Merge pull request #71 from gnosis/batch-mint

Batch mint/burn conditional tokens when splitting/merging
gnosis · Aug 28, 2019 · 75adb59 · 75adb59
2 parents 9a174be + f282ab2
commit 75adb59
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Showing 2 changed files with 56 additions and 12 deletions.
diff --git a/contracts/ConditionalTokens.sol b/contracts/ConditionalTokens.sol
@@ -118,18 +118,15 @@ contract ConditionalTokens is ERC1155 {
         // freeIndexSet starts as the full collection
         uint freeIndexSet = fullIndexSet;
         // This loop checks that all condition sets are disjoint (the same outcome is not part of more than 1 set)
+        uint[] memory positionIds = new uint[](partition.length);
+        uint[] memory amounts = new uint[](partition.length);
         for (uint i = 0; i < partition.length; i++) {
             uint indexSet = partition[i];
             require(indexSet > 0 && indexSet < fullIndexSet, "got invalid index set");
             require((indexSet & freeIndexSet) == indexSet, "partition not disjoint");
             freeIndexSet ^= indexSet;
-            _mint(
-                msg.sender,
-                // position ID is the ERC 1155 token ID
-                getPositionId(collateralToken, getCollectionId(parentCollectionId, conditionId, indexSet)),
-                amount,
-                ""
-            );
+            positionIds[i] = getPositionId(collateralToken, getCollectionId(parentCollectionId, conditionId, indexSet));
+            amounts[i] = amount;
         }
 
         if (freeIndexSet == 0) {
@@ -155,6 +152,13 @@ contract ConditionalTokens is ERC1155 {
             );
         }
 
+        _batchMint(
+            msg.sender,
+            // position ID is the ERC 1155 token ID
+            positionIds,
+            amounts,
+            ""
+        );
         emit PositionSplit(msg.sender, collateralToken, parentCollectionId, conditionId, partition, amount);
     }
 
@@ -171,17 +175,21 @@ contract ConditionalTokens is ERC1155 {
 
         uint fullIndexSet = (1 << outcomeSlotCount) - 1;
         uint freeIndexSet = fullIndexSet;
+        uint[] memory positionIds = new uint[](partition.length);
+        uint[] memory amounts = new uint[](partition.length);
         for (uint i = 0; i < partition.length; i++) {
             uint indexSet = partition[i];
             require(indexSet > 0 && indexSet < fullIndexSet, "got invalid index set");
             require((indexSet & freeIndexSet) == indexSet, "partition not disjoint");
             freeIndexSet ^= indexSet;
-            _burn(
-                msg.sender,
-                getPositionId(collateralToken, getCollectionId(parentCollectionId, conditionId, indexSet)),
-                amount
-            );
+            positionIds[i] = getPositionId(collateralToken, getCollectionId(parentCollectionId, conditionId, indexSet));
+            amounts[i] = amount;
         }
+        _batchBurn(
+            msg.sender,
+            positionIds,
+            amounts
+        );
 
         if (freeIndexSet == 0) {
             if (parentCollectionId == bytes32(0)) {

diff --git a/contracts/ERC1155/ERC1155.sol b/contracts/ERC1155/ERC1155.sol
@@ -184,6 +184,26 @@ contract ERC1155 is ERC165, IERC1155
         _doSafeTransferAcceptanceCheck(msg.sender, address(0), to, id, value, data);
     }
 
+    /**
+     * @dev Internal function to batch mint amounts of tokens with the given IDs
+     * @param to The address that will own the minted token
+     * @param ids IDs of the tokens to be minted
+     * @param values Amounts of the tokens to be minted
+     * @param data Data forwarded to `onERC1155Received` if `to` is a contract receiver
+     */
+    function _batchMint(address to, uint256[] memory ids, uint256[] memory values, bytes memory data) internal {
+        require(to != address(0), "ERC1155: batch mint to the zero address");
+        require(ids.length == values.length, "ERC1155: IDs and values must have same lengths");
+
+        for(uint i = 0; i < ids.length; i++) {
+            _balances[ids[i]][to] = values[i].add(_balances[ids[i]][to]);
+        }
+
+        emit TransferBatch(msg.sender, address(0), to, ids, values);
+
+        _doSafeBatchTransferAcceptanceCheck(msg.sender, address(0), to, ids, values, data);
+    }
+
     /**
      * @dev Internal function to burn an amount of a token with the given ID
      * @param owner Account which owns the token to be burnt
@@ -195,6 +215,22 @@ contract ERC1155 is ERC165, IERC1155
         emit TransferSingle(msg.sender, owner, address(0), id, value);
     }
 
+    /**
+     * @dev Internal function to batch burn an amounts of tokens with the given IDs
+     * @param owner Account which owns the token to be burnt
+     * @param ids IDs of the tokens to be burnt
+     * @param values Amounts of the tokens to be burnt
+     */
+    function _batchBurn(address owner, uint256[] memory ids, uint256[] memory values) internal {
+        require(ids.length == values.length, "ERC1155: IDs and values must have same lengths");
+
+        for(uint i = 0; i < ids.length; i++) {
+            _balances[ids[i]][owner] = _balances[ids[i]][owner].sub(values[i]);
+        }
+
+        emit TransferBatch(msg.sender, owner, address(0), ids, values);
+    }
+
     function _doSafeTransferAcceptanceCheck(
         address operator,
         address from,