Add burn to giftable tokebs

python/giftable_erc20_token/factory.py

@@ -12,6 +12,9 @@ from chainlib.eth.contract import (
         ABIContractEncoder,
         ABIContractType,
         )
+from chainlib.eth.constant import ZERO_ADDRESS
+from chainlib.jsonrpc import JSONRPCRequest
+from hexathon import add_0x
 
 # local imports
 from giftable_erc20_token.data import data_dir
@@ -107,6 +110,48 @@ class GiftableToken(ERC20):
         return tx
 
 
+    def burn(self, contract_address, sender_address, value, tx_format=TxFormat.JSONRPC):
+        enc = ABIContractEncoder()
+        enc.method('burn')
+        enc.typ(ABIContractType.UINT256)
+        enc.uint256(value)
+        data = enc.get()
+        tx = self.template(sender_address, contract_address, use_nonce=True)
+        tx = self.set_code(tx, data)
+        tx = self.finalize(tx, tx_format)
+        return tx
+
+
+    def burned(self, contract_address, sender_address=ZERO_ADDRESS, id_generator=None):
+        j = JSONRPCRequest(id_generator)
+        o = j.template()
+        o['method'] = 'eth_call'
+        enc = ABIContractEncoder()
+        enc.method('burned')
+        data = add_0x(enc.get())
+        tx = self.template(sender_address, contract_address)
+        tx = self.set_code(tx, data)
+        o['params'].append(self.normalize(tx))
+        o['params'].append('latest')
+        o = j.finalize(o)
+        return o
+
+
+    def total_minted(self, contract_address, sender_address=ZERO_ADDRESS, id_generator=None):
+        j = JSONRPCRequest(id_generator)
+        o = j.template()
+        o['method'] = 'eth_call'
+        enc = ABIContractEncoder()
+        enc.method('totalMinted')
+        data = add_0x(enc.get())
+        tx = self.template(sender_address, contract_address)
+        tx = self.set_code(tx, data)
+        o['params'].append(self.normalize(tx))
+        o['params'].append('latest')
+        o = j.finalize(o)
+        return o
+
+
 def bytecode(**kwargs):
     return GiftableToken.bytecode(version=kwargs.get('version'))
 

python/tests/test_giftable.py

@@ -80,5 +80,44 @@ class TestExpire(TestGiftableExpireToken):
         self.assertEqual(supply, mint_amount)
 
 
+    def test_burn(self):
+        mint_amount = self.initial_supply
+        nonce_oracle = RPCNonceOracle(self.accounts[1], self.rpc)
+        c = GiftableToken(self.chain_spec, signer=self.signer, nonce_oracle=nonce_oracle)
+        (tx_hash, o) = c.burn(self.address, self.accounts[1], int(mint_amount / 4))
+        self.rpc.do(o)
+        o = receipt(tx_hash)
+        r = self.rpc.do(o)
+        self.assertEqual(r['status'], 0)
+
+        nonce_oracle = RPCNonceOracle(self.accounts[0], self.rpc)
+        c = GiftableToken(self.chain_spec, signer=self.signer, nonce_oracle=nonce_oracle)
+        (tx_hash, o) = c.burn(self.address, self.accounts[0], int(mint_amount / 4))
+        self.rpc.do(o)
+        o = receipt(tx_hash)
+        r = self.rpc.do(o)
+        self.assertEqual(r['status'], 1)
+
+        o = c.burned(self.address, sender_address=self.accounts[0])
+        r = self.rpc.do(o)
+        burned = c.parse_balance(r)
+        self.assertEqual(burned, int(mint_amount / 4))
+
+        o = c.balance_of(self.address, self.accounts[0], sender_address=self.accounts[0])
+        r = self.rpc.do(o)
+        balance = c.parse_balance(r)
+        self.assertEqual(balance, mint_amount - burned)
+
+        o = c.total_supply(self.address, sender_address=self.accounts[0])
+        r = self.rpc.do(o)
+        balance = c.parse_balance(r)
+        self.assertEqual(balance, mint_amount - burned)
+
+        o = c.total_minted(self.address, sender_address=self.accounts[0])
+        r = self.rpc.do(o)
+        balance = c.parse_balance(r)
+        self.assertEqual(balance, mint_amount)
+
+
 if __name__ == '__main__':
     unittest.main()

solidity/GiftableToken.sol

@@ -5,8 +5,11 @@ pragma solidity >=0.6.11;
 
 contract GiftableToken {
 
+	// Implements EIP173
 	address public owner;
-	mapping(address => bool) minters;
+
+	// Implements Writer
+	mapping(address => bool) writer;
 
 	// Implements ERC20
 	string public name;
@@ -15,62 +18,90 @@ contract GiftableToken {
 	// Implements ERC20
 	uint8 public decimals;
 	// Implements ERC20
-	uint256 public totalSupply;
-	// Implements ERC20
 	mapping (address => uint256) public balanceOf;
 	// Implements ERC20
 	mapping (address => mapping (address => uint256)) public allowance;
 
-	// timestamp when token contract expires
+	// Implements Burner
+	uint256 public totalMinted;
+	// Implements Burner
+	uint256 public burned;
+
+	// Implements expire
 	uint256 public expires;
 	bool expired;
 
+	// Implements ERC20
 	event Transfer(address indexed _from, address indexed _to, uint256 _value);
+	// Implements ERC20
 	event TransferFrom(address indexed _from, address indexed _to, address indexed _spender, uint256 _value);
+	// Implements ERC20
 	event Approval(address indexed _owner, address indexed _spender, uint256 _value);
+
+	// Implements Minter
 	event Mint(address indexed _minter, address indexed _beneficiary, uint256 _value);
+
+	// Implement Expire
 	event Expired(uint256 _timestamp);
 
+	// Implements Writer
+	event WriterAdded(address _writer);
+	// Implements Writer
+	event WriterRemoved(address _writer);
+
+	// Implements Burner
+	event Burn(uint256 _value);
+
 	constructor(string memory _name, string memory _symbol, uint8 _decimals, uint256 _expireTimestamp) public {
 		owner = msg.sender;
 		name = _name;
 		symbol = _symbol;
 		decimals = _decimals;
-		minters[msg.sender] = true;
 		expires = _expireTimestamp;
 	}
 
+	// Implements ERC20
+	function totalSupply() public returns (uint256) {
+		return totalMinted - burned;
+	}
+
+	// Implements Minter
+	mapping(address => bool) writers;
 	function mintTo(address _to, uint256 _value) public returns (bool) {
-		require(minters[msg.sender] || msg.sender == owner);
+		require(writers[msg.sender] || msg.sender == owner);
 
 		balanceOf[_to] += _value;
-		totalSupply += _value;
+		totalMinted += _value;
 
 		emit Mint(msg.sender, _to, _value);
 
 		return true;
 	}
 
+	// Implements Writer
 	function addWriter(address _minter) public returns (bool) {
 		require(msg.sender == owner);
 
-		minters[_minter] = true;
+		writers[_minter] = true;
 
 		return true;
 	}
 
+	// Implements Writer
 	function removeWriter(address _minter) public returns (bool) {
 		require(msg.sender == owner || msg.sender == _minter);
 
-		minters[_minter] = false;
+		writers[_minter] = false;
 
 		return true;
 	}
 
+	// Implements Writer
 	function isWriter(address _minter) public view returns(bool) {
-		return minters[_minter] || _minter == owner;
+		return writers[_minter] || _minter == owner;
 	}
 
+	// Implements Expire
 	function applyExpiry() public returns(uint8) {
 		if (expires == 0) {
 			return 0;
@@ -97,6 +128,17 @@ contract GiftableToken {
 		return true;
 	}
 
+	// Implements Burner
+	function burn(uint256 _value) public returns (bool) {
+		require(msg.sender == owner, 'ERR_ACCESS');
+		require(balanceOf[msg.sender] >= _value, 'ERR_FUNDS');
+
+		balanceOf[msg.sender] -= _value;
+		burned += _value;
+
+		emit Burn(_value);
+	}
+
 	// Implements ERC20
 	function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
 		require(applyExpiry() == 0);
@@ -140,6 +182,12 @@ contract GiftableToken {
 		if (_sum == 0x9493f8b2) { // EIP173
 			return true;
 		}
+		if (_sum == 0xabe1f1f5) { // Writer
+			return true;
+		}
+		if (_sum == 0xfccc2e79) { // Burner
+			return true;
+		}
 		return false;
 	}
 }