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this commit optimizes the make_byte_array_copier and
make_dynarray_copier routines. specifically, it reduces the number of
words to copy in the main loop by 1. for batch copies
(memory/calldata/code -> memory), this reduces gas by 3, and for
non-batch copies (e.g. storage -> memory), this reduces gas by one loop
iteration and one read. importantly, when the number of bytes is small
(e.g. copy Bytes[32]), this triggers an optimization in `copy_bytes` so
the whole copy operation is a single load/store (plus the load/store
for the length)
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@nrryuya @ssteiger @jacqueswww @iamdefinitelyahuman @fubuloubu @charles-cooper @shogochiai @samajammin @skellet0r @spinoch
# @dev Implementation of ERC-20 token standard.
# @author Takayuki Jimba (@yudetamago)
# https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
from vyper.interfaces import ERC20
from vyper.interfaces import ERC20Detailed
implements: ERC20
implements: ERC20Detailed
event Transfer:
sender: indexed(address)
receiver: indexed(address)
value: uint256
event Approval:
owner: indexed(address)
spender: indexed(address)
value: uint256
name: public(String[32])
symbol: public(String[32])
decimals: public(uint8)
# NOTE: By declaring `balanceOf` as public, vyper automatically generates a 'balanceOf()' getter
# method to allow access to account balances.
# The _KeyType will become a required parameter for the getter and it will return _ValueType.
# See: https://vyper.readthedocs.io/en/v0.1.0-beta.8/types.html?highlight=getter#mappings
balanceOf: public(HashMap[address, uint256])
# By declaring `allowance` as public, vyper automatically generates the `allowance()` getter
allowance: public(HashMap[address, HashMap[address, uint256]])
# By declaring `totalSupply` as public, we automatically create the `totalSupply()` getter
totalSupply: public(uint256)
minter: address
@external
def __init__(_name: String[32], _symbol: String[32], _decimals: uint8, _supply: uint256):
init_supply: uint256 = _supply * 10 ** convert(_decimals, uint256)
self.name = _name
self.symbol = _symbol
self.decimals = _decimals
self.balanceOf[msg.sender] = init_supply
self.totalSupply = init_supply
self.minter = msg.sender
log Transfer(ZERO_ADDRESS, msg.sender, init_supply)
@external
def transfer(_to : address, _value : uint256) -> bool:
"""
@dev Transfer token for a specified address
@param _to The address to transfer to.
@param _value The amount to be transferred.
"""
# NOTE: vyper does not allow underflows
# so the following subtraction would revert on insufficient balance
self.balanceOf[msg.sender] -= _value
self.balanceOf[_to] += _value
log Transfer(msg.sender, _to, _value)
return True
@external
def transferFrom(_from : address, _to : address, _value : uint256) -> bool:
"""
@dev Transfer tokens from one address to another.
@param _from address The address which you want to send tokens from
@param _to address The address which you want to transfer to
@param _value uint256 the amount of tokens to be transferred
"""
# NOTE: vyper does not allow underflows
# so the following subtraction would revert on insufficient balance
self.balanceOf[_from] -= _value
self.balanceOf[_to] += _value
# NOTE: vyper does not allow underflows
# so the following subtraction would revert on insufficient allowance
self.allowance[_from][msg.sender] -= _value
log Transfer(_from, _to, _value)
return True
@external
def approve(_spender : address, _value : uint256) -> bool:
"""
@dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
Beware that changing an allowance with this method brings the risk that someone may use both the old
and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
@param _spender The address which will spend the funds.
@param _value The amount of tokens to be spent.
"""
self.allowance[msg.sender][_spender] = _value
log Approval(msg.sender, _spender, _value)
return True
@external
def mint(_to: address, _value: uint256):
"""
@dev Mint an amount of the token and assigns it to an account.
This encapsulates the modification of balances such that the
proper events are emitted.
@param _to The account that will receive the created tokens.
@param _value The amount that will be created.
"""
assert msg.sender == self.minter
assert _to != ZERO_ADDRESS
self.totalSupply += _value
self.balanceOf[_to] += _value
log Transfer(ZERO_ADDRESS, _to, _value)
@internal
def _burn(_to: address, _value: uint256):
"""
@dev Internal function that burns an amount of the token of a given
account.
@param _to The account whose tokens will be burned.
@param _value The amount that will be burned.
"""
assert _to != ZERO_ADDRESS
self.totalSupply -= _value
self.balanceOf[_to] -= _value
log Transfer(_to, ZERO_ADDRESS, _value)
@external
def burn(_value: uint256):
"""
@dev Burn an amount of the token of msg.sender.
@param _value The amount that will be burned.
"""
self._burn(msg.sender, _value)
@external
def burnFrom(_to: address, _value: uint256):
"""
@dev Burn an amount of the token from a given account.
@param _to The account whose tokens will be burned.
@param _value The amount that will be burned.
"""
self.allowance[_to][msg.sender] -= _value
self._burn(_to, _value)