the ERC1155s to this contract before calling it)
     * @param _account account the newly minted ERC20s will go to
     * @param _amount amount of tokens to be wrapped
     */
    function wrapTokens(address _account, uint256 _amount) public {
        if (msg.sender != augurFoundry) {
            shareToken.safeTransferFrom(
                msg.sender,
                address(this),
                tokenId,
                _amount,
                ""
            );
        }
        _mint(_account, _amount);
    }

    /**@dev A function that burns ERC20s and gives back ERC1155s
     * Requirements:
     *
     * - if the msg.sender is not augurFoundry or _account then the caller must have allowance for ``_account``'s tokens of at least
     * `amount`.
     * - if the market has finalized then claim() function should be called.
     * @param _account account the newly minted ERC20s will go to
     * @param _amount amount of tokens to be unwrapped
     */
    function unWrapTokens(address _account, uint256 _amount) public {
        if (msg.sender != _account && msg.sender != augurFoundry) {
            uint256 decreasedAllowance = allowance(_account, msg.sender).sub(
                _amount,
                "ERC20: burn amount exceeds allowance"
            );
            _approve(_account, msg.sender, decreasedAllowance);
        }
        _burn(_account, _amount);

        shareToken.safeTransferFrom(
            address(this),
            _account,
            tokenId,
            _amount,
            ""
        );
    }
}