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148 lines
4.9 KiB
148 lines
4.9 KiB
6 years ago
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pragma solidity >=0.4.9 <0.6.0;
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7 years ago
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/// @title Voting with delegation.
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contract Ballot {
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// This declares a new complex type which will
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// be used for variables later.
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// It will represent a single voter.
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struct Voter {
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uint weight; // weight is accumulated by delegation
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bool voted; // if true, that person already voted
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address delegate; // person delegated to
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uint vote; // index of the voted proposal
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}
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// This is a type for a single proposal.
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struct Proposal
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{
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bytes32 name; // short name (up to 32 bytes)
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uint voteCount; // number of accumulated votes
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}
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address public chairperson;
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// This declares a state variable that
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// stores a `Voter` struct for each possible address.
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mapping(address => Voter) public voters;
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// A dynamically-sized array of `Proposal` structs.
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Proposal[] public proposals;
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/// Create a new ballot to choose one of `proposalNames`.
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constructor(bytes32[] memory proposalNames) public {
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chairperson = msg.sender;
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voters[chairperson].weight = 1;
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// For each of the provided proposal names,
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// create a new proposal object and add it
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// to the end of the array.
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for (uint i = 0; i < proposalNames.length; i++) {
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// `Proposal({...})` creates a temporary
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// Proposal object and `proposals.push(...)`
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// appends it to the end of `proposals`.
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proposals.push(Proposal({
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name: proposalNames[i],
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voteCount: 0
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}));
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}
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}
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// Give `voter` the right to vote on this ballot.
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// May only be called by `chairperson`.
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function giveRightToVote(address voter) public {
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if (msg.sender != chairperson || voters[voter].voted) {
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// `throw` terminates and reverts all changes to
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// the state and to Ether balances. It is often
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// a good idea to use this if functions are
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// called incorrectly. But watch out, this
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// will also consume all provided gas.
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revert();
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}
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voters[voter].weight = 1;
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}
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/// Delegate your vote to the voter `to`.
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function delegate(address to) public {
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// assigns reference
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Voter memory sender = voters[msg.sender];
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if (sender.voted)
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revert();
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// Forward the delegation as long as
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// `to` also delegated.
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// In general, such loops are very dangerous,
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// because if they run too long, they might
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// need more gas than is available in a block.
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// In this case, the delegation will not be executed,
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// but in other situations, such loops might
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// cause a contract to get "stuck" completely.
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while (
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voters[to].delegate != address(0) &&
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voters[to].delegate != msg.sender
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) {
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to = voters[to].delegate;
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}
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// We found a loop in the delegation, not allowed.
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if (to == msg.sender) {
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revert();
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}
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// Since `sender` is a reference, this
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// modifies `voters[msg.sender].voted`
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sender.voted = true;
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sender.delegate = to;
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Voter memory delegate = voters[to];
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if (delegate.voted) {
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// If the delegate already voted,
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// directly add to the number of votes
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proposals[delegate.vote].voteCount += sender.weight;
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} else {
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// If the delegate did not vote yet,
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// add to her weight.
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delegate.weight += sender.weight;
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}
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}
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/// Give your vote (including votes delegated to you)
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/// to proposal `proposals[proposal].name`.
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function vote(uint proposal) public {
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Voter memory sender = voters[msg.sender];
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if (sender.voted)
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revert();
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sender.voted = true;
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sender.vote = proposal;
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// If `proposal` is out of the range of the array,
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// this will throw automatically and revert all
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// changes.
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proposals[proposal].voteCount += sender.weight;
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}
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/// @dev Computes the winning proposal taking all
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/// previous votes into account.
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function winningProposal() public view
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returns (uint winningProposal)
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{
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uint winningVoteCount = 0;
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for (uint p = 0; p < proposals.length; p++) {
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if (proposals[p].voteCount > winningVoteCount) {
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winningVoteCount = proposals[p].voteCount;
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winningProposal = p;
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}
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}
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}
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// Calls winningProposal() function to get the index
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// of the winner contained in the proposals array and then
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// returns the name of the winner
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function winnerName() view public
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returns (bytes32 winnerName)
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{
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winnerName = proposals[winningProposal()].name;
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}
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5 years ago
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function testWithArray (bytes32[] memory param) public {}
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}
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