contract.gno

 1// based on Wikipedia's Solidity example: https://en.wikipedia.org/wiki/Solidity
 2package wikicoin
 3
 4import (
 5	"chain/runtime/unsafe"
 6
 7	"gno.land/p/nt/avl/v0"
 8	"gno.land/p/nt/ufmt/v0"
 9)
10
11var balances = avl.NewTree() // addr -> balance
12var minter address
13
14// Constructor code is only run when the contract is created
15func init() {
16	minter = unsafe.OriginCaller()
17}
18
19func Mint(cur realm, receiver address, amount uint) {
20	if unsafe.OriginCaller() != minter {
21		panic("restricted")
22	}
23	curBalance := BalanceOf(receiver)
24	newBalance := curBalance + amount
25	balances.Set(receiver.String(), newBalance)
26}
27
28func Send(cur realm, receiver address, amount uint) {
29	sender := unsafe.OriginCaller()
30	senderBalance := BalanceOf(sender)
31	if amount > senderBalance {
32		panic(ufmt.Sprintf("insufficient balance: %d", senderBalance))
33	}
34	receiverBalance := BalanceOf(receiver)
35	balances.Set(sender.String(), senderBalance-amount)
36	balances.Set(receiver.String(), receiverBalance+amount)
37}
38
39func BalanceOf(addr address) uint {
40	balance := balances.Get(addr.String())
41	if balance == nil {
42		return 0
43	}
44	return balance.(uint)
45}