1package grc20
2
3import (
4 "errors"
5 "std"
6
7 "gno.land/p/demo/grc/exts"
8)
9
10var (
11 ErrInsufficientBalance = errors.New("insufficient balance")
12 ErrInsufficientAllowance = errors.New("insufficient allowance")
13 ErrInvalidAddress = errors.New("invalid address")
14 ErrCannotTransferToSelf = errors.New("cannot send transfer to self")
15)
16
17type Token interface {
18 exts.TokenMetadata
19
20 // Returns the amount of tokens in existence.
21 TotalSupply() uint64
22
23 // Returns the amount of tokens owned by `account`.
24 BalanceOf(account std.Address) uint64
25
26 // Moves `amount` tokens from the caller's account to `to`.
27 //
28 // Returns an error if the operation failed.
29 Transfer(to std.Address, amount uint64) error
30
31 // Returns the remaining number of tokens that `spender` will be
32 // allowed to spend on behalf of `owner` through {transferFrom}. This is
33 // zero by default.
34 //
35 // This value changes when {approve} or {transferFrom} are called.
36 Allowance(owner, spender std.Address) uint64
37
38 // Sets `amount` as the allowance of `spender` over the caller's tokens.
39 //
40 // Returns an error if the operation failed.
41 //
42 // IMPORTANT: Beware that changing an allowance with this method brings the risk
43 // that someone may use both the old and the new allowance by unfortunate
44 // transaction ordering. One possible solution to mitigate this race
45 // condition is to first reduce the spender's allowance to 0 and set the
46 // desired value afterwards:
47 // https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
48 Approve(spender std.Address, amount uint64) error
49
50 // Moves `amount` tokens from `from` to `to` using the
51 // allowance mechanism. `amount` is then deducted from the caller's
52 // allowance.
53 //
54 // Returns an error if the operation failed.
55 TransferFrom(from, to std.Address, amount uint64) error
56}
57
58const (
59 MintEvent = "Mint"
60 BurnEvent = "Burn"
61 TransferEvent = "Transfer"
62 ApprovalEvent = "Approval"
63)
types.gno
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