Merge pull request #140 from AragonOne/vesting

Vested Token implementation (Standard Token with vesting calendar)

contracts/SafeMath.sol

@@ -11,6 +11,13 @@ contract SafeMath {
     return c;
   }
 
+  function safeDiv(uint a, uint b) internal returns (uint) {
+    assert(b > 0);
+    uint c = a / b;
+    assert(a == b * c + a % b);
+    return c;
+  }
+
   function safeSub(uint a, uint b) internal returns (uint) {
     assert(b <= a);
     return a - b;
@@ -22,8 +29,23 @@ contract SafeMath {
     return c;
   }
 
+  function max64(uint64 a, uint64 b) internal constant returns (uint64) {
+    return a >= b ? a : b;
+  }
+
+  function min64(uint64 a, uint64 b) internal constant returns (uint64) {
+    return a < b ? a : b;
+  }
+
+  function max256(uint256 a, uint256 b) internal constant returns (uint256) {
+    return a >= b ? a : b;
+  }
+
+  function min256(uint256 a, uint256 b) internal constant returns (uint256) {
+    return a < b ? a : b;
+  }
+
   function assert(bool assertion) internal {
     if (!assertion) throw;
   }
 }
-

contracts/test-helpers/VestedTokenMock.sol

+pragma solidity ^0.4.4;
+
+import '../token/VestedToken.sol';
+
+// mock class using StandardToken
+contract VestedTokenMock is VestedToken {
+  function VestedTokenMock(address initialAccount, uint initialBalance) {
+    balances[initialAccount] = initialBalance;
+    totalSupply = initialBalance;
+  }
+}

contracts/token/VestedToken.sol

+pragma solidity ^0.4.8;
+
+import "./StandardToken.sol";
+
+contract VestedToken is StandardToken {
+  struct TokenGrant {
+    address granter;
+    uint256 value;
+    uint64 cliff;
+    uint64 vesting;
+    uint64 start;
+  }
+
+  mapping (address => TokenGrant[]) public grants;
+
+  function grantVestedTokens(address _to, uint256 _value, uint64 _start, uint64 _cliff, uint64 _vesting) {
+    if (_cliff < _start) throw;
+    if (_vesting < _start) throw;
+    if (_vesting < _cliff) throw;
+
+    TokenGrant memory grant = TokenGrant({start: _start, value: _value, cliff: _cliff, vesting: _vesting, granter: msg.sender});
+    grants[_to].push(grant);
+
+    transfer(_to, _value);
+  }
+
+  function revokeTokenGrant(address _holder, uint _grantId) {
+    TokenGrant grant = grants[_holder][_grantId];
+
+    if (grant.granter != msg.sender) throw;
+    uint256 nonVested = nonVestedTokens(grant, uint64(now));
+
+    // remove grant from array
+    delete grants[_holder][_grantId];
+    grants[_holder][_grantId] = grants[_holder][grants[_holder].length - 1];
+    grants[_holder].length -= 1;
+
+    balances[msg.sender] = safeAdd(balances[msg.sender], nonVested);
+    balances[_holder] = safeSub(balances[_holder], nonVested);
+    Transfer(_holder, msg.sender, nonVested);
+  }
+
+  function tokenGrantsCount(address _holder) constant returns (uint index) {
+    return grants[_holder].length;
+  }
+
+  function tokenGrant(address _holder, uint _grantId) constant returns (address granter, uint256 value, uint256 vested, uint64 start, uint64 cliff, uint64 vesting) {
+    TokenGrant grant = grants[_holder][_grantId];
+
+    granter = grant.granter;
+    value = grant.value;
+    start = grant.start;
+    cliff = grant.cliff;
+    vesting = grant.vesting;
+
+    vested = vestedTokens(grant, uint64(now));
+  }
+
+  function vestedTokens(TokenGrant grant, uint64 time) private constant returns (uint256) {
+    return calculateVestedTokens(grant.value, uint256(time), uint256(grant.start), uint256(grant.cliff), uint256(grant.vesting));
+  }
+
+  function calculateVestedTokens(uint256 tokens, uint256 time, uint256 start, uint256 cliff, uint256 vesting) constant returns (uint256 vestedTokens) {
+    if (time < cliff) return 0;
+    if (time > vesting) return tokens;
+
+    uint256 cliffTokens = safeDiv(safeMul(tokens, safeSub(cliff, start)), safeSub(vesting, start));
+    vestedTokens = cliffTokens;
+
+    uint256 vestingTokens = safeSub(tokens, cliffTokens);
+
+    vestedTokens = safeAdd(vestedTokens, safeDiv(safeMul(vestingTokens, safeSub(time, cliff)), safeSub(vesting, start)));
+  }
+
+  function nonVestedTokens(TokenGrant grant, uint64 time) private constant returns (uint256) {
+    return safeSub(grant.value, vestedTokens(grant, time));
+  }
+
+  function lastTokenIsTransferableDate(address holder) constant public returns (uint64 date) {
+    date = uint64(now);
+    uint256 grantIndex = grants[holder].length;
+    for (uint256 i = 0; i < grantIndex; i++) {
+      date = max64(grants[holder][i].vesting, date);
+    }
+  }
+
+  function transferableTokens(address holder, uint64 time) constant public returns (uint256 nonVested) {
+    uint256 grantIndex = grants[holder].length;
+
+    for (uint256 i = 0; i < grantIndex; i++) {
+      nonVested = safeAdd(nonVested, nonVestedTokens(grants[holder][i], time));
+    }
+
+    return safeSub(balances[holder], nonVested);
+  }
+
+  function transfer(address _to, uint _value) returns (bool success){
+    if (_value > transferableTokens(msg.sender, uint64(now))) throw;
+
+    return super.transfer(_to, _value);
+  }
+}

package.json

@@ -12,6 +12,7 @@
   },
   "scripts": {
     "test": "truffle test",
+    "console": "truffle console",
     "install": "scripts/install.sh"
   },
   "repository": {

test/VestedToken.js

+const assertJump = require('./helpers/assertJump');
+const timer = require('./helpers/timer');
+
+contract('VestedToken', function(accounts) {
+  let token = null
+  let now = 0
+
+  const tokenAmount = 50
+
+  const granter = accounts[0]
+  const receiver = accounts[1]
+
+  beforeEach(async () => {
+    token = await VestedTokenMock.new(granter, 100);
+    now = web3.eth.getBlock(web3.eth.blockNumber).timestamp;
+  })
+
+  it('granter can grant tokens without vesting', async () => {
+    await token.transfer(receiver, tokenAmount, { from: granter })
+
+    assert.equal(await token.balanceOf(receiver), tokenAmount);
+    assert.equal(await token.transferableTokens(receiver, now), tokenAmount);
+  })
+
+  describe('getting a token grant', async () => {
+    const cliff = 10000
+    const vesting = 20000 // seconds
+
+    beforeEach(async () => {
+      await token.grantVestedTokens(receiver, tokenAmount, now, now + cliff, now + vesting, { from: granter })
+    })
+
+    it('tokens are received', async () => {
+      assert.equal(await token.balanceOf(receiver), tokenAmount);
+    })
+
+    it('has 0 transferable tokens before cliff', async () => {
+      assert.equal(await token.transferableTokens(receiver, now), 0);
+    })
+
+    it('all tokens are transferable after vesting', async () => {
+      assert.equal(await token.transferableTokens(receiver, now + vesting + 1), tokenAmount);
+    })
+
+    it('throws when trying to transfer non vested tokens', async () => {
+      try {
+        await token.transfer(accounts[7], 1, { from: receiver })
+      } catch(error) {
+        return assertJump(error);
+      }
+      assert.fail('should have thrown before');
+    })
+
+    it('can be revoked by granter', async () => {
+      await token.revokeTokenGrant(receiver, 0, { from: granter });
+      assert.equal(await token.balanceOf(receiver), 0);
+      assert.equal(await token.balanceOf(granter), 100);
+    })
+
+    it('cannot be revoked by non granter', async () => {
+      try {
+        await token.revokeTokenGrant(receiver, 0, { from: accounts[3] });
+      } catch(error) {
+        return assertJump(error);
+      }
+      assert.fail('should have thrown before');
+    })
+
+    it('can be revoked by granter and non vested tokens are returned', async () => {
+      await timer(cliff);
+      await token.revokeTokenGrant(receiver, 0, { from: granter });
+      assert.equal(await token.balanceOf(receiver), tokenAmount * cliff / vesting);
+    })
+
+    it('can transfer all tokens after vesting ends', async () => {
+      await timer(vesting + 1);
+      await token.transfer(accounts[7], tokenAmount, { from: receiver })
+      assert.equal(await token.balanceOf(accounts[7]), tokenAmount);
+    })
+  })
+});

test/helpers/timer.js

+// timer for tests specific to testrpc
+module.exports = s => {
+  return new Promise((resolve, reject) => {
+    web3.currentProvider.sendAsync({
+      jsonrpc: '2.0', 
+      method: 'evm_increaseTime',
+      params: [s], // 60 seaconds, may need to be hex, I forget
+      id: new Date().getTime() // Id of the request; anything works, really
+    }, function(err) {
+      if (err) return reject(err);
+      resolve();
+    });
+    //setTimeout(() => resolve(), s * 1000 + 600) // 600ms breathing room for testrpc to sync
+  });
+};