Merge branch 'v2-prototype' into feature/combinatorial-testing

* v2-prototype: (68 commits)
  Stop exporting ArtifactWriter
  Fix no-unused-variable tslint rule to include parameters and fix issues
  Fix linter exclude rule
  Validate all signature types rather then only ECSignatures
  Store the instantiated OrderValidationUtils
  Remove global hooks from tests and deploy contracts from within the specific tests
  Add EmitStatement to ASTVisitor
  Fix tslint issues
  Add back artifacts file
  Fix a bug in SolCompilerArtifacts adapter config overriding
  Move OrderValidationUtils (+ tests) and ExchangeTransferSimulator to order-utils
  export parseECSignature method
  Export ArtifactWriter from migrations package
  Remove unused artifact file
  Pass in generated contract wrapper to orderValidationUtils at instantiation
  Refactor orderValidationUtils to use the generated contract wrapper instead of the higher-level one
  Refactor ExchangeTransferSimulator public interface to accet an AbstractBalanceAndProxyAllowanceLazyStore so that this module could be re-used in different contexts.
  Increase timeout for contract migrations
  Remove some copy-paste code
  Await transactions in migrations
  ...

30 files changed, 724 insertions, 141 deletions

diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
index 2c321e134..dd25bf41a 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
@@ -34,34 +34,30 @@ contract ERC20Proxy is
     uint8 constant PROXY_ID = 1;
 
     /// @dev Internal version of `transferFrom`.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFromInternal(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
     )
         internal
     {
-        // Data must be intended for this proxy.
-        uint256 length = assetMetadata.length;
+        // Decode asset data.
+        (
+            uint8 proxyId,
+            address token
+        ) = decodeERC20AssetData(assetData);
 
+        // Data must be intended for this proxy.
         require(
-            length == 21,
-            LENGTH_21_REQUIRED
-        );
-        // TODO: Is this too inflexible in the future?
-        require(
-            uint8(assetMetadata[length - 1]) == PROXY_ID,
+            proxyId == PROXY_ID,
             ASSET_PROXY_ID_MISMATCH
         );
 
-        // Decode metadata.
-        address token = readAddress(assetMetadata, 0);
-
         // Transfer tokens.
         bool success = IERC20Token(token).transferFrom(from, to, amount);
         require(
@@ -79,4 +75,30 @@ contract ERC20Proxy is
     {
         return PROXY_ID;
     }
+
+    /// @dev Decodes ERC20 Asset data.
+    /// @param assetData Encoded byte array.
+    /// @return proxyId Intended ERC20 proxy id.
+    /// @return token ERC20 token address.
+    function decodeERC20AssetData(bytes memory assetData)
+        internal
+        pure
+        returns (
+            uint8 proxyId,
+            address token
+        )
+    {
+        // Validate encoded data length
+        uint256 length = assetData.length;
+        require(
+            length == 21,
+            LENGTH_21_REQUIRED
+        );
+
+        // Decode data
+        token = readAddress(assetData, 0);
+        proxyId = uint8(assetData[length - 1]);
+
+        return (proxyId, token);
+    }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
index 07e01c774..25136133d 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
@@ -34,29 +34,30 @@ contract ERC721Proxy is
     uint8 constant PROXY_ID = 2;
 
     /// @dev Internal version of `transferFrom`.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFromInternal(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
     )
         internal
     {
-        // Data must be intended for this proxy.
-        uint256 length = assetMetadata.length;
+        // Decode asset data.
+        (
+            uint8 proxyId,
+            address token,
+            uint256 tokenId,
+            bytes memory receiverData
+        ) = decodeERC721AssetData(assetData);
 
-        require(
-            length == 53,
-            LENGTH_53_REQUIRED
-        );
 
-        // TODO: Is this too inflexible in the future?
+        // Data must be intended for this proxy.
         require(
-            uint8(assetMetadata[length - 1]) == PROXY_ID,
+            proxyId == PROXY_ID,
             ASSET_PROXY_ID_MISMATCH
         );
 
@@ -66,15 +67,13 @@ contract ERC721Proxy is
             INVALID_AMOUNT
         );
 
-        // Decode metadata
-        address token = readAddress(assetMetadata, 0);
-        uint256 tokenId = readUint256(assetMetadata, 20);
-
-        // Transfer token.
-        // Either succeeds or throws.
-        // @TODO: Call safeTransferFrom if there is additional
-        //        data stored in `assetMetadata`.
-        ERC721Token(token).transferFrom(from, to, tokenId);
+        // Transfer token. Saves gas by calling safeTransferFrom only
+        // when there is receiverData present. Either succeeds or throws.
+        if(receiverData.length > 0) {
+            ERC721Token(token).safeTransferFrom(from, to, tokenId, receiverData);
+        } else {
+            ERC721Token(token).transferFrom(from, to, tokenId);
+        }
     }
 
     /// @dev Gets the proxy id associated with the proxy address.
@@ -86,4 +85,44 @@ contract ERC721Proxy is
     {
         return PROXY_ID;
     }
+
+    /// @dev Decodes ERC721 Asset data.
+    /// @param assetData Encoded byte array.
+    /// @return proxyId Intended ERC721 proxy id.
+    /// @return token ERC721 token address.
+    /// @return tokenId ERC721 token id.
+    /// @return receiverData Additional data with no specific format, which
+    ///                      is passed to the receiving contract's onERC721Received.
+    function decodeERC721AssetData(bytes memory assetData)
+        internal
+        pure
+        returns (
+            uint8 proxyId,
+            address token,
+            uint256 tokenId,
+            bytes memory receiverData
+        )
+    {
+        // Validate encoded data length
+        uint256 length = assetData.length;
+        require(
+            length >= 53,
+            LENGTH_AT_LEAST_53_REQUIRED
+        );
+
+        // Decode asset data.
+        token = readAddress(assetData, 0);
+        tokenId = readUint256(assetData, 20);
+        if (length > 53) {
+            receiverData = readBytes(assetData, 52);
+        }
+        proxyId = uint8(assetData[length - 1]);
+
+        return (
+            proxyId,
+            token,
+            tokenId,
+            receiverData
+        );
+    }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
index 5fa33cbef..9032658e7 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
@@ -28,12 +28,12 @@ contract MixinAssetProxy is
 {
 
     /// @dev Transfers assets. Either succeeds or throws.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFrom(
-        bytes assetMetadata,
+        bytes assetData,
         address from,
         address to,
         uint256 amount
@@ -42,7 +42,7 @@ contract MixinAssetProxy is
         onlyAuthorized
     {
         transferFromInternal(
-            assetMetadata,
+            assetData,
             from,
             to,
             amount
@@ -50,12 +50,12 @@ contract MixinAssetProxy is
     }
 
     /// @dev Makes multiple transfers of assets. Either succeeds or throws.
-    /// @param assetMetadata Array of byte arrays encoded for the respective asset proxy.
+    /// @param assetData Array of byte arrays encoded for the respective asset proxy.
     /// @param from Array of addresses to transfer assets from.
     /// @param to Array of addresses to transfer assets to.
     /// @param amounts Array of amounts of assets to transfer.
     function batchTransferFrom(
-        bytes[] memory assetMetadata,
+        bytes[] memory assetData,
         address[] memory from,
         address[] memory to,
         uint256[] memory amounts
@@ -63,9 +63,9 @@ contract MixinAssetProxy is
         public
         onlyAuthorized
     {
-        for (uint256 i = 0; i < assetMetadata.length; i++) {
+        for (uint256 i = 0; i < assetData.length; i++) {
             transferFromInternal(
-                assetMetadata[i],
+                assetData[i],
                 from[i],
                 to[i],
                 amounts[i]
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol
index 7e1848889..22f43b12f 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol
@@ -26,12 +26,12 @@ contract IAssetProxy is
 {
 
     /// @dev Transfers assets. Either succeeds or throws.
-    /// @param assetMetadata Byte array encoded for the respective asset proxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFrom(
-        bytes assetMetadata,
+        bytes assetData,
         address from,
         address to,
         uint256 amount
@@ -39,12 +39,12 @@ contract IAssetProxy is
         external;
     
     /// @dev Makes multiple transfers of assets. Either succeeds or throws.
-    /// @param assetMetadata Array of byte arrays encoded for the respective asset proxy.
+    /// @param assetData Array of byte arrays encoded for the respective asset proxy.
     /// @param from Array of addresses to transfer assets from.
     /// @param to Array of addresses to transfer assets to.
     /// @param amounts Array of amounts of assets to transfer.
     function batchTransferFrom(
-        bytes[] memory assetMetadata,
+        bytes[] memory assetData,
         address[] memory from,
         address[] memory to,
         uint256[] memory amounts
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
index e0c7fc796..80180a0d9 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
@@ -29,9 +29,9 @@ contract LibAssetProxyErrors {
     /// AssetProxy errors ///
     string constant ASSET_PROXY_ID_MISMATCH = "ASSET_PROXY_ID_MISMATCH";          // Proxy id in metadata does not match this proxy id.
     string constant INVALID_AMOUNT = "INVALID_AMOUNT";                            // Transfer amount must equal 1.
-    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                          // Transfer failed. 
+    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                          // Transfer failed.
 
     /// Length validation errors ///
     string constant LENGTH_21_REQUIRED = "LENGTH_21_REQUIRED";                    // Byte array must have a length of 21.
-    string constant LENGTH_53_REQUIRED = "LENGTH_53_REQUIRED";                    // Byte array must have a length of 53.
+    string constant LENGTH_AT_LEAST_53_REQUIRED = "LENGTH_AT_LEAST_53_REQUIRED";  // Byte array must have a length of at least 53.
 }
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAssetProxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAssetProxy.sol
index de9d65a53..a52cb56f9 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAssetProxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAssetProxy.sol
@@ -26,12 +26,12 @@ contract MAssetProxy is
 {
 
     /// @dev Internal version of `transferFrom`.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFromInternal(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol b/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol
index b7b308069..51f99bafa 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol
@@ -40,11 +40,11 @@ contract Exchange is
     string constant public VERSION = "2.0.1-alpha";
 
     // Mixins are instantiated in the order they are inherited
-    constructor (bytes memory _zrxProxyData)
+    constructor (bytes memory _zrxAssetData)
         public
         MixinExchangeCore()
         MixinMatchOrders()
-        MixinSettlement(_zrxProxyData)
+        MixinSettlement(_zrxAssetData)
         MixinSignatureValidator()
         MixinTransactions()
         MixinAssetProxyDispatcher()
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
index 8f9342739..e77d81c06 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -80,12 +80,12 @@ contract MixinAssetProxyDispatcher is
     }
 
     /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
-    /// @param assetMetadata Byte array encoded for the respective asset proxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
     /// @param from Address to transfer token from.
     /// @param to Address to transfer token to.
     /// @param amount Amount of token to transfer.
     function dispatchTransferFrom(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
@@ -96,16 +96,16 @@ contract MixinAssetProxyDispatcher is
         if (amount > 0) {
 
             // Lookup asset proxy
-            uint256 length = assetMetadata.length;
+            uint256 length = assetData.length;
             require(
                 length > 0,
                 LENGTH_GREATER_THAN_0_REQUIRED
             );
-            uint8 assetProxyId = uint8(assetMetadata[length - 1]);
+            uint8 assetProxyId = uint8(assetData[length - 1]);
             IAssetProxy assetProxy = assetProxies[assetProxyId];
 
             // transferFrom will either succeed or throw.
-            assetProxy.transferFrom(assetMetadata, from, to, amount);
+            assetProxy.transferFrom(assetData, from, to, amount);
         }
     }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
index 646d3ed58..83e9dfdf4 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
@@ -40,7 +40,7 @@ contract MixinSettlement is
     bytes internal ZRX_PROXY_DATA;
 
     /// @dev Gets the ZRX metadata used for fee transfers.
-    function zrxProxyData()
+    function zrxAssetData()
         external
         view
         returns (bytes memory)
@@ -48,13 +48,13 @@ contract MixinSettlement is
         return ZRX_PROXY_DATA;
     }
 
-    /// TODO: _zrxProxyData should be a constant in production.
+    /// TODO: _zrxAssetData should be a constant in production.
     /// @dev Constructor sets the metadata that will be used for paying ZRX fees.
-    /// @param _zrxProxyData Byte array containing ERC20 proxy id concatenated with address of ZRX.
-    constructor (bytes memory _zrxProxyData)
+    /// @param _zrxAssetData Byte array containing ERC20 proxy id concatenated with address of ZRX.
+    constructor (bytes memory _zrxAssetData)
         public
     {
-        ZRX_PROXY_DATA = _zrxProxyData;
+        ZRX_PROXY_DATA = _zrxAssetData;
     }
 
     /// @dev Settles an order by transferring assets between counterparties.
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
index 0ad0710ce..e09f80bcc 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
@@ -40,7 +40,8 @@ contract MixinWrapperFunctions is
     function fillOrKillOrder(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (FillResults memory fillResults)
     {
@@ -65,7 +66,8 @@ contract MixinWrapperFunctions is
     function fillOrderNoThrow(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (FillResults memory fillResults)
     {
@@ -91,12 +93,12 @@ contract MixinWrapperFunctions is
         // |          | 0x0E0  |         |   8.  takerFeeAmount                        |
         // |          | 0x100  |         |   9.  expirationTimeSeconds                 |
         // |          | 0x120  |         |   10. salt                                  |
-        // |          | 0x140  |         |   11. Offset to makerAssetProxyMetadata (*) |
-        // |          | 0x160  |         |   12. Offset to takerAssetProxyMetadata (*) |
-        // |          | 0x180  | 32      | makerAssetProxyMetadata Length              |
-        // |          | 0x1A0  | **      | makerAssetProxyMetadata Contents            |
-        // |          | 0x1C0  | 32      | takerAssetProxyMetadata Length              |
-        // |          | 0x1E0  | **      | takerAssetProxyMetadata Contents            |
+        // |          | 0x140  |         |   11. Offset to makerAssetData (*)          |
+        // |          | 0x160  |         |   12. Offset to takerAssetData (*)          |
+        // |          | 0x180  | 32      | makerAssetData Length                       |
+        // |          | 0x1A0  | **      | makerAssetData Contents                     |
+        // |          | 0x1C0  | 32      | takerAssetData Length                       |
+        // |          | 0x1E0  | **      | takerAssetData Contents                     |
         // |          | 0x200  | 32      | signature Length                            |
         // |          | 0x220  | **      | signature Contents                          |
 
@@ -163,43 +165,43 @@ contract MixinWrapperFunctions is
             mstore(add(dataAreaEnd, 0xE0), mload(add(sourceOffset, 0xE0)))      // takerFeeAmount
             mstore(add(dataAreaEnd, 0x100), mload(add(sourceOffset, 0x100)))    // expirationTimeSeconds
             mstore(add(dataAreaEnd, 0x120), mload(add(sourceOffset, 0x120)))    // salt
-            mstore(add(dataAreaEnd, 0x140), mload(add(sourceOffset, 0x140)))    // Offset to makerAssetProxyMetadata
-            mstore(add(dataAreaEnd, 0x160), mload(add(sourceOffset, 0x160)))    // Offset to takerAssetProxyMetadata
+            mstore(add(dataAreaEnd, 0x140), mload(add(sourceOffset, 0x140)))    // Offset to makerAssetData
+            mstore(add(dataAreaEnd, 0x160), mload(add(sourceOffset, 0x160)))    // Offset to takerAssetData
             dataAreaEnd := add(dataAreaEnd, 0x180)
             sourceOffset := add(sourceOffset, 0x180)
 
-            // Write offset to <order.makerAssetProxyMetadata>
+            // Write offset to <order.makerAssetData>
             mstore(add(dataAreaStart, mul(10, 0x20)), sub(dataAreaEnd, dataAreaStart))
 
-            // Calculate length of <order.makerAssetProxyMetadata>
+            // Calculate length of <order.makerAssetData>
             arrayLenBytes := mload(sourceOffset)
             sourceOffset := add(sourceOffset, 0x20)
             arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
 
-            // Write length of <order.makerAssetProxyMetadata>
+            // Write length of <order.makerAssetData>
             mstore(dataAreaEnd, arrayLenBytes)
             dataAreaEnd := add(dataAreaEnd, 0x20)
 
-            // Write contents of <order.makerAssetProxyMetadata>
+            // Write contents of <order.makerAssetData>
             for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
                 mstore(dataAreaEnd, mload(sourceOffset))
                 dataAreaEnd := add(dataAreaEnd, 0x20)
                 sourceOffset := add(sourceOffset, 0x20)
             }
 
-            // Write offset to <order.takerAssetProxyMetadata>
+            // Write offset to <order.takerAssetData>
             mstore(add(dataAreaStart, mul(11, 0x20)), sub(dataAreaEnd, dataAreaStart))
 
-            // Calculate length of <order.takerAssetProxyMetadata>
+            // Calculate length of <order.takerAssetData>
             arrayLenBytes := mload(sourceOffset)
             sourceOffset := add(sourceOffset, 0x20)
             arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
 
-            // Write length of <order.takerAssetProxyMetadata>
+            // Write length of <order.takerAssetData>
             mstore(dataAreaEnd, arrayLenBytes)
             dataAreaEnd := add(dataAreaEnd, 0x20)
 
-            // Write contents of  <order.takerAssetProxyMetadata>
+            // Write contents of  <order.takerAssetData>
             for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
                 mstore(dataAreaEnd, mload(sourceOffset))
                 dataAreaEnd := add(dataAreaEnd, 0x20)
@@ -264,7 +266,8 @@ contract MixinWrapperFunctions is
     function batchFillOrders(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
     {
         for (uint256 i = 0; i < orders.length; i++) {
@@ -283,7 +286,8 @@ contract MixinWrapperFunctions is
     function batchFillOrKillOrders(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
     {
         for (uint256 i = 0; i < orders.length; i++) {
@@ -303,7 +307,8 @@ contract MixinWrapperFunctions is
     function batchFillOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
     {
         for (uint256 i = 0; i < orders.length; i++) {
@@ -323,7 +328,8 @@ contract MixinWrapperFunctions is
     function marketSellOrders(
         LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (FillResults memory totalFillResults)
     {
@@ -366,7 +372,8 @@ contract MixinWrapperFunctions is
     function marketSellOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (FillResults memory totalFillResults)
     {
@@ -408,7 +415,8 @@ contract MixinWrapperFunctions is
     function marketBuyOrders(
         LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (FillResults memory totalFillResults)
     {
@@ -459,7 +467,8 @@ contract MixinWrapperFunctions is
     function marketBuyOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (FillResults memory totalFillResults)
     {
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
index 3ce5ef157..2c331dc34 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
@@ -28,7 +28,8 @@ contract IAssetProxyDispatcher {
     function registerAssetProxy(
         uint8 assetProxyId,
         address newAssetProxy,
-        address oldAssetProxy)
+        address oldAssetProxy
+    )
         external;
 
     /// @dev Gets an asset proxy.
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol
index d973bf001..2f9a5bc7c 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol
@@ -28,6 +28,7 @@ contract ITransactions {
         uint256 salt,
         address signer,
         bytes data,
-        bytes signature)
+        bytes signature
+    )
         external;
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol
index 8682b394a..acd4f359c 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol
@@ -33,7 +33,8 @@ contract IWrapperFunctions is
     function fillOrKillOrder(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (LibFillResults.FillResults memory fillResults);
 
@@ -46,7 +47,8 @@ contract IWrapperFunctions is
     function fillOrderNoThrow(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (LibFillResults.FillResults memory fillResults);
 
@@ -57,7 +59,8 @@ contract IWrapperFunctions is
     function batchFillOrders(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public;
 
     /// @dev Synchronously executes multiple calls of fillOrKill.
@@ -67,7 +70,8 @@ contract IWrapperFunctions is
     function batchFillOrKillOrders(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public;
 
     /// @dev Fills an order with specified parameters and ECDSA signature.
@@ -78,7 +82,8 @@ contract IWrapperFunctions is
     function batchFillOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public;
 
     /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
@@ -89,7 +94,8 @@ contract IWrapperFunctions is
     function marketSellOrders(
         LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (LibFillResults.FillResults memory totalFillResults);
 
@@ -102,7 +108,8 @@ contract IWrapperFunctions is
     function marketSellOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (LibFillResults.FillResults memory totalFillResults);
 
@@ -114,7 +121,8 @@ contract IWrapperFunctions is
     function marketBuyOrders(
         LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (LibFillResults.FillResults memory totalFillResults);
 
@@ -127,7 +135,8 @@ contract IWrapperFunctions is
     function marketBuyOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (LibFillResults.FillResults memory totalFillResults);
 
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
index 87c5f6361..82eafb529 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
@@ -33,12 +33,12 @@ contract MAssetProxyDispatcher is
     );
 
     /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
-    /// @param assetMetadata Byte array encoded for the respective asset proxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
     /// @param from Address to transfer token from.
     /// @param to Address to transfer token to.
     /// @param amount Amount of token to transfer.
     function dispatchTransferFrom(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
diff --git a/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol b/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol
index 0c7b18c0c..b2fe2df06 100644
--- a/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol
+++ b/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol
@@ -31,7 +31,8 @@ contract DummyERC20Token is Mintable, Ownable {
         string _name,
         string _symbol,
         uint256 _decimals,
-        uint256 _totalSupply)
+        uint256 _totalSupply
+    )
         public
     {
         name = _name;
diff --git a/packages/contracts/src/contracts/current/test/DummyERC721Receiver/DummyERC721Receiver.sol b/packages/contracts/src/contracts/current/test/DummyERC721Receiver/DummyERC721Receiver.sol
new file mode 100644
index 000000000..c584d0b54
--- /dev/null
+++ b/packages/contracts/src/contracts/current/test/DummyERC721Receiver/DummyERC721Receiver.sol
@@ -0,0 +1,63 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Smart Contract Solutions, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../tokens/ERC721Token/IERC721Receiver.sol";
+
+contract DummyERC721Receiver is
+    IERC721Receiver
+{
+
+    event TokenReceived(
+        address from,
+        uint256 tokenId,
+        bytes data
+    );
+
+    /**
+    * @notice Handle the receipt of an NFT
+    * @dev The ERC721 smart contract calls this function on the recipient
+    *  after a `safetransfer`. This function MAY throw to revert and reject the
+    *  transfer. This function MUST use 50,000 gas or less. Return of other
+    *  than the magic value MUST result in the transaction being reverted.
+    *  Note: the contract address is always the message sender.
+    * @param _from The sending address
+    * @param _tokenId The NFT identifier which is being transfered
+    * @param _data Additional data with no specified format
+    * @return `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`
+    */
+    function onERC721Received(
+        address _from,
+        uint256 _tokenId,
+        bytes _data
+    )
+        public
+        returns (bytes4)
+    {
+        emit TokenReceived(_from, _tokenId, _data);
+        return ERC721_RECEIVED;
+    }
+}
diff --git a/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol b/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
index 369a2950d..5503eb2f2 100644
--- a/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
+++ b/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
@@ -34,7 +34,8 @@ contract DummyERC721Token is
     */
     constructor (
         string name,
-        string symbol)
+        string symbol
+    )
         public
         ERC721Token(name, symbol)
     {}
diff --git a/packages/contracts/src/contracts/current/test/TestAssetDataDecoders/TestAssetDataDecoders.sol b/packages/contracts/src/contracts/current/test/TestAssetDataDecoders/TestAssetDataDecoders.sol
new file mode 100644
index 000000000..2c6a8fdb0
--- /dev/null
+++ b/packages/contracts/src/contracts/current/test/TestAssetDataDecoders/TestAssetDataDecoders.sol
@@ -0,0 +1,77 @@
+/*
+
+  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/AssetProxy/ERC20Proxy.sol";
+import "../../protocol/AssetProxy/ERC721Proxy.sol";
+
+contract TestAssetDataDecoders is
+    ERC20Proxy,
+    ERC721Proxy
+{
+
+    /// @dev Decodes ERC20 Asset data.
+    /// @param assetData Encoded byte array.
+    /// @return proxyId Intended ERC20 proxy id.
+    /// @return token ERC20 token address.
+    function publicDecodeERC20Data(bytes memory assetData)
+        public
+        pure
+        returns (
+            uint8 proxyId,
+            address token
+        )
+    {
+        (proxyId, token) = decodeERC20AssetData(assetData);
+        return (proxyId, token);
+    }
+
+    /// @dev Decodes ERC721 Asset data.
+    /// @param assetData Encoded byte array.
+    /// @return proxyId Intended ERC721 proxy id.
+    /// @return token ERC721 token address.
+    /// @return tokenId ERC721 token id.
+    /// @return receiverData Additional data with no specific format, which
+    ///                      is passed to the receiving contract's onERC721Received.
+    function publicDecodeERC721Data(bytes memory assetData)
+        public
+        pure
+        returns (
+            uint8 proxyId,
+            address token,
+            uint256 tokenId,
+            bytes memory receiverData
+        )
+    {
+        (
+            proxyId,
+            token,
+            tokenId,
+            receiverData
+        ) = decodeERC721AssetData(assetData);
+
+        return (
+            proxyId,
+            token,
+            tokenId,
+            receiverData
+        );
+    }
+}
diff --git a/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
index 11ca0617d..2ae69e0ef 100644
--- a/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
@@ -23,12 +23,12 @@ import "../../protocol/Exchange/MixinAssetProxyDispatcher.sol";
 
 contract TestAssetProxyDispatcher is MixinAssetProxyDispatcher {
     function publicDispatchTransferFrom(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount)
         public
     {
-        dispatchTransferFrom(assetMetadata, from, to, amount);
+        dispatchTransferFrom(assetData, from, to, amount);
     }
 }
diff --git a/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol b/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
index 69554605d..22c84504c 100644
--- a/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
+++ b/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
@@ -68,7 +68,8 @@ contract TestLibBytes is
     /// @return address from byte array.
     function publicReadAddress(
         bytes memory b,
-        uint256 index)
+        uint256 index
+    )
         public
         pure
         returns (address result)
@@ -84,7 +85,8 @@ contract TestLibBytes is
     function publicWriteAddress(
         bytes memory b,
         uint256 index,
-        address input)
+        address input
+    )
         public
         pure
         returns (bytes memory)
@@ -99,7 +101,8 @@ contract TestLibBytes is
     /// @return bytes32 value from byte array.
     function publicReadBytes32(
         bytes memory b,
-        uint256 index)
+        uint256 index
+    )
         public
         pure
         returns (bytes32 result)
@@ -115,7 +118,8 @@ contract TestLibBytes is
     function publicWriteBytes32(
         bytes memory b,
         uint256 index,
-        bytes32 input)
+        bytes32 input
+    )
         public
         pure
         returns (bytes memory)
@@ -130,7 +134,8 @@ contract TestLibBytes is
     /// @return uint256 value from byte array.
     function publicReadUint256(
         bytes memory b,
-        uint256 index)
+        uint256 index
+    )
         public
         pure
         returns (uint256 result)
@@ -146,7 +151,8 @@ contract TestLibBytes is
     function publicWriteUint256(
         bytes memory b,
         uint256 index,
-        uint256 input)
+        uint256 input
+    )
         public
         pure
         returns (bytes memory)
@@ -166,4 +172,38 @@ contract TestLibBytes is
         result = readFirst4(b);
         return result;
     }
+
+    /// @dev Reads nested bytes from a specific position.
+    /// @param b Byte array containing nested bytes.
+    /// @param index Index of nested bytes.
+    /// @return result Nested bytes.
+    function publicReadBytes(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (bytes memory result)
+    {
+        result = readBytes(b, index);
+        return result;
+    }
+
+    /// @dev Inserts bytes at 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 bytes to insert.
+    /// @return b Updated input byte array
+    function publicWriteBytes(
+        bytes memory b,
+        uint256 index,
+        bytes memory input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        writeBytes(b, index, input);
+        return b;
+    }
 }
diff --git a/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol b/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol
new file mode 100644
index 000000000..b7e2e06b8
--- /dev/null
+++ b/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol
@@ -0,0 +1,56 @@
+/*
+
+  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 "../../utils/LibMem/LibMem.sol";
+
+contract TestLibMem is
+    LibMem
+{
+
+    /// @dev Copies a block of memory from one location to another.
+    /// @param mem Memory contents we want to apply memCopy to
+    /// @param dest Destination offset into <mem>.
+    /// @param source Source offset into <mem>.
+    /// @param length Length of bytes to copy from <source> to <dest>
+    /// @return mem Memory contents after calling memCopy.
+    function testMemcpy(
+        bytes mem,
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        public // not external, we need input in memory
+        pure
+        returns (bytes)
+    {
+        // Sanity check. Overflows are not checked.
+        require(source + length <= mem.length);
+        require(dest + length <= mem.length);
+
+        // Get pointer to memory contents
+        uint256 offset = getMemAddress(mem) + 32;
+
+        // Execute memCopy adjusted for memory array location
+        memCopy(offset + dest, offset + source, length);
+
+        // Return modified memory contents
+        return mem;
+    }
+}
diff --git a/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol b/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
index df2221c93..d1d10476f 100644
--- a/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
+++ b/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
@@ -18,14 +18,18 @@
 
 pragma solidity ^0.4.24;
 
-contract LibBytes {
+import "../LibMem/LibMem.sol";
+
+contract LibBytes is
+    LibMem
+{
 
     // Revert reasons
-    string constant GT_ZERO_LENGTH_REQUIRED = "Length must be greater than 0.";
-    string constant GTE_4_LENGTH_REQUIRED = "Length must be greater than or equal to 4.";
-    string constant GTE_20_LENGTH_REQUIRED = "Length must be greater than or equal to 20.";
-    string constant GTE_32_LENGTH_REQUIRED = "Length must be greater than or equal to 32.";
-    string constant INDEX_OUT_OF_BOUNDS = "Specified array index is out of bounds.";
+    string constant GREATER_THAN_ZERO_LENGTH_REQUIRED = "GREATER_THAN_ZERO_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED";
 
     /// @dev Pops the last byte off of a byte array by modifying its length.
     /// @param b Byte array that will be modified.
@@ -37,12 +41,12 @@ contract LibBytes {
     {
         require(
             b.length > 0,
-            GT_ZERO_LENGTH_REQUIRED
+            GREATER_THAN_ZERO_LENGTH_REQUIRED
         );
 
         // Store last byte.
         result = b[b.length - 1];
-        
+
         assembly {
             // Decrement length of byte array.
             let newLen := sub(mload(b), 1)
@@ -61,7 +65,7 @@ contract LibBytes {
     {
         require(
             b.length >= 20,
-            GTE_20_LENGTH_REQUIRED
+            GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
         );
 
         // Store last 20 bytes.
@@ -124,8 +128,8 @@ contract LibBytes {
     {
         require(
             b.length >= index + 20,  // 20 is length of address
-            GTE_20_LENGTH_REQUIRED
-        ); 
+            GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
+        );
 
         // Add offset to index:
         // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
@@ -156,8 +160,8 @@ contract LibBytes {
     {
         require(
             b.length >= index + 20,  // 20 is length of address
-            GTE_20_LENGTH_REQUIRED
-        ); 
+            GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
+        );
 
         // Add offset to index:
         // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
@@ -195,7 +199,7 @@ contract LibBytes {
     {
         require(
             b.length >= index + 32,
-            GTE_32_LENGTH_REQUIRED
+            GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED
         );
 
         // Arrays are prefixed by a 256 bit length parameter
@@ -222,7 +226,7 @@ contract LibBytes {
     {
         require(
             b.length >= index + 32,
-            GTE_32_LENGTH_REQUIRED
+            GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED
         );
 
         // Arrays are prefixed by a 256 bit length parameter
@@ -274,11 +278,72 @@ contract LibBytes {
     {
         require(
             b.length >= 4,
-            GTE_4_LENGTH_REQUIRED
+            GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED
         );
         assembly {
             result := mload(add(b, 32))
         }
         return result;
     }
+
+    /// @dev Reads nested bytes from a specific position.
+    /// @param b Byte array containing nested bytes.
+    /// @param index Index of nested bytes.
+    /// @return result Nested bytes.
+    function readBytes(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        // Read length of nested bytes
+        uint256 nestedBytesLength = readUint256(b, index);
+        index += 32;
+
+        // Assert length of <b> is valid, given
+        // length of nested bytes
+        require(
+            b.length >= index + nestedBytesLength,
+            GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED
+        );
+
+        // Allocate memory and copy value to result
+        result = new bytes(nestedBytesLength);
+        memCopy(
+            getMemAddress(result) + 32, // +32 skips array length
+            getMemAddress(b) + index + 32,
+            nestedBytesLength
+        );
+
+        return result;
+    }
+
+    /// @dev Inserts bytes at 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 bytes to insert.
+    function writeBytes(
+        bytes memory b,
+        uint256 index,
+        bytes memory input
+    )
+        internal
+        pure
+    {
+        // Assert length of <b> is valid, given
+        // length of input
+        require(
+            b.length >= index + 32 /* 32 bytes to store length */ + input.length,
+            GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED
+        );
+
+        // Copy <input> into <b>
+        memCopy(
+            getMemAddress(b) + 32 + index,  // +32 to skip length of <b>
+            getMemAddress(input),           // includes length of <input>
+            input.length + 32               // +32 bytes to store <input> length
+        );
+    }
 }
diff --git a/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol b/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol
new file mode 100644
index 000000000..6afb9973a
--- /dev/null
+++ b/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol
@@ -0,0 +1,140 @@
+/*
+
+  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 LibMem
+{
+
+    /// @dev Gets the memory address for a byte array.
+    /// @param input Byte array to lookup.
+    /// @return memoryAddress Memory address of byte array.
+    function getMemAddress(bytes memory input)
+        internal
+        pure
+        returns (uint256 memoryAddress)
+    {
+        assembly {
+            memoryAddress := input
+        }
+        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 {
+                    // Record the total number of full words to copy
+                    let nWords := div(length, 32)
+
+                    // 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
+                    for {let i := 0} lt(i, nWords) {i := add(i, 1)} {
+                        mstore(dest, mload(source))
+                        source := add(source, 32)
+                        dest := add(dest, 32)
+                    }
+
+                    // Write the last 32 bytes
+                    mstore(dEnd, last)
+                }
+            } else {
+                assembly {
+                    // Record the total number of full words to copy
+                    let nWords := div(length, 32)
+
+                    // 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
+                    for {let i := 0} lt(i, nWords) {i := add(i, 1)} {
+                        mstore(dEnd, mload(sEnd))
+                        sEnd := sub(sEnd, 32)
+                        dEnd := sub(dEnd, 32)
+                    }
+
+                    // Write the first 32 bytes
+                    mstore(dest, first)
+                }
+            }
+        }
+    }
+}
diff --git a/packages/contracts/src/utils/artifacts.ts b/packages/contracts/src/utils/artifacts.ts
index 357c66a0a..bf7221d6d 100644
--- a/packages/contracts/src/utils/artifacts.ts
+++ b/packages/contracts/src/utils/artifacts.ts
@@ -2,6 +2,7 @@ import { ContractArtifact } from '@0xproject/sol-compiler';
 
 import * as AssetProxyOwner from '../artifacts/AssetProxyOwner.json';
 import * as DummyERC20Token from '../artifacts/DummyERC20Token.json';
+import * as DummyERC721Receiver from '../artifacts/DummyERC721Receiver.json';
 import * as DummyERC721Token from '../artifacts/DummyERC721Token.json';
 import * as ERC20Proxy from '../artifacts/ERC20Proxy.json';
 import * as ERC721Proxy from '../artifacts/ERC721Proxy.json';
@@ -9,8 +10,10 @@ import * as Exchange from '../artifacts/Exchange.json';
 import * as MixinAuthorizable from '../artifacts/MixinAuthorizable.json';
 import * as MultiSigWallet from '../artifacts/MultiSigWallet.json';
 import * as MultiSigWalletWithTimeLock from '../artifacts/MultiSigWalletWithTimeLock.json';
+import * as TestAssetDataDecoders from '../artifacts/TestAssetDataDecoders.json';
 import * as TestAssetProxyDispatcher from '../artifacts/TestAssetProxyDispatcher.json';
 import * as TestLibBytes from '../artifacts/TestLibBytes.json';
+import * as TestLibMem from '../artifacts/TestLibMem.json';
 import * as TestLibs from '../artifacts/TestLibs.json';
 import * as TestSignatureValidator from '../artifacts/TestSignatureValidator.json';
 import * as TokenRegistry from '../artifacts/TokenRegistry.json';
@@ -21,6 +24,7 @@ import * as ZRX from '../artifacts/ZRXToken.json';
 export const artifacts = {
     AssetProxyOwner: (AssetProxyOwner as any) as ContractArtifact,
     DummyERC20Token: (DummyERC20Token as any) as ContractArtifact,
+    DummyERC721Receiver: (DummyERC721Receiver as any) as ContractArtifact,
     DummyERC721Token: (DummyERC721Token as any) as ContractArtifact,
     ERC20Proxy: (ERC20Proxy as any) as ContractArtifact,
     ERC721Proxy: (ERC721Proxy as any) as ContractArtifact,
@@ -30,7 +34,9 @@ export const artifacts = {
     MultiSigWallet: (MultiSigWallet as any) as ContractArtifact,
     MultiSigWalletWithTimeLock: (MultiSigWalletWithTimeLock as any) as ContractArtifact,
     TestAssetProxyDispatcher: (TestAssetProxyDispatcher as any) as ContractArtifact,
+    TestAssetDataDecoders: (TestAssetDataDecoders as any) as ContractArtifact,
     TestLibBytes: (TestLibBytes as any) as ContractArtifact,
+    TestLibMem: (TestLibMem as any) as ContractArtifact,
     TestLibs: (TestLibs as any) as ContractArtifact,
     TestSignatureValidator: (TestSignatureValidator as any) as ContractArtifact,
     TokenRegistry: (TokenRegistry as any) as ContractArtifact,
diff --git a/packages/contracts/src/utils/constants.ts b/packages/contracts/src/utils/constants.ts
index fa2a4af3c..af3f26d82 100644
--- a/packages/contracts/src/utils/constants.ts
+++ b/packages/contracts/src/utils/constants.ts
@@ -19,11 +19,11 @@ const TESTRPC_PRIVATE_KEYS_STRINGS = [
 export const constants = {
     INVALID_OPCODE: 'invalid opcode',
     REVERT: 'revert',
-    LIB_BYTES_GT_ZERO_LENGTH_REQUIRED: 'Length must be greater than 0.',
-    LIB_BYTES_GTE_4_LENGTH_REQUIRED: 'Length must be greater than or equal to 4.',
-    LIB_BYTES_GTE_20_LENGTH_REQUIRED: 'Length must be greater than or equal to 20.',
-    LIB_BYTES_GTE_32_LENGTH_REQUIRED: 'Length must be greater than or equal to 32.',
-    LIB_BYTES_INDEX_OUT_OF_BOUNDS: 'Specified array index is out of bounds.',
+    LIB_BYTES_GREATER_THAN_ZERO_LENGTH_REQUIRED: 'GREATER_THAN_ZERO_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED',
     ERC20_INSUFFICIENT_BALANCE: 'Insufficient balance to complete transfer.',
     ERC20_INSUFFICIENT_ALLOWANCE: 'Insufficient allowance to complete transfer.',
     TESTRPC_NETWORK_ID: 50,
diff --git a/packages/contracts/src/utils/coverage.ts b/packages/contracts/src/utils/coverage.ts
index 41c83f703..de29a3ecc 100644
--- a/packages/contracts/src/utils/coverage.ts
+++ b/packages/contracts/src/utils/coverage.ts
@@ -14,7 +14,8 @@ export const coverage = {
     _getCoverageSubprovider(): CoverageSubprovider {
         const defaultFromAddress = devConstants.TESTRPC_FIRST_ADDRESS;
         const solCompilerArtifactAdapter = new SolCompilerArtifactAdapter();
-        const subprovider = new CoverageSubprovider(solCompilerArtifactAdapter, defaultFromAddress);
+        const isVerbose = true;
+        const subprovider = new CoverageSubprovider(solCompilerArtifactAdapter, defaultFromAddress, isVerbose);
         return subprovider;
     },
 };
diff --git a/packages/contracts/src/utils/match_order_tester.ts b/packages/contracts/src/utils/match_order_tester.ts
index f4f7f965b..fbb1b99db 100644
--- a/packages/contracts/src/utils/match_order_tester.ts
+++ b/packages/contracts/src/utils/match_order_tester.ts
@@ -237,11 +237,11 @@ export class MatchOrderTester {
         const expectedNewERC20BalancesByOwner = _.cloneDeep(erc20BalancesByOwner);
         const expectedNewERC721TokenIdsByOwner = _.cloneDeep(erc721TokenIdsByOwner);
         // Left Maker Asset (Right Taker Asset)
-        const makerAssetProxyIdLeft = assetProxyUtils.decodeProxyDataId(signedOrderLeft.makerAssetData);
+        const makerAssetProxyIdLeft = assetProxyUtils.decodeAssetDataId(signedOrderLeft.makerAssetData);
         if (makerAssetProxyIdLeft === AssetProxyId.ERC20) {
             // Decode asset data
-            const erc20ProxyData = assetProxyUtils.decodeERC20ProxyData(signedOrderLeft.makerAssetData);
-            const makerAssetAddressLeft = erc20ProxyData.tokenAddress;
+            const erc20AssetData = assetProxyUtils.decodeERC20AssetData(signedOrderLeft.makerAssetData);
+            const makerAssetAddressLeft = erc20AssetData.tokenAddress;
             const takerAssetAddressRight = makerAssetAddressLeft;
             // Left Maker
             expectedNewERC20BalancesByOwner[makerAddressLeft][makerAssetAddressLeft] = expectedNewERC20BalancesByOwner[
@@ -259,9 +259,9 @@ export class MatchOrderTester {
             ][makerAssetAddressLeft].add(expectedTransferAmounts.amountReceivedByTaker);
         } else if (makerAssetProxyIdLeft === AssetProxyId.ERC721) {
             // Decode asset data
-            const erc721ProxyData = assetProxyUtils.decodeERC721ProxyData(signedOrderLeft.makerAssetData);
-            const makerAssetAddressLeft = erc721ProxyData.tokenAddress;
-            const makerAssetIdLeft = erc721ProxyData.tokenId;
+            const erc721AssetData = assetProxyUtils.decodeERC721AssetData(signedOrderLeft.makerAssetData);
+            const makerAssetAddressLeft = erc721AssetData.tokenAddress;
+            const makerAssetIdLeft = erc721AssetData.tokenId;
             const takerAssetAddressRight = makerAssetAddressLeft;
             const takerAssetIdRight = makerAssetIdLeft;
             // Left Maker
@@ -272,11 +272,11 @@ export class MatchOrderTester {
         }
         // Left Taker Asset (Right Maker Asset)
         // Note: This exchange is only between the order makers: the Taker does not receive any of the left taker asset.
-        const takerAssetProxyIdLeft = assetProxyUtils.decodeProxyDataId(signedOrderLeft.takerAssetData);
+        const takerAssetProxyIdLeft = assetProxyUtils.decodeAssetDataId(signedOrderLeft.takerAssetData);
         if (takerAssetProxyIdLeft === AssetProxyId.ERC20) {
             // Decode asset data
-            const erc20ProxyData = assetProxyUtils.decodeERC20ProxyData(signedOrderLeft.takerAssetData);
-            const takerAssetAddressLeft = erc20ProxyData.tokenAddress;
+            const erc20AssetData = assetProxyUtils.decodeERC20AssetData(signedOrderLeft.takerAssetData);
+            const takerAssetAddressLeft = erc20AssetData.tokenAddress;
             const makerAssetAddressRight = takerAssetAddressLeft;
             // Left Maker
             expectedNewERC20BalancesByOwner[makerAddressLeft][takerAssetAddressLeft] = expectedNewERC20BalancesByOwner[
@@ -290,9 +290,9 @@ export class MatchOrderTester {
             );
         } else if (takerAssetProxyIdLeft === AssetProxyId.ERC721) {
             // Decode asset data
-            const erc721ProxyData = assetProxyUtils.decodeERC721ProxyData(signedOrderRight.makerAssetData);
-            const makerAssetAddressRight = erc721ProxyData.tokenAddress;
-            const makerAssetIdRight = erc721ProxyData.tokenId;
+            const erc721AssetData = assetProxyUtils.decodeERC721AssetData(signedOrderRight.makerAssetData);
+            const makerAssetAddressRight = erc721AssetData.tokenAddress;
+            const makerAssetIdRight = erc721AssetData.tokenId;
             const takerAssetAddressLeft = makerAssetAddressRight;
             const takerAssetIdLeft = makerAssetIdRight;
             // Right Maker
diff --git a/packages/contracts/src/utils/profiler.ts b/packages/contracts/src/utils/profiler.ts
new file mode 100644
index 000000000..85ee24f22
--- /dev/null
+++ b/packages/contracts/src/utils/profiler.ts
@@ -0,0 +1,27 @@
+import { devConstants } from '@0xproject/dev-utils';
+import { ProfilerSubprovider, SolCompilerArtifactAdapter } from '@0xproject/sol-cov';
+import * as _ from 'lodash';
+
+let profilerSubprovider: ProfilerSubprovider;
+
+export const profiler = {
+    start(): void {
+        profiler.getProfilerSubproviderSingleton().start();
+    },
+    stop(): void {
+        profiler.getProfilerSubproviderSingleton().stop();
+    },
+    getProfilerSubproviderSingleton(): ProfilerSubprovider {
+        if (_.isUndefined(profilerSubprovider)) {
+            profilerSubprovider = profiler._getProfilerSubprovider();
+        }
+        return profilerSubprovider;
+    },
+    _getProfilerSubprovider(): ProfilerSubprovider {
+        const defaultFromAddress = devConstants.TESTRPC_FIRST_ADDRESS;
+        const solCompilerArtifactAdapter = new SolCompilerArtifactAdapter();
+        const isVerbose = true;
+        const subprovider = new ProfilerSubprovider(solCompilerArtifactAdapter, defaultFromAddress, isVerbose);
+        return subprovider;
+    },
+};
diff --git a/packages/contracts/src/utils/types.ts b/packages/contracts/src/utils/types.ts
index 64f6400c5..a6e1cd6d0 100644
--- a/packages/contracts/src/utils/types.ts
+++ b/packages/contracts/src/utils/types.ts
@@ -90,11 +90,14 @@ export enum ContractName {
     AccountLevels = 'AccountLevels',
     EtherDelta = 'EtherDelta',
     Arbitrage = 'Arbitrage',
+    TestAssetDataDecoders = 'TestAssetDataDecoders',
     TestAssetProxyDispatcher = 'TestAssetProxyDispatcher',
+    TestLibMem = 'TestLibMem',
     TestLibs = 'TestLibs',
     TestSignatureValidator = 'TestSignatureValidator',
     ERC20Proxy = 'ERC20Proxy',
     ERC721Proxy = 'ERC721Proxy',
+    DummyERC721Receiver = 'DummyERC721Receiver',
     DummyERC721Token = 'DummyERC721Token',
     TestLibBytes = 'TestLibBytes',
     Authorizable = 'Authorizable',
diff --git a/packages/contracts/src/utils/web3_wrapper.ts b/packages/contracts/src/utils/web3_wrapper.ts
index df9bf88c8..c475d96a9 100644
--- a/packages/contracts/src/utils/web3_wrapper.ts
+++ b/packages/contracts/src/utils/web3_wrapper.ts
@@ -1,8 +1,10 @@
 import { devConstants, env, EnvVars, web3Factory } from '@0xproject/dev-utils';
 import { prependSubprovider } from '@0xproject/subproviders';
+import { logUtils } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 
 import { coverage } from './coverage';
+import { profiler } from './profiler';
 
 enum ProviderType {
     Ganache = 'ganache',
@@ -45,9 +47,29 @@ const providerConfigs = testProvider === ProviderType.Ganache ? ganacheConfigs :
 
 export const provider = web3Factory.getRpcProvider(providerConfigs);
 const isCoverageEnabled = env.parseBoolean(EnvVars.SolidityCoverage);
+const isProfilerEnabled = env.parseBoolean(EnvVars.SolidityProfiler);
+if (isCoverageEnabled && isProfilerEnabled) {
+    throw new Error(
+        `Unfortunately for now you can't enable both coverage and profiler at the same time. They both use coverage.json file and there is no way to configure that.`,
+    );
+}
 if (isCoverageEnabled) {
     const coverageSubprovider = coverage.getCoverageSubproviderSingleton();
     prependSubprovider(provider, coverageSubprovider);
 }
+if (isProfilerEnabled) {
+    if (testProvider === ProviderType.Ganache) {
+        logUtils.warn(
+            "Gas costs in Ganache traces are incorrect and we don't recommend using it for profiling. Please switch to Geth",
+        );
+        process.exit(1);
+    }
+    const profilerSubprovider = profiler.getProfilerSubproviderSingleton();
+    logUtils.log(
+        "By default profilerSubprovider is stopped so that you don't get noise from setup code. Don't forget to start it before the code you want to profile and stop it afterwards",
+    );
+    profilerSubprovider.stop();
+    prependSubprovider(provider, profilerSubprovider);
+}
 
 export const web3Wrapper = new Web3Wrapper(provider);