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Minor tidy up #339

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merged 2 commits into from
Jun 14, 2022
Merged

Minor tidy up #339

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055451a
Minor tidy ups
Vectorized Jun 14, 2022
d9b93c1
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Vectorized Jun 14, 2022
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33 changes: 19 additions & 14 deletions contracts/ERC721A.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,11 @@ interface ERC721A__IERC721Receiver {
}

/**
* @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
* the Metadata extension. Built to optimize for lower gas during batch mints.
* @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard,
* including the Metadata extension. Built to optimize for lower gas during batch mints.
*
* Assumes serials are sequentially minted starting at _startTokenId() (defaults to 0, e.g. 0, 1, 2, 3..).
* Assumes serials are sequentially minted starting at `_startTokenId()`
* (defaults to 0, e.g. 0, 1, 2, 3..).
*
* Assumes that an owner cannot have more than 2**64 - 1 (max value of uint64) of supply.
*
Expand Down Expand Up @@ -332,11 +333,13 @@ contract ERC721A is IERC721A {
}

/**
* @dev Casts the boolean to uint256 without branching.
* @dev Returns the `nextInitialized` flag set if `quantity` equals 1.
*/
function _boolToUint256(bool value) private pure returns (uint256 result) {
function _nextInitializedFlag(uint256 quantity) private pure returns (uint256 result) {
// For branchless setting of the `nextInitialized` flag.
assembly {
result := value
// `(quantity == 1) << BITPOS_NEXT_INITIALIZED`.
result := shl(BITPOS_NEXT_INITIALIZED, eq(quantity, 1))
}
}

Expand Down Expand Up @@ -499,16 +502,16 @@ contract ERC721A is IERC721A {
// - `nextInitialized` to `quantity == 1`.
_packedOwnerships[startTokenId] = _packOwnershipData(
to,
(_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED) | _nextExtraData(address(0), to, 0)
_nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)
);

uint256 tokenId = startTokenId;
uint256 end = quantity + startTokenId;
uint256 end = startTokenId + quantity;
do {
emit Transfer(address(0), to, tokenId++);
} while (tokenId < end);

_currentIndex = startTokenId + quantity;
_currentIndex = end;
}
_afterTokenTransfers(address(0), to, startTokenId, quantity);
}
Expand Down Expand Up @@ -558,7 +561,7 @@ contract ERC721A is IERC721A {
// - `nextInitialized` to `quantity == 1`.
_packedOwnerships[startTokenId] = _packOwnershipData(
to,
(_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED) | _nextExtraData(address(0), to, 0)
_nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)
);

emit ConsecutiveTransfer(startTokenId, startTokenId + quantity - 1, address(0), to);
Expand Down Expand Up @@ -703,10 +706,11 @@ contract ERC721A is IERC721A {

(uint256 approvedAddressSlot, address approvedAddress) = _getApprovedAddress(tokenId);

if (approvalCheck)
if (approvalCheck) {
// The nested ifs save around 20+ gas over a compound boolean condition.
if (!_isOwnerOrApproved(approvedAddress, from, _msgSenderERC721A()))
if (!isApprovedForAll(from, _msgSenderERC721A())) revert TransferCallerNotOwnerNorApproved();
}

_beforeTokenTransfers(from, address(0), tokenId, 1);

Expand Down Expand Up @@ -830,7 +834,8 @@ contract ERC721A is IERC721A {
) internal view virtual returns (uint24) {}

/**
* @dev Hook that is called before a set of serially-ordered token ids are about to be transferred. This includes minting.
* @dev Hook that is called before a set of serially-ordered token ids are about to be transferred.
* This includes minting.
* And also called before burning one token.
*
* startTokenId - the first token id to be transferred
Expand All @@ -852,8 +857,8 @@ contract ERC721A is IERC721A {
) internal virtual {}

/**
* @dev Hook that is called after a set of serially-ordered token ids have been transferred. This includes
* minting.
* @dev Hook that is called after a set of serially-ordered token ids have been transferred.
* This includes minting.
* And also called after one token has been burned.
*
* startTokenId - the first token id to be transferred
Expand Down