def transfer(from_acct,to_acct,amount):
"""
Transfer amount of tokens from from_acct to to_acct
:param from_acct: the account from which the amount of tokens will be transferred
:param to_acct: the account to which the amount of tokens will be transferred
:param amount: the amount of the tokens to be transferred, >= 0
:return: True means success, False or raising exception means failure.
"""
if len(to_acct) != 20 or len(from_acct) != 20:
raise Exception("address length error")
if CheckWitness(from_acct) == False:
return False
fromKey = concat(BALANCE_PREFIX,from_acct)
fromBalance = Get(ctx,fromKey)
if amount > fromBalance:
return False
if amount == fromBalance:
Delete(ctx,fromKey)
else:
Put(ctx,fromKey,fromBalance - amount)
toKey = concat(BALANCE_PREFIX,to_acct)
toBalance = Get(ctx,toKey)
Put(ctx,toKey,toBalance + amount)
# Notify(["transfer", AddressToBase58(from_acct), AddressToBase58(to_acct), amount])
TransferEvent(AddressToBase58(from_acct), AddressToBase58(to_acct), amount)
return True
def _regis(addr):
uIndex=userIdIndex()
uIndex+=1
addr58=AddressToBase58(addr)
user=User(0,'',[],0,addr58)
saveUserIdIndex(uIndex)
saveIndexToUser(uIndex,user)
saveAddrToUserId(addr,uIndex)
return uIndex
def transferFrom(spender,from_acct,to_acct,amount):
"""
spender spends amount of tokens on the behalf of from_acct, spender makes a transaction of amount of tokens
from from_acct to to_acct
:param spender:
:param from_acct:
:param to_acct:
:param amount:
:return:
"""
if len(spender) != 20 or len(from_acct) != 20 or len(to_acct) != 20:
raise Exception("address length error")
if CheckWitness(spender) == False:
return False
fromKey = concat(BALANCE_PREFIX, from_acct)
fromBalance = Get(ctx, fromKey)
if amount > fromBalance:
return False
approveKey = concat(concat(APPROVE_PREFIX,from_acct),spender)
approvedAmount = Get(ctx,approveKey)
toKey = concat(BALANCE_PREFIX,to_acct)
toBalance = Get(ctx, toKey)
if amount > approvedAmount:
return False
elif amount == approvedAmount:
Delete(ctx,approveKey)
Delete(ctx, fromBalance - amount)
else:
Put(ctx,approveKey,approvedAmount - amount)
Put(ctx, fromKey, fromBalance - amount)
Put(ctx, toKey, toBalance + amount)
# Notify(["transfer", AddressToBase58(from_acct), AddressToBase58(to_acct), amount])
TransferEvent(AddressToBase58(from_acct), AddressToBase58(to_acct), amount)
return True
def approve(owner,spender,amount):
"""
owner allow spender to spend amount of token from owner account
Note here, the amount should be less than the balance of owner right now.
:param owner:
:param spender:
:param amount: amount>=0
:return: True means success, False or raising exception means failure.
"""
if len(spender) != 20 or len(owner) != 20:
raise Exception("address length error")
if CheckWitness(owner) == False:
return False
if amount > balanceOf(owner):
return False
key = concat(concat(APPROVE_PREFIX,owner),spender)
Put(ctx, key, amount)
# Notify(["approval", AddressToBase58(owner), AddressToBase58(spender), amount])
ApprovalEvent(AddressToBase58(owner), AddressToBase58(spender), amount)
return True
def transfer(from_acct, to_acct, amount):
"""
Transfer amount of tokens from from_acct to to_acct
:param from_acct: the account from which the amount of tokens will be transferred
:param to_acct: the account to which the amount of tokens will be transferred
:param amount: the amount of the tokens to be transferred, >= 0
:return: True means success, False or raising exception means failure.
"""
if len(to_acct) != 20 or len(from_acct) != 20:
raise Exception("address length error")
if CheckWitness(from_acct) == False:
return False
# This part is marked as commits since transferring of 0 MYT should fire event, too.
# if from_acct == to_acct or amount == 0:
# return True
fromKey = concat(BALANCE_PREFIX, from_acct)
fromBalance = Get(ctx, fromKey)
if amount > fromBalance:
return False
if amount == fromBalance:
Delete(ctx, fromKey)
else:
Put(ctx, fromKey, fromBalance - amount)
toKey = concat(BALANCE_PREFIX, to_acct)
toBalance = Get(ctx, toKey)
Put(ctx, toKey, toBalance + amount)
fromBase58 = AddressToBase58(from_acct)
toBase58 = AddressToBase58(to_acct)
Notify(['transfer', fromBase58, toBase58, amount])
# Notify(['transfer', from_acct, to_acct, amount])
return True
def init():
"""
initialize the contract, put some important info into the storage in the blockchain
:return:
"""
if Get(ctx, SUPPLY_KEY):
Notify('Already initialized!')
return False
else:
total = TOTAL_AMOUNT * FACTOR
Put(ctx, SUPPLY_KEY, total)
Put(ctx, concat(BALANCE_PREFIX, OWNER), total)
ownerBase58 = AddressToBase58(OWNER)
Notify(['transfer', '', OWNER, total])
return True
def init():
"""
initialize the contract, put some important info into the storage in the blockchain
:return:
"""
if Get(ctx,SUPPLY_KEY):
Notify("Already initialized!")
return False
else:
total = TOTAL_AMOUNT * FACTOR
Put(ctx,SUPPLY_KEY,total)
Put(ctx,concat(BALANCE_PREFIX,OWNER),total)
# Notify(["transfer", "", Base58ToAddress(OWNER), total])
ownerBase58 = AddressToBase58(OWNER)
TransferEvent("", ownerBase58, total)
return True