智能合约语言

1/ SPDX-License-Identifier: GPL-3.0
2pragma solidity >= 0.7.0;
3
4contract Coin {
5    // The keyword "public" makes variables
6    // accessible from other contracts
7    address public minter;
8    mapping (address => uint) public balances;
9
10    // Events allow clients to react to specific
11    // contract changes you declare
12    event Sent(address from, address to, uint amount);
13
14    // Constructor code is only run when the contract
15    // is created
16    constructor() {
17        minter = msg.sender;
18    }
19
20    // Sends an amount of newly created coins to an address
21    // Can only be called by the contract creator
22    function mint(address receiver, uint amount) public {
23        require(msg.sender == minter);
24        require(amount < 1e60);
25        balances[receiver] += amount;
26    }
27
28    // Sends an amount of existing coins
29    // from any caller to an address
30    function send(address receiver, uint amount) public {
31        require(amount <= balances[msg.sender], "Insufficient balance.");
32        balances[msg.sender] -= amount;
33        balances[receiver] += amount;
34        emit Sent(msg.sender, receiver, amount);
35    }
36}
37
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1# Open Auction
2
3# Auction params
4# Beneficiary receives money from the highest bidder
5beneficiary: public(address)
6auctionStart: public(uint256)
7auctionEnd: public(uint256)
8
9# Current state of auction
10highestBidder: public(address)
11highestBid: public(uint256)
12
13# Set to true at the end, disallows any change
14ended: public(bool)
15
16# Keep track of refunded bids so we can follow the withdraw pattern
17pendingReturns: public(HashMap[address, uint256])
18@external
19def __init__(_beneficiary: address, _bidding_time: uint256):
20    self.beneficiary = _beneficiary
21    self.auctionStart = block.timestamp
22    self.auctionEnd = self.auctionStart + _bidding_time
23
24# Bid on the auction with the value sent
25# together with this transaction.
26# The value will only be refunded if the
27# auction is not won.
28@external
29@payable
30def bid():
31    # Check if bidding period is over.
32    assert block.timestamp < self.auctionEnd
33    # Check if bid is high enough
34    assert msg.value > self.highestBid
35    # Track the refund for the previous high bidder
36    self.pendingReturns[self.highestBidder] += self.highestBid
37    # Track new high bid
38    self.highestBidder = msg.sender
39    self.highestBid = msg.value The withdraw pattern is
40# used here to avoid a security issue. If refunds were directly
41# sent as part of bid(), a malicious bidding contract could block
42# those refunds and thus block new higher bids from coming in.
43@external
44def withdraw():
45    pending_amount: uint256 = self.pendingReturns[msg.sender]
46    self.pendingReturns[msg.sender] = 0
47    send(msg.sender, pending_amount)
48
49# End the auction and send the highest bid
50# to the beneficiary.
51@external
52def endAuction():
53    # It is a good guideline to structure functions that interact
54    # with other contracts (i.e. they call functions or send Ether)
55    # into three phases:
56    # 1. checking conditions
57    # 2. performing actions (potentially changing conditions)
58    # 3. interacting with other contracts
59    # If these phases are mixed up, the other contract could call
60    # back into the current contract and modify the state or cause
61    # effects (ether payout) to be performed multiple times.
62    # If functions called internally include interaction with external
63    # contracts, they also have to be considered interaction with
64    # external contracts.
65
66    # 1. Conditions
67    # Check if auction endtime has been reached
68    assert block.timestamp >= self.auctionEnd
69    # Check if this function has already been called
70    assert not self.ended
71
72    # 2. Effects
73    self.ended = True
74
75    # 3. Interaction
76    send(self.beneficiary, self.highestBid)
77
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1{
2    function power(base, exponent) -> result
3    {
4        switch exponent
5        case 0 { result := 1 }
6        case 1 { result := base }
7        default
8        {
9            result := power(mul(base, base), div(exponent, 2))
10            if mod(exponent, 2) { result := mul(base, result) }
11        }
12    }
13    let res := power(calldataload(0), calldataload(32))
14    mstore(0, res)
15    return(0, 32)
16}
17
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