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Description
🧐 Motivation
Currently, the Bytes library includes a function to slice a chunk of data. I think this is useful, but for cases when the original array can be discarded, I think developers would benefit from implementing an splice function.
We could consider these functions for the Arrays library too, so we can offer a generalized library for doing this with any native solidity type.
📝 Details
Here's a reference implementation for the Arrays library for bytes32[] memory arrays:
/**
* @dev Splices a slice of a bytes32 array. Avoids expanding memory.
*
* Replicates https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice[Javascript's `Array.splice`]
*
* NOTE: Clears the array if `start` is greater than `end`.
*/
function _splice(bytes32[] memory data, uint256 start, uint256 end) private pure returns (bytes32[] memory) {
// sanitize
uint256 length = data.length;
end = Math.min(end, length);
start = Math.min(start, end);
if (start != 0) {
// allocate and copy
for (uint256 i = start; i < end; i++) {
data[i - start] = data[i];
}
}
assembly ("memory-safe") {
mstore(data, sub(end, start)) // Reset the length of the array. Can't overflow because `end` is less than `data.length`.
}
return data;
}Metadata
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