Commit to using safemath

Author: felix2feng

contracts/SetToken.sol

@@ -4,7 +4,6 @@ pragma solidity 0.4.21;
 import "zeppelin-solidity/contracts/token/ERC20/StandardToken.sol";
 import "zeppelin-solidity/contracts/token/ERC20/ERC20.sol";
 import "zeppelin-solidity/contracts/token/ERC20/DetailedERC20.sol";
-import "zeppelin-solidity/contracts/math/SafeMath.sol";
 import "./external/SafeMathUint256.sol";
 import "./lib/Set.sol";
 
@@ -15,10 +14,9 @@ import "./lib/Set.sol";
  * @dev Implementation of the basic {Set} token.
  */
 contract SetToken is StandardToken, DetailedERC20("", "", 18), Set {
-  using SafeMath for uint256;
+  using SafeMathUint256 for uint256;
 
   uint256 public totalSupply;
-
   address[] public components;
   uint[] public units;
 
@@ -76,8 +74,7 @@ contract SetToken is StandardToken, DetailedERC20("", "", 18), Set {
       // Transfer value is defined as the currentUnits (in GWei)
       // multiplied by quantity in Wei divided by the units of gWei.
       // We do this to allow fractional units to be defined
-      // uint transferValue = currentUnits.mul(quantity).div(10**9);
-      uint transferValue = SafeMathUint256.fxpMul(currentUnits, quantity, 10**9);
+      uint transferValue = currentUnits.fxpMul(quantity, 10**9);
 
       // Protect against the case that the gWei divisor results in a value that is
       // 0 and the user is able to generate Sets without sending a balance
@@ -120,14 +117,16 @@ contract SetToken is StandardToken, DetailedERC20("", "", 18), Set {
       address currentComponent = components[i];
       uint currentUnits = units[i];
 
-      // The transaction will fail if any of the components fail to transfer
-      // uint transferValue = currentUnits.mul(quantity).div(10**9);
-      uint transferValue = SafeMathUint256.fxpMul(currentUnits, quantity, 10**9);
+      // Transfer value is defined as the currentUnits (in GWei)
+      // multiplied by quantity in Wei divided by the units of gWei.
+      // We do this to allow fractional units to be defined
+      uint transferValue = currentUnits.fxpMul(quantity, 10**9);
 
       // Protect against the case that the gWei divisor results in a value that is
       // 0 and the user is able to generate Sets without sending a balance
       assert(transferValue > 0);
 
+      // The transaction will fail if any of the components fail to transfer
       assert(ERC20(currentComponent).transfer(msg.sender, transferValue));
     }
 

contracts/external/SafeMathUint256.sol

@@ -1,37 +1,13 @@
 pragma solidity 0.4.21;
 
+import "zeppelin-solidity/contracts/math/SafeMath.sol";
 
 /**
  * @title SafeMathUint256
  * @dev Uint256 math operations with safety checks that throw on error
  */
 library SafeMathUint256 {
-    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
-        if (a == 0) {
-            return 0;
-        }
-        uint256 c = a * b;
-        assert(c / a == b);
-        return c;
-    }
-
-    function div(uint256 a, uint256 b) internal pure returns (uint256) {
-        // assert(b > 0); // Solidity automatically throws when dividing by 0
-        uint256 c = a / b;
-        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
-        return c;
-    }
-
-    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
-        require(b <= a);
-        return a - b;
-    }
-
-    function add(uint256 a, uint256 b) internal pure returns (uint256) {
-        uint256 c = a + b;
-        require(c >= a);
-        return c;
-    }
+    using SafeMath for uint256;
 
     function min(uint256 a, uint256 b) internal pure returns (uint256) {
         if (a <= b) {
@@ -63,10 +39,10 @@ library SafeMathUint256 {
 
     // Float [fixed point] Operations
     function fxpMul(uint256 a, uint256 b, uint256 base) internal pure returns (uint256) {
-        return div(mul(a, b), base);
+        return a.mul(b).div(base);
     }
 
     function fxpDiv(uint256 a, uint256 b, uint256 base) internal pure returns (uint256) {
-        return div(mul(a, base), b);
+        return a.mul(base).div(b);
     }
 }