ArtistV6.sol

contract ArtistV6 {
    struct Shareholder {
        address account;
        uint32 percentAllocation;
    }

    // Mapping of edition id to descriptive data.
    mapping(uint256 => Edition) public editions;
    // Balances for collectors captable
    mapping(uint256 => mapping(address => uint32)) collectorBalances;

    // etc...

    function getShareholdersCapTable(uint256 _editionId) public returns (Shareholder[] memory shareholders) {
        uint32 numSold = editions[_editionId].numSold;

        uint32 royaltyRemainder = uint32(PERCENTAGE_SCALE) % numSold;
        uint32 royaltyPerToken = uint32(PERCENTAGE_SCALE) / numSold;

        address[] memory shareholderAddresses = new address[](numSold);

        // build shareholder addresses array (with duplicates if owner owns more than 1)
        uint256 shiftedEditionId = (_editionId << 128);
        for (uint256 i = 0; i < numSold; i++) {
            uint256 tokenId = shiftedEditionId | (i + 1);
            address shareholder = ownerOf(tokenId);
            shareholderAddresses[i] = shareholder;

            collectorBalances[_editionId][shareholder] += 1;
        }

        // Loop over shareholderAddresses
        uint32 shareholderIndex = 0;
        Shareholder[] memory shareholdersWithNulls = new Shareholder[](numSold);
        for (uint32 j = 0; j < shareholderAddresses.length; j++) {
            // Create shareholder struct if it doesn't exist
            if (collectorBalances[_editionId][shareholderAddresses[j]] != 0) {
                shareholdersWithNulls[shareholderIndex] = Shareholder({
                    account: shareholderAddresses[j],
                    percentAllocation: royaltyPerToken * collectorBalances[_editionId][shareholderAddresses[j]]
                });

                // Zero out balance
                collectorBalances[_editionId][shareholderAddresses[j]] = 0;

                shareholderIndex++;
            }
        }

        // add remainder to the first shareholder (if zero, it's more efficient to just add it anyway)
        shareholdersWithNulls[0].percentAllocation += royaltyRemainder;

        // Remove any null items left over from the last step
        Shareholder[] memory unsortedShareholders = new Shareholder[](shareholderIndex);
        for (uint32 k = 0; k < shareholderIndex; k++) {
            // For every one that isn't null, add to final array
            if (shareholdersWithNulls[k].account != address(0)) {
                unsortedShareholders[k] = shareholdersWithNulls[k];
            }
        }

        // Sort & return shareholders
        return sortSharedholders(unsortedShareholders);
    }
}