Reorganize the repo structure (#2503)

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

contracts/utils/structs/EnumerableSet.sol

@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev Library for managing
+ * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
+ * types.
+ *
+ * Sets have the following properties:
+ *
+ * - Elements are added, removed, and checked for existence in constant time
+ * (O(1)).
+ * - Elements are enumerated in O(n). No guarantees are made on the ordering.
+ *
+ * ```
+ * contract Example {
+ *     // Add the library methods
+ *     using EnumerableSet for EnumerableSet.AddressSet;
+ *
+ *     // Declare a set state variable
+ *     EnumerableSet.AddressSet private mySet;
+ * }
+ * ```
+ *
+ * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
+ * and `uint256` (`UintSet`) are supported.
+ */
+library EnumerableSet {
+    // To implement this library for multiple types with as little code
+    // repetition as possible, we write it in terms of a generic Set type with
+    // bytes32 values.
+    // The Set implementation uses private functions, and user-facing
+    // implementations (such as AddressSet) are just wrappers around the
+    // underlying Set.
+    // This means that we can only create new EnumerableSets for types that fit
+    // in bytes32.
+
+    struct Set {
+        // Storage of set values
+        bytes32[] _values;
+
+        // Position of the value in the `values` array, plus 1 because index 0
+        // means a value is not in the set.
+        mapping (bytes32 => uint256) _indexes;
+    }
+
+    /**
+     * @dev Add a value to a set. O(1).
+     *
+     * Returns true if the value was added to the set, that is if it was not
+     * already present.
+     */
+    function _add(Set storage set, bytes32 value) private returns (bool) {
+        if (!_contains(set, value)) {
+            set._values.push(value);
+            // The value is stored at length-1, but we add 1 to all indexes
+            // and use 0 as a sentinel value
+            set._indexes[value] = set._values.length;
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * @dev Removes a value from a set. O(1).
+     *
+     * Returns true if the value was removed from the set, that is if it was
+     * present.
+     */
+    function _remove(Set storage set, bytes32 value) private returns (bool) {
+        // We read and store the value's index to prevent multiple reads from the same storage slot
+        uint256 valueIndex = set._indexes[value];
+
+        if (valueIndex != 0) { // Equivalent to contains(set, value)
+            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
+            // the array, and then remove the last element (sometimes called as 'swap and pop').
+            // This modifies the order of the array, as noted in {at}.
+
+            uint256 toDeleteIndex = valueIndex - 1;
+            uint256 lastIndex = set._values.length - 1;
+
+            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
+            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
+
+            bytes32 lastvalue = set._values[lastIndex];
+
+            // Move the last value to the index where the value to delete is
+            set._values[toDeleteIndex] = lastvalue;
+            // Update the index for the moved value
+            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based
+
+            // Delete the slot where the moved value was stored
+            set._values.pop();
+
+            // Delete the index for the deleted slot
+            delete set._indexes[value];
+
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * @dev Returns true if the value is in the set. O(1).
+     */
+    function _contains(Set storage set, bytes32 value) private view returns (bool) {
+        return set._indexes[value] != 0;
+    }
+
+    /**
+     * @dev Returns the number of values on the set. O(1).
+     */
+    function _length(Set storage set) private view returns (uint256) {
+        return set._values.length;
+    }
+
+   /**
+    * @dev Returns the value stored at position `index` in the set. O(1).
+    *
+    * Note that there are no guarantees on the ordering of values inside the
+    * array, and it may change when more values are added or removed.
+    *
+    * Requirements:
+    *
+    * - `index` must be strictly less than {length}.
+    */
+    function _at(Set storage set, uint256 index) private view returns (bytes32) {
+        require(set._values.length > index, "EnumerableSet: index out of bounds");
+        return set._values[index];
+    }
+
+    // Bytes32Set
+
+    struct Bytes32Set {
+        Set _inner;
+    }
+
+    /**
+     * @dev Add a value to a set. O(1).
+     *
+     * Returns true if the value was added to the set, that is if it was not
+     * already present.
+     */
+    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
+        return _add(set._inner, value);
+    }
+
+    /**
+     * @dev Removes a value from a set. O(1).
+     *
+     * Returns true if the value was removed from the set, that is if it was
+     * present.
+     */
+    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
+        return _remove(set._inner, value);
+    }
+
+    /**
+     * @dev Returns true if the value is in the set. O(1).
+     */
+    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
+        return _contains(set._inner, value);
+    }
+
+    /**
+     * @dev Returns the number of values in the set. O(1).
+     */
+    function length(Bytes32Set storage set) internal view returns (uint256) {
+        return _length(set._inner);
+    }
+
+   /**
+    * @dev Returns the value stored at position `index` in the set. O(1).
+    *
+    * Note that there are no guarantees on the ordering of values inside the
+    * array, and it may change when more values are added or removed.
+    *
+    * Requirements:
+    *
+    * - `index` must be strictly less than {length}.
+    */
+    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
+        return _at(set._inner, index);
+    }
+
+    // AddressSet
+
+    struct AddressSet {
+        Set _inner;
+    }
+
+    /**
+     * @dev Add a value to a set. O(1).
+     *
+     * Returns true if the value was added to the set, that is if it was not
+     * already present.
+     */
+    function add(AddressSet storage set, address value) internal returns (bool) {
+        return _add(set._inner, bytes32(uint256(uint160(value))));
+    }
+
+    /**
+     * @dev Removes a value from a set. O(1).
+     *
+     * Returns true if the value was removed from the set, that is if it was
+     * present.
+     */
+    function remove(AddressSet storage set, address value) internal returns (bool) {
+        return _remove(set._inner, bytes32(uint256(uint160(value))));
+    }
+
+    /**
+     * @dev Returns true if the value is in the set. O(1).
+     */
+    function contains(AddressSet storage set, address value) internal view returns (bool) {
+        return _contains(set._inner, bytes32(uint256(uint160(value))));
+    }
+
+    /**
+     * @dev Returns the number of values in the set. O(1).
+     */
+    function length(AddressSet storage set) internal view returns (uint256) {
+        return _length(set._inner);
+    }
+
+   /**
+    * @dev Returns the value stored at position `index` in the set. O(1).
+    *
+    * Note that there are no guarantees on the ordering of values inside the
+    * array, and it may change when more values are added or removed.
+    *
+    * Requirements:
+    *
+    * - `index` must be strictly less than {length}.
+    */
+    function at(AddressSet storage set, uint256 index) internal view returns (address) {
+        return address(uint160(uint256(_at(set._inner, index))));
+    }
+
+
+    // UintSet
+
+    struct UintSet {
+        Set _inner;
+    }
+
+    /**
+     * @dev Add a value to a set. O(1).
+     *
+     * Returns true if the value was added to the set, that is if it was not
+     * already present.
+     */
+    function add(UintSet storage set, uint256 value) internal returns (bool) {
+        return _add(set._inner, bytes32(value));
+    }
+
+    /**
+     * @dev Removes a value from a set. O(1).
+     *
+     * Returns true if the value was removed from the set, that is if it was
+     * present.
+     */
+    function remove(UintSet storage set, uint256 value) internal returns (bool) {
+        return _remove(set._inner, bytes32(value));
+    }
+
+    /**
+     * @dev Returns true if the value is in the set. O(1).
+     */
+    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
+        return _contains(set._inner, bytes32(value));
+    }
+
+    /**
+     * @dev Returns the number of values on the set. O(1).
+     */
+    function length(UintSet storage set) internal view returns (uint256) {
+        return _length(set._inner);
+    }
+
+   /**
+    * @dev Returns the value stored at position `index` in the set. O(1).
+    *
+    * Note that there are no guarantees on the ordering of values inside the
+    * array, and it may change when more values are added or removed.
+    *
+    * Requirements:
+    *
+    * - `index` must be strictly less than {length}.
+    */
+    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
+        return uint256(_at(set._inner, index));
+    }
+}