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// Solidity Sample File
// https://solidity.readthedocs.io/en/latest/solidity-by-example.html#voting
pragma solidity >=0.4.22 <0.7.0;
/// @title Voting with delegation.
contract Ballot <beginfold id='1'>{</beginfold id='1'>
// This declares a new complex type which will
// be used for variables later.
// It will represent a single voter.
struct Voter <beginfold id='1'>{</beginfold id='1'>
uint weight; // weight is accumulated by delegation
bool voted; // if true, that person already voted
address delegate; // person delegated to
uint vote; // index of the voted proposal
<endfold id='1'>}</endfold id='1'>
// This is a type for a single proposal.
struct Proposal <beginfold id='1'>{</beginfold id='1'>
bytes32 name; // short name (up to 32 bytes)
uint voteCount; // number of accumulated votes
<endfold id='1'>}</endfold id='1'>
address public chairperson;
// This declares a state variable that
// stores a `Voter` struct for each possible address.
mapping(address => Voter) public voters;
// A dynamically-sized array of `Proposal` structs.
Proposal[] public proposals;
/// Create a new ballot to choose one of `proposalNames`.
constructor(bytes32[] memory proposalNames) public <beginfold id='1'>{</beginfold id='1'>
chairperson = msg.sender;
voters[chairperson].weight = 1;
// For each of the provided proposal names,
// create a new proposal object and add it
// to the end of the array.
for (uint i = 0; i < proposalNames.length; i++) <beginfold id='1'>{</beginfold id='1'>
// `Proposal({...})` creates a temporary
// Proposal object and `proposals.push(...)`
// appends it to the end of `proposals`.
proposals.push(Proposal(<beginfold id='1'>{</beginfold id='1'>
name: proposalNames[i],
voteCount: 0
<endfold id='1'>}</endfold id='1'>));
<endfold id='1'>}</endfold id='1'>
<endfold id='1'>}</endfold id='1'>
// Give `voter` the right to vote on this ballot.
// May only be called by `chairperson`.
function giveRightToVote(address voter) public <beginfold id='1'>{</beginfold id='1'>
// If the first argument of `require` evaluates
// to `false`, execution terminates and all
// changes to the state and to Ether balances
// are reverted.
// This used to consume all gas in old EVM versions, but
// not anymore.
// It is often a good idea to use `require` to check if
// functions are called correctly.
// As a second argument, you can also provide an
// explanation about what went wrong.
require(
msg.sender == chairperson,
"Only chairperson can give right to vote."
);
require(
!voters[voter].voted,
"The voter already voted."
);
require(voters[voter].weight == 0);
voters[voter].weight = 1;
<endfold id='1'>}</endfold id='1'>
/// Delegate your vote to the voter `to`.
function delegate(address to) public <beginfold id='1'>{</beginfold id='1'>
// assigns reference
Voter storage sender = voters[msg.sender];
require(!sender.voted, "You already voted.");
require(to != msg.sender, "Self-delegation is disallowed.");
// Forward the delegation as long as
// `to` also delegated.
// In general, such loops are very dangerous,
// because if they run too long, they might
// need more gas than is available in a block.
// In this case, the delegation will not be executed,
// but in other situations, such loops might
// cause a contract to get "stuck" completely.
while (voters[to].delegate != address(0)) <beginfold id='1'>{</beginfold id='1'>
to = voters[to].delegate;
// We found a loop in the delegation, not allowed.
require(to != msg.sender, "Found loop in delegation.");
<endfold id='1'>}</endfold id='1'>
// Since `sender` is a reference, this
// modifies `voters[msg.sender].voted`
sender.voted = true;
sender.delegate = to;
Voter storage delegate_ = voters[to];
if (delegate_.voted) <beginfold id='1'>{</beginfold id='1'>
// If the delegate already voted,
// directly add to the number of votes
proposals[delegate_.vote].voteCount += sender.weight;
<endfold id='1'>}</endfold id='1'> else <beginfold id='1'>{</beginfold id='1'>
// If the delegate did not vote yet,
// add to her weight.
delegate_.weight += sender.weight;
<endfold id='1'>}</endfold id='1'>
<endfold id='1'>}</endfold id='1'>
/// Give your vote (including votes delegated to you)
/// to proposal `proposals[proposal].name`.
function vote(uint proposal) public <beginfold id='1'>{</beginfold id='1'>
Voter storage sender = voters[msg.sender];
require(sender.weight != 0, "Has no right to vote");
require(!sender.voted, "Already voted.");
sender.voted = true;
sender.vote = proposal;
// If `proposal` is out of the range of the array,
// this will throw automatically and revert all
// changes.
proposals[proposal].voteCount += sender.weight;
<endfold id='1'>}</endfold id='1'>
/// @dev Computes the winning proposal taking all
/// previous votes into account.
function winningProposal() public view
returns (uint winningProposal_)
<beginfold id='1'>{</beginfold id='1'>
uint winningVoteCount = 0;
for (uint p = 0; p < proposals.length; p++) <beginfold id='1'>{</beginfold id='1'>
if (proposals[p].voteCount > winningVoteCount) <beginfold id='1'>{</beginfold id='1'>
winningVoteCount = proposals[p].voteCount;
winningProposal_ = p;
<endfold id='1'>}</endfold id='1'>
<endfold id='1'>}</endfold id='1'>
<endfold id='1'>}</endfold id='1'>
// Calls winningProposal() function to get the index
// of the winner contained in the proposals array and then
// returns the name of the winner
function winnerName() public view
returns (bytes32 winnerName_)
<beginfold id='1'>{</beginfold id='1'>
winnerName_ = proposals[winningProposal()].name;
<endfold id='1'>}</endfold id='1'>
<endfold id='1'>}</endfold id='1'>
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