313 lines
8.3 KiB
Go
313 lines
8.3 KiB
Go
package native
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import (
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"errors"
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"math/big"
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"github.com/nspcc-dev/neo-go/pkg/core/interop"
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"github.com/nspcc-dev/neo-go/pkg/core/interop/runtime"
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"github.com/nspcc-dev/neo-go/pkg/core/state"
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"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
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"github.com/nspcc-dev/neo-go/pkg/smartcontract"
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"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
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"github.com/nspcc-dev/neo-go/pkg/util"
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"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
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)
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// prefixAccount is the standard prefix used to store account data.
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const prefixAccount = 20
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// makeAccountKey creates a key from account script hash.
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func makeAccountKey(h util.Uint160) []byte {
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k := make([]byte, util.Uint160Size+1)
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k[0] = prefixAccount
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copy(k[1:], h.BytesBE())
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return k
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}
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// nep5TokenNative represents NEP-5 token contract.
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type nep5TokenNative struct {
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interop.ContractMD
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name string
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symbol string
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decimals int64
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factor int64
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onPersist func(*interop.Context) error
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incBalance func(*interop.Context, util.Uint160, *state.StorageItem, *big.Int) error
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}
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// totalSupplyKey is the key used to store totalSupply value.
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var totalSupplyKey = []byte{11}
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func (c *nep5TokenNative) Metadata() *interop.ContractMD {
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return &c.ContractMD
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}
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var _ interop.Contract = (*nep5TokenNative)(nil)
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func newNEP5Native(name string) *nep5TokenNative {
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n := &nep5TokenNative{ContractMD: *interop.NewContractMD(name)}
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desc := newDescriptor("name", smartcontract.StringType)
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md := newMethodAndPrice(n.Name, 1, smartcontract.NoneFlag)
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n.AddMethod(md, desc, true)
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desc = newDescriptor("symbol", smartcontract.StringType)
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md = newMethodAndPrice(n.Symbol, 1, smartcontract.NoneFlag)
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n.AddMethod(md, desc, true)
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desc = newDescriptor("decimals", smartcontract.IntegerType)
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md = newMethodAndPrice(n.Decimals, 1, smartcontract.NoneFlag)
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n.AddMethod(md, desc, true)
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desc = newDescriptor("totalSupply", smartcontract.IntegerType)
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md = newMethodAndPrice(n.TotalSupply, 1, smartcontract.NoneFlag)
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n.AddMethod(md, desc, true)
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desc = newDescriptor("balanceOf", smartcontract.IntegerType,
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manifest.NewParameter("account", smartcontract.Hash160Type))
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md = newMethodAndPrice(n.balanceOf, 1, smartcontract.NoneFlag)
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n.AddMethod(md, desc, true)
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desc = newDescriptor("transfer", smartcontract.BoolType,
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manifest.NewParameter("from", smartcontract.Hash160Type),
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manifest.NewParameter("to", smartcontract.Hash160Type),
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manifest.NewParameter("amount", smartcontract.IntegerType),
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)
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md = newMethodAndPrice(n.Transfer, 1, smartcontract.NoneFlag)
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n.AddMethod(md, desc, false)
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n.AddEvent("Transfer", desc.Parameters...)
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return n
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}
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func (c *nep5TokenNative) Initialize(_ *interop.Context) error {
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return nil
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}
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func (c *nep5TokenNative) Name(_ *interop.Context, _ []stackitem.Item) stackitem.Item {
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return stackitem.NewByteArray([]byte(c.name))
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}
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func (c *nep5TokenNative) Symbol(_ *interop.Context, _ []stackitem.Item) stackitem.Item {
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return stackitem.NewByteArray([]byte(c.symbol))
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}
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func (c *nep5TokenNative) Decimals(_ *interop.Context, _ []stackitem.Item) stackitem.Item {
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return stackitem.NewBigInteger(big.NewInt(c.decimals))
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}
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func (c *nep5TokenNative) TotalSupply(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
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return stackitem.NewBigInteger(c.getTotalSupply(ic))
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}
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func (c *nep5TokenNative) getTotalSupply(ic *interop.Context) *big.Int {
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si := ic.DAO.GetStorageItem(c.Hash, totalSupplyKey)
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if si == nil {
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return big.NewInt(0)
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}
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return bigint.FromBytes(si.Value)
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}
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func (c *nep5TokenNative) saveTotalSupply(ic *interop.Context, supply *big.Int) error {
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si := &state.StorageItem{Value: bigint.ToBytes(supply)}
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return ic.DAO.PutStorageItem(c.Hash, totalSupplyKey, si)
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}
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func (c *nep5TokenNative) Transfer(ic *interop.Context, args []stackitem.Item) stackitem.Item {
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from := toUint160(args[0])
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to := toUint160(args[1])
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amount := toBigInt(args[2])
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err := c.transfer(ic, from, to, amount)
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return stackitem.NewBool(err == nil)
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}
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func addrToStackItem(u *util.Uint160) stackitem.Item {
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if u == nil {
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return stackitem.Null{}
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}
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return stackitem.NewByteArray(u.BytesBE())
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}
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func (c *nep5TokenNative) emitTransfer(ic *interop.Context, from, to *util.Uint160, amount *big.Int) {
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ne := state.NotificationEvent{
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ScriptHash: c.Hash,
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Item: stackitem.NewArray([]stackitem.Item{
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stackitem.NewByteArray([]byte("Transfer")),
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addrToStackItem(from),
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addrToStackItem(to),
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stackitem.NewBigInteger(amount),
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}),
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}
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ic.Notifications = append(ic.Notifications, ne)
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}
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func (c *nep5TokenNative) transfer(ic *interop.Context, from, to util.Uint160, amount *big.Int) error {
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if amount.Sign() == -1 {
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return errors.New("negative amount")
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}
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ok, err := runtime.CheckHashedWitness(ic, nep5ScriptHash{
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callingScriptHash: c.Hash,
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entryScriptHash: c.Hash,
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currentScriptHash: c.Hash,
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}, from)
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if err != nil {
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return err
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} else if !ok {
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return errors.New("invalid signature")
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}
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keyFrom := makeAccountKey(from)
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siFrom := ic.DAO.GetStorageItem(c.Hash, keyFrom)
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if siFrom == nil {
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return errors.New("insufficient funds")
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}
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isEmpty := from.Equals(to) || amount.Sign() == 0
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inc := amount
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if isEmpty {
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inc = big.NewInt(0)
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} else {
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inc = new(big.Int).Neg(inc)
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}
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if err := c.incBalance(ic, from, siFrom, inc); err != nil {
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return err
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}
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if err := ic.DAO.PutStorageItem(c.Hash, keyFrom, siFrom); err != nil {
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return err
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}
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if !isEmpty {
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keyTo := makeAccountKey(to)
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siTo := ic.DAO.GetStorageItem(c.Hash, keyTo)
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if siTo == nil {
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siTo = new(state.StorageItem)
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}
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if err := c.incBalance(ic, to, siTo, amount); err != nil {
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return err
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}
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if err := ic.DAO.PutStorageItem(c.Hash, keyTo, siTo); err != nil {
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return err
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}
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}
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c.emitTransfer(ic, &from, &to, amount)
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return nil
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}
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func (c *nep5TokenNative) balanceOf(ic *interop.Context, args []stackitem.Item) stackitem.Item {
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h := toUint160(args[0])
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bs, err := ic.DAO.GetNEP5Balances(h)
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if err != nil {
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panic(err)
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}
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balance := bs.Trackers[c.Hash].Balance
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return stackitem.NewBigInteger(big.NewInt(balance))
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}
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func (c *nep5TokenNative) mint(ic *interop.Context, h util.Uint160, amount *big.Int) {
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if amount.Sign() == 0 {
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return
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}
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c.addTokens(ic, h, amount)
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c.emitTransfer(ic, nil, &h, amount)
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}
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func (c *nep5TokenNative) burn(ic *interop.Context, h util.Uint160, amount *big.Int) {
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if amount.Sign() == 0 {
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return
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}
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amount = new(big.Int).Neg(amount)
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c.addTokens(ic, h, amount)
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c.emitTransfer(ic, &h, nil, amount)
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}
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func (c *nep5TokenNative) addTokens(ic *interop.Context, h util.Uint160, amount *big.Int) {
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if amount.Sign() == 0 {
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return
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}
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key := makeAccountKey(h)
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si := ic.DAO.GetStorageItem(c.Hash, key)
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if si == nil {
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si = new(state.StorageItem)
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}
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if err := c.incBalance(ic, h, si, amount); err != nil {
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panic(err)
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}
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if err := ic.DAO.PutStorageItem(c.Hash, key, si); err != nil {
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panic(err)
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}
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supply := c.getTotalSupply(ic)
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supply.Add(supply, amount)
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err := c.saveTotalSupply(ic, supply)
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if err != nil {
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panic(err)
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}
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}
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func (c *nep5TokenNative) OnPersist(ic *interop.Context) error {
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return c.onPersist(ic)
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}
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func newDescriptor(name string, ret smartcontract.ParamType, ps ...manifest.Parameter) *manifest.Method {
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return &manifest.Method{
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Name: name,
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Parameters: ps,
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ReturnType: ret,
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}
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}
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func newMethodAndPrice(f interop.Method, price int64, flags smartcontract.CallFlag) *interop.MethodAndPrice {
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return &interop.MethodAndPrice{
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Func: f,
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Price: price,
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RequiredFlags: flags,
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}
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}
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func toBigInt(s stackitem.Item) *big.Int {
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bi, err := s.TryInteger()
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if err != nil {
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panic(err)
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}
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return bi
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}
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func toUint160(s stackitem.Item) util.Uint160 {
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buf, err := s.TryBytes()
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if err != nil {
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panic(err)
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}
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u, err := util.Uint160DecodeBytesBE(buf)
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if err != nil {
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panic(err)
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}
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return u
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}
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// scriptHash is an auxiliary structure which implements ScriptHashGetter
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// interface over NEP5 native contract and is used for runtime.CheckHashedWitness
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type nep5ScriptHash struct {
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callingScriptHash util.Uint160
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entryScriptHash util.Uint160
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currentScriptHash util.Uint160
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}
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// GetCallingScriptHash implements ScriptHashGetter interface
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func (s nep5ScriptHash) GetCallingScriptHash() util.Uint160 {
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return s.callingScriptHash
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}
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// GetEntryScriptHash implements ScriptHashGetter interface
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func (s nep5ScriptHash) GetEntryScriptHash() util.Uint160 {
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return s.entryScriptHash
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}
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// GetCurrentScriptHash implements ScriptHashGetter interface
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func (s nep5ScriptHash) GetCurrentScriptHash() util.Uint160 {
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return s.currentScriptHash
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}
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