Transformers

Transformers extend the core protocol. They are trustless and permissioned by the Transformer Deployer. A Transformer is identified by the nonce of the Transformer Deployer that corresponds to its address. These contracts are executed in the context of the Flash Wallet (via delegatecall).

Below is a catalog of Transformers.

Transformer	Description	Nonce	Resources
FillQuoteTransformer	Aggregates Liquidity across DEXs and Native 0x Orders.	9	Code; Usage
AffiliateFeesTransformer	Allows integrators to charge an affiliate fee when an order is filled by their platform.	8	Code; Usage
PayTakerTransformer	Forwards funds in the Flash Wallet to the Taker.	7	Code; Usage
WethTransformer	Wraps ETH into WETH (and unwraps)	6	Code; Usage

Implementing a Transformer

Transformers are currently used by the TransformERC20Feature to aggregate liquidity and perform operations on ERC20 tokens (ex, wrapping ETH). Your transformer should inherit from Transformer Contract and implement the interface in IERC20Transformer.

// @dev A transformation callback used in `TransformERC20.transformERC20()`.
interface IERC20Transformer {

    /// @dev Context information to pass into `transform()` by `TransformERC20.transformERC20()`.
    struct TransformContext {
        // The caller of `TransformERC20.transformERC20()`.
        address payable sender;
        // taker The taker address, which may be distinct from `sender` in the case
        // meta-transactions.
        address payable taker;
        // Arbitrary data to pass to the transformer.
        bytes data;
    }

    /// @dev Called from `TransformERC20.transformERC20()`. This will be
    ///      delegatecalled in the context of the FlashWallet instance being used.
    /// @param context Context information.
    /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
    function transform(TransformContext calldata context)
        external
        returns (bytes4 success);
    }