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300 lines
10 KiB
JavaScript
300 lines
10 KiB
JavaScript
const format = require('../format-lines');
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const VALUE_SIZES = [224, 160];
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const header = `\
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pragma solidity ^0.8.0;
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import "./math/Math.sol";
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import "./math/SafeCast.sol";
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/**
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* @dev This library defines the \`History\` struct, for checkpointing values as they change at different points in
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* time, and later looking up past values by block number. See {Votes} as an example.
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*
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* To create a history of checkpoints define a variable type \`Checkpoints.History\` in your contract, and store a new
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* checkpoint for the current transaction block using the {push} function.
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*
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* _Available since v4.5._
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*/
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`;
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const types = opts => `\
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struct ${opts.historyTypeName} {
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${opts.checkpointTypeName}[] ${opts.checkpointFieldName};
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}
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struct ${opts.checkpointTypeName} {
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${opts.keyTypeName} ${opts.keyFieldName};
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${opts.valueTypeName} ${opts.valueFieldName};
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}
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`;
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/* eslint-disable max-len */
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const operations = opts => `\
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/**
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* @dev Pushes a (\`key\`, \`value\`) pair into a ${opts.historyTypeName} so that it is stored as the checkpoint.
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*
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* Returns previous value and new value.
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*/
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function push(
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${opts.historyTypeName} storage self,
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${opts.keyTypeName} key,
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${opts.valueTypeName} value
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) internal returns (${opts.valueTypeName}, ${opts.valueTypeName}) {
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return _insert(self.${opts.checkpointFieldName}, key, value);
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}
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/**
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* @dev Returns the value in the 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(${opts.historyTypeName} storage self, ${opts.keyTypeName} key) internal view returns (${opts.valueTypeName}) {
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uint256 len = self.${opts.checkpointFieldName}.length;
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uint256 pos = _lowerBinaryLookup(self.${opts.checkpointFieldName}, key, 0, len);
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return pos == len ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos).${opts.valueFieldName};
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}
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/**
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* @dev Returns the value in the most recent checkpoint with key lower or equal than the search key.
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*/
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function upperLookup(${opts.historyTypeName} storage self, ${opts.keyTypeName} key) internal view returns (${opts.valueTypeName}) {
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uint256 len = self.${opts.checkpointFieldName}.length;
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uint256 pos = _upperBinaryLookup(self.${opts.checkpointFieldName}, key, 0, len);
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return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
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}
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`;
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const legacyOperations = opts => `\
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/**
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* @dev Returns the value at a given block number. If a checkpoint is not available at that block, the closest one
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* before it is returned, or zero otherwise. Because the number returned corresponds to that at the end of the
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* block, the requested block number must be in the past, excluding the current block.
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*/
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function getAtBlock(${opts.historyTypeName} storage self, uint256 blockNumber) internal view returns (uint256) {
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require(blockNumber < block.number, "Checkpoints: block not yet mined");
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uint32 key = SafeCast.toUint32(blockNumber);
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uint256 len = self.${opts.checkpointFieldName}.length;
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uint256 pos = _upperBinaryLookup(self.${opts.checkpointFieldName}, key, 0, len);
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return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
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}
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/**
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* @dev Returns the value at a given block number. If a checkpoint is not available at that block, the closest one
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* before it is returned, or zero otherwise. Similar to {upperLookup} but optimized for the case when the searched
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* checkpoint is probably "recent", defined as being among the last sqrt(N) checkpoints where N is the number of
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* checkpoints.
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*/
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function getAtProbablyRecentBlock(${opts.historyTypeName} storage self, uint256 blockNumber) internal view returns (uint256) {
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require(blockNumber < block.number, "Checkpoints: block not yet mined");
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uint32 key = SafeCast.toUint32(blockNumber);
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uint256 len = self.${opts.checkpointFieldName}.length;
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uint256 low = 0;
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uint256 high = len;
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if (len > 5) {
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uint256 mid = len - Math.sqrt(len);
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if (key < _unsafeAccess(self.${opts.checkpointFieldName}, mid)._blockNumber) {
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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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uint256 pos = _upperBinaryLookup(self.${opts.checkpointFieldName}, key, low, high);
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return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
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}
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/**
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* @dev Pushes a value onto a History so that it is stored as the checkpoint for the current block.
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*
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* Returns previous value and new value.
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*/
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function push(${opts.historyTypeName} storage self, uint256 value) internal returns (uint256, uint256) {
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return _insert(self.${opts.checkpointFieldName}, SafeCast.toUint32(block.number), SafeCast.toUint224(value));
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}
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/**
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* @dev Pushes a value onto a History, by updating the latest value using binary operation \`op\`. The new value will
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* be set to \`op(latest, delta)\`.
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*
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* Returns previous value and new value.
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*/
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function push(
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${opts.historyTypeName} storage self,
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function(uint256, uint256) view returns (uint256) op,
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uint256 delta
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) internal returns (uint256, uint256) {
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return push(self, op(latest(self), delta));
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}
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`;
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const common = opts => `\
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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(${opts.historyTypeName} storage self) internal view returns (${opts.valueTypeName}) {
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uint256 pos = self.${opts.checkpointFieldName}.length;
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return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
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}
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/**
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* @dev Returns whether there is a checkpoint in the structure (i.e. it is not empty), and if so the key and value
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* in the most recent checkpoint.
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*/
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function latestCheckpoint(${opts.historyTypeName} storage self)
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internal
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view
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returns (
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bool exists,
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${opts.keyTypeName} ${opts.keyFieldName},
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${opts.valueTypeName} ${opts.valueFieldName}
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)
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{
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uint256 pos = self.${opts.checkpointFieldName}.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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${opts.checkpointTypeName} memory ckpt = _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1);
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return (true, ckpt.${opts.keyFieldName}, ckpt.${opts.valueFieldName});
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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(${opts.historyTypeName} storage self) internal view returns (uint256) {
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return self.${opts.checkpointFieldName}.length;
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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(
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${opts.checkpointTypeName}[] storage self,
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${opts.keyTypeName} key,
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${opts.valueTypeName} value
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) private returns (${opts.valueTypeName}, ${opts.valueTypeName}) {
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uint256 pos = self.length;
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if (pos > 0) {
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// Copying to memory is important here.
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${opts.checkpointTypeName} memory last = _unsafeAccess(self, pos - 1);
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// Checkpoint keys must be non-decreasing.
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require(last.${opts.keyFieldName} <= key, "Checkpoint: decreasing keys");
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// Update or push new checkpoint
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if (last.${opts.keyFieldName} == key) {
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_unsafeAccess(self, pos - 1).${opts.valueFieldName} = value;
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} else {
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self.push(${opts.checkpointTypeName}({${opts.keyFieldName}: key, ${opts.valueFieldName}: value}));
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}
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return (last.${opts.valueFieldName}, value);
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} else {
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self.push(${opts.checkpointTypeName}({${opts.keyFieldName}: key, ${opts.valueFieldName}: value}));
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return (0, value);
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}
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}
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/**
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* @dev Return the index of the oldest checkpoint whose key is greater than the search key, or \`high\` if there is none.
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* \`low\` and \`high\` define a section where to do the search, with inclusive \`low\` and exclusive \`high\`.
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*
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* WARNING: \`high\` should not be greater than the array's length.
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*/
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function _upperBinaryLookup(
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${opts.checkpointTypeName}[] storage self,
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${opts.keyTypeName} key,
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uint256 low,
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uint256 high
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) private view returns (uint256) {
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while (low < high) {
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uint256 mid = Math.average(low, high);
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if (_unsafeAccess(self, mid).${opts.keyFieldName} > 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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* @dev Return the index of the oldest checkpoint whose 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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${opts.checkpointTypeName}[] storage self,
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${opts.keyTypeName} 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).${opts.keyFieldName} < key) {
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low = mid + 1;
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} else {
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high = mid;
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}
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}
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return high;
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}
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/**
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* @dev Access an element of the array without performing bounds check. The position is assumed to be within bounds.
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*/
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function _unsafeAccess(${opts.checkpointTypeName}[] storage self, uint256 pos)
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private
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pure
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returns (${opts.checkpointTypeName} storage result)
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{
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assembly {
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mstore(0, self.slot)
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result.slot := add(keccak256(0, 0x20), pos)
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}
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}
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`;
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/* eslint-enable max-len */
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// OPTIONS
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const defaultOpts = size => ({
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historyTypeName: `Trace${size}`,
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checkpointTypeName: `Checkpoint${size}`,
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checkpointFieldName: '_checkpoints',
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keyTypeName: `uint${256 - size}`,
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keyFieldName: '_key',
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valueTypeName: `uint${size}`,
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valueFieldName: '_value',
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});
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const OPTS = VALUE_SIZES.map(size => defaultOpts(size));
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const LEGACY_OPTS = {
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...defaultOpts(224),
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historyTypeName: 'History',
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checkpointTypeName: 'Checkpoint',
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keyFieldName: '_blockNumber',
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};
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// GENERATE
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module.exports = format(
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header.trimEnd(),
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'library Checkpoints {',
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[
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// Legacy types & functions
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types(LEGACY_OPTS),
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legacyOperations(LEGACY_OPTS),
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common(LEGACY_OPTS),
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// New flavors
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...OPTS.flatMap(opts => [types(opts), operations(opts), common(opts)]),
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],
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'}',
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);
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