Renamed exchange into protocol. Added ERC165 to protocol contract. Renamed SettableTransferXcert to PausableXcert.

contracts/mocks/XcertMock.sol

@@ -1,14 +1,14 @@
 pragma solidity ^0.4.19;
 
 import "../../contracts/tokens/BurnableXcert.sol";
-import "../../contracts/tokens/SettableTransferXcert.sol";
+import "../../contracts/tokens/PausableXcert.sol";
 import "../../contracts/tokens/ChainableXcert.sol";
 
-contract XcertMock is BurnableXcert, SettableTransferXcert, ChainableXcert {
+contract XcertMock is BurnableXcert, PausableXcert, ChainableXcert {
 
 function XcertMock(string _name, string _symbol)
     BurnableXcert(_name, _symbol)
-    SettableTransferXcert(_name, _symbol)
+    PausableXcert(_name, _symbol)
     ChainableXcert(_name, _symbol)
     public
   {

contracts/exchange/Minter.sol → contracts/protocol/Minter.sol

@@ -6,11 +6,12 @@ import "../tokens/Xcert.sol";
 import "../tokens/ERC20.sol";
 import "./TokenTransferProxy.sol";
 import "./XcertMintProxy.sol";
+import "../tokens/ERC165.sol";
 
 /*
  * @dev based on: https://github.com/0xProject/contracts/blob/master/contracts/Exchange.sol
  */
-contract Minter{
+contract Minter is ERC165 {
 
   using SafeMath for uint256;
 
@@ -46,6 +47,12 @@ contract Minter{
    */
   mapping(bytes32 => bool) public mintPerformed;
 
+  /*
+   * @dev Mapping of supported intefraces.
+   * You must not set element 0xffffffff to true.
+   */
+  mapping(bytes4 => bool) internal supportedInterfaces;
+
   /*
    * @dev This event emmits when xcert gets mint directly to the taker.
    */
@@ -107,6 +114,8 @@ contract Minter{
     XCT_TOKEN_CONTRACT = _xctToken;
     TOKEN_TRANSFER_PROXY_CONTRACT = _tokenTransferProxy;
     XCERT_MINT_PROXY_CONTRACT = _xcertMintProxy;
+    supportedInterfaces[0x01ffc9a7] = true; // ERC165
+    supportedInterfaces[0xca4a3079] = true; // Minter
   }
 
 
@@ -354,6 +363,18 @@ contract Minter{
     );
   }
 
+  /*
+   * @dev Function to check which interfaces are suported by this contract.
+   * @param interfaceID If of the interface.
+   */
+  function supportsInterface(bytes4 interfaceID)
+    external
+    view
+    returns (bool)
+  {
+    return supportedInterfaces[interfaceID];
+  }
+
   /*
    * @dev Transfers XCT tokens via TokenTransferProxy using transferFrom function.
    * @param _token Address of token to transferFrom.

contracts/exchange/Swapper.sol → contracts/protocol/Swapper.sol

@@ -6,11 +6,12 @@ import "../tokens/ERC20.sol";
 import "../tokens/ERC721.sol";
 import "./TokenTransferProxy.sol";
 import "./NFTokenTransferProxy.sol";
+import "../tokens/ERC165.sol";
 
 /*
  * @dev based on: https://github.com/0xProject/contracts/blob/master/contracts/Exchange.sol
  */
-contract Swapper {
+contract Swapper is ERC165 {
 
   using SafeMath for uint256;
 
@@ -46,6 +47,12 @@ contract Swapper {
    */
   mapping(bytes32 => bool) public swapPerformed;
 
+  /*
+   * @dev Mapping of supported intefraces.
+   * You must not set element 0xffffffff to true.
+   */
+  mapping(bytes4 => bool) internal supportedInterfaces;
+
   /*
    * @dev This event emmits when NFToken changes ownership.
    */
@@ -111,6 +118,8 @@ contract Swapper {
     TOKEN_CONTRACT = _xctToken;
     TOKEN_TRANSFER_PROXY_CONTRACT = _tokenTransferProxy;
     NFTOKEN_TRANSFER_PROXY_CONTRACT = _nfTokenTransferProxy;
+    supportedInterfaces[0x01ffc9a7] = true; // ERC165
+    supportedInterfaces[0xe20524dd] = true; // Swapper
   }
 
   /*
@@ -353,6 +362,18 @@ contract Swapper {
     );
   }
 
+  /*
+   * @dev Function to check which interfaces are suported by this contract.
+   * @param interfaceID If of the interface.
+   */
+  function supportsInterface(bytes4 interfaceID)
+    external
+    view
+    returns (bool)
+  {
+    return supportedInterfaces[interfaceID];
+  }
+
   /*
    * @dev Check is payer can pay the feeAmounts.
    * @param _to Address of the payer.

contracts/exchange/Trader.sol → contracts/protocol/Trader.sol

@@ -6,11 +6,12 @@ import "../tokens/ERC20.sol";
 import "../tokens/ERC721.sol";
 import "./TokenTransferProxy.sol";
 import "./NFTokenTransferProxy.sol";
+import "../tokens/ERC165.sol";
 
 /*
  * @dev based on: https://github.com/0xProject/contracts/blob/master/contracts/Exchange.sol
  */
-contract Trader {
+contract Trader is ERC165 {
 
   using SafeMath for uint256;
 
@@ -46,6 +47,12 @@ contract Trader {
    */
   mapping(bytes32 => bool) public transferPerformed;
 
+  /*
+   * @dev Mapping of supported intefraces.
+   * You must not set element 0xffffffff to true.
+   */
+  mapping(bytes4 => bool) internal supportedInterfaces;
+
   /*
    * @dev This event emmits when NFToken changes ownership.
    */
@@ -104,6 +111,8 @@ contract Trader {
     TOKEN_CONTRACT = _xctToken;
     TOKEN_TRANSFER_PROXY_CONTRACT = _tokenTransferProxy;
     NFTOKEN_TRANSFER_PROXY_CONTRACT = _nfTokenTransferProxy;
+    supportedInterfaces[0x01ffc9a7] = true; // ERC165
+    supportedInterfaces[0x6b28faee] = true; // Trader
   }
 
   /*
@@ -326,6 +335,18 @@ contract Trader {
     );
   }
 
+  /*
+   * @dev Function to check which interfaces are suported by this contract.
+   * @param interfaceID If of the interface.
+   */
+  function supportsInterface(bytes4 interfaceID)
+    external
+    view
+    returns (bool)
+  {
+    return supportedInterfaces[interfaceID];
+  }
+
   /*
    * @dev Check is payer can pay the feeAmounts.
    * @param _to Address of the payer.

contracts/tokens/PausableXcert.sol

@@ -0,0 +1,53 @@
+pragma solidity ^0.4.19;
+
+import "./Xcert.sol";
+
+contract PausableXcert is Xcert {
+
+  /*
+   * @dev This emits when ability of beeing able to transfer NFTokens changes (paused/unpaused).
+   */
+  event IsPaused(bool _isPaused);
+
+  /*
+   * @dev Are NFTokens paused or not.
+   */
+  bool public isPaused;
+
+  function PausableXcert(string _name, string _symbol)
+    Xcert(_name, _symbol)
+    public
+  {
+    supportedInterfaces[0xbedb86fb] = true; // PausableXcert
+    isPaused = false;
+  }
+
+  /*
+   * @dev Guarantees that the msg.sender is allowed to transfer NFToken.
+   * @param _tokenId ID of the NFToken to transfer.
+   */
+  modifier canTransfer(uint256 _tokenId) {
+    address owner = idToOwner[_tokenId];
+    require(!isPaused && (
+      owner == msg.sender
+      || getApproved(_tokenId) == msg.sender
+      || ownerToOperators[owner][msg.sender])
+    );
+
+    _;
+  }
+
+  /*
+   * @dev Sets if NFTokens are paused or not.
+   * @param _isPaused Pause status.
+   */
+  function setPause(bool _isPaused)
+    external
+    onlyOwner
+  {
+    require(isPaused != _isPaused);
+    isPaused = _isPaused;
+    IsPaused(_isPaused);
+  }
+
+}

contracts/utils/Selector.sol

@@ -2,33 +2,69 @@ pragma solidity ^0.4.19;
 
 import "../tokens/Xcert.sol";
 import "../tokens/BurnableXcert.sol";
-import "../tokens/SettableTransferXcert.sol";
+import "../tokens/PausableXcert.sol";
 import "../tokens/ChainableXcert.sol";
+import "../protocol/Minter.sol";
+import "../protocol/Trader.sol";
+import "../protocol/Swapper.sol";
 
 contract Selector {
 
     function calculateXcertSelector() public pure returns (bytes4) {
-        Xcert i;
-        return i.mint.selector
-           ^ i.getProof.selector
-           ^ i.setMintAuthorizedAddress.selector
-           ^ i.isMintAuthorizedAddress.selector;
+      Xcert i;
+      return i.mint.selector
+         ^ i.getProof.selector
+         ^ i.setMintAuthorizedAddress.selector
+         ^ i.isMintAuthorizedAddress.selector;
     }
 
     function calculateBurnableXcertSelector() public pure returns (bytes4) {
-        BurnableXcert i;
-        return i.burn.selector;
+      BurnableXcert i;
+      return i.burn.selector;
     }
 
-    function calculateSettableTransferXcertSelector() public pure returns (bytes4) {
-        SettableTransferXcert i;
-        return i.setTransferable.selector;
+    function calculatePausableXcertSelector() public pure returns (bytes4) {
+      PausableXcert i;
+      return i.setPause.selector;
     }
 
-     function calculateChainableXcertSelector() public pure returns (bytes4) {
-        ChainableXcert i;
-        return i.chain.selector
-           ^ i.getProofByIndex.selector
-           ^ i.getProofCount.selector;
+    function calculateChainableXcertSelector() public pure returns (bytes4) {
+      ChainableXcert i;
+      return i.chain.selector
+         ^ i.getProofByIndex.selector
+         ^ i.getProofCount.selector;
+    }
+
+    function calculateMinterSelector() public pure returns (bytes4) {
+      Minter i;
+      return i.getTokenAddress.selector
+         ^ i.getTokenTransferProxyAddress.selector
+         ^ i.getXcertMintProxyAddress.selector
+         ^ i.performMint.selector
+         ^ i.cancelMint.selector
+         ^ i.getMintDataClaim.selector
+         ^ i.isValidSignature.selector;
+    }
+
+    function calculateTraderSelector() public pure returns (bytes4) {
+      Trader i;
+      return i.getTokenAddress.selector
+         ^ i.getTokenTransferProxyAddress.selector
+         ^ i.getNFTokenTransferProxyAddress.selector
+         ^ i.performTransfer.selector
+         ^ i.cancelTransfer.selector
+         ^ i.getTransferDataClaim.selector
+         ^ i.isValidSignature.selector;
+    }
+
+    function calculateSwapperSelector() public pure returns (bytes4) {
+      Swapper i;
+      return i.getTokenAddress.selector
+         ^ i.getTokenTransferProxyAddress.selector
+         ^ i.getNFTokenTransferProxyAddress.selector
+         ^ i.performSwap.selector
+         ^ i.cancelSwap.selector
+         ^ i.getSwapDataClaim.selector
+         ^ i.isValidSignature.selector;
     }
 }