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@@ -206,6 +206,193 @@ library Checkpoints {
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}
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}
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+ struct Trace208 {
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+ Checkpoint208[] _checkpoints;
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+ }
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+
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+ struct Checkpoint208 {
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+ uint48 _key;
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+ uint208 _value;
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+ }
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+
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+ /**
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+ * @dev Pushes a (`key`, `value`) pair into a Trace208 so that it is stored as the checkpoint.
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+ *
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+ * Returns previous value and new value.
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+ *
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+ * IMPORTANT: Never accept `key` as a user input, since an arbitrary `type(uint48).max` key set will disable the library.
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+ */
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+ function push(Trace208 storage self, uint48 key, uint208 value) internal returns (uint208, uint208) {
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+ return _insert(self._checkpoints, key, value);
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+ }
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+
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+ /**
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+ * @dev Returns the value in the first (oldest) checkpoint with key greater or equal than the search key, or zero if there is none.
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+ */
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+ function lowerLookup(Trace208 storage self, uint48 key) internal view returns (uint208) {
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+ uint256 len = self._checkpoints.length;
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+ uint256 pos = _lowerBinaryLookup(self._checkpoints, key, 0, len);
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+ return pos == len ? 0 : _unsafeAccess(self._checkpoints, pos)._value;
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+ }
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+
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+ /**
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+ * @dev Returns the value in the last (most recent) checkpoint with key lower or equal than the search key, or zero if there is none.
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+ */
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+ function upperLookup(Trace208 storage self, uint48 key) internal view returns (uint208) {
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+ uint256 len = self._checkpoints.length;
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+ uint256 pos = _upperBinaryLookup(self._checkpoints, key, 0, len);
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+ return pos == 0 ? 0 : _unsafeAccess(self._checkpoints, pos - 1)._value;
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+ }
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+
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+ /**
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+ * @dev Returns the value in the last (most recent) checkpoint with key lower or equal than the search key, or zero if there is none.
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+ *
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+ * NOTE: This is a variant of {upperLookup} that is optimised to find "recent" checkpoint (checkpoints with high keys).
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+ */
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+ function upperLookupRecent(Trace208 storage self, uint48 key) internal view returns (uint208) {
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+ uint256 len = self._checkpoints.length;
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+
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+ uint256 low = 0;
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+ uint256 high = len;
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+
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+ if (len > 5) {
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+ uint256 mid = len - Math.sqrt(len);
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+ if (key < _unsafeAccess(self._checkpoints, mid)._key) {
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+ high = mid;
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+ } else {
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+ low = mid + 1;
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+ }
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+ }
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+
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+ uint256 pos = _upperBinaryLookup(self._checkpoints, key, low, high);
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+
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+ return pos == 0 ? 0 : _unsafeAccess(self._checkpoints, pos - 1)._value;
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+ }
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+
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+ /**
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+ * @dev Returns the value in the most recent checkpoint, or zero if there are no checkpoints.
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+ */
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+ function latest(Trace208 storage self) internal view returns (uint208) {
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+ uint256 pos = self._checkpoints.length;
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+ return pos == 0 ? 0 : _unsafeAccess(self._checkpoints, pos - 1)._value;
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+ }
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+
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+ /**
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+ * @dev Returns whether there is a checkpoint in the structure (i.e. it is not empty), and if so the key and value
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+ * in the most recent checkpoint.
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+ */
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+ function latestCheckpoint(Trace208 storage self) internal view returns (bool exists, uint48 _key, uint208 _value) {
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+ uint256 pos = self._checkpoints.length;
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+ if (pos == 0) {
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+ return (false, 0, 0);
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+ } else {
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+ Checkpoint208 memory ckpt = _unsafeAccess(self._checkpoints, pos - 1);
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+ return (true, ckpt._key, ckpt._value);
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+ }
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+ }
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+
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+ /**
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+ * @dev Returns the number of checkpoint.
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+ */
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+ function length(Trace208 storage self) internal view returns (uint256) {
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+ return self._checkpoints.length;
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+ }
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+
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+ /**
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+ * @dev Returns checkpoint at given position.
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+ */
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+ function at(Trace208 storage self, uint32 pos) internal view returns (Checkpoint208 memory) {
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+ return self._checkpoints[pos];
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+ }
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+
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+ /**
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+ * @dev Pushes a (`key`, `value`) pair into an ordered list of checkpoints, either by inserting a new checkpoint,
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+ * or by updating the last one.
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+ */
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+ function _insert(Checkpoint208[] storage self, uint48 key, uint208 value) private returns (uint208, uint208) {
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+ uint256 pos = self.length;
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+
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+ if (pos > 0) {
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+ // Copying to memory is important here.
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+ Checkpoint208 memory last = _unsafeAccess(self, pos - 1);
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+
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+ // Checkpoint keys must be non-decreasing.
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+ if (last._key > key) {
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+ revert CheckpointUnorderedInsertion();
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+ }
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+
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+ // Update or push new checkpoint
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+ if (last._key == key) {
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+ _unsafeAccess(self, pos - 1)._value = value;
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+ } else {
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+ self.push(Checkpoint208({_key: key, _value: value}));
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+ }
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+ return (last._value, value);
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+ } else {
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+ self.push(Checkpoint208({_key: key, _value: value}));
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+ return (0, value);
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+ }
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+ }
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+
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+ /**
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+ * @dev Return the index of the last (most recent) checkpoint with key lower or equal than the search key, or `high` if there is none.
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+ * `low` and `high` define a section where to do the search, with inclusive `low` and exclusive `high`.
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+ *
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+ * WARNING: `high` should not be greater than the array's length.
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+ */
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+ function _upperBinaryLookup(
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+ Checkpoint208[] storage self,
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+ uint48 key,
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+ uint256 low,
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+ uint256 high
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+ ) private view returns (uint256) {
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+ while (low < high) {
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+ uint256 mid = Math.average(low, high);
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+ if (_unsafeAccess(self, mid)._key > key) {
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+ high = mid;
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+ } else {
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+ low = mid + 1;
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+ }
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+ }
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+ return high;
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+ }
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+
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+ /**
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+ * @dev Return the index of the first (oldest) checkpoint with key is greater or equal than the search key, or `high` if there is none.
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+ * `low` and `high` define a section where to do the search, with inclusive `low` and exclusive `high`.
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+ *
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+ * WARNING: `high` should not be greater than the array's length.
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+ */
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+ function _lowerBinaryLookup(
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+ Checkpoint208[] storage self,
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+ uint48 key,
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+ uint256 low,
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+ uint256 high
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+ ) private view returns (uint256) {
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+ while (low < high) {
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+ uint256 mid = Math.average(low, high);
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+ if (_unsafeAccess(self, mid)._key < key) {
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+ low = mid + 1;
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+ } else {
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+ high = mid;
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+ }
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+ }
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+ return high;
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+ }
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+
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+ /**
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+ * @dev Access an element of the array without performing bounds check. The position is assumed to be within bounds.
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+ */
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+ function _unsafeAccess(
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+ Checkpoint208[] storage self,
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+ uint256 pos
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+ ) private pure returns (Checkpoint208 storage result) {
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+ assembly {
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+ mstore(0, self.slot)
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+ result.slot := add(keccak256(0, 0x20), pos)
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+ }
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+ }
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+
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struct Trace160 {
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Checkpoint160[] _checkpoints;
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}
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Hadrien Croubois