100 lines
2.8 KiB
Solidity
100 lines
2.8 KiB
Solidity
pragma solidity ^0.5.0;
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/**
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* @title EnumerableSet
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* @dev Data structure - https://en.wikipedia.org/wiki/Set_(abstract_data_type)
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*
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* An EnumerableSet.AddressSet is a data structure containing a number of unique addresses.
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*
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* - It is possible to add and remove addresses in O(1).
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* - It is also possible to query if the AddressSet contains an address in O(1).
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* - It is possible to retrieve an array with all the addresses in the AddressSet using enumerate.
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* This operation is O(N) where N is the number of addresses in the AddressSet. The order in
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* which the addresses are retrieved is not guaranteed.
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*
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* Initialization of a set must include an empty array:
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* `EnumerableSet.AddressSet set = EnumerableSet.AddressSet({values: new address[](0)});`
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*
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* @author Alberto Cuesta Cañada
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*/
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library EnumerableSet {
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struct AddressSet {
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// Position of the value in the `values` array, plus 1 because index 0
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// means a value is not in the set.
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mapping (address => uint256) index;
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address[] values;
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}
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/**
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* @dev Add a value. O(1).
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*/
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function newAddressSet()
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internal
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pure
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returns (AddressSet memory)
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{
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return AddressSet({values: new address[](0)});
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}
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/**
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* @dev Add a value. O(1). Returns false if the value was already in the set.
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*/
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function add(AddressSet storage set, address value)
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internal
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returns (bool)
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{
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if (!contains(set, value)){
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set.index[value] = set.values.push(value);
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return true;
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} else {
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return false;
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}
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}
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/**
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* @dev Remove a value. O(1). Returns false if the calue was not present in the set.
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*/
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function remove(AddressSet storage set, address value)
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internal
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returns (bool)
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{
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if (contains(set, value)){
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// Replaced the value to remove with the last one in the array. O(1)
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set.values[set.index[value] - 1] = set.values[set.values.length - 1];
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set.values.pop();
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delete set.index[value];
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return true;
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} else {
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return false;
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}
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}
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/**
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* @dev Returns true if the value is in the set. O(1).
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*/
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function contains(AddressSet storage set, address value)
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internal
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view
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returns (bool)
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{
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return set.index[value] != 0;
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}
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/**
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* @dev Return an array with all values in the set. O(N).
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*/
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function enumerate(AddressSet storage set)
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internal
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view
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returns (address[] memory)
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{
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address[] memory output = new address[](set.values.length);
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for (uint256 i; i < set.values.length; i++){
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output[i] = set.values[i];
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}
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return output;
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}
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}
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