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MixItemDagOnlyOwner.sol
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MixItemDagOnlyOwner.sol
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pragma solidity ^0.6.6;
import "./MixItemDag.sol";
/**
* @title MixItemDagOnlyOwner
* @author Jonathan Brown <jbrown@mix-blockchain.org>
* @dev Maintains a directed acyclic graph of items where child items have the same owner as the parent.
*/
contract MixItemDagOnlyOwner is MixItemDag {
/**
* @param _itemStoreRegistry Address of the MixItemStoreRegistry contract.
*/
constructor(MixItemStoreRegistry _itemStoreRegistry) MixItemDag(_itemStoreRegistry) public {}
/**
* @dev Add a child to an item. The child must not exist yet.
* @param itemId itemId of the parent. Must have same owner.
* @param childItemStore The ItemStore contract that will contain the child.
* @param childNonce The nonce that will be used to create the child.
*/
function addChild(bytes32 itemId, MixItemStoreInterface childItemStore, bytes32 childNonce) override external {
// Get parent ItemStore.
MixItemStoreInterface itemStore = itemStoreRegistry.getItemStore(itemId);
// Ensure the parent exists.
require (itemStore.getInUse(itemId), "Parent does not exist.");
// Ensure the child has the same owner as the parent.
require (itemStore.getOwner(itemId) == msg.sender, "Child has different owner than parent.");
// Get the child itemId. Ensure it does not exist.
bytes32 childId = childItemStore.getNewItemId(msg.sender, childNonce);
// Get parent state.
ItemState storage state = itemState[itemId];
// Get the index of the new child.
uint i = state.childCount;
// Store the childId.
itemChildIds[itemId][i] = childId;
// Increment the child count.
state.childCount = uint128(i + 1);
// Log the new child.
emit AddChild(itemId, msg.sender, childId, i);
// Get child state.
state = itemState[childId];
// Get the index of the new parent.
i = state.parentCount;
// Store the parentId.
itemParentIds[childId][i] = itemId;
// Increment the parent count.
state.parentCount = uint128(i + 1);
}
}