def burn(account: UInt160, amount: int):
"""
Burns zNEO tokens.
:param account: the address of the account that is pulling out cryptocurrency of this contract
:type account: UInt160
:param amount: the amount of gas to be refunded
:type amount: int
:raise AssertionError: raised if `account` length is not 20, amount is less than than 0 or the account doesn't have
enough zNEO to burn
"""
assert len(account) == 20
assert amount >= 0
if check_witness(account):
if amount != 0:
current_total_supply = totalSupply()
account_balance = balanceOf(account)
assert account_balance >= amount
put(SUPPLY_KEY, current_total_supply - amount)
if account_balance == amount:
delete(account)
else:
put(account, account_balance - amount)
on_transfer(account, None, amount)
post_transfer(account, None, amount, None, False)
call_contract(NEO, 'transfer',
[executing_script_hash, account, amount, None])
def set_balance(owner: UInt160, amount: int):
old = balanceOf(owner)
new = old + (amount)
debug(['set_balance: ', amount])
key = mk_balance_key(owner)
if (new > 0):
put(key, new)
else:
delete(key)
def transfer(from_address: UInt160, to_address: UInt160, amount: int,
data: Any) -> bool:
"""
Transfers a specified amount of NEP17 tokens from one account to another
If the method succeeds, it must fire the `transfer` event and must return true, even if the amount is 0,
or from and to are the same address.
:param from_address: the address to transfer from
:type from_address: UInt160
:param to_address: the address to transfer to
:type to_address: UInt160
:param amount: the amount of NEP17 tokens to transfer
:type amount: int
:param data: whatever data is pertinent to the onPayment method
:type data: Any
:return: whether the transfer was successful
:raise AssertionError: raised if `from_address` or `to_address` length is not 20 or if `amount` if less than zero.
"""
# the parameters from and to should be 20-byte addresses. If not, this method should throw an exception.
assert len(from_address) == 20 and len(to_address) == 20
# the parameter amount must be greater than or equal to 0. If not, this method should throw an exception.
assert amount >= 0
# The function MUST return false if the from account balance does not have enough tokens to spend.
from_balance = storage.get(from_address).to_int()
if from_balance < amount:
return False
# The function should check whether the from address equals the caller contract hash.
# If so, the transfer should be processed;
# If not, the function should use the check_witness to verify the transfer.
if from_address != runtime.calling_script_hash:
if not runtime.check_witness(from_address):
return False
# skip balance changes if transferring to yourself or transferring 0 cryptocurrency
if from_address != to_address and amount != 0:
if from_balance == amount:
storage.delete(from_address)
else:
storage.put(from_address, from_balance - amount)
to_balance = storage.get(to_address).to_int()
storage.put(to_address, to_balance + amount)
# if the method succeeds, it must fire the transfer event
on_transfer(from_address, to_address, amount)
# if the to_address is a smart contract, it must call the contracts onPayment
post_transfer(from_address, to_address, amount, data)
# and then it must return true
return True
def transfer(from_address: bytes, to_address: bytes, amount: int) -> bool:
"""
Transfers a specified amount of NEP5 tokens from one account to another
If the method succeeds, it must fire the `transfer` event and must return true, even if the amount is 0,
or from and to are the same address.
:param from_address: the address to transfer from
:type from_address: bytes
:param to_address: the address to transfer to
:type to_address: bytes
:param amount: the amount of NEP5 tokens to transfer
:type amount: int
:return: whether the transfer was successful
:raise AssertionError: raised if `from_address` or `to_address` length is not 20 or if `amount` if less than zero.
"""
# the parameters from and to should be 20-byte addresses. If not, this method should throw an exception.
assert len(from_address) == 20 and len(to_address) == 20
# the parameter amount must be greater than or equal to 0. If not, this method should throw an exception.
assert amount >= 0
# The function MUST return false if the from account balance does not have enough tokens to spend.
from_balance = get(from_address).to_int()
if from_balance < amount:
return False
# The function should check whether the from address equals the caller contract hash.
# If so, the transfer should be processed;
# If not, the function should use the check_witness to verify the transfer.
if from_address != calling_script_hash:
if not check_witness(from_address):
return False
# if the `to_address` is a deployed contract, the function should check the payable flag of this contract
# TODO: include example when objects are implemented
if from_address == to_address:
# transfer to self
return True
if from_balance == amount:
delete(from_address)
else:
put(from_address, from_balance - amount)
to_balance = get(to_address).to_int()
put(to_address, to_balance + amount)
# if the method succeeds, it must fire the transfer event, and must return true
on_transfer(from_address, to_address, amount)
return True
def cancel_player_bet(player: UInt160, bet_id: UInt256):
if len(get(POOL_OWNER_KEY + bet_id)) == 0:
raise Exception("Pool doesn't exist.")
if not check_witness(player):
raise Exception('No authorization.')
if len(get(POOL_RESULT_KEY + bet_id)) > 0:
raise Exception('Pool is finished already')
if len(get(POOL_BET_KEY + bet_id + player)) == 0:
raise Exception("Player didn't bet on this pool")
# 5% fee of the bet for cancelling
refund_value = PRICE_IN_GAS - PRICE_IN_GAS * 5 // 100
transfer_gas(executing_script_hash, player, refund_value)
delete(POOL_BET_KEY + bet_id + player)
def kyc_remove(addresses: List[UInt160]) -> int:
"""
Removes the given addresses from the kyc whitelist
:param addresses: a list with the addresses to be removed
:return: the number of removed addresses
"""
removed_addresses = 0
if is_administrator():
for address in addresses:
if len(address) == 20:
kyc_key = KYC_WHITELIST_PREFIX + address
storage.delete(kyc_key)
removed_addresses += 1
return removed_addresses
def main(operation: str, arg: str, val: str) -> Any:
print("context")
if operation == 'sget':
return get(arg)
elif operation == 'sput':
put(arg, val)
return True
elif operation == 'sdel':
delete(arg)
return True
return 'unknown operation'
def main(operation: str, arg: str, val: str) -> Any:
storage_context = get_context()
print("context")
if operation == 'sget':
return get(arg, storage_context)
elif operation == 'sput':
put(arg, val, storage_context)
return True
elif operation == 'sdel':
delete(arg, storage_context)
return True
return 'unknown operation'
def burn(account: UInt160, amount: int):
"""
Burns DSTONE tokens.
:param account: the address of the account that is sending cryptocurrency to this contract
:param amount: the amount of gas to be refunded
:raise AssertionError: raised if amount is less than than 0 or the check_witness using ADMIN goes wrong
"""
assert amount >= 0 and check_witness(ADMIN)
if amount != 0:
current_total_supply = totalSupply()
account_balance = balanceOf(account)
assert account_balance >= amount
put(TOTAL_SUPPLY, current_total_supply - amount)
if account_balance == amount:
delete(account)
else:
put(account, account_balance - amount)
on_transfer(account, None, amount)
post_transfer(account, None, amount, None)
def deleteStream(stream: Dict[str, Any]):
"""
Delete a stream from storage
Args:
stream (Dict[str, Any]): Stream object
"""
b_id = cast(bytes, stream['id'])
delete(b'streams/' + b_id)
sender_key = cast(bytes, stream['sender']) + b':' + b_id
recipient_key = cast(bytes, stream['recipient']) + b':' + b_id
delete(b'bysender/' + sender_key)
delete(b'byrecipient/' + recipient_key)
def Main(key: Union[bytes, str]):
context = get_context()
delete(key, context)
def transferFrom(spender: UInt160, from_address: UInt160, to_address: UInt160,
amount: int, data: Any) -> bool:
"""
A spender transfers an amount of zNEO tokens allowed from one account to another.
If the method succeeds, it must fire the `Transfer` event and must return true, even if the amount is 0,
or from and to are the same address.
:param spender: the address that is trying to transfer zNEO tokens
:type spender: UInt160
:param from_address: the address to transfer from
:type from_address: UInt160
:param to_address: the address to transfer to
:type to_address: UInt160
:param amount: the amount of zNEO tokens to transfer
:type amount: int
:param data: whatever data is pertinent to the onPayment method
:type data: Any
:return: whether the transfer was successful
:raise AssertionError: raised if `spender`, `from_address` or `to_address` length is not 20 or if `amount` if less
than zero.
"""
# the parameters from and to should be 20-byte addresses. If not, this method should throw an exception.
assert len(spender) == 20 and len(from_address) == 20 and len(
to_address) == 20
# the parameter amount must be greater than or equal to 0. If not, this method should throw an exception.
assert amount >= 0
# The function MUST return false if the from account balance does not have enough tokens to spend.
from_balance = get(from_address).to_int()
if from_balance < amount:
return False
# The function MUST return false if the from account balance does not allow enough tokens to be spent by the spender.
allowed = allowance(from_address, spender)
if allowed < amount:
return False
# The function should check whether the spender address equals the caller contract hash.
# If so, the transfer should be processed;
# If not, the function should use the check_witness to verify the transfer.
if spender != calling_script_hash:
if not check_witness(spender):
return False
if allowed == amount:
delete(ALLOWANCE_PREFIX + from_address + spender)
else:
put(ALLOWANCE_PREFIX + from_address + spender, allowed - amount)
# skip balance changes if transferring to yourself or transferring 0 cryptocurrency
if from_address != to_address and amount != 0:
if from_balance == amount:
delete(from_address)
else:
put(from_address, from_balance - amount)
to_balance = get(to_address).to_int()
put(to_address, to_balance + amount)
# if the method succeeds, it must fire the transfer event
on_transfer(from_address, to_address, amount)
# if the to_address is a smart contract, it must call the contracts onPayment
post_transfer(from_address, to_address, amount, data, True)
# and then it must return true
return True
def Main(key: bytes):
delete(key)
def remove_locked_view_counter(tokenId: bytes):
key = mk_lv_key(tokenId)
debug(['remove_locked_view_counter: ', key, tokenId])
delete(key)
def Main(key: int):
delete(key)
def delete_value(key: str):
storage.delete(key)
def remove_owner_of(tokenId: bytes):
key = mk_token_key(tokenId)
debug(['remove_owner_of: ', key, tokenId])
delete(key)
def remove_token(self, token_id: bytes):
storage.delete(account_prefix_key(self.address) + token_id)
self._balance = self._balance - 1
self.set_account()
def Main(key: ByteString):
context = get_context()
delete(key, context)
def Main(key: str):
delete(key)
def remove_meta(tokenId: bytes):
key = mk_meta_key(tokenId)
debug(['remove_meta: ', key, tokenId])
delete(key)
def transfer_from(originator: UInt160, from_address: UInt160,
to_address: UInt160, amount: int, data: Any) -> bool:
"""
Transfers an amount from the `from` account to the `to` account if the `originator` has been approved to transfer
the requested amount.
:param originator: the address where the actual token is
:type originator: UInt160
:param from_address: the address to transfer from with originator's approval
:type from_address: UInt160
:param to_address: the address to transfer to
:type to_address: UInt160
:param amount: the amount of NEP17 tokens to transfer
:type amount: int
:param data: any pertinent data that might validate the transaction
:type data: Any
:return: whether the transfer was successful
:raise AssertionError: raised if `from_address` or `to_address` length is not 20 or if `amount` if less than zero.
"""
# the parameters from and to should be 20-byte addresses. If not, this method should throw an exception.
assert len(originator) == 20 and len(from_address) == 20 and len(
to_address) == 20
# the parameter amount must be greater than or equal to 0. If not, this method should throw an exception.
assert amount >= 0
# The function should check whether the from address equals the caller contract hash.
# If so, the transfer should be processed;
# If not, the function should use the check_witness to verify the transfer.
if from_address != runtime.calling_script_hash:
if not runtime.check_witness(from_address):
return False
approved_transfer_amount = allowance(originator, from_address)
if approved_transfer_amount < amount:
return False
originator_balance = balance_of(originator)
if originator_balance < amount:
return False
# update allowance between originator and from
if approved_transfer_amount == amount:
storage.delete(TRANSFER_ALLOWANCE_PREFIX + originator + from_address)
else:
storage.put(TRANSFER_ALLOWANCE_PREFIX + originator + from_address,
approved_transfer_amount - amount)
# skip balance changes if transferring to yourself or transferring 0 cryptocurrency
if amount != 0 and from_address != to_address:
# update originator's balance
if originator_balance == amount:
storage.delete(originator)
else:
storage.put(originator, originator_balance - amount)
# updates to's balance
to_balance = storage.get(to_address).to_int()
storage.put(to_address, to_balance + amount)
# if the method succeeds, it must fire the transfer event
on_transfer(from_address, to_address, amount)
# if the to_address is a smart contract, it must call the contracts onPayment
post_transfer(from_address, to_address, amount, data)
# and then it must return true
return True
def remove_locked_content(tokenId: bytes):
key = mk_locked_key(tokenId)
debug(['remove_locked_content: ', key, tokenId])
delete(key)
def remove_royalties(tokenId: bytes):
key = mk_royalties_key(tokenId)
debug(['remove_royalties: ', key, tokenId])
delete(key)
def transferFrom(originator: bytes, from_address: bytes, to_address: bytes,
amount: int) -> bool:
"""
Transfers an amount from the `from` account to the `to` account if the `originator` has been approved to transfer
the requested amount.
:param originator: the address where the actual token is
:type originator: bytes
:param from_address: the address to transfer from with originator's approval
:type from_address: bytes
:param to_address: the address to transfer to
:type to_address: bytes
:param amount: the amount of NEP5 tokens to transfer
:type amount: int
:return: whether the transfer was successful
:raise AssertionError: raised if `from_address` or `to_address` length is not 20 or if `amount` if less than zero.
"""
# the parameters from and to should be 20-byte addresses. If not, this method should throw an exception.
assert len(originator) == 20 and len(from_address) == 20 and len(
to_address) == 20
# the parameter amount must be greater than or equal to 0. If not, this method should throw an exception.
assert amount >= 0
# The function should check whether the from address equals the caller contract hash.
# If so, the transfer should be processed;
# If not, the function should use the check_witness to verify the transfer.
if from_address != calling_script_hash:
if not check_witness(from_address):
return False
# if the `to_address` is a deployed contract, the function should check the payable flag of this contract
# TODO: include example when objects are implemented
approved_transfer_amount = allowance(originator, from_address)
if approved_transfer_amount < amount:
return False
originator_balance = balanceOf(originator)
if originator_balance < amount:
return False
# don't accept a meaningless value
if amount == 0 or originator == to_address or from_address == to_address:
return True # nep5 standard: return true when amount is 0 or from == to
# update allowance between originator and from
if approved_transfer_amount == amount:
delete(TRANSFER_ALLOWANCE_PREFIX + originator + from_address)
else:
put(TRANSFER_ALLOWANCE_PREFIX + originator + from_address,
approved_transfer_amount - amount)
# update originator's balance
if originator_balance == amount:
delete(originator)
else:
put(originator, originator_balance - amount)
# updates to's balance
to_balance = get(to_address).to_int()
put(to_address, to_balance + amount)
# if the method succeeds, it must fire the transfer event, and must return true
on_transfer(from_address, to_address, amount)
return True
