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0001 <!DOCTYPE html> 0002 <html><head> 0003 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/> 0004 <title>test.sol</title> 0005 <meta name="generator" content="KF5::SyntaxHighlighting - Definition (Solidity) - Theme (Breeze Light)"/> 0006 </head><body style="background-color:#ffffff;color:#1f1c1b"><pre> 0007 <span style="color:#898887">// Solidity Sample File</span> 0008 <span style="color:#898887">// https://solidity.readthedocs.io/en/latest/solidity-by-example.html#voting</span> 0009 0010 <span style="font-weight:bold">pragma</span> <span style="color:#644a9b;font-weight:bold">solidity</span> >=0.4.22 <0.7.0; 0011 0012 <span style="color:#898887">/// </span><span style="color:#ca60ca">@title</span><span style="color:#898887"> Voting with delegation.</span> 0013 <span style="font-weight:bold">contract</span> Ballot <span style="color:#ca60ca">{</span> 0014 <span style="color:#898887">// This declares a new complex type which will</span> 0015 <span style="color:#898887">// be used for variables later.</span> 0016 <span style="color:#898887">// It will represent a single voter.</span> 0017 <span style="font-weight:bold">struct</span> Voter <span style="color:#ca60ca">{</span> 0018 <span style="color:#0057ae">uint</span> weight<span style="color:#ca60ca">;</span> <span style="color:#898887">// weight is accumulated by delegation</span> 0019 <span style="color:#0057ae">bool</span> voted<span style="color:#ca60ca">;</span> <span style="color:#898887">// if true, that person already voted</span> 0020 <span style="color:#0057ae">address</span> delegate<span style="color:#ca60ca">;</span> <span style="color:#898887">// person delegated to</span> 0021 <span style="color:#0057ae">uint</span> vote<span style="color:#ca60ca">;</span> <span style="color:#898887">// index of the voted proposal</span> 0022 <span style="color:#ca60ca">}</span> 0023 0024 <span style="color:#898887">// This is a type for a single proposal.</span> 0025 <span style="font-weight:bold">struct</span> Proposal <span style="color:#ca60ca">{</span> 0026 <span style="color:#0057ae">bytes32</span> name<span style="color:#ca60ca">;</span> <span style="color:#898887">// short name (up to 32 bytes)</span> 0027 <span style="color:#0057ae">uint</span> voteCount<span style="color:#ca60ca">;</span> <span style="color:#898887">// number of accumulated votes</span> 0028 <span style="color:#ca60ca">}</span> 0029 0030 <span style="color:#0057ae">address</span> <span style="font-weight:bold">public</span> chairperson<span style="color:#ca60ca">;</span> 0031 0032 <span style="color:#898887">// This declares a state variable that</span> 0033 <span style="color:#898887">// stores a `Voter` struct for each possible address.</span> 0034 <span style="color:#0057ae">mapping</span><span style="color:#ca60ca">(</span><span style="color:#0057ae">address</span> <span style="color:#ca60ca">=></span> Voter<span style="color:#ca60ca">)</span> <span style="font-weight:bold">public</span> voters<span style="color:#ca60ca">;</span> 0035 0036 <span style="color:#898887">// A dynamically-sized array of `Proposal` structs.</span> 0037 Proposal<span style="color:#ca60ca">[]</span> <span style="font-weight:bold">public</span> proposals<span style="color:#ca60ca">;</span> 0038 0039 <span style="color:#898887">/// Create a new ballot to choose one of `proposalNames`.</span> 0040 <span style="font-weight:bold">constructor</span><span style="color:#ca60ca">(</span><span style="color:#0057ae">bytes32</span><span style="color:#ca60ca">[]</span> <span style="font-weight:bold">memory</span> proposalNames<span style="color:#ca60ca">)</span> <span style="font-weight:bold">public</span> <span style="color:#ca60ca">{</span> 0041 chairperson <span style="color:#ca60ca">=</span> <span style="color:#644a9b;font-weight:bold">msg</span><span style="color:#ca60ca">.</span>sender<span style="color:#ca60ca">;</span> 0042 voters<span style="color:#ca60ca">[</span>chairperson<span style="color:#ca60ca">].</span>weight <span style="color:#ca60ca">=</span> <span style="color:#b08000">1</span><span style="color:#ca60ca">;</span> 0043 0044 <span style="color:#898887">// For each of the provided proposal names,</span> 0045 <span style="color:#898887">// create a new proposal object and add it</span> 0046 <span style="color:#898887">// to the end of the array.</span> 0047 <span style="font-weight:bold">for</span> <span style="color:#ca60ca">(</span><span style="color:#0057ae">uint</span> i <span style="color:#ca60ca">=</span> <span style="color:#b08000">0</span><span style="color:#ca60ca">;</span> i <span style="color:#ca60ca"><</span> proposalNames<span style="color:#ca60ca">.</span>length<span style="color:#ca60ca">;</span> i<span style="color:#644a9b;font-weight:bold">++</span><span style="color:#ca60ca">)</span> <span style="color:#ca60ca">{</span> 0048 <span style="color:#898887">// `Proposal({...})` creates a temporary</span> 0049 <span style="color:#898887">// Proposal object and `proposals.push(...)`</span> 0050 <span style="color:#898887">// appends it to the end of `proposals`.</span> 0051 proposals<span style="color:#ca60ca">.</span>push<span style="color:#ca60ca">(</span>Proposal<span style="color:#ca60ca">({</span> 0052 name<span style="color:#ca60ca">:</span> proposalNames<span style="color:#ca60ca">[</span>i<span style="color:#ca60ca">],</span> 0053 voteCount<span style="color:#ca60ca">:</span> <span style="color:#b08000">0</span> 0054 <span style="color:#ca60ca">}));</span> 0055 <span style="color:#ca60ca">}</span> 0056 <span style="color:#ca60ca">}</span> 0057 0058 <span style="color:#898887">// Give `voter` the right to vote on this ballot.</span> 0059 <span style="color:#898887">// May only be called by `chairperson`.</span> 0060 <span style="font-weight:bold">function</span> giveRightToVote<span style="color:#ca60ca">(</span><span style="color:#0057ae">address</span> voter<span style="color:#ca60ca">)</span> <span style="font-weight:bold">public</span> <span style="color:#ca60ca">{</span> 0061 <span style="color:#898887">// If the first argument of `require` evaluates</span> 0062 <span style="color:#898887">// to `false`, execution terminates and all</span> 0063 <span style="color:#898887">// changes to the state and to Ether balances</span> 0064 <span style="color:#898887">// are reverted.</span> 0065 <span style="color:#898887">// This used to consume all gas in old EVM versions, but</span> 0066 <span style="color:#898887">// not anymore.</span> 0067 <span style="color:#898887">// It is often a good idea to use `require` to check if</span> 0068 <span style="color:#898887">// functions are called correctly.</span> 0069 <span style="color:#898887">// As a second argument, you can also provide an</span> 0070 <span style="color:#898887">// explanation about what went wrong.</span> 0071 <span style="color:#644a9b;font-weight:bold">require</span><span style="color:#ca60ca">(</span> 0072 <span style="color:#644a9b;font-weight:bold">msg</span><span style="color:#ca60ca">.</span>sender <span style="color:#ca60ca">==</span> chairperson<span style="color:#ca60ca">,</span> 0073 <span style="color:#bf0303">"Only chairperson can give right to vote."</span> 0074 <span style="color:#ca60ca">);</span> 0075 <span style="color:#644a9b;font-weight:bold">require</span><span style="color:#ca60ca">(</span> 0076 <span style="color:#ca60ca">!</span>voters<span style="color:#ca60ca">[</span>voter<span style="color:#ca60ca">].</span>voted<span style="color:#ca60ca">,</span> 0077 <span style="color:#bf0303">"The voter already voted."</span> 0078 <span style="color:#ca60ca">);</span> 0079 <span style="color:#644a9b;font-weight:bold">require</span><span style="color:#ca60ca">(</span>voters<span style="color:#ca60ca">[</span>voter<span style="color:#ca60ca">].</span>weight <span style="color:#ca60ca">==</span> <span style="color:#b08000">0</span><span style="color:#ca60ca">);</span> 0080 voters<span style="color:#ca60ca">[</span>voter<span style="color:#ca60ca">].</span>weight <span style="color:#ca60ca">=</span> <span style="color:#b08000">1</span><span style="color:#ca60ca">;</span> 0081 <span style="color:#ca60ca">}</span> 0082 0083 <span style="color:#898887">/// Delegate your vote to the voter `to`.</span> 0084 <span style="font-weight:bold">function</span> delegate<span style="color:#ca60ca">(</span><span style="color:#0057ae">address</span> to<span style="color:#ca60ca">)</span> <span style="font-weight:bold">public</span> <span style="color:#ca60ca">{</span> 0085 <span style="color:#898887">// assigns reference</span> 0086 Voter <span style="font-weight:bold">storage</span> sender <span style="color:#ca60ca">=</span> voters<span style="color:#ca60ca">[</span><span style="color:#644a9b;font-weight:bold">msg</span><span style="color:#ca60ca">.</span>sender<span style="color:#ca60ca">];</span> 0087 <span style="color:#644a9b;font-weight:bold">require</span><span style="color:#ca60ca">(!</span>sender<span style="color:#ca60ca">.</span>voted<span style="color:#ca60ca">,</span> <span style="color:#bf0303">"You already voted."</span><span style="color:#ca60ca">);</span> 0088 0089 <span style="color:#644a9b;font-weight:bold">require</span><span style="color:#ca60ca">(</span>to <span style="color:#ca60ca">!=</span> <span style="color:#644a9b;font-weight:bold">msg</span><span style="color:#ca60ca">.</span>sender<span style="color:#ca60ca">,</span> <span style="color:#bf0303">"Self-delegation is disallowed."</span><span style="color:#ca60ca">);</span> 0090 0091 <span style="color:#898887">// Forward the delegation as long as</span> 0092 <span style="color:#898887">// `to` also delegated.</span> 0093 <span style="color:#898887">// In general, such loops are very dangerous,</span> 0094 <span style="color:#898887">// because if they run too long, they might</span> 0095 <span style="color:#898887">// need more gas than is available in a block.</span> 0096 <span style="color:#898887">// In this case, the delegation will not be executed,</span> 0097 <span style="color:#898887">// but in other situations, such loops might</span> 0098 <span style="color:#898887">// cause a contract to get "stuck" completely.</span> 0099 <span style="font-weight:bold">while</span> <span style="color:#ca60ca">(</span>voters<span style="color:#ca60ca">[</span>to<span style="color:#ca60ca">].</span>delegate <span style="color:#ca60ca">!=</span> <span style="color:#0057ae">address</span><span style="color:#ca60ca">(</span><span style="color:#b08000">0</span><span style="color:#ca60ca">))</span> <span style="color:#ca60ca">{</span> 0100 to <span style="color:#ca60ca">=</span> voters<span style="color:#ca60ca">[</span>to<span style="color:#ca60ca">].</span>delegate<span style="color:#ca60ca">;</span> 0101 0102 <span style="color:#898887">// We found a loop in the delegation, not allowed.</span> 0103 <span style="color:#644a9b;font-weight:bold">require</span><span style="color:#ca60ca">(</span>to <span style="color:#ca60ca">!=</span> <span style="color:#644a9b;font-weight:bold">msg</span><span style="color:#ca60ca">.</span>sender<span style="color:#ca60ca">,</span> <span style="color:#bf0303">"Found loop in delegation."</span><span style="color:#ca60ca">);</span> 0104 <span style="color:#ca60ca">}</span> 0105 0106 <span style="color:#898887">// Since `sender` is a reference, this</span> 0107 <span style="color:#898887">// modifies `voters[msg.sender].voted`</span> 0108 sender<span style="color:#ca60ca">.</span>voted <span style="color:#ca60ca">=</span> <span style="font-weight:bold">true</span><span style="color:#ca60ca">;</span> 0109 sender<span style="color:#ca60ca">.</span>delegate <span style="color:#ca60ca">=</span> to<span style="color:#ca60ca">;</span> 0110 Voter <span style="font-weight:bold">storage</span> delegate_ <span style="color:#ca60ca">=</span> voters<span style="color:#ca60ca">[</span>to<span style="color:#ca60ca">];</span> 0111 <span style="font-weight:bold">if</span> <span style="color:#ca60ca">(</span>delegate_<span style="color:#ca60ca">.</span>voted<span style="color:#ca60ca">)</span> <span style="color:#ca60ca">{</span> 0112 <span style="color:#898887">// If the delegate already voted,</span> 0113 <span style="color:#898887">// directly add to the number of votes</span> 0114 proposals<span style="color:#ca60ca">[</span>delegate_<span style="color:#ca60ca">.</span>vote<span style="color:#ca60ca">].</span>voteCount <span style="color:#ca60ca">+=</span> sender<span style="color:#ca60ca">.</span>weight<span style="color:#ca60ca">;</span> 0115 <span style="color:#ca60ca">}</span> <span style="font-weight:bold">else</span> <span style="color:#ca60ca">{</span> 0116 <span style="color:#898887">// If the delegate did not vote yet,</span> 0117 <span style="color:#898887">// add to her weight.</span> 0118 delegate_<span style="color:#ca60ca">.</span>weight <span style="color:#ca60ca">+=</span> sender<span style="color:#ca60ca">.</span>weight<span style="color:#ca60ca">;</span> 0119 <span style="color:#ca60ca">}</span> 0120 <span style="color:#ca60ca">}</span> 0121 0122 <span style="color:#898887">/// Give your vote (including votes delegated to you)</span> 0123 <span style="color:#898887">/// to proposal `proposals[proposal].name`.</span> 0124 <span style="font-weight:bold">function</span> vote<span style="color:#ca60ca">(</span><span style="color:#0057ae">uint</span> proposal<span style="color:#ca60ca">)</span> <span style="font-weight:bold">public</span> <span style="color:#ca60ca">{</span> 0125 Voter <span style="font-weight:bold">storage</span> sender <span style="color:#ca60ca">=</span> voters<span style="color:#ca60ca">[</span><span style="color:#644a9b;font-weight:bold">msg</span><span style="color:#ca60ca">.</span>sender<span style="color:#ca60ca">];</span> 0126 <span style="color:#644a9b;font-weight:bold">require</span><span style="color:#ca60ca">(</span>sender<span style="color:#ca60ca">.</span>weight <span style="color:#ca60ca">!=</span> <span style="color:#b08000">0</span><span style="color:#ca60ca">,</span> <span style="color:#bf0303">"Has no right to vote"</span><span style="color:#ca60ca">);</span> 0127 <span style="color:#644a9b;font-weight:bold">require</span><span style="color:#ca60ca">(!</span>sender<span style="color:#ca60ca">.</span>voted<span style="color:#ca60ca">,</span> <span style="color:#bf0303">"Already voted."</span><span style="color:#ca60ca">);</span> 0128 sender<span style="color:#ca60ca">.</span>voted <span style="color:#ca60ca">=</span> <span style="font-weight:bold">true</span><span style="color:#ca60ca">;</span> 0129 sender<span style="color:#ca60ca">.</span>vote <span style="color:#ca60ca">=</span> proposal<span style="color:#ca60ca">;</span> 0130 0131 <span style="color:#898887">// If `proposal` is out of the range of the array,</span> 0132 <span style="color:#898887">// this will throw automatically and revert all</span> 0133 <span style="color:#898887">// changes.</span> 0134 proposals<span style="color:#ca60ca">[</span>proposal<span style="color:#ca60ca">].</span>voteCount <span style="color:#ca60ca">+=</span> sender<span style="color:#ca60ca">.</span>weight<span style="color:#ca60ca">;</span> 0135 <span style="color:#ca60ca">}</span> 0136 0137 <span style="color:#898887">/// </span><span style="color:#ca60ca">@dev</span><span style="color:#898887"> Computes the winning proposal taking all</span> 0138 <span style="color:#898887">/// previous votes into account.</span> 0139 <span style="font-weight:bold">function</span> winningProposal<span style="color:#ca60ca">()</span> <span style="font-weight:bold">public</span> <span style="font-weight:bold">view</span> 0140 <span style="font-weight:bold">returns</span> <span style="color:#ca60ca">(</span><span style="color:#0057ae">uint</span> winningProposal_<span style="color:#ca60ca">)</span> 0141 <span style="color:#ca60ca">{</span> 0142 <span style="color:#0057ae">uint</span> winningVoteCount <span style="color:#ca60ca">=</span> <span style="color:#b08000">0</span><span style="color:#ca60ca">;</span> 0143 <span style="font-weight:bold">for</span> <span style="color:#ca60ca">(</span><span style="color:#0057ae">uint</span> p <span style="color:#ca60ca">=</span> <span style="color:#b08000">0</span><span style="color:#ca60ca">;</span> p <span style="color:#ca60ca"><</span> proposals<span style="color:#ca60ca">.</span>length<span style="color:#ca60ca">;</span> p<span style="color:#644a9b;font-weight:bold">++</span><span style="color:#ca60ca">)</span> <span style="color:#ca60ca">{</span> 0144 <span style="font-weight:bold">if</span> <span style="color:#ca60ca">(</span>proposals<span style="color:#ca60ca">[</span>p<span style="color:#ca60ca">].</span>voteCount <span style="color:#ca60ca">></span> winningVoteCount<span style="color:#ca60ca">)</span> <span style="color:#ca60ca">{</span> 0145 winningVoteCount <span style="color:#ca60ca">=</span> proposals<span style="color:#ca60ca">[</span>p<span style="color:#ca60ca">].</span>voteCount<span style="color:#ca60ca">;</span> 0146 winningProposal_ <span style="color:#ca60ca">=</span> p<span style="color:#ca60ca">;</span> 0147 <span style="color:#ca60ca">}</span> 0148 <span style="color:#ca60ca">}</span> 0149 <span style="color:#ca60ca">}</span> 0150 0151 <span style="color:#898887">// Calls winningProposal() function to get the index</span> 0152 <span style="color:#898887">// of the winner contained in the proposals array and then</span> 0153 <span style="color:#898887">// returns the name of the winner</span> 0154 <span style="font-weight:bold">function</span> winnerName<span style="color:#ca60ca">()</span> <span style="font-weight:bold">public</span> <span style="font-weight:bold">view</span> 0155 <span style="font-weight:bold">returns</span> <span style="color:#ca60ca">(</span><span style="color:#0057ae">bytes32</span> winnerName_<span style="color:#ca60ca">)</span> 0156 <span style="color:#ca60ca">{</span> 0157 winnerName_ <span style="color:#ca60ca">=</span> proposals<span style="color:#ca60ca">[</span>winningProposal<span style="color:#ca60ca">()].</span>name<span style="color:#ca60ca">;</span> 0158 <span style="color:#ca60ca">}</span> 0159 <span style="color:#ca60ca">}</span> 0160 </pre></body></html>