const format = require('../format-lines');
const { OPTS, LEGACY_OPTS } = require('./Checkpoints.opts.js');
const header = `\
pragma solidity ^0.8.0;
import "./math/Math.sol";
import "./math/SafeCast.sol";
/**
* @dev This library defines the \`History\` struct, for checkpointing values as they change at different points in
* time, and later looking up past values by block number. See {Votes} as an example.
*
* To create a history of checkpoints define a variable type \`Checkpoints.History\` in your contract, and store a new
* checkpoint for the current transaction block using the {push} function.
*
* _Available since v4.5._
*/
`;
const types = opts => `\
struct ${opts.historyTypeName} {
${opts.checkpointTypeName}[] ${opts.checkpointFieldName};
}
struct ${opts.checkpointTypeName} {
${opts.keyTypeName} ${opts.keyFieldName};
${opts.valueTypeName} ${opts.valueFieldName};
}
`;
const operations = opts => `\
/**
* @dev Pushes a (\`key\`, \`value\`) pair into a ${opts.historyTypeName} so that it is stored as the checkpoint.
*
* Returns previous value and new value.
*/
function push(
${opts.historyTypeName} storage self,
${opts.keyTypeName} key,
${opts.valueTypeName} value
) internal returns (${opts.valueTypeName}, ${opts.valueTypeName}) {
return _insert(self.${opts.checkpointFieldName}, key, value);
}
/**
* @dev Returns the value in the first (oldest) checkpoint with key greater or equal than the search key, or zero if there is none.
*/
function lowerLookup(${opts.historyTypeName} storage self, ${opts.keyTypeName} key) internal view returns (${opts.valueTypeName}) {
uint256 len = self.${opts.checkpointFieldName}.length;
uint256 pos = _lowerBinaryLookup(self.${opts.checkpointFieldName}, key, 0, len);
return pos == len ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos).${opts.valueFieldName};
}
/**
* @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.
*/
function upperLookup(${opts.historyTypeName} storage self, ${opts.keyTypeName} key) internal view returns (${opts.valueTypeName}) {
uint256 len = self.${opts.checkpointFieldName}.length;
uint256 pos = _upperBinaryLookup(self.${opts.checkpointFieldName}, key, 0, len);
return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
}
/**
* @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.
*
* NOTE: This is a variant of {upperLookup} that is optimised to find "recent" checkpoint (checkpoints with high keys).
*/
function upperLookupRecent(${opts.historyTypeName} storage self, ${opts.keyTypeName} key) internal view returns (${opts.valueTypeName}) {
uint256 len = self.${opts.checkpointFieldName}.length;
uint256 low = 0;
uint256 high = len;
if (len > 5) {
uint256 mid = len - Math.sqrt(len);
if (key < _unsafeAccess(self.${opts.checkpointFieldName}, mid)._key) {
high = mid;
} else {
low = mid + 1;
}
}
uint256 pos = _upperBinaryLookup(self.${opts.checkpointFieldName}, key, low, high);
return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
}
`;
const legacyOperations = opts => `\
/**
* @dev Returns the value at a given block number. If a checkpoint is not available at that block, the closest one
* before it is returned, or zero otherwise. Because the number returned corresponds to that at the end of the
* block, the requested block number must be in the past, excluding the current block.
*/
function getAtBlock(${opts.historyTypeName} storage self, uint256 blockNumber) internal view returns (uint256) {
require(blockNumber < block.number, "Checkpoints: block not yet mined");
uint32 key = SafeCast.toUint32(blockNumber);
uint256 len = self.${opts.checkpointFieldName}.length;
uint256 pos = _upperBinaryLookup(self.${opts.checkpointFieldName}, key, 0, len);
return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
}
/**
* @dev Returns the value at a given block number. If a checkpoint is not available at that block, the closest one
* before it is returned, or zero otherwise. Similar to {upperLookup} but optimized for the case when the searched
* checkpoint is probably "recent", defined as being among the last sqrt(N) checkpoints where N is the number of
* checkpoints.
*/
function getAtProbablyRecentBlock(${opts.historyTypeName} storage self, uint256 blockNumber) internal view returns (uint256) {
require(blockNumber < block.number, "Checkpoints: block not yet mined");
uint32 key = SafeCast.toUint32(blockNumber);
uint256 len = self.${opts.checkpointFieldName}.length;
uint256 low = 0;
uint256 high = len;
if (len > 5) {
uint256 mid = len - Math.sqrt(len);
if (key < _unsafeAccess(self.${opts.checkpointFieldName}, mid)._blockNumber) {
high = mid;
} else {
low = mid + 1;
}
}
uint256 pos = _upperBinaryLookup(self.${opts.checkpointFieldName}, key, low, high);
return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
}
/**
* @dev Pushes a value onto a History so that it is stored as the checkpoint for the current block.
*
* Returns previous value and new value.
*/
function push(${opts.historyTypeName} storage self, uint256 value) internal returns (uint256, uint256) {
return _insert(self.${opts.checkpointFieldName}, SafeCast.toUint32(block.number), SafeCast.toUint224(value));
}
/**
* @dev Pushes a value onto a History, by updating the latest value using binary operation \`op\`. The new value will
* be set to \`op(latest, delta)\`.
*
* Returns previous value and new value.
*/
function push(
${opts.historyTypeName} storage self,
function(uint256, uint256) view returns (uint256) op,
uint256 delta
) internal returns (uint256, uint256) {
return push(self, op(latest(self), delta));
}
`;
const common = opts => `\
/**
* @dev Returns the value in the most recent checkpoint, or zero if there are no checkpoints.
*/
function latest(${opts.historyTypeName} storage self) internal view returns (${opts.valueTypeName}) {
uint256 pos = self.${opts.checkpointFieldName}.length;
return pos == 0 ? 0 : _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1).${opts.valueFieldName};
}
/**
* @dev Returns whether there is a checkpoint in the structure (i.e. it is not empty), and if so the key and value
* in the most recent checkpoint.
*/
function latestCheckpoint(${opts.historyTypeName} storage self)
internal
view
returns (
bool exists,
${opts.keyTypeName} ${opts.keyFieldName},
${opts.valueTypeName} ${opts.valueFieldName}
)
{
uint256 pos = self.${opts.checkpointFieldName}.length;
if (pos == 0) {
return (false, 0, 0);
} else {
${opts.checkpointTypeName} memory ckpt = _unsafeAccess(self.${opts.checkpointFieldName}, pos - 1);
return (true, ckpt.${opts.keyFieldName}, ckpt.${opts.valueFieldName});
}
}
/**
* @dev Returns the number of checkpoint.
*/
function length(${opts.historyTypeName} storage self) internal view returns (uint256) {
return self.${opts.checkpointFieldName}.length;
}
/**
* @dev Pushes a (\`key\`, \`value\`) pair into an ordered list of checkpoints, either by inserting a new checkpoint,
* or by updating the last one.
*/
function _insert(
${opts.checkpointTypeName}[] storage self,
${opts.keyTypeName} key,
${opts.valueTypeName} value
) private returns (${opts.valueTypeName}, ${opts.valueTypeName}) {
uint256 pos = self.length;
if (pos > 0) {
// Copying to memory is important here.
${opts.checkpointTypeName} memory last = _unsafeAccess(self, pos - 1);
// Checkpoint keys must be non-decreasing.
require(last.${opts.keyFieldName} <= key, "Checkpoint: decreasing keys");
// Update or push new checkpoint
if (last.${opts.keyFieldName} == key) {
_unsafeAccess(self, pos - 1).${opts.valueFieldName} = value;
} else {
self.push(${opts.checkpointTypeName}({${opts.keyFieldName}: key, ${opts.valueFieldName}: value}));
}
return (last.${opts.valueFieldName}, value);
} else {
self.push(${opts.checkpointTypeName}({${opts.keyFieldName}: key, ${opts.valueFieldName}: value}));
return (0, value);
}
}
/**
* @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.
* \`low\` and \`high\` define a section where to do the search, with inclusive \`low\` and exclusive \`high\`.
*
* WARNING: \`high\` should not be greater than the array's length.
*/
function _upperBinaryLookup(
${opts.checkpointTypeName}[] storage self,
${opts.keyTypeName} key,
uint256 low,
uint256 high
) private view returns (uint256) {
while (low < high) {
uint256 mid = Math.average(low, high);
if (_unsafeAccess(self, mid).${opts.keyFieldName} > key) {
high = mid;
} else {
low = mid + 1;
}
}
return high;
}
/**
* @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.
* \`low\` and \`high\` define a section where to do the search, with inclusive \`low\` and exclusive \`high\`.
*
* WARNING: \`high\` should not be greater than the array's length.
*/
function _lowerBinaryLookup(
${opts.checkpointTypeName}[] storage self,
${opts.keyTypeName} key,
uint256 low,
uint256 high
) private view returns (uint256) {
while (low < high) {
uint256 mid = Math.average(low, high);
if (_unsafeAccess(self, mid).${opts.keyFieldName} < key) {
low = mid + 1;
} else {
high = mid;
}
}
return high;
}
/**
* @dev Access an element of the array without performing bounds check. The position is assumed to be within bounds.
*/
function _unsafeAccess(${opts.checkpointTypeName}[] storage self, uint256 pos)
private
pure
returns (${opts.checkpointTypeName} storage result)
{
assembly {
mstore(0, self.slot)
result.slot := add(keccak256(0, 0x20), pos)
}
}
`;
module.exports = format(
header.trimEnd(),
'library Checkpoints {',
[
types(LEGACY_OPTS),
legacyOperations(LEGACY_OPTS),
common(LEGACY_OPTS),
...OPTS.flatMap(opts => [types(opts), operations(opts), common(opts)]),
],
'}',
);