def do_approve(self, storage: StorageAPI, t_owner, t_spender, amount):
if not CheckWitness(t_owner):
print("Incorrect permission")
return False
if amount < 0:
print("Negative amount")
return False
from_balance = storage.get(t_owner)
# cannot approve an amount that is
# currently greater than the from balance
if from_balance >= amount:
approval_key = concat(t_owner, t_spender)
if len(approval_key) != 40:
return False
if amount == 0:
storage.delete(approval_key)
else:
storage.put(approval_key, amount)
OnApprove(t_owner, t_spender, amount)
return True
return False
def kyc_deregister(self, args, token: Token):
"""
:param args:list a list of addresses to deregister
:param token: Token A token object with your ICO settings
:return:
int: The number of addresses deregistered from KYC
"""
ok_count = 0
storage = StorageAPI()
owner = storage.get(token.owner_key)
if CheckWitness(owner):
for address in args:
if len(address) == 20:
kyc_storage_key = concat(self.kyc_key, address)
storage.delete(kyc_storage_key)
OnKYCDeregister(address)
ok_count += 1
return ok_count
def cancel_change_owner(token: Token):
"""
Cancel a pending ownership transfer request
:param token: Token The token to cancel the ownership transfer for
:return:
bool: Whether the operation was successful
"""
storage = StorageAPI()
new_owner = storage.get(token.new_owner_key)
if not new_owner:
print(
"Can't cancel_change_owner unless an owner change is already pending"
)
return False
owner = storage.get(token.owner_key)
if not CheckWitness(owner):
print("Must be owner to cancel change_owner")
return False
# delete the new owner to cancel the transfer.
storage.delete(token.new_owner_key)
return True
def do_transfer_from(self, storage: StorageAPI, t_from, t_to, amount):
if amount <= 0:
return False
available_key = concat(t_from, t_to)
if len(available_key) != 40:
return False
available_to_to_addr = storage.get(available_key)
if available_to_to_addr < amount:
print("Insufficient funds approved")
return False
from_balance = storage.get(t_from)
if from_balance < amount:
print("Insufficient tokens in from balance")
return False
to_balance = storage.get(t_to)
new_from_balance = from_balance - amount
new_to_balance = to_balance + amount
storage.put(t_to, new_to_balance)
storage.put(t_from, new_from_balance)
print("transfer complete")
new_allowance = available_to_to_addr - amount
if new_allowance == 0:
print("removing all balance")
storage.delete(available_key)
else:
print("updating allowance to new allowance")
storage.put(available_key, new_allowance)
OnTransfer(t_from, t_to, amount)
return True
def resume_sale(token: Token):
"""
Resume the sale
:param token: Token The token of the sale to resume
:return:
bool: Whether the operation was successful
"""
storage = StorageAPI()
owner = storage.get(token.owner_key)
if not CheckWitness(owner):
print("Must be owner to resume sale")
return False
# mark the sale as active
storage.delete(token.sale_paused_key)
return True
def do_transfer(self, storage: StorageAPI, t_from, t_to, amount):
if amount <= 0:
return False
if len(t_to) != 20:
return False
if CheckWitness(t_from):
if t_from == t_to:
print("transfer to self!")
return True
from_val = storage.get(t_from)
if from_val < amount:
print("insufficient funds")
return False
if from_val == amount:
storage.delete(t_from)
else:
difference = from_val - amount
storage.put(t_from, difference)
to_value = storage.get(t_to)
to_total = to_value + amount
storage.put(t_to, to_total)
OnTransfer(t_from, t_to, amount)
return True
else:
print("from address is not the tx sender")
return False
def accept_owner(token: Token):
"""
Change the owner of this smart contract who will be able to perform protected operations
:param token: Token The token to change the owner for
:return:
bool: Whether the operation was successful
"""
storage = StorageAPI()
new_owner = storage.get(token.new_owner_key)
if not new_owner:
print("Must call change_owner before accept_owner")
return False
if not CheckWitness(new_owner):
print("Must be new_owner to accept owner")
return False
# setup the new owner.
storage.put(token.owner_key, new_owner)
# now that it's accepted, make the change official by removing the pending new_owner
storage.delete(token.new_owner_key)
return True
