mirror of
https://github.com/nspcc-dev/neo-go.git
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419 lines
12 KiB
Go
419 lines
12 KiB
Go
/*
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Package nft contains divisible non-fungible NEP-11-compatible token
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implementation. This token can be minted with GAS transfer to contract address,
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it will retrieve NeoFS container ID and object ID from the transfer data and
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produce NFT which represents NeoFS object.
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*/
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package nft
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import (
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"github.com/nspcc-dev/neo-go/pkg/interop"
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"github.com/nspcc-dev/neo-go/pkg/interop/contract"
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"github.com/nspcc-dev/neo-go/pkg/interop/iterator"
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"github.com/nspcc-dev/neo-go/pkg/interop/native/crypto"
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"github.com/nspcc-dev/neo-go/pkg/interop/native/gas"
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"github.com/nspcc-dev/neo-go/pkg/interop/native/management"
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"github.com/nspcc-dev/neo-go/pkg/interop/native/std"
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"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
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"github.com/nspcc-dev/neo-go/pkg/interop/storage"
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"github.com/nspcc-dev/neo-go/pkg/interop/util"
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)
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const (
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decimals = 2
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multiplier = 100
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)
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// Prefixes used for contract data storage.
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const (
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totalSupplyPrefix = "s"
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// balancePrefix contains map from [address + token id] to address's balance of the specified token.
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balancePrefix = "b"
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// tokenOwnerPrefix contains map from [token id + owner] to token's owner.
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tokenOwnerPrefix = "t"
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// tokenPrefix contains map from token id to its properties (serialised containerID + objectID).
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tokenPrefix = "i"
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)
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var (
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// contractOwner is a special address that can perform some management
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// functions on this contract like updating/destroying it and can also
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// be used for contract address verification.
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contractOwner = util.FromAddress("NbrUYaZgyhSkNoRo9ugRyEMdUZxrhkNaWB")
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)
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// ObjectIdentifier represents NFT structure and contains the container ID and
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// object ID of the NeoFS object.
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type ObjectIdentifier struct {
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ContainerID []byte
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ObjectID []byte
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}
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// Common methods
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// Symbol returns token symbol, it's NFSO.
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func Symbol() string {
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return "NFSO"
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}
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// Decimals returns token decimals, this NFT is divisible.
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func Decimals() int {
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return decimals
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}
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// TotalSupply is a contract method that returns the number of tokens minted.
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func TotalSupply() int {
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return totalSupply(storage.GetReadOnlyContext())
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}
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// totalSupply is an internal implementation of TotalSupply operating with
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// given context. The number itself is stored raw in the DB with totalSupplyPrefix
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// key.
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func totalSupply(ctx storage.Context) int {
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var res int
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val := storage.Get(ctx, []byte(totalSupplyPrefix))
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if val != nil {
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res = val.(int)
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}
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return res
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}
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// mkBalancePrefix creates DB key-prefix for account balances specified
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// by concatenating balancePrefix and account address.
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func mkBalancePrefix(holder interop.Hash160) []byte {
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res := []byte(balancePrefix)
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return append(res, holder...)
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}
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// mkBalanceKey creates DB key for account specified by concatenating balancePrefix,
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// account address and token ID.
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func mkBalanceKey(holder interop.Hash160, tokenID []byte) []byte {
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res := mkBalancePrefix(holder)
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return append(res, tokenID...)
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}
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// mkTokenOwnerPrefix creates DB key prefix for token specified by its ID.
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func mkTokenOwnerPrefix(tokenID []byte) []byte {
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res := []byte(tokenOwnerPrefix)
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return append(res, tokenID...)
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}
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// mkTokenOwnerKey creates DB key for token specified by concatenating tokenOwnerPrefix,
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// token ID and holder.
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func mkTokenOwnerKey(tokenID []byte, holder interop.Hash160) []byte {
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res := mkTokenOwnerPrefix(tokenID)
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return append(res, holder...)
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}
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// mkTokenKey creates DB key for token specified by its ID.
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func mkTokenKey(tokenID []byte) []byte {
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res := []byte(tokenPrefix)
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return append(res, tokenID...)
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}
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// BalanceOf returns the overall number of tokens owned by specified address.
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func BalanceOf(holder interop.Hash160) int {
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if len(holder) != interop.Hash160Len {
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panic("bad owner address")
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}
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ctx := storage.GetReadOnlyContext()
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balance := 0
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iter := tokensOf(ctx, holder)
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for iterator.Next(iter) {
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tokenID := iterator.Value(iter).([]byte)
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key := mkBalanceKey(holder, tokenID)
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balance += getBalanceOf(ctx, key)
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}
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return balance
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}
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// getBalanceOf returns balance of the account of the specified tokenID using
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// database key.
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func getBalanceOf(ctx storage.Context, balanceKey []byte) int {
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val := storage.Get(ctx, balanceKey)
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if val != nil {
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return val.(int)
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}
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return 0
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}
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// addToBalance adds amount to the account balance. Amount can be negative. It returns
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// updated balance value.
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func addToBalance(ctx storage.Context, holder interop.Hash160, tokenID []byte, amount int) int {
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key := mkBalanceKey(holder, tokenID)
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old := getBalanceOf(ctx, key)
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old += amount
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if old > 0 {
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storage.Put(ctx, key, old)
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} else {
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storage.Delete(ctx, key)
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}
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return old
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}
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// TokensOf returns an iterator with all tokens held by specified address.
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func TokensOf(holder interop.Hash160) iterator.Iterator {
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if len(holder) != interop.Hash160Len {
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panic("bad owner address")
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}
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ctx := storage.GetReadOnlyContext()
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return tokensOf(ctx, holder)
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}
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func tokensOf(ctx storage.Context, holder interop.Hash160) iterator.Iterator {
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key := mkBalancePrefix(holder)
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// We don't store zero balances, thus only relevant token IDs of the holder will
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// be returned.
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iter := storage.Find(ctx, key, storage.KeysOnly|storage.RemovePrefix)
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return iter
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}
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// Transfer token from its owner to another user, if there's one owner of the token.
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// It will return false if token is shared between multiple owners.
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func Transfer(to interop.Hash160, token []byte, data interface{}) bool {
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if len(to) != interop.Hash160Len {
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panic("invalid 'to' address")
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}
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ctx := storage.GetContext()
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var (
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owner interop.Hash160
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ok bool
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)
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iter := ownersOf(ctx, token)
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for iterator.Next(iter) {
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if ok {
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// Token is shared between multiple owners.
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return false
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}
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owner = iterator.Value(iter).(interop.Hash160)
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ok = true
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}
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if !ok {
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panic("unknown token")
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}
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// Note that although calling script hash is not checked explicitly in
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// this contract it is in fact checked for in `CheckWitness` itself.
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if !runtime.CheckWitness(owner) {
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return false
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}
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key := mkBalanceKey(owner, token)
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amount := getBalanceOf(ctx, key)
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if string(owner) != string(to) {
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addToBalance(ctx, owner, token, -amount)
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removeOwner(ctx, token, owner)
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addToBalance(ctx, to, token, amount)
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addOwner(ctx, token, to)
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}
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postTransfer(owner, to, token, amount, data)
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return true
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}
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// postTransfer emits Transfer event and calls onNEP11Payment if needed.
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func postTransfer(from interop.Hash160, to interop.Hash160, token []byte, amount int, data interface{}) {
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runtime.Notify("Transfer", from, to, amount, token)
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if management.GetContract(to) != nil {
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contract.Call(to, "onNEP11Payment", contract.All, from, amount, token, data)
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}
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}
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// end of common methods.
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// Optional methods.
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// Properties returns properties of the given NFT.
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func Properties(id []byte) map[string]string {
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ctx := storage.GetReadOnlyContext()
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if !isTokenValid(ctx, id) {
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panic("unknown token")
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}
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key := mkTokenKey(id)
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props := storage.Get(ctx, key).([]byte)
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t := std.Deserialize(props).(ObjectIdentifier)
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result := map[string]string{
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"name": "NeoFS Object " + std.Base64Encode(id), // Not a hex for contract simplicity.
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"containerID": std.Base64Encode(t.ContainerID),
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"objectID": std.Base64Encode(t.ObjectID),
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}
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return result
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}
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// Tokens returns all token IDs minted by the contract.
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func Tokens() iterator.Iterator {
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ctx := storage.GetReadOnlyContext()
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prefix := []byte(tokenPrefix)
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iter := storage.Find(ctx, prefix, storage.KeysOnly|storage.RemovePrefix)
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return iter
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}
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func isTokenValid(ctx storage.Context, tokenID []byte) bool {
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key := mkTokenKey(tokenID)
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result := storage.Get(ctx, key)
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return result != nil
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}
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// End of optional methods.
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// Divisible methods.
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// TransferDivisible token from its owner to another user, notice that it only has three
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// parameters because token owner can be deduced from token ID itself.
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func TransferDivisible(from, to interop.Hash160, amount int, token []byte, data interface{}) bool {
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if len(from) != interop.Hash160Len {
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panic("invalid 'from' address")
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}
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if len(to) != interop.Hash160Len {
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panic("invalid 'to' address")
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}
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if amount < 0 {
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panic("negative 'amount'")
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}
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if amount > multiplier {
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panic("invalid 'amount'")
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}
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ctx := storage.GetContext()
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if !isTokenValid(ctx, token) {
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panic("unknown token")
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}
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// Note that although calling script hash is not checked explicitly in
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// this contract it is in fact checked for in `CheckWitness` itself.
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if !runtime.CheckWitness(from) {
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return false
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}
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key := mkBalanceKey(from, token)
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balance := getBalanceOf(ctx, key)
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if amount > balance {
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return false
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}
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if string(from) != string(to) {
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updBalance := addToBalance(ctx, from, token, -amount)
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if updBalance == 0 {
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removeOwner(ctx, token, from)
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}
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updBalance = addToBalance(ctx, to, token, amount)
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if updBalance != 0 {
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addOwner(ctx, token, to)
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}
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}
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postTransfer(from, to, token, amount, data)
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return true
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}
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// OwnerOf returns owner of specified token.
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func OwnerOf(token []byte) iterator.Iterator {
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ctx := storage.GetReadOnlyContext()
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if !isTokenValid(ctx, token) {
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panic("unknown token")
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}
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return ownersOf(ctx, token)
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}
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// BalanceOfDivisible returns the number of token with the specified tokenID owned by specified address.
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func BalanceOfDivisible(holder interop.Hash160, token []byte) int {
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if len(holder) != interop.Hash160Len {
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panic("bad holder address")
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}
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ctx := storage.GetReadOnlyContext()
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key := mkBalanceKey(holder, token)
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return getBalanceOf(ctx, key)
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}
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// end of divisible methods.
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// ownersOf returns iterator over owners of the specified token. Owner is
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// stored as value of the token key (prefix + token ID + owner).
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func ownersOf(ctx storage.Context, token []byte) iterator.Iterator {
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key := mkTokenOwnerPrefix(token)
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iter := storage.Find(ctx, key, storage.ValuesOnly)
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return iter
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}
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func addOwner(ctx storage.Context, token []byte, holder interop.Hash160) {
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key := mkTokenOwnerKey(token, holder)
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storage.Put(ctx, key, holder)
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}
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func removeOwner(ctx storage.Context, token []byte, holder interop.Hash160) {
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key := mkTokenOwnerKey(token, holder)
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storage.Delete(ctx, key)
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}
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// OnNEP17Payment mints tokens if at least 10 GAS is provided. You don't call
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// this method directly, instead it's called by GAS contract when you transfer
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// GAS from your address to the address of this NFT contract.
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func OnNEP17Payment(from interop.Hash160, amount int, data interface{}) {
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if string(runtime.GetCallingScriptHash()) != gas.Hash {
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panic("only GAS is accepted")
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}
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if amount < 10_00000000 {
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panic("minting NFSO costs at least 10 GAS")
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}
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tokenInfo := data.([]interface{})
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if len(tokenInfo) != 2 {
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panic("invalid 'data'")
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}
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containerID := tokenInfo[0].([]byte)
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if len(containerID) != interop.Hash256Len {
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panic("invalid container ID")
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}
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objectID := tokenInfo[1].([]byte)
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if len(objectID) != interop.Hash256Len {
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panic("invalid object ID")
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}
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t := ObjectIdentifier{
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ContainerID: containerID,
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ObjectID: objectID,
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}
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props := std.Serialize(t)
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id := crypto.Ripemd160(props)
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var ctx = storage.GetContext()
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if isTokenValid(ctx, id) {
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panic("NFSO for the specified object is already minted")
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}
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key := mkTokenKey(id)
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storage.Put(ctx, key, props)
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total := totalSupply(ctx)
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addOwner(ctx, id, from)
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addToBalance(ctx, from, id, multiplier)
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total++
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storage.Put(ctx, []byte(totalSupplyPrefix), total)
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postTransfer(nil, from, id, multiplier, nil) // no `data` during minting
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}
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// Verify allows owner to manage contract's address, including earned GAS
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// transfer from contract's address to somewhere else. It just checks for transaction
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// to also be signed by contract owner, so contract's witness should be empty.
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func Verify() bool {
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return runtime.CheckWitness(contractOwner)
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}
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// Destroy destroys the contract, only owner can do that.
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func Destroy() {
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if !Verify() {
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panic("only owner can destroy")
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}
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management.Destroy()
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}
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// Update updates the contract, only owner can do that.
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func Update(nef, manifest []byte) {
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if !Verify() {
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panic("only owner can update")
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}
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management.Update(nef, manifest)
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}
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