Merge pull request #839 from 0xProject/refactor/contracts/forwarder-interfaces

Refactor forwarder file structure

20 files changed, 844 insertions, 373 deletions

diff --git a/packages/contracts/src/2.0.0/forwarder/Forwarder.sol b/packages/contracts/src/2.0.0/forwarder/Forwarder.sol
index 38128d93e..fc17a4c72 100644
--- a/packages/contracts/src/2.0.0/forwarder/Forwarder.sol
+++ b/packages/contracts/src/2.0.0/forwarder/Forwarder.sol
@@ -19,22 +19,22 @@
 pragma solidity 0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "./MixinWethFees.sol";
-import "./MixinMarketSellTokens.sol";
-import "./MixinMarketBuyTokens.sol";
+import "./MixinFees.sol";
+import "./MixinForwarderCore.sol";
 import "./MixinConstants.sol";
-import "../utils/Ownable/Ownable.sol";
+import "./MixinMarketBuyZrx.sol";
+import "./MixinExpectedResults.sol";
+import "./MixinTransfer.sol";
 
 
 contract Forwarder is
-    Ownable,
     MixinConstants,
-    MixinWethFees,
+    MixinExpectedResults,
+    MixinFees,
     MixinMarketBuyZrx,
-    MixinMarketBuyTokens,
-    MixinMarketSellTokens
+    MixinTransfer,
+    MixinForwarderCore
 {
-    uint256 constant internal MAX_UINT = 2**256 - 1;
 
     constructor (
         address _exchange,
@@ -45,7 +45,6 @@ contract Forwarder is
         bytes memory _wethAssetData
     )
         public
-        Ownable()
         MixinConstants(
             _exchange,
             _etherToken,
@@ -53,30 +52,6 @@ contract Forwarder is
             _zrxAssetData,
             _wethAssetData
         )
-    {
-        setERC20ProxyApproval(_erc20AssetProxyId);
-    }
-
-    /// @dev Default payabale function, this allows us to withdraw WETH
-    function ()
-        public
-        payable
-    {
-        require(
-            msg.sender == address(ETHER_TOKEN),
-            "DEFAULT_FUNCTION_WETH_CONTRACT_ONLY"
-        );
-    }
-
-    /// @dev Sets the allowances to the proxy for this contract
-    function setERC20ProxyApproval(bytes4 erc20AssetProxyId)
-        public
-        onlyOwner
-    {
-        address proxyAddress = EXCHANGE.getAssetProxy(erc20AssetProxyId);
-        if (proxyAddress != address(0)) {
-            ETHER_TOKEN.approve(proxyAddress, MAX_UINT);
-            ZRX_TOKEN.approve(proxyAddress, MAX_UINT);
-        }
-    }
+        MixinForwarderCore()
+    {}
 }
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinConstants.sol b/packages/contracts/src/2.0.0/forwarder/MixinConstants.sol
index ea82e9d64..2b064d579 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinConstants.sol
+++ b/packages/contracts/src/2.0.0/forwarder/MixinConstants.sol
@@ -18,20 +18,12 @@
 
 pragma solidity 0.4.24;
 
-import "../protocol/Exchange/Exchange.sol";
-import { WETH9 as EtherToken } from "../tokens/WETH9/WETH9.sol";
-import "../tokens/ERC20Token/IERC20Token.sol";
+import "./mixins/MConstants.sol";
 
 
-contract MixinConstants {
-
-    // solhint-disable var-name-mixedcase
-    Exchange internal EXCHANGE;
-    EtherToken internal ETHER_TOKEN;
-    IERC20Token internal ZRX_TOKEN;
-    bytes internal ZRX_ASSET_DATA;
-    bytes internal WETH_ASSET_DATA;
-    // solhint-enable var-name-mixedcase
+contract MixinConstants is
+    MConstants
+{
 
     constructor (
         address _exchange,
@@ -42,11 +34,10 @@ contract MixinConstants {
     )
         public
     {
-        EXCHANGE = Exchange(_exchange);
-        ETHER_TOKEN = EtherToken(_etherToken);
+        EXCHANGE = IExchange(_exchange);
+        ETHER_TOKEN = IEtherToken(_etherToken);
         ZRX_TOKEN = IERC20Token(_zrxToken);
         ZRX_ASSET_DATA = _zrxAssetData;
         WETH_ASSET_DATA = _wethAssetData;
     }
-
-}
\ No newline at end of file
+}
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinERC721.sol b/packages/contracts/src/2.0.0/forwarder/MixinERC721.sol
deleted file mode 100644
index b5be223b6..000000000
--- a/packages/contracts/src/2.0.0/forwarder/MixinERC721.sol
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
-
-  Copyright 2018 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 0.4.24;
-pragma experimental ABIEncoderV2;
-
-import "../utils/LibBytes/LibBytes.sol";
-import "../tokens/ERC721Token/IERC721Token.sol";
-
-
-contract MixinERC721 {
-
-    using LibBytes for bytes;
-
-    bytes4 constant internal ERC721_RECEIVED = bytes4(keccak256("onERC721Received(address,uint256,bytes)"));
-    bytes4 constant internal ERC721_RECEIVED_OPERATOR = bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"));
-
-    function onERC721Received(address, uint256, bytes memory)
-        public
-        pure
-        returns(bytes4)
-    {
-        return ERC721_RECEIVED;
-    }
-
-    function onERC721Received(address, address, uint256, bytes memory)
-        public
-        pure
-        returns(bytes4)
-    {
-        return ERC721_RECEIVED_OPERATOR;
-    }
-
-    function transferERC721Token(
-        bytes memory assetData,
-        address to
-    )
-        internal
-    {
-        // Decode asset data.
-        address token = assetData.readAddress(16);
-        uint256 tokenId = assetData.readUint256(36);
-        bytes memory receiverData = assetData.readBytesWithLength(100);
-        IERC721Token(token).safeTransferFrom(
-            address(this),
-            to,
-            tokenId,
-            receiverData
-        );
-    }
-}
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinExpectedResults.sol b/packages/contracts/src/2.0.0/forwarder/MixinExpectedResults.sol
index 6406d1d37..a575c9675 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinExpectedResults.sol
+++ b/packages/contracts/src/2.0.0/forwarder/MixinExpectedResults.sol
@@ -23,13 +23,15 @@ import "../utils/LibBytes/LibBytes.sol";
 import "../protocol/Exchange/libs/LibFillResults.sol";
 import "../protocol/Exchange/libs/LibMath.sol";
 import "../protocol/Exchange/libs/LibOrder.sol";
-import "./MixinConstants.sol";
+import "./mixins/MConstants.sol";
+import "./mixins/MExpectedResults.sol";
 
 
 contract MixinExpectedResults is
     LibMath,
     LibFillResults,
-    MixinConstants
+    MConstants,
+    MExpectedResults
 {
 
     /// @dev Calculates a total FillResults for buying makerAssetFillAmount over all orders.
@@ -61,6 +63,30 @@ contract MixinExpectedResults is
         return totalFillResults;
     }
 
+    /// @dev Calculates a FillResults total for selling takerAssetFillAmount over all orders. 
+    ///      Including the fees required to be paid. 
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param takerAssetFillAmount A number representing the amount of this order to fill.
+    /// @return totalFillResults Amounts filled and fees paid by maker and taker.
+    function calculateMarketSellResults(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount
+    )
+        public
+        view
+        returns (FillResults memory totalFillResults)
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            uint256 remainingTakerAssetFillAmount = safeSub(takerAssetFillAmount, totalFillResults.takerAssetFilledAmount);
+            FillResults memory singleFillResult = calculateFillResults(orders[i], remainingTakerAssetFillAmount);
+            addFillResults(totalFillResults, singleFillResult);
+            if (totalFillResults.takerAssetFilledAmount == takerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
     /// @dev Calculates fill results for buyFeeTokens. This handles fees on buying ZRX
     ///      so the end result is the expected amount of ZRX (not less after fees).
     /// @param orders An array of Order struct containing order specifications.
@@ -132,28 +158,4 @@ contract MixinExpectedResults is
         );
         return fillResults;
     }
-
-    /// @dev Calculates a FillResults total for selling takerAssetFillAmount over all orders. 
-    ///      Including the fees required to be paid. 
-    /// @param orders An array of Order struct containing order specifications.
-    /// @param takerAssetFillAmount A number representing the amount of this order to fill.
-    /// @return totalFillResults Amounts filled and fees paid by maker and taker.
-    function calculateMarketSellResults(
-        LibOrder.Order[] memory orders,
-        uint256 takerAssetFillAmount
-    )
-        internal
-        view
-        returns (FillResults memory totalFillResults)
-    {
-        for (uint256 i = 0; i < orders.length; i++) {
-            uint256 remainingTakerAssetFillAmount = safeSub(takerAssetFillAmount, totalFillResults.takerAssetFilledAmount);
-            FillResults memory singleFillResult = calculateFillResults(orders[i], remainingTakerAssetFillAmount);
-            addFillResults(totalFillResults, singleFillResult);
-            if (totalFillResults.takerAssetFilledAmount == takerAssetFillAmount) {
-                break;
-            }
-        }
-        return totalFillResults;
-    }
 }
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinWethFees.sol b/packages/contracts/src/2.0.0/forwarder/MixinFees.sol
index 12392be79..8ea00a1d5 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinWethFees.sol
+++ b/packages/contracts/src/2.0.0/forwarder/MixinFees.sol
@@ -18,19 +18,31 @@
 
 pragma solidity 0.4.24;
 
-import { WETH9 as EtherToken } from "../tokens/WETH9/WETH9.sol";
 import "../protocol/Exchange/libs/LibMath.sol";
-import "./MixinConstants.sol";
+import "./mixins/MConstants.sol";
+import "./mixins/MFees.sol";
 
 
-contract MixinWethFees is
+contract MixinFees is
     LibMath,
-    MixinConstants
+    MConstants,
+    MFees
 {
 
-    uint16  constant public PERCENTAGE_DENOMINATOR = 10000; // 9800 == 98%, 10000 == 100%
-    uint16  constant public MAX_FEE = 1000; // 10%
-    uint16  constant public ALLOWABLE_EXCHANGE_PERCENTAGE = 9500; // 95%
+    uint16 constant public PERCENTAGE_DENOMINATOR = 10000; // 9800 == 98%, 10000 == 100%
+    uint16 constant public MAX_FEE = 1000; // 10%
+    uint16 constant public ALLOWABLE_EXCHANGE_PERCENTAGE = 9500; // 95%
+
+    /// @dev Default payabale function, this allows us to withdraw WETH
+    function ()
+        public
+        payable
+    {
+        require(
+            msg.sender == address(ETHER_TOKEN),
+            "DEFAULT_FUNCTION_WETH_CONTRACT_ONLY"
+        );
+    }
 
     /// @dev Pays the feeRecipient feeProportion of the total takerEthAmount, denominated in ETH
     /// @param takerEthAmount The total amount that was transacted in WETH, fees are calculated from this value.
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinMarketBuyTokens.sol b/packages/contracts/src/2.0.0/forwarder/MixinForwarderCore.sol
index 165fec61f..eadeaf5ba 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinMarketBuyTokens.sol
+++ b/packages/contracts/src/2.0.0/forwarder/MixinForwarderCore.sol
@@ -20,25 +20,118 @@ pragma solidity 0.4.24;
 pragma experimental ABIEncoderV2;
 
 import "../utils/LibBytes/LibBytes.sol";
-import "./MixinWethFees.sol";
-import "./MixinMarketBuyZrx.sol";
-import "./MixinExpectedResults.sol";
-import "./MixinERC20.sol";
-import "./MixinERC721.sol";
-import "./MixinConstants.sol";
+import "./mixins/MFees.sol";
+import "./mixins/MMarketBuyZrx.sol";
+import "./mixins/MExpectedResults.sol";
+import "./mixins/MTransfer.sol";
+import "./mixins/MConstants.sol";
+import "./mixins/MForwarderCore.sol";
 import "../protocol/Exchange/libs/LibOrder.sol";
+import "../protocol/Exchange/libs/LibFillResults.sol";
 
 
-contract MixinMarketBuyTokens is
-    MixinConstants,
-    MixinWethFees,
-    MixinMarketBuyZrx,
-    MixinExpectedResults,
-    MixinERC20,
-    MixinERC721
+contract MixinForwarderCore is
+    LibFillResults,
+    MConstants,
+    MExpectedResults,
+    MFees,
+    MMarketBuyZrx,
+    MTransfer,
+    MForwarderCore
 {
-    bytes4 public constant ERC20_DATA_ID = bytes4(keccak256("ERC20Token(address)"));
-    bytes4 public constant ERC721_DATA_ID = bytes4(keccak256("ERC721Token(address,uint256,bytes)"));
+    bytes4 constant internal ERC20_DATA_ID = bytes4(keccak256("ERC20Token(address)"));
+    bytes4 constant internal ERC721_DATA_ID = bytes4(keccak256("ERC721Token(address,uint256,bytes)"));
+    uint256 constant internal MAX_UINT = 2**256 - 1;
+
+    constructor ()
+        public
+    {
+        address proxyAddress = EXCHANGE.getAssetProxy(ERC20_DATA_ID);
+        if (proxyAddress != address(0)) {
+            ETHER_TOKEN.approve(proxyAddress, MAX_UINT);
+            ZRX_TOKEN.approve(proxyAddress, MAX_UINT);
+        }
+    }
+
+    /// @dev Market sells ETH for ERC20 tokens, performing fee abstraction if required. This does not support ERC721 tokens. This function is payable
+    ///      and will convert all incoming ETH into WETH and perform the trade on behalf of the caller.
+    ///      This function allows for a deduction of a proportion of incoming ETH sent to the feeRecipient.
+    ///      The caller is sent all tokens from the operation.
+    ///      If the purchased token amount does not meet an acceptable threshold then this function reverts.
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param signatures An array of Proof that order has been created by maker.
+    /// @param feeOrders An array of Order struct containing order specifications for fees.
+    /// @param feeSignatures An array of Proof that order has been created by maker for the fee orders.
+    /// @param feeProportion A proportion deducted off the incoming ETH and sent to feeRecipient. The maximum value for this
+    ///        is 1000, aka 10%. Supports up to 2 decimal places. I.e 0.59% is 59.
+    /// @param feeRecipient An address of the fee recipient whom receives feeProportion of ETH.
+    /// @return FillResults amounts filled and fees paid by maker and taker.
+    function marketSellEthForERC20(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint16  feeProportion,
+        address feeRecipient
+    )
+        public
+        payable
+        returns (FillResults memory totalFillResults)
+    {
+        uint256 takerEthAmount = msg.value;
+        require(
+            takerEthAmount > 0,
+            "VALUE_GREATER_THAN_ZERO"
+        );
+        // Deduct the fee from the total amount of ETH sent in
+        uint256 ethFeeAmount = payEthFee(
+            takerEthAmount,
+            feeProportion,
+            feeRecipient
+        );
+        uint256 wethSellAmount = safeSub(takerEthAmount, ethFeeAmount);
+
+        // Deposit the remaining to be used for trading
+        ETHER_TOKEN.deposit.value(wethSellAmount)();
+        // Populate the known assetData, as it is always WETH the caller can provide null bytes to save gas
+        // marketSellOrders fills the remaining
+        address makerTokenAddress = LibBytes.readAddress(orders[0].makerAssetData, 16);
+        orders[0].takerAssetData = WETH_ASSET_DATA;
+        if (makerTokenAddress == address(ZRX_TOKEN)) {
+            // If this is ZRX then we market sell from the orders, rather than a 2 step of buying ZRX fees from feeOrders
+            // then buying ZRX from orders
+            totalFillResults = marketSellEthForZRXInternal(
+                orders,
+                signatures,
+                wethSellAmount
+            );
+        } else {
+            totalFillResults = marketSellEthForERC20Internal(
+                orders,
+                signatures,
+                feeOrders,
+                feeSignatures,
+                wethSellAmount
+            );
+        }
+        // Prevent accidental WETH owned by this contract and it being spent
+        require(
+            takerEthAmount >= totalFillResults.takerAssetFilledAmount,
+            "INVALID_MSG_VALUE"
+        );
+        // Ensure no WETH is left in this contract
+        require(
+            wethSellAmount == totalFillResults.takerAssetFilledAmount,
+            "UNACCEPTABLE_THRESHOLD"
+        );
+        // Transfer all tokens to msg.sender
+        transferERC20Token(
+            makerTokenAddress,
+            msg.sender,
+            totalFillResults.makerAssetFilledAmount
+        );
+        return totalFillResults;
+    }
 
     /// @dev Buys the exact amount of assets (ERC20 and ERC721), performing fee abstraction if required.
     ///      All order assets must be of the same type. Deducts a proportional fee to fee recipient.
@@ -113,6 +206,85 @@ contract MixinMarketBuyTokens is
         return totalFillResults;
     }
 
+    /// @dev Market sells WETH for ERC20 tokens.
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param signatures An array of Proof that order has been created by maker.
+    /// @param feeOrders An array of Order struct containing order specifications for fees.
+    /// @param feeSignatures An array of Proof that order has been created by maker for the fee orders.
+    /// @param wethSellAmount The amount of WETH to sell.
+    /// @return FillResults amounts filled and fees paid by maker and taker.
+    function marketSellEthForERC20Internal(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint256 wethSellAmount
+    )
+        internal
+        returns (FillResults memory totalFillResults)
+    {
+        uint256 remainingWethSellAmount = wethSellAmount;
+        FillResults memory calculatedMarketSellResults = calculateMarketSellResults(orders, wethSellAmount);
+        if (calculatedMarketSellResults.takerFeePaid > 0) {
+            // Fees are required for these orders. Buy enough ZRX to cover the future market buy
+            FillResults memory feeTokensResults = marketBuyZrxInternal(
+                feeOrders,
+                feeSignatures,
+                calculatedMarketSellResults.takerFeePaid
+            );
+            // Ensure the token abstraction was fair if fees were proportionally too high, we fail
+            require(
+                isAcceptableThreshold(
+                    wethSellAmount,
+                    safeSub(wethSellAmount, feeTokensResults.takerAssetFilledAmount)
+                ),
+                "UNACCEPTABLE_THRESHOLD"
+            );
+            remainingWethSellAmount = safeSub(remainingWethSellAmount, feeTokensResults.takerAssetFilledAmount);
+            totalFillResults.takerFeePaid = feeTokensResults.takerFeePaid;
+            totalFillResults.takerAssetFilledAmount = feeTokensResults.takerAssetFilledAmount;
+        }
+        // Make our market sell to buy the requested tokens with the remaining balance
+        FillResults memory requestedTokensResults = EXCHANGE.marketSellOrders(
+            orders,
+            remainingWethSellAmount,
+            signatures
+        );
+        // Update our return FillResult with the market sell
+        addFillResults(totalFillResults, requestedTokensResults);
+        return totalFillResults;
+    }
+
+    /// @dev Market sells WETH for ZRX tokens.
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param signatures An array of Proof that order has been created by maker.
+    /// @param wethSellAmount The amount of WETH to sell.
+    /// @return FillResults amounts filled and fees paid by maker and taker.
+    function marketSellEthForZRXInternal(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        uint256 wethSellAmount
+    )
+        internal
+        returns (FillResults memory totalFillResults)
+    {
+        // Make our market sell to buy the requested tokens with the remaining balance
+        totalFillResults = EXCHANGE.marketSellOrders(
+            orders,
+            wethSellAmount,
+            signatures
+        );
+        // Exchange does not special case ZRX in the makerAssetFilledAmount, if fees were deducted then using this amount
+        // for future transfers is invalid.
+        uint256 zrxAmountBought = safeSub(totalFillResults.makerAssetFilledAmount, totalFillResults.takerFeePaid);
+        require(
+            isAcceptableThreshold(totalFillResults.makerAssetFilledAmount, zrxAmountBought),
+            "UNACCEPTABLE_THRESHOLD"
+        );
+        totalFillResults.makerAssetFilledAmount = zrxAmountBought;
+        return totalFillResults;
+    }
+
     /// @dev Buys an exact amount of an ERC20 token using WETH.
     /// @param orders Orders to fill. The maker asset is the ERC20 token to buy. The taker asset is WETH.
     /// @param signatures Proof that the orders were created by their respective makers.
@@ -127,8 +299,8 @@ contract MixinMarketBuyTokens is
         bytes[] memory feeSignatures,
         uint256 makerTokenFillAmount
     )
-        private
-        returns (FillResults memory totalFillResults)
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults)
     {
         // We read the maker token address to check if it is ZRX and later use it for transfer
         address makerTokenAddress = LibBytes.readAddress(orders[0].makerAssetData, 16);
@@ -189,7 +361,7 @@ contract MixinMarketBuyTokens is
             );
         }
         // Transfer all purchased tokens to msg.sender
-        transferToken(
+        transferERC20Token(
             makerTokenAddress,
             msg.sender,
             marketBuyResults.makerAssetFilledAmount
@@ -209,8 +381,8 @@ contract MixinMarketBuyTokens is
         LibOrder.Order[] memory feeOrders,
         bytes[] memory feeSignatures
     )
-        private
-        returns (FillResults memory totalFillResults)
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults)
     {
         uint256 totalZrxFeeAmount;
         uint256 ordersLength = orders.length;
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinMarketBuyZrx.sol b/packages/contracts/src/2.0.0/forwarder/MixinMarketBuyZrx.sol
index cc98cb63d..e272f8aad 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinMarketBuyZrx.sol
+++ b/packages/contracts/src/2.0.0/forwarder/MixinMarketBuyZrx.sol
@@ -19,17 +19,18 @@
 pragma solidity 0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "../protocol/Exchange/Exchange.sol";
 import "../protocol/Exchange/libs/LibFillResults.sol";
 import "../protocol/Exchange/libs/LibOrder.sol";
 import "../protocol/Exchange/libs/LibMath.sol";
-import "./MixinConstants.sol";
+import "./mixins/MConstants.sol";
+import "./mixins/MMarketBuyZrx.sol";
 
 
 contract MixinMarketBuyZrx is
     LibMath,
     LibFillResults,
-    MixinConstants
+    MConstants,
+    MMarketBuyZrx
 {
 
     /// @dev Buys zrxBuyAmount of ZRX fee tokens, taking into account the fees on buying fee tokens. This will guarantee
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinMarketSellTokens.sol b/packages/contracts/src/2.0.0/forwarder/MixinMarketSellTokens.sol
deleted file mode 100644
index f4f509846..000000000
--- a/packages/contracts/src/2.0.0/forwarder/MixinMarketSellTokens.sol
+++ /dev/null
@@ -1,197 +0,0 @@
-/*
-
-  Copyright 2018 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 0.4.24;
-pragma experimental ABIEncoderV2;
-
-import "../protocol/Exchange/libs/LibOrder.sol";
-import "../utils/LibBytes/LibBytes.sol";
-import "./MixinWethFees.sol";
-import "./MixinExpectedResults.sol";
-import "./MixinERC20.sol";
-import "./MixinConstants.sol";
-import "./MixinMarketBuyZrx.sol";
-
-
-contract MixinMarketSellTokens is
-    MixinConstants,
-    MixinWethFees,
-    MixinMarketBuyZrx,
-    MixinExpectedResults,
-    MixinERC20
-{
-    /// @dev Market sells ETH for ERC20 tokens, performing fee abstraction if required. This does not support ERC721 tokens. This function is payable
-    ///      and will convert all incoming ETH into WETH and perform the trade on behalf of the caller.
-    ///      This function allows for a deduction of a proportion of incoming ETH sent to the feeRecipient.
-    ///      The caller is sent all tokens from the operation.
-    ///      If the purchased token amount does not meet an acceptable threshold then this function reverts.
-    /// @param orders An array of Order struct containing order specifications.
-    /// @param signatures An array of Proof that order has been created by maker.
-    /// @param feeOrders An array of Order struct containing order specifications for fees.
-    /// @param feeSignatures An array of Proof that order has been created by maker for the fee orders.
-    /// @param feeProportion A proportion deducted off the incoming ETH and sent to feeRecipient. The maximum value for this
-    ///        is 1000, aka 10%. Supports up to 2 decimal places. I.e 0.59% is 59.
-    /// @param feeRecipient An address of the fee recipient whom receives feeProportion of ETH.
-    /// @return FillResults amounts filled and fees paid by maker and taker.
-    function marketSellEthForERC20(
-        LibOrder.Order[] memory orders,
-        bytes[] memory signatures,
-        LibOrder.Order[] memory feeOrders,
-        bytes[] memory feeSignatures,
-        uint16  feeProportion,
-        address feeRecipient
-    )
-        public
-        payable
-        returns (FillResults memory totalFillResults)
-    {
-        uint256 takerEthAmount = msg.value;
-        require(
-            takerEthAmount > 0,
-            "VALUE_GREATER_THAN_ZERO"
-        );
-        // Deduct the fee from the total amount of ETH sent in
-        uint256 ethFeeAmount = payEthFee(
-            takerEthAmount,
-            feeProportion,
-            feeRecipient
-        );
-        uint256 wethSellAmount = safeSub(takerEthAmount, ethFeeAmount);
-
-        // Deposit the remaining to be used for trading
-        ETHER_TOKEN.deposit.value(wethSellAmount)();
-        // Populate the known assetData, as it is always WETH the caller can provide null bytes to save gas
-        // marketSellOrders fills the remaining
-        address makerTokenAddress = LibBytes.readAddress(orders[0].makerAssetData, 16);
-        orders[0].takerAssetData = WETH_ASSET_DATA;
-        if (makerTokenAddress == address(ZRX_TOKEN)) {
-            // If this is ZRX then we market sell from the orders, rather than a 2 step of buying ZRX fees from feeOrders
-            // then buying ZRX from orders
-            totalFillResults = marketSellEthForZRXInternal(
-                orders,
-                signatures,
-                wethSellAmount
-            );
-        } else {
-            totalFillResults = marketSellEthForERC20Internal(
-                orders,
-                signatures,
-                feeOrders,
-                feeSignatures,
-                wethSellAmount
-            );
-        }
-        // Prevent accidental WETH owned by this contract and it being spent
-        require(
-            takerEthAmount >= totalFillResults.takerAssetFilledAmount,
-            "INVALID_MSG_VALUE"
-        );
-        // Ensure no WETH is left in this contract
-        require(
-            wethSellAmount == totalFillResults.takerAssetFilledAmount,
-            "UNACCEPTABLE_THRESHOLD"
-        );
-        // Transfer all tokens to msg.sender
-        transferToken(
-            makerTokenAddress,
-            msg.sender,
-            totalFillResults.makerAssetFilledAmount
-        );
-        return totalFillResults;
-    }
-
-    /// @dev Market sells WETH for ERC20 tokens.
-    /// @param orders An array of Order struct containing order specifications.
-    /// @param signatures An array of Proof that order has been created by maker.
-    /// @param feeOrders An array of Order struct containing order specifications for fees.
-    /// @param feeSignatures An array of Proof that order has been created by maker for the fee orders.
-    /// @param wethSellAmount The amount of WETH to sell.
-    /// @return FillResults amounts filled and fees paid by maker and taker.
-    function marketSellEthForERC20Internal(
-        LibOrder.Order[] memory orders,
-        bytes[] memory signatures,
-        LibOrder.Order[] memory feeOrders,
-        bytes[] memory feeSignatures,
-        uint256 wethSellAmount
-    )
-        internal
-        returns (FillResults memory totalFillResults)
-    {
-        uint256 remainingWethSellAmount = wethSellAmount;
-        FillResults memory calculatedMarketSellResults = calculateMarketSellResults(orders, wethSellAmount);
-        if (calculatedMarketSellResults.takerFeePaid > 0) {
-            // Fees are required for these orders. Buy enough ZRX to cover the future market buy
-            FillResults memory feeTokensResults = marketBuyZrxInternal(
-                feeOrders,
-                feeSignatures,
-                calculatedMarketSellResults.takerFeePaid
-            );
-            // Ensure the token abstraction was fair if fees were proportionally too high, we fail
-            require(
-                isAcceptableThreshold(
-                    wethSellAmount,
-                    safeSub(wethSellAmount, feeTokensResults.takerAssetFilledAmount)
-                ),
-                "UNACCEPTABLE_THRESHOLD"
-            );
-            remainingWethSellAmount = safeSub(remainingWethSellAmount, feeTokensResults.takerAssetFilledAmount);
-            totalFillResults.takerFeePaid = feeTokensResults.takerFeePaid;
-            totalFillResults.takerAssetFilledAmount = feeTokensResults.takerAssetFilledAmount;
-        }
-        // Make our market sell to buy the requested tokens with the remaining balance
-        FillResults memory requestedTokensResults = EXCHANGE.marketSellOrders(
-            orders,
-            remainingWethSellAmount,
-            signatures
-        );
-        // Update our return FillResult with the market sell
-        addFillResults(totalFillResults, requestedTokensResults);
-        return totalFillResults;
-    }
-
-    /// @dev Market sells WETH for ZRX tokens.
-    /// @param orders An array of Order struct containing order specifications.
-    /// @param signatures An array of Proof that order has been created by maker.
-    /// @param wethSellAmount The amount of WETH to sell.
-    /// @return FillResults amounts filled and fees paid by maker and taker.
-    function marketSellEthForZRXInternal(
-        LibOrder.Order[] memory orders,
-        bytes[] memory signatures,
-        uint256 wethSellAmount
-    )
-        internal
-        returns (FillResults memory totalFillResults)
-    {
-        // Make our market sell to buy the requested tokens with the remaining balance
-        totalFillResults = EXCHANGE.marketSellOrders(
-            orders,
-            wethSellAmount,
-            signatures
-        );
-        // Exchange does not special case ZRX in the makerAssetFilledAmount, if fees were deducted then using this amount
-        // for future transfers is invalid.
-        uint256 zrxAmountBought = safeSub(totalFillResults.makerAssetFilledAmount, totalFillResults.takerFeePaid);
-        require(
-            isAcceptableThreshold(totalFillResults.makerAssetFilledAmount, zrxAmountBought),
-            "UNACCEPTABLE_THRESHOLD"
-        );
-        totalFillResults.makerAssetFilledAmount = zrxAmountBought;
-        return totalFillResults;
-    }
-
-}
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinERC20.sol b/packages/contracts/src/2.0.0/forwarder/MixinTransfer.sol
index 23c130d69..6c49330f2 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinERC20.sol
+++ b/packages/contracts/src/2.0.0/forwarder/MixinTransfer.sol
@@ -18,12 +18,47 @@
 
 pragma solidity 0.4.24;
 
+import "../utils/LibBytes/LibBytes.sol";
+import "../tokens/ERC721Token/IERC721Token.sol";
+import "./mixins/MTransfer.sol";
 
-contract MixinERC20 {
+
+contract MixinTransfer is
+    MTransfer
+{
+
+    using LibBytes for bytes;
 
     bytes4 constant internal ERC20_TRANSFER_SELECTOR = bytes4(keccak256("transfer(address,uint256)"));
+    bytes4 constant internal ERC721_RECEIVED = bytes4(keccak256("onERC721Received(address,uint256,bytes)"));
+    bytes4 constant internal ERC721_RECEIVED_OPERATOR = bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"));
 
-    function transferToken(
+    function onERC721Received(
+        address,
+        uint256,
+        bytes memory
+    )
+        public
+        pure
+        returns(bytes4)
+    {
+        return ERC721_RECEIVED;
+    }
+
+    function onERC721Received(
+        address,
+        address,
+        uint256,
+        bytes memory
+    )
+        public
+        pure
+        returns(bytes4)
+    {
+        return ERC721_RECEIVED_OPERATOR;
+    }
+
+    function transferERC20Token(
         address token,
         address to,
         uint256 amount
@@ -64,4 +99,22 @@ contract MixinERC20 {
             "TRANSFER_FAILED"
         );
     }
+
+    function transferERC721Token(
+        bytes memory assetData,
+        address to
+    )
+        internal
+    {
+        // Decode asset data.
+        address token = assetData.readAddress(16);
+        uint256 tokenId = assetData.readUint256(36);
+        bytes memory receiverData = assetData.readBytesWithLength(100);
+        IERC721Token(token).safeTransferFrom(
+            address(this),
+            to,
+            tokenId,
+            receiverData
+        );
+    }
 }
diff --git a/packages/contracts/src/2.0.0/forwarder/interfaces/IExpectedResults.sol b/packages/contracts/src/2.0.0/forwarder/interfaces/IExpectedResults.sol
new file mode 100644
index 000000000..89187b750
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/interfaces/IExpectedResults.sol
@@ -0,0 +1,66 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/libs/LibFillResults.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+
+
+contract IExpectedResults {
+
+    /// @dev Calculates a total FillResults for buying makerAssetFillAmount over all orders.
+    ///      Including the fees required to be paid. 
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param makerAssetFillAmount A number representing the amount of this order to fill.
+    /// @return totalFillResults Amounts filled and fees paid by maker and taker.
+    function calculateMarketBuyResults(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount
+    )
+        public
+        view
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Calculates a FillResults total for selling takerAssetFillAmount over all orders. 
+    ///      Including the fees required to be paid. 
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param takerAssetFillAmount A number representing the amount of this order to fill.
+    /// @return totalFillResults Amounts filled and fees paid by maker and taker.
+    function calculateMarketSellResults(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount
+    )
+        public
+        view
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Calculates fill results for buyFeeTokens. This handles fees on buying ZRX
+    ///      so the end result is the expected amount of ZRX (not less after fees).
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param zrxFillAmount A number representing the amount zrx to buy
+    /// @return totalFillResults Expected fill result amounts from buying fees
+    function calculateMarketBuyZrxResults(
+        LibOrder.Order[] memory orders,
+        uint256 zrxFillAmount
+    )
+        public
+        view
+        returns (LibFillResults.FillResults memory totalFillResults);
+}
diff --git a/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarder.sol b/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarder.sol
new file mode 100644
index 000000000..745dd29a9
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarder.sol
@@ -0,0 +1,30 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./IForwarderCore.sol";
+import "./IExpectedResults.sol";
+
+
+// solhint-disable no-empty-blocks
+contract IForwarder is
+    IForwarderCore,
+    IExpectedResults
+{}
diff --git a/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarderCore.sol b/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarderCore.sol
new file mode 100644
index 000000000..7ac2a8af3
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarderCore.sol
@@ -0,0 +1,79 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/libs/LibOrder.sol";
+import "../../protocol/Exchange/libs/LibFillResults.sol";
+
+
+contract IForwarderCore {
+
+    /// @dev Market sells ETH for ERC20 tokens, performing fee abstraction if required. This does not support ERC721 tokens. This function is payable
+    ///      and will convert all incoming ETH into WETH and perform the trade on behalf of the caller.
+    ///      This function allows for a deduction of a proportion of incoming ETH sent to the feeRecipient.
+    ///      The caller is sent all tokens from the operation.
+    ///      If the purchased token amount does not meet an acceptable threshold then this function reverts.
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param signatures An array of Proof that order has been created by maker.
+    /// @param feeOrders An array of Order struct containing order specifications for fees.
+    /// @param feeSignatures An array of Proof that order has been created by maker for the fee orders.
+    /// @param feeProportion A proportion deducted off the incoming ETH and sent to feeRecipient. The maximum value for this
+    ///        is 1000, aka 10%. Supports up to 2 decimal places. I.e 0.59% is 59.
+    /// @param feeRecipient An address of the fee recipient whom receives feeProportion of ETH.
+    /// @return FillResults amounts filled and fees paid by maker and taker.
+    function marketSellEthForERC20(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint16  feeProportion,
+        address feeRecipient
+    )
+        public
+        payable
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Buys the exact amount of assets (ERC20 and ERC721), performing fee abstraction if required.
+    ///      All order assets must be of the same type. Deducts a proportional fee to fee recipient.
+    ///      This function is payable and will convert all incoming ETH into WETH and perform the trade on behalf of the caller.
+    ///      The caller is sent all assets from the fill of orders. This function will revert unless the requested amount of assets are purchased.
+    ///      Any excess ETH sent will be returned to the caller
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param signatures An array of Proof that order has been created by maker.
+    /// @param feeOrders An array of Order struct containing order specifications for fees.
+    /// @param makerTokenFillAmount The amount of maker asset to buy.
+    /// @param feeSignatures An array of Proof that order has been created by maker for the fee orders.
+    /// @param feeProportion A proportion deducted off the ETH spent and sent to feeRecipient. The maximum value for this
+    ///        is 1000, aka 10%. Supports up to 2 decimal places. I.e 0.59% is 59.
+    /// @param feeRecipient An address of the fee recipient whom receives feeProportion of ETH.
+    /// @return FillResults amounts filled and fees paid by maker and taker.
+    function marketBuyTokensWithEth(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint256 makerTokenFillAmount,
+        uint16  feeProportion,
+        address feeRecipient
+    )
+        public
+        payable
+        returns (LibFillResults.FillResults memory totalFillResults);
+}
diff --git a/packages/contracts/src/2.0.0/forwarder/mixins/MConstants.sol b/packages/contracts/src/2.0.0/forwarder/mixins/MConstants.sol
new file mode 100644
index 000000000..348bf169e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/mixins/MConstants.sol
@@ -0,0 +1,35 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+
+import "../../protocol/Exchange/interfaces/IExchange.sol";
+import "../../tokens/EtherToken/IEtherToken.sol";
+import "../../tokens/ERC20Token/IERC20Token.sol";
+
+
+contract MConstants {
+
+    // solhint-disable var-name-mixedcase
+    IExchange internal EXCHANGE;
+    IEtherToken internal ETHER_TOKEN;
+    IERC20Token internal ZRX_TOKEN;
+    bytes internal ZRX_ASSET_DATA;
+    bytes internal WETH_ASSET_DATA;
+    // solhint-enable var-name-mixedcase
+}
diff --git a/packages/contracts/src/2.0.0/forwarder/mixins/MExpectedResults.sol b/packages/contracts/src/2.0.0/forwarder/mixins/MExpectedResults.sol
new file mode 100644
index 000000000..cf03bb32e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/mixins/MExpectedResults.sol
@@ -0,0 +1,42 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/libs/LibFillResults.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+import "../interfaces/IExpectedResults.sol";
+
+
+contract MExpectedResults is
+    IExpectedResults
+{
+
+    /// @dev Simulates the 0x Exchange fillOrder validation and calculations, without performing any state changes.
+    /// @param order An Order struct containing order specifications.
+    /// @param takerAssetFillAmount A number representing the amount of this order to fill.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function calculateFillResults(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount
+    )
+        internal
+        view
+        returns (LibFillResults.FillResults memory fillResults);
+}
diff --git a/packages/contracts/src/2.0.0/forwarder/mixins/MFees.sol b/packages/contracts/src/2.0.0/forwarder/mixins/MFees.sol
new file mode 100644
index 000000000..f332637ea
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/mixins/MFees.sol
@@ -0,0 +1,63 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+
+
+contract MFees {
+
+    /// @dev Pays the feeRecipient feeProportion of the total takerEthAmount, denominated in ETH
+    /// @param takerEthAmount The total amount that was transacted in WETH, fees are calculated from this value.
+    /// @param feeProportion The proportion of fees
+    /// @param feeRecipient The recipient of the fees
+    /// @return ethFeeAmount Amount of ETH paid to feeRecipient as fee.
+    function payEthFee(
+        uint256 takerEthAmount,
+        uint16 feeProportion,
+        address feeRecipient
+    )
+        internal
+        returns (uint256 ethFeeAmount);
+
+    /// @dev Withdraws the remaining WETH, deduct and pay fees from this amount based on the takerTokenAmount to the feeRecipient.
+    ///      If a user overpaid ETH initially, the fees are calculated from the amount traded and deducted from withdrawAmount.
+    ///      Any remaining ETH is sent back to the user.
+    /// @param ethWithdrawAmount The amount to withdraw from the WETH contract.
+    /// @param wethAmountSold The total amount that was transacted in WETH, fees are calculated from this value.
+    /// @param feeProportion The proportion of fees
+    /// @param feeRecipient The recipient of the fees
+    function withdrawPayAndDeductEthFee(
+        uint256 ethWithdrawAmount,
+        uint256 wethAmountSold,
+        uint16 feeProportion,
+        address feeRecipient
+    )
+        internal;
+
+    /// @dev Checks whether the amount of tokens sold against the amount of tokens requested
+    ///      is within a certain threshold. This ensures the caller gets a fair deal when
+    ///      performing any token fee abstraction. Threshold is 95%. If fee abstraction costs more than
+    ///      5% of the total transaction, we return false.
+    /// @param requestedSellAmount The amount the user requested, or sent in to a payable function
+    /// @param tokenAmountSold The amount of the token that was sold after fee abstraction
+    /// @return bool of whether this is within an acceptable threshold
+    function isAcceptableThreshold(uint256 requestedSellAmount, uint256 tokenAmountSold)
+        internal
+        pure
+        returns (bool);
+}
diff --git a/packages/contracts/src/2.0.0/forwarder/mixins/MForwarderCore.sol b/packages/contracts/src/2.0.0/forwarder/mixins/MForwarderCore.sol
new file mode 100644
index 000000000..4a54e76b1
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/mixins/MForwarderCore.sol
@@ -0,0 +1,92 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/libs/LibOrder.sol";
+import "../../protocol/Exchange/libs/LibFillResults.sol";
+import "../interfaces/IForwarderCore.sol";
+
+
+contract MForwarderCore is
+    IForwarderCore
+{
+
+    /// @dev Market sells WETH for ERC20 tokens.
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param signatures An array of Proof that order has been created by maker.
+    /// @param feeOrders An array of Order struct containing order specifications for fees.
+    /// @param feeSignatures An array of Proof that order has been created by maker for the fee orders.
+    /// @param wethSellAmount The amount of WETH to sell.
+    /// @return FillResults amounts filled and fees paid by maker and taker.
+    function marketSellEthForERC20Internal(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint256 wethSellAmount
+    )
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Market sells WETH for ZRX tokens.
+    /// @param orders An array of Order struct containing order specifications.
+    /// @param signatures An array of Proof that order has been created by maker.
+    /// @param wethSellAmount The amount of WETH to sell.
+    /// @return FillResults amounts filled and fees paid by maker and taker.
+    function marketSellEthForZRXInternal(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        uint256 wethSellAmount
+    )
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Buys an exact amount of an ERC20 token using WETH.
+    /// @param orders Orders to fill. The maker asset is the ERC20 token to buy. The taker asset is WETH.
+    /// @param signatures Proof that the orders were created by their respective makers.
+    /// @param feeOrders to fill. The maker asset is ZRX and the taker asset is WETH.
+    /// @param feeSignatures Proof that the feeOrders were created by their respective makers.
+    /// @param makerTokenFillAmount Amount of the ERC20 token to buy.
+    /// @return totalFillResults Aggregated fill results of buying the ERC20 and ZRX tokens.
+    function marketBuyERC20TokensInternal(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint256 makerTokenFillAmount
+    )
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Buys an all of the ERC721 tokens in the orders.
+    /// @param orders Orders to fill. The maker asset is the ERC721 token to buy. The taker asset is WETH.
+    /// @param signatures Proof that the orders were created by their respective makers.
+    /// @param feeOrders to fill. The maker asset is ZRX and the taker asset is WETH.
+    /// @param feeSignatures Proof that the feeOrders were created by their respective makers.
+    /// @return totalFillResults Aggregated fill results of buying the ERC721 tokens and ZRX tokens.
+    function batchBuyERC721TokensInternal(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures
+    )
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults);
+}
diff --git a/packages/contracts/src/2.0.0/forwarder/mixins/MMarketBuyZrx.sol b/packages/contracts/src/2.0.0/forwarder/mixins/MMarketBuyZrx.sol
new file mode 100644
index 000000000..3501ef001
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/mixins/MMarketBuyZrx.sol
@@ -0,0 +1,42 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+
+import "../../protocol/Exchange/libs/LibFillResults.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+
+
+contract MMarketBuyZrx {
+
+    /// @dev Buys zrxBuyAmount of ZRX fee tokens, taking into account the fees on buying fee tokens. This will guarantee
+    ///      At least zrxBuyAmount of ZRX fee tokens are purchased (sometimes slightly over due to rounding issues).
+    ///      It is possible that a request to buy 200 ZRX fee tokens will require purchasing 202 ZRX tokens
+    ///      As 2 ZRX is required to purchase the 200 ZRX fee tokens. This guarantees at least 200 ZRX for future purchases.
+    /// @param orders An array of Order struct containing order specifications for fees.
+    /// @param signatures An array of Proof that order has been created by maker for the fee orders.
+    /// @param zrxBuyAmount The number of requested ZRX fee tokens.
+    /// @return totalFillResults Amounts filled and fees paid by maker and taker. makerTokenAmount is the zrx amount deducted of fees
+    function marketBuyZrxInternal(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        uint256 zrxBuyAmount
+    )
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults);
+}
diff --git a/packages/contracts/src/2.0.0/forwarder/mixins/MTransfer.sol b/packages/contracts/src/2.0.0/forwarder/mixins/MTransfer.sol
new file mode 100644
index 000000000..418a6288b
--- /dev/null
+++ b/packages/contracts/src/2.0.0/forwarder/mixins/MTransfer.sol
@@ -0,0 +1,46 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+
+
+contract MTransfer {
+
+    function onERC721Received(address, uint256, bytes memory)
+        public
+        pure
+        returns(bytes4);
+
+    function onERC721Received(address, address, uint256, bytes memory)
+        public
+        pure
+        returns(bytes4);
+    
+    function transferERC20Token(
+        address token,
+        address to,
+        uint256 amount
+    )
+        internal;
+
+    function transferERC721Token(
+        bytes memory assetData,
+        address to
+    )
+        internal;
+}
diff --git a/packages/contracts/src/2.0.0/tokens/EtherToken/IEtherToken.sol b/packages/contracts/src/2.0.0/tokens/EtherToken/IEtherToken.sol
new file mode 100644
index 000000000..9e2e68766
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/EtherToken/IEtherToken.sol
@@ -0,0 +1,33 @@
+/*
+
+  Copyright 2018 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 0.4.24;
+
+import "../ERC20Token/IERC20Token.sol";
+
+
+contract IEtherToken is
+    IERC20Token
+{
+    function deposit()
+        public
+        payable;
+    
+    function withdraw(uint256 amount)
+        public;
+}
diff --git a/packages/contracts/src/2.0.0/tokens/WETH9/WETH9.sol b/packages/contracts/src/2.0.0/tokens/EtherToken/WETH9.sol
index 1fdb04de5..1fdb04de5 100644
--- a/packages/contracts/src/2.0.0/tokens/WETH9/WETH9.sol
+++ b/packages/contracts/src/2.0.0/tokens/EtherToken/WETH9.sol