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// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;
pragma experimental ABIEncoderV2;

import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
import "../errors/LibTransformERC20RichErrors.sol";
import "./Transformer.sol";
import "./LibERC20Transformer.sol";


/// @dev A transformer that wraps or unwraps WETH.
contract WethTransformer is
    Transformer
{
    using LibRichErrorsV06 for bytes;
    using LibSafeMathV06 for uint256;
    using LibERC20Transformer for IERC20TokenV06;

    /// @dev Transform data to ABI-encode and pass into `transform()`.
    struct TransformData {
        // The token to wrap/unwrap. Must be either ETH or WETH.
        IERC20TokenV06 token;
        // Amount of `token` to wrap or unwrap.
        // `uint(-1)` will unwrap the entire balance.
        uint256 amount;
    }

    /// @dev The WETH contract address.
    IEtherTokenV06 public immutable weth;
    /// @dev Maximum uint256 value.
    uint256 private constant MAX_UINT256 = uint256(-1);

    /// @dev Construct the transformer and store the WETH address in an immutable.
    /// @param weth_ The weth token.
    constructor(IEtherTokenV06 weth_)
        public
        Transformer()
    {
        weth = weth_;
    }

    /// @dev Wraps and unwraps WETH.
    /// @param context Context information.
    /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
    function transform(TransformContext calldata context)
        external
        override
        returns (bytes4 success)
    {
        TransformData memory data = abi.decode(context.data, (TransformData));
        if (!data.token.isTokenETH() && data.token != weth) {
            LibTransformERC20RichErrors.InvalidTransformDataError(
                LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_TOKENS,
                context.data
            ).rrevert();
        }

        uint256 amount = data.amount;
        if (amount == MAX_UINT256) {
            amount = data.token.getTokenBalanceOf(address(this));
        }

        if (amount != 0) {
            if (data.token.isTokenETH()) {
                // Wrap ETH.
                weth.deposit{value: amount}();
            } else {
                // Unwrap WETH.
                weth.withdraw(amount);
            }
        }
        return LibERC20Transformer.TRANSFORMER_SUCCESS;
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;


library LibRichErrorsV06 {

    // bytes4(keccak256("Error(string)"))
    bytes4 internal constant STANDARD_ERROR_SELECTOR = 0x08c379a0;

    // solhint-disable func-name-mixedcase
    /// @dev ABI encode a standard, string revert error payload.
    ///      This is the same payload that would be included by a `revert(string)`
    ///      solidity statement. It has the function signature `Error(string)`.
    /// @param message The error string.
    /// @return The ABI encoded error.
    function StandardError(string memory message)
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            STANDARD_ERROR_SELECTOR,
            bytes(message)
        );
    }
    // solhint-enable func-name-mixedcase

    /// @dev Reverts an encoded rich revert reason `errorData`.
    /// @param errorData ABI encoded error data.
    function rrevert(bytes memory errorData)
        internal
        pure
    {
        assembly {
            revert(add(errorData, 0x20), mload(errorData))
        }
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;

import "./errors/LibRichErrorsV06.sol";
import "./errors/LibSafeMathRichErrorsV06.sol";


library LibSafeMathV06 {

    function safeMul(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        if (c / a != b) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                a,
                b
            ));
        }
        return c;
    }

    function safeDiv(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        if (b == 0) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                a,
                b
            ));
        }
        uint256 c = a / b;
        return c;
    }

    function safeSub(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        if (b > a) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                a,
                b
            ));
        }
        return a - b;
    }

    function safeAdd(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        uint256 c = a + b;
        if (c < a) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                a,
                b
            ));
        }
        return c;
    }

    function max256(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        return a >= b ? a : b;
    }

    function min256(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        return a < b ? a : b;
    }

    function safeMul128(uint128 a, uint128 b)
        internal
        pure
        returns (uint128)
    {
        if (a == 0) {
            return 0;
        }
        uint128 c = a * b;
        if (c / a != b) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                a,
                b
            ));
        }
        return c;
    }

    function safeDiv128(uint128 a, uint128 b)
        internal
        pure
        returns (uint128)
    {
        if (b == 0) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                a,
                b
            ));
        }
        uint128 c = a / b;
        return c;
    }

    function safeSub128(uint128 a, uint128 b)
        internal
        pure
        returns (uint128)
    {
        if (b > a) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                a,
                b
            ));
        }
        return a - b;
    }

    function safeAdd128(uint128 a, uint128 b)
        internal
        pure
        returns (uint128)
    {
        uint128 c = a + b;
        if (c < a) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                a,
                b
            ));
        }
        return c;
    }

    function max128(uint128 a, uint128 b)
        internal
        pure
        returns (uint128)
    {
        return a >= b ? a : b;
    }

    function min128(uint128 a, uint128 b)
        internal
        pure
        returns (uint128)
    {
        return a < b ? a : b;
    }

    function safeDowncastToUint128(uint256 a)
        internal
        pure
        returns (uint128)
    {
        if (a > type(uint128).max) {
            LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256DowncastError(
                LibSafeMathRichErrorsV06.DowncastErrorCodes.VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128,
                a
            ));
        }
        return uint128(a);
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;


library LibSafeMathRichErrorsV06 {

    // bytes4(keccak256("Uint256BinOpError(uint8,uint256,uint256)"))
    bytes4 internal constant UINT256_BINOP_ERROR_SELECTOR =
        0xe946c1bb;

    // bytes4(keccak256("Uint256DowncastError(uint8,uint256)"))
    bytes4 internal constant UINT256_DOWNCAST_ERROR_SELECTOR =
        0xc996af7b;

    enum BinOpErrorCodes {
        ADDITION_OVERFLOW,
        MULTIPLICATION_OVERFLOW,
        SUBTRACTION_UNDERFLOW,
        DIVISION_BY_ZERO
    }

    enum DowncastErrorCodes {
        VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT32,
        VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT64,
        VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT96,
        VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128
    }

    // solhint-disable func-name-mixedcase
    function Uint256BinOpError(
        BinOpErrorCodes errorCode,
        uint256 a,
        uint256 b
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            UINT256_BINOP_ERROR_SELECTOR,
            errorCode,
            a,
            b
        );
    }

    function Uint256DowncastError(
        DowncastErrorCodes errorCode,
        uint256 a
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            UINT256_DOWNCAST_ERROR_SELECTOR,
            errorCode,
            a
        );
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;

import "./IERC20TokenV06.sol";


interface IEtherTokenV06 is
    IERC20TokenV06
{
    /// @dev Wrap ether.
    function deposit() external payable;

    /// @dev Unwrap ether.
    function withdraw(uint256 amount) external;
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;


interface IERC20TokenV06 {

    // solhint-disable no-simple-event-func-name
    event Transfer(
        address indexed from,
        address indexed to,
        uint256 value
    );

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

    /// @dev send `value` token to `to` from `msg.sender`
    /// @param to The address of the recipient
    /// @param value The amount of token to be transferred
    /// @return True if transfer was successful
    function transfer(address to, uint256 value)
        external
        returns (bool);

    /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
    /// @param from The address of the sender
    /// @param to The address of the recipient
    /// @param value The amount of token to be transferred
    /// @return True if transfer was successful
    function transferFrom(
        address from,
        address to,
        uint256 value
    )
        external
        returns (bool);

    /// @dev `msg.sender` approves `spender` to spend `value` tokens
    /// @param spender The address of the account able to transfer the tokens
    /// @param value The amount of wei to be approved for transfer
    /// @return Always true if the call has enough gas to complete execution
    function approve(address spender, uint256 value)
        external
        returns (bool);

    /// @dev Query total supply of token
    /// @return Total supply of token
    function totalSupply()
        external
        view
        returns (uint256);

    /// @dev Get the balance of `owner`.
    /// @param owner The address from which the balance will be retrieved
    /// @return Balance of owner
    function balanceOf(address owner)
        external
        view
        returns (uint256);

    /// @dev Get the allowance for `spender` to spend from `owner`.
    /// @param owner The address of the account owning tokens
    /// @param spender The address of the account able to transfer the tokens
    /// @return Amount of remaining tokens allowed to spent
    function allowance(address owner, address spender)
        external
        view
        returns (uint256);

    /// @dev Get the number of decimals this token has.
    function decimals()
        external
        view
        returns (uint8);
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;


library LibTransformERC20RichErrors {

    // solhint-disable func-name-mixedcase,separate-by-one-line-in-contract

    function InsufficientEthAttachedError(
        uint256 ethAttached,
        uint256 ethNeeded
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("InsufficientEthAttachedError(uint256,uint256)")),
            ethAttached,
            ethNeeded
        );
    }

    function IncompleteTransformERC20Error(
        address outputToken,
        uint256 outputTokenAmount,
        uint256 minOutputTokenAmount
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("IncompleteTransformERC20Error(address,uint256,uint256)")),
            outputToken,
            outputTokenAmount,
            minOutputTokenAmount
        );
    }

    function NegativeTransformERC20OutputError(
        address outputToken,
        uint256 outputTokenLostAmount
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("NegativeTransformERC20OutputError(address,uint256)")),
            outputToken,
            outputTokenLostAmount
        );
    }

    function TransformerFailedError(
        address transformer,
        bytes memory transformerData,
        bytes memory resultData
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("TransformerFailedError(address,bytes,bytes)")),
            transformer,
            transformerData,
            resultData
        );
    }

    // Common Transformer errors ///////////////////////////////////////////////

    function OnlyCallableByDeployerError(
        address caller,
        address deployer
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("OnlyCallableByDeployerError(address,address)")),
            caller,
            deployer
        );
    }

    function InvalidExecutionContextError(
        address actualContext,
        address expectedContext
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("InvalidExecutionContextError(address,address)")),
            actualContext,
            expectedContext
        );
    }

    enum InvalidTransformDataErrorCode {
        INVALID_TOKENS,
        INVALID_ARRAY_LENGTH
    }

    function InvalidTransformDataError(
        InvalidTransformDataErrorCode errorCode,
        bytes memory transformData
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("InvalidTransformDataError(uint8,bytes)")),
            errorCode,
            transformData
        );
    }

    // FillQuoteTransformer errors /////////////////////////////////////////////

    function IncompleteFillSellQuoteError(
        address sellToken,
        uint256 soldAmount,
        uint256 sellAmount
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("IncompleteFillSellQuoteError(address,uint256,uint256)")),
            sellToken,
            soldAmount,
            sellAmount
        );
    }

    function IncompleteFillBuyQuoteError(
        address buyToken,
        uint256 boughtAmount,
        uint256 buyAmount
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("IncompleteFillBuyQuoteError(address,uint256,uint256)")),
            buyToken,
            boughtAmount,
            buyAmount
        );
    }

    function InsufficientTakerTokenError(
        uint256 tokenBalance,
        uint256 tokensNeeded
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("InsufficientTakerTokenError(uint256,uint256)")),
            tokenBalance,
            tokensNeeded
        );
    }

    function InsufficientProtocolFeeError(
        uint256 ethBalance,
        uint256 ethNeeded
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("InsufficientProtocolFeeError(uint256,uint256)")),
            ethBalance,
            ethNeeded
        );
    }

    function InvalidERC20AssetDataError(
        bytes memory assetData
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("InvalidERC20AssetDataError(bytes)")),
            assetData
        );
    }

    function InvalidTakerFeeTokenError(
        address token
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            bytes4(keccak256("InvalidTakerFeeTokenError(address)")),
            token
        );
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;
pragma experimental ABIEncoderV2;

import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
import "../errors/LibTransformERC20RichErrors.sol";
import "./IERC20Transformer.sol";


/// @dev Abstract base class for transformers.
abstract contract Transformer is
    IERC20Transformer
{
    using LibRichErrorsV06 for bytes;

    /// @dev The address of the deployer.
    address public immutable deployer;
    /// @dev The original address of this contract.
    address internal immutable _implementation;

    /// @dev Create this contract.
    constructor() public {
        deployer = msg.sender;
        _implementation = address(this);
    }

    /// @dev Destruct this contract. Only callable by the deployer and will not
    ///      succeed in the context of a delegatecall (from another contract).
    /// @param ethRecipient The recipient of ETH held in this contract.
    function die(address payable ethRecipient)
        external
        virtual
    {
        // Only the deployer can call this.
        if (msg.sender != deployer) {
            LibTransformERC20RichErrors
                .OnlyCallableByDeployerError(msg.sender, deployer)
                .rrevert();
        }
        // Must be executing our own context.
        if (address(this) != _implementation) {
            LibTransformERC20RichErrors
                .InvalidExecutionContextError(address(this), _implementation)
                .rrevert();
        }
        selfdestruct(ethRecipient);
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;
pragma experimental ABIEncoderV2;

import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";


/// @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;
        // The recipient address, which may be distinct from `sender` e.g. in
        // meta-transactions.
        address payable recipient;
        // 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);
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;
pragma experimental ABIEncoderV2;

import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";


library LibERC20Transformer {

    using LibERC20TokenV06 for IERC20TokenV06;

    /// @dev ETH pseudo-token address.
    address constant internal ETH_TOKEN_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
    /// @dev ETH pseudo-token.
    IERC20TokenV06 constant internal ETH_TOKEN = IERC20TokenV06(ETH_TOKEN_ADDRESS);
    /// @dev Return value indicating success in `IERC20Transformer.transform()`.
    ///      This is just `keccak256('TRANSFORMER_SUCCESS')`.
    bytes4 constant internal TRANSFORMER_SUCCESS = 0x13c9929e;

    /// @dev Transfer ERC20 tokens and ETH.
    /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
    /// @param to The recipient.
    /// @param amount The transfer amount.
    function transformerTransfer(
        IERC20TokenV06 token,
        address payable to,
        uint256 amount
    )
        internal
    {
        if (isTokenETH(token)) {
            to.transfer(amount);
        } else {
            token.compatTransfer(to, amount);
        }
    }

    /// @dev Check if a token is the ETH pseudo-token.
    /// @param token The token to check.
    /// @return isETH `true` if the token is the ETH pseudo-token.
    function isTokenETH(IERC20TokenV06 token)
        internal
        pure
        returns (bool isETH)
    {
        return address(token) == ETH_TOKEN_ADDRESS;
    }

    /// @dev Check the balance of an ERC20 token or ETH.
    /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
    /// @param owner Holder of the tokens.
    /// @return tokenBalance The balance of `owner`.
    function getTokenBalanceOf(IERC20TokenV06 token, address owner)
        internal
        view
        returns (uint256 tokenBalance)
    {
        if (isTokenETH(token)) {
            return owner.balance;
        }
        return token.balanceOf(owner);
    }

    /// @dev RLP-encode a 32-bit or less account nonce.
    /// @param nonce A positive integer in the range 0 <= nonce < 2^32.
    /// @return rlpNonce The RLP encoding.
    function rlpEncodeNonce(uint32 nonce)
        internal
        pure
        returns (bytes memory rlpNonce)
    {
        // See https://github.com/ethereum/wiki/wiki/RLP for RLP encoding rules.
        if (nonce == 0) {
            rlpNonce = new bytes(1);
            rlpNonce[0] = 0x80;
        } else if (nonce < 0x80) {
            rlpNonce = new bytes(1);
            rlpNonce[0] = byte(uint8(nonce));
        } else if (nonce <= 0xFF) {
            rlpNonce = new bytes(2);
            rlpNonce[0] = 0x81;
            rlpNonce[1] = byte(uint8(nonce));
        } else if (nonce <= 0xFFFF) {
            rlpNonce = new bytes(3);
            rlpNonce[0] = 0x82;
            rlpNonce[1] = byte(uint8((nonce & 0xFF00) >> 8));
            rlpNonce[2] = byte(uint8(nonce));
        } else if (nonce <= 0xFFFFFF) {
            rlpNonce = new bytes(4);
            rlpNonce[0] = 0x83;
            rlpNonce[1] = byte(uint8((nonce & 0xFF0000) >> 16));
            rlpNonce[2] = byte(uint8((nonce & 0xFF00) >> 8));
            rlpNonce[3] = byte(uint8(nonce));
        } else {
            rlpNonce = new bytes(5);
            rlpNonce[0] = 0x84;
            rlpNonce[1] = byte(uint8((nonce & 0xFF000000) >> 24));
            rlpNonce[2] = byte(uint8((nonce & 0xFF0000) >> 16));
            rlpNonce[3] = byte(uint8((nonce & 0xFF00) >> 8));
            rlpNonce[4] = byte(uint8(nonce));
        }
    }

    /// @dev Compute the expected deployment address by `deployer` at
    ///      the nonce given by `deploymentNonce`.
    /// @param deployer The address of the deployer.
    /// @param deploymentNonce The nonce that the deployer had when deploying
    ///        a contract.
    /// @return deploymentAddress The deployment address.
    function getDeployedAddress(address deployer, uint32 deploymentNonce)
        internal
        pure
        returns (address payable deploymentAddress)
    {
        // The address of if a deployed contract is the lower 20 bytes of the
        // hash of the RLP-encoded deployer's account address + account nonce.
        // See: https://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
        bytes memory rlpNonce = rlpEncodeNonce(deploymentNonce);
        return address(uint160(uint256(keccak256(abi.encodePacked(
            byte(uint8(0xC0 + 21 + rlpNonce.length)),
            byte(uint8(0x80 + 20)),
            deployer,
            rlpNonce
        )))));
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;

import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
import "./IERC20TokenV06.sol";


library LibERC20TokenV06 {
    bytes constant private DECIMALS_CALL_DATA = hex"313ce567";

    /// @dev Calls `IERC20TokenV06(token).approve()`.
    ///      Reverts if the return data is invalid or the call reverts.
    /// @param token The address of the token contract.
    /// @param spender The address that receives an allowance.
    /// @param allowance The allowance to set.
    function compatApprove(
        IERC20TokenV06 token,
        address spender,
        uint256 allowance
    )
        internal
    {
        bytes memory callData = abi.encodeWithSelector(
            token.approve.selector,
            spender,
            allowance
        );
        _callWithOptionalBooleanResult(address(token), callData);
    }

    /// @dev Calls `IERC20TokenV06(token).approve()` and sets the allowance to the
    ///      maximum if the current approval is not already >= an amount.
    ///      Reverts if the return data is invalid or the call reverts.
    /// @param token The address of the token contract.
    /// @param spender The address that receives an allowance.
    /// @param amount The minimum allowance needed.
    function approveIfBelow(
        IERC20TokenV06 token,
        address spender,
        uint256 amount
    )
        internal
    {
        if (token.allowance(address(this), spender) < amount) {
            compatApprove(token, spender, uint256(-1));
        }
    }

    /// @dev Calls `IERC20TokenV06(token).transfer()`.
    ///      Reverts if the return data is invalid or the call reverts.
    /// @param token The address of the token contract.
    /// @param to The address that receives the tokens
    /// @param amount Number of tokens to transfer.
    function compatTransfer(
        IERC20TokenV06 token,
        address to,
        uint256 amount
    )
        internal
    {
        bytes memory callData = abi.encodeWithSelector(
            token.transfer.selector,
            to,
            amount
        );
        _callWithOptionalBooleanResult(address(token), callData);
    }

    /// @dev Calls `IERC20TokenV06(token).transferFrom()`.
    ///      Reverts if the return data is invalid or the call reverts.
    /// @param token The address of the token contract.
    /// @param from The owner of the tokens.
    /// @param to The address that receives the tokens
    /// @param amount Number of tokens to transfer.
    function compatTransferFrom(
        IERC20TokenV06 token,
        address from,
        address to,
        uint256 amount
    )
        internal
    {
        bytes memory callData = abi.encodeWithSelector(
            token.transferFrom.selector,
            from,
            to,
            amount
        );
        _callWithOptionalBooleanResult(address(token), callData);
    }

    /// @dev Retrieves the number of decimals for a token.
    ///      Returns `18` if the call reverts.
    /// @param token The address of the token contract.
    /// @return tokenDecimals The number of decimals places for the token.
    function compatDecimals(IERC20TokenV06 token)
        internal
        view
        returns (uint8 tokenDecimals)
    {
        tokenDecimals = 18;
        (bool didSucceed, bytes memory resultData) = address(token).staticcall(DECIMALS_CALL_DATA);
        if (didSucceed && resultData.length >= 32) {
            tokenDecimals = uint8(LibBytesV06.readUint256(resultData, 0));
        }
    }

    /// @dev Retrieves the allowance for a token, owner, and spender.
    ///      Returns `0` if the call reverts.
    /// @param token The address of the token contract.
    /// @param owner The owner of the tokens.
    /// @param spender The address the spender.
    /// @return allowance_ The allowance for a token, owner, and spender.
    function compatAllowance(IERC20TokenV06 token, address owner, address spender)
        internal
        view
        returns (uint256 allowance_)
    {
        (bool didSucceed, bytes memory resultData) = address(token).staticcall(
            abi.encodeWithSelector(
                token.allowance.selector,
                owner,
                spender
            )
        );
        if (didSucceed && resultData.length >= 32) {
            allowance_ = LibBytesV06.readUint256(resultData, 0);
        }
    }

    /// @dev Retrieves the balance for a token owner.
    ///      Returns `0` if the call reverts.
    /// @param token The address of the token contract.
    /// @param owner The owner of the tokens.
    /// @return balance The token balance of an owner.
    function compatBalanceOf(IERC20TokenV06 token, address owner)
        internal
        view
        returns (uint256 balance)
    {
        (bool didSucceed, bytes memory resultData) = address(token).staticcall(
            abi.encodeWithSelector(
                token.balanceOf.selector,
                owner
            )
        );
        if (didSucceed && resultData.length >= 32) {
            balance = LibBytesV06.readUint256(resultData, 0);
        }
    }

    /// @dev Executes a call on address `target` with calldata `callData`
    ///      and asserts that either nothing was returned or a single boolean
    ///      was returned equal to `true`.
    /// @param target The call target.
    /// @param callData The abi-encoded call data.
    function _callWithOptionalBooleanResult(
        address target,
        bytes memory callData
    )
        private
    {
        (bool didSucceed, bytes memory resultData) = target.call(callData);
        // Revert if the call reverted.
        if (!didSucceed) {
            LibRichErrorsV06.rrevert(resultData);
        }
        // If we get back 0 returndata, this may be a non-standard ERC-20 that
        // does not return a boolean. Check that it at least contains code.
        if (resultData.length == 0) {
            uint256 size;
            assembly { size := extcodesize(target) }
            require(size > 0, "invalid token address, contains no code");
            return;
        }
        // If we get back at least 32 bytes, we know the target address
        // contains code, and we assume it is a token that returned a boolean
        // success value, which must be true.
        if (resultData.length >= 32) {
            uint256 result = LibBytesV06.readUint256(resultData, 0);
            if (result == 1) {
                return;
            } else {
                LibRichErrorsV06.rrevert(resultData);
            }
        }
        // If 0 < returndatasize < 32, the target is a contract, but not a
        // valid token.
        LibRichErrorsV06.rrevert(resultData);
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;

import "./errors/LibBytesRichErrorsV06.sol";
import "./errors/LibRichErrorsV06.sol";


library LibBytesV06 {

    using LibBytesV06 for bytes;

    /// @dev Gets the memory address for a byte array.
    /// @param input Byte array to lookup.
    /// @return memoryAddress Memory address of byte array. This
    ///         points to the header of the byte array which contains
    ///         the length.
    function rawAddress(bytes memory input)
        internal
        pure
        returns (uint256 memoryAddress)
    {
        assembly {
            memoryAddress := input
        }
        return memoryAddress;
    }

    /// @dev Gets the memory address for the contents of a byte array.
    /// @param input Byte array to lookup.
    /// @return memoryAddress Memory address of the contents of the byte array.
    function contentAddress(bytes memory input)
        internal
        pure
        returns (uint256 memoryAddress)
    {
        assembly {
            memoryAddress := add(input, 32)
        }
        return memoryAddress;
    }

    /// @dev Copies `length` bytes from memory location `source` to `dest`.
    /// @param dest memory address to copy bytes to.
    /// @param source memory address to copy bytes from.
    /// @param length number of bytes to copy.
    function memCopy(
        uint256 dest,
        uint256 source,
        uint256 length
    )
        internal
        pure
    {
        if (length < 32) {
            // Handle a partial word by reading destination and masking
            // off the bits we are interested in.
            // This correctly handles overlap, zero lengths and source == dest
            assembly {
                let mask := sub(exp(256, sub(32, length)), 1)
                let s := and(mload(source), not(mask))
                let d := and(mload(dest), mask)
                mstore(dest, or(s, d))
            }
        } else {
            // Skip the O(length) loop when source == dest.
            if (source == dest) {
                return;
            }

            // For large copies we copy whole words at a time. The final
            // word is aligned to the end of the range (instead of after the
            // previous) to handle partial words. So a copy will look like this:
            //
            //  ####
            //      ####
            //          ####
            //            ####
            //
            // We handle overlap in the source and destination range by
            // changing the copying direction. This prevents us from
            // overwriting parts of source that we still need to copy.
            //
            // This correctly handles source == dest
            //
            if (source > dest) {
                assembly {
                    // We subtract 32 from `sEnd` and `dEnd` because it
                    // is easier to compare with in the loop, and these
                    // are also the addresses we need for copying the
                    // last bytes.
                    length := sub(length, 32)
                    let sEnd := add(source, length)
                    let dEnd := add(dest, length)

                    // Remember the last 32 bytes of source
                    // This needs to be done here and not after the loop
                    // because we may have overwritten the last bytes in
                    // source already due to overlap.
                    let last := mload(sEnd)

                    // Copy whole words front to back
                    // Note: the first check is always true,
                    // this could have been a do-while loop.
                    // solhint-disable-next-line no-empty-blocks
                    for {} lt(source, sEnd) {} {
                        mstore(dest, mload(source))
                        source := add(source, 32)
                        dest := add(dest, 32)
                    }

                    // Write the last 32 bytes
                    mstore(dEnd, last)
                }
            } else {
                assembly {
                    // We subtract 32 from `sEnd` and `dEnd` because those
                    // are the starting points when copying a word at the end.
                    length := sub(length, 32)
                    let sEnd := add(source, length)
                    let dEnd := add(dest, length)

                    // Remember the first 32 bytes of source
                    // This needs to be done here and not after the loop
                    // because we may have overwritten the first bytes in
                    // source already due to overlap.
                    let first := mload(source)

                    // Copy whole words back to front
                    // We use a signed comparisson here to allow dEnd to become
                    // negative (happens when source and dest < 32). Valid
                    // addresses in local memory will never be larger than
                    // 2**255, so they can be safely re-interpreted as signed.
                    // Note: the first check is always true,
                    // this could have been a do-while loop.
                    // solhint-disable-next-line no-empty-blocks
                    for {} slt(dest, dEnd) {} {
                        mstore(dEnd, mload(sEnd))
                        sEnd := sub(sEnd, 32)
                        dEnd := sub(dEnd, 32)
                    }

                    // Write the first 32 bytes
                    mstore(dest, first)
                }
            }
        }
    }

    /// @dev Returns a slices from a byte array.
    /// @param b The byte array to take a slice from.
    /// @param from The starting index for the slice (inclusive).
    /// @param to The final index for the slice (exclusive).
    /// @return result The slice containing bytes at indices [from, to)
    function slice(
        bytes memory b,
        uint256 from,
        uint256 to
    )
        internal
        pure
        returns (bytes memory result)
    {
        // Ensure that the from and to positions are valid positions for a slice within
        // the byte array that is being used.
        if (from > to) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                from,
                to
            ));
        }
        if (to > b.length) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                to,
                b.length
            ));
        }

        // Create a new bytes structure and copy contents
        result = new bytes(to - from);
        memCopy(
            result.contentAddress(),
            b.contentAddress() + from,
            result.length
        );
        return result;
    }

    /// @dev Returns a slice from a byte array without preserving the input.
    ///      When `from == 0`, the original array will match the slice.
    ///      In other cases its state will be corrupted.
    /// @param b The byte array to take a slice from. Will be destroyed in the process.
    /// @param from The starting index for the slice (inclusive).
    /// @param to The final index for the slice (exclusive).
    /// @return result The slice containing bytes at indices [from, to)
    function sliceDestructive(
        bytes memory b,
        uint256 from,
        uint256 to
    )
        internal
        pure
        returns (bytes memory result)
    {
        // Ensure that the from and to positions are valid positions for a slice within
        // the byte array that is being used.
        if (from > to) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                from,
                to
            ));
        }
        if (to > b.length) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                to,
                b.length
            ));
        }

        // Create a new bytes structure around [from, to) in-place.
        assembly {
            result := add(b, from)
            mstore(result, sub(to, from))
        }
        return result;
    }

    /// @dev Pops the last byte off of a byte array by modifying its length.
    /// @param b Byte array that will be modified.
    /// @return result The byte that was popped off.
    function popLastByte(bytes memory b)
        internal
        pure
        returns (bytes1 result)
    {
        if (b.length == 0) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanZeroRequired,
                b.length,
                0
            ));
        }

        // Store last byte.
        result = b[b.length - 1];

        assembly {
            // Decrement length of byte array.
            let newLen := sub(mload(b), 1)
            mstore(b, newLen)
        }
        return result;
    }

    /// @dev Tests equality of two byte arrays.
    /// @param lhs First byte array to compare.
    /// @param rhs Second byte array to compare.
    /// @return equal True if arrays are the same. False otherwise.
    function equals(
        bytes memory lhs,
        bytes memory rhs
    )
        internal
        pure
        returns (bool equal)
    {
        // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
        // We early exit on unequal lengths, but keccak would also correctly
        // handle this.
        return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
    }

    /// @dev Reads an address from a position in a byte array.
    /// @param b Byte array containing an address.
    /// @param index Index in byte array of address.
    /// @return result address from byte array.
    function readAddress(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (address result)
    {
        if (b.length < index + 20) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                b.length,
                index + 20 // 20 is length of address
            ));
        }

        // Add offset to index:
        // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
        // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
        index += 20;

        // Read address from array memory
        assembly {
            // 1. Add index to address of bytes array
            // 2. Load 32-byte word from memory
            // 3. Apply 20-byte mask to obtain address
            result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
        }
        return result;
    }

    /// @dev Writes an address into a specific position in a byte array.
    /// @param b Byte array to insert address into.
    /// @param index Index in byte array of address.
    /// @param input Address to put into byte array.
    function writeAddress(
        bytes memory b,
        uint256 index,
        address input
    )
        internal
        pure
    {
        if (b.length < index + 20) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                b.length,
                index + 20 // 20 is length of address
            ));
        }

        // Add offset to index:
        // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
        // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
        index += 20;

        // Store address into array memory
        assembly {
            // The address occupies 20 bytes and mstore stores 32 bytes.
            // First fetch the 32-byte word where we'll be storing the address, then
            // apply a mask so we have only the bytes in the word that the address will not occupy.
            // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.

            // 1. Add index to address of bytes array
            // 2. Load 32-byte word from memory
            // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
            let neighbors := and(
                mload(add(b, index)),
                0xffffffffffffffffffffffff0000000000000000000000000000000000000000
            )

            // Make sure input address is clean.
            // (Solidity does not guarantee this)
            input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)

            // Store the neighbors and address into memory
            mstore(add(b, index), xor(input, neighbors))
        }
    }

    /// @dev Reads a bytes32 value from a position in a byte array.
    /// @param b Byte array containing a bytes32 value.
    /// @param index Index in byte array of bytes32 value.
    /// @return result bytes32 value from byte array.
    function readBytes32(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (bytes32 result)
    {
        if (b.length < index + 32) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                b.length,
                index + 32
            ));
        }

        // Arrays are prefixed by a 256 bit length parameter
        index += 32;

        // Read the bytes32 from array memory
        assembly {
            result := mload(add(b, index))
        }
        return result;
    }

    /// @dev Writes a bytes32 into a specific position in a byte array.
    /// @param b Byte array to insert <input> into.
    /// @param index Index in byte array of <input>.
    /// @param input bytes32 to put into byte array.
    function writeBytes32(
        bytes memory b,
        uint256 index,
        bytes32 input
    )
        internal
        pure
    {
        if (b.length < index + 32) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                b.length,
                index + 32
            ));
        }

        // Arrays are prefixed by a 256 bit length parameter
        index += 32;

        // Read the bytes32 from array memory
        assembly {
            mstore(add(b, index), input)
        }
    }

    /// @dev Reads a uint256 value from a position in a byte array.
    /// @param b Byte array containing a uint256 value.
    /// @param index Index in byte array of uint256 value.
    /// @return result uint256 value from byte array.
    function readUint256(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (uint256 result)
    {
        result = uint256(readBytes32(b, index));
        return result;
    }

    /// @dev Writes a uint256 into a specific position in a byte array.
    /// @param b Byte array to insert <input> into.
    /// @param index Index in byte array of <input>.
    /// @param input uint256 to put into byte array.
    function writeUint256(
        bytes memory b,
        uint256 index,
        uint256 input
    )
        internal
        pure
    {
        writeBytes32(b, index, bytes32(input));
    }

    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
    /// @param b Byte array containing a bytes4 value.
    /// @param index Index in byte array of bytes4 value.
    /// @return result bytes4 value from byte array.
    function readBytes4(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (bytes4 result)
    {
        if (b.length < index + 4) {
            LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsFourRequired,
                b.length,
                index + 4
            ));
        }

        // Arrays are prefixed by a 32 byte length field
        index += 32;

        // Read the bytes4 from array memory
        assembly {
            result := mload(add(b, index))
            // Solidity does not require us to clean the trailing bytes.
            // We do it anyway
            result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
        }
        return result;
    }

    /// @dev Writes a new length to a byte array.
    ///      Decreasing length will lead to removing the corresponding lower order bytes from the byte array.
    ///      Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array.
    /// @param b Bytes array to write new length to.
    /// @param length New length of byte array.
    function writeLength(bytes memory b, uint256 length)
        internal
        pure
    {
        assembly {
            mstore(b, length)
        }
    }
}

// SPDX-License-Identifier: Apache-2.0
/*

  Copyright 2020 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.6.5;


library LibBytesRichErrorsV06 {

    enum InvalidByteOperationErrorCodes {
        FromLessThanOrEqualsToRequired,
        ToLessThanOrEqualsLengthRequired,
        LengthGreaterThanZeroRequired,
        LengthGreaterThanOrEqualsFourRequired,
        LengthGreaterThanOrEqualsTwentyRequired,
        LengthGreaterThanOrEqualsThirtyTwoRequired,
        LengthGreaterThanOrEqualsNestedBytesLengthRequired,
        DestinationLengthGreaterThanOrEqualSourceLengthRequired
    }

    // bytes4(keccak256("InvalidByteOperationError(uint8,uint256,uint256)"))
    bytes4 internal constant INVALID_BYTE_OPERATION_ERROR_SELECTOR =
        0x28006595;

    // solhint-disable func-name-mixedcase
    function InvalidByteOperationError(
        InvalidByteOperationErrorCodes errorCode,
        uint256 offset,
        uint256 required
    )
        internal
        pure
        returns (bytes memory)
    {
        return abi.encodeWithSelector(
            INVALID_BYTE_OPERATION_ERROR_SELECTOR,
            errorCode,
            offset,
            required
        );
    }
}

{
  "remappings": [
    "@0x/contracts-utils=/Users/zixingxin/protocol/node_modules/@0x/contracts-utils",
    "@0x/contracts-erc20=/Users/zixingxin/protocol/contracts/zero-ex/node_modules/@0x/contracts-erc20"
  ],
  "optimizer": {
    "enabled": true,
    "runs": 1000000,
    "details": {
      "yul": true,
      "deduplicate": true,
      "cse": true,
      "constantOptimizer": true
    }
  },
  "outputSelection": {
    "*": {
      "*": [
        "evm.bytecode",
        "evm.deployedBytecode",
        "abi"
      ]
    }
  },
  "evmVersion": "istanbul"
}

• No Contract Security Audit Submitted- Submit Audit Here

[{"inputs":[{"internalType":"contract IEtherTokenV06","name":"weth_","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"inputs":[],"name":"deployer","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address payable","name":"ethRecipient","type":"address"}],"name":"die","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"components":[{"internalType":"address payable","name":"sender","type":"address"},{"internalType":"address payable","name":"recipient","type":"address"},{"internalType":"bytes","name":"data","type":"bytes"}],"internalType":"struct IERC20Transformer.TransformContext","name":"context","type":"tuple"}],"name":"transform","outputs":[{"internalType":"bytes4","name":"success","type":"bytes4"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"weth","outputs":[{"internalType":"contract IEtherTokenV06","name":"","type":"address"}],"stateMutability":"view","type":"function"}]

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0000000000000000000000004200000000000000000000000000000000000006

-----Decoded View---------------
Arg [0] : weth_ (address): 0x4200000000000000000000000000000000000006

-----Encoded View---------------
1 Constructor Arguments found :
Arg [0] : 0000000000000000000000004200000000000000000000000000000000000006