package stackitem import ( "bytes" "encoding/hex" "encoding/json" "errors" "fmt" "math" "math/big" "reflect" "unicode/utf8" "github.com/nspcc-dev/neo-go/pkg/crypto/hash" "github.com/nspcc-dev/neo-go/pkg/encoding/bigint" "github.com/nspcc-dev/neo-go/pkg/util" "github.com/nspcc-dev/neo-go/pkg/util/slice" ) const ( // MaxBigIntegerSizeBits is the maximum size of BigInt item in bits. MaxBigIntegerSizeBits = 32 * 8 // MaxSize is the maximum item size allowed in the VM. MaxSize = 1024 * 1024 // MaxComparableNumOfItems is the maximum number of items that can be compared for structs. MaxComparableNumOfItems = MaxDeserialized // MaxClonableNumOfItems is the maximum number of items that can be cloned in structs. MaxClonableNumOfItems = MaxDeserialized // MaxByteArrayComparableSize is the maximum allowed length of ByteArray for Equals method. // It is set to be the maximum uint16 value. MaxByteArrayComparableSize = math.MaxUint16 // MaxKeySize is the maximum size of map key. MaxKeySize = 64 ) // Item represents the "real" value that is pushed on the stack. type Item interface { fmt.Stringer Value() interface{} // Dup duplicates current Item. Dup() Item // TryBool converts Item to a boolean value. TryBool() (bool, error) // TryBytes converts Item to a byte slice. If the underlying type is a // byte slice, it's returned as is without copying. TryBytes() ([]byte, error) // TryInteger converts Item to an integer. TryInteger() (*big.Int, error) // Equals checks if 2 StackItems are equal. Equals(s Item) bool // Type returns stack item type. Type() Type // Convert converts Item to another type. Convert(Type) (Item, error) } // Convertible is something that can be converted to/from Item. type Convertible interface { ToStackItem() (Item, error) FromStackItem(Item) error } var ( // ErrInvalidConversion is returned on attempt to make an incorrect // conversion between item types. ErrInvalidConversion = errors.New("invalid conversion") // ErrTooBig is returned when item exceeds some size constraints like // maximum allowed integer value of number of elements in array. It // can also be returned by serialization functions if resulting // value exceeds MaxSize. ErrTooBig = errors.New("too big") errTooBigComparable = fmt.Errorf("%w: uncomparable", ErrTooBig) errTooBigInteger = fmt.Errorf("%w: integer", ErrTooBig) errTooBigKey = fmt.Errorf("%w: map key", ErrTooBig) errTooBigSize = fmt.Errorf("%w: size", ErrTooBig) errTooBigElements = fmt.Errorf("%w: many elements", ErrTooBig) ) // mkInvConversion creates conversion error with additional metadata (from and // to types). func mkInvConversion(from Item, to Type) error { return fmt.Errorf("%w: %s/%s", ErrInvalidConversion, from, to) } // Make tries to make appropriate stack item from provided value. // It will panic if it's not possible. func Make(v interface{}) Item { switch val := v.(type) { case int: return (*BigInteger)(big.NewInt(int64(val))) case int64: return (*BigInteger)(big.NewInt(val)) case uint8: return (*BigInteger)(big.NewInt(int64(val))) case uint16: return (*BigInteger)(big.NewInt(int64(val))) case uint32: return (*BigInteger)(big.NewInt(int64(val))) case uint64: return (*BigInteger)(new(big.Int).SetUint64(val)) case []byte: return NewByteArray(val) case string: return NewByteArray([]byte(val)) case bool: return Bool(val) case []Item: return &Array{ value: val, } case *big.Int: return NewBigInteger(val) case Item: return val case []int: var a []Item for _, i := range val { a = append(a, Make(i)) } return Make(a) default: i64T := reflect.TypeOf(int64(0)) if reflect.TypeOf(val).ConvertibleTo(i64T) { i64Val := reflect.ValueOf(val).Convert(i64T).Interface() return Make(i64Val) } panic( fmt.Sprintf( "invalid stack item type: %v (%v)", val, reflect.TypeOf(val), ), ) } } // ToString converts Item to string if it is a valid UTF-8. func ToString(item Item) (string, error) { bs, err := item.TryBytes() if err != nil { return "", err } if !utf8.Valid(bs) { return "", fmt.Errorf("%w: not UTF-8", ErrInvalidValue) } return string(bs), nil } // convertPrimitive converts primitive item to a specified type. func convertPrimitive(item Item, typ Type) (Item, error) { if item.Type() == typ { return item, nil } switch typ { case IntegerT: bi, err := item.TryInteger() if err != nil { return nil, err } return NewBigInteger(bi), nil case ByteArrayT, BufferT: b, err := item.TryBytes() if err != nil { return nil, err } if typ == BufferT { return NewBuffer(slice.Copy(b)), nil } // ByteArray can't really be changed, so it's OK to reuse `b`. return NewByteArray(b), nil case BooleanT: b, err := item.TryBool() if err != nil { return nil, err } return NewBool(b), nil default: return nil, mkInvConversion(item, typ) } } // Struct represents a struct on the stack. type Struct struct { value []Item rc } // NewStruct returns an new Struct object. func NewStruct(items []Item) *Struct { return &Struct{ value: items, } } // Value implements Item interface. func (i *Struct) Value() interface{} { return i.value } // Remove removes element at `pos` index from Struct value. // It will panics on bad index. func (i *Struct) Remove(pos int) { i.value = append(i.value[:pos], i.value[pos+1:]...) } // Append adds Item at the end of Struct value. func (i *Struct) Append(item Item) { i.value = append(i.value, item) } // Clear removes all elements from Struct item value. func (i *Struct) Clear() { i.value = i.value[:0] } // Len returns length of Struct value. func (i *Struct) Len() int { return len(i.value) } // String implements Item interface. func (i *Struct) String() string { return "Struct" } // Dup implements Item interface. func (i *Struct) Dup() Item { // it's a reference type, so no copying here. return i } // TryBool implements Item interface. func (i *Struct) TryBool() (bool, error) { return true, nil } // TryBytes implements Item interface. func (i *Struct) TryBytes() ([]byte, error) { return nil, mkInvConversion(i, ByteArrayT) } // TryInteger implements Item interface. func (i *Struct) TryInteger() (*big.Int, error) { return nil, mkInvConversion(i, IntegerT) } // Equals implements Item interface. func (i *Struct) Equals(s Item) bool { if s == nil { return false } val, ok := s.(*Struct) if !ok { return false } var limit = MaxComparableNumOfItems - 1 // 1 for current element. return i.equalStruct(val, &limit) } func (i *Struct) equalStruct(s *Struct, limit *int) bool { if i == s { return true } else if len(i.value) != len(s.value) { return false } for j := range i.value { *limit-- if *limit == 0 { panic(errTooBigElements) } sa, oka := i.value[j].(*Struct) sb, okb := s.value[j].(*Struct) if oka && okb { if !sa.equalStruct(sb, limit) { return false } } else if !i.value[j].Equals(s.value[j]) { return false } } return true } // Type implements Item interface. func (i *Struct) Type() Type { return StructT } // Convert implements Item interface. func (i *Struct) Convert(typ Type) (Item, error) { switch typ { case StructT: return i, nil case ArrayT: arr := make([]Item, len(i.value)) copy(arr, i.value) return NewArray(arr), nil case BooleanT: return NewBool(true), nil default: return nil, mkInvConversion(i, typ) } } // Clone returns a Struct with all Struct fields copied by value. // Array fields are still copied by reference. func (i *Struct) Clone() (*Struct, error) { var limit = MaxClonableNumOfItems - 1 // For this struct itself. return i.clone(&limit) } func (i *Struct) clone(limit *int) (*Struct, error) { ret := &Struct{value: make([]Item, len(i.value))} for j := range i.value { *limit-- if *limit < 0 { return nil, ErrTooBig } switch t := i.value[j].(type) { case *Struct: var err error ret.value[j], err = t.clone(limit) if err != nil { return nil, err } default: ret.value[j] = t } } return ret, nil } // Null represents null on the stack. type Null struct{} // String implements Item interface. func (i Null) String() string { return "Null" } // Value implements Item interface. func (i Null) Value() interface{} { return nil } // Dup implements Item interface. // There is no need to perform a real copy here, // as Null has no internal state. func (i Null) Dup() Item { return i } // TryBool implements Item interface. func (i Null) TryBool() (bool, error) { return false, nil } // TryBytes implements Item interface. func (i Null) TryBytes() ([]byte, error) { return nil, mkInvConversion(i, ByteArrayT) } // TryInteger implements Item interface. func (i Null) TryInteger() (*big.Int, error) { return nil, mkInvConversion(i, IntegerT) } // Equals implements Item interface. func (i Null) Equals(s Item) bool { _, ok := s.(Null) return ok } // Type implements Item interface. func (i Null) Type() Type { return AnyT } // Convert implements Item interface. func (i Null) Convert(typ Type) (Item, error) { if typ == AnyT || !typ.IsValid() { return nil, mkInvConversion(i, typ) } return i, nil } // BigInteger represents a big integer on the stack. type BigInteger big.Int // NewBigInteger returns an new BigInteger object. func NewBigInteger(value *big.Int) *BigInteger { // There are 2 cases, when `BitLen` differs from actual size: // 1. Positive integer with highest bit on byte boundary = 1. // 2. Negative integer with highest bit on byte boundary = 1 // minus some value. (-0x80 -> 0x80, -0x7F -> 0x81, -0x81 -> 0x7FFF). sz := value.BitLen() if sz > MaxBigIntegerSizeBits { panic(errTooBigInteger) } else if sz == MaxBigIntegerSizeBits { if value.Sign() == 1 || value.TrailingZeroBits() != MaxBigIntegerSizeBits-1 { panic(errTooBigInteger) } } return (*BigInteger)(value) } // Big casts i to the big.Int type. func (i *BigInteger) Big() *big.Int { return (*big.Int)(i) } // Bytes converts i to a slice of bytes. func (i *BigInteger) Bytes() []byte { return bigint.ToBytes(i.Big()) } // TryBool implements Item interface. func (i *BigInteger) TryBool() (bool, error) { return i.Big().Sign() != 0, nil } // TryBytes implements Item interface. func (i *BigInteger) TryBytes() ([]byte, error) { return i.Bytes(), nil } // TryInteger implements Item interface. func (i *BigInteger) TryInteger() (*big.Int, error) { return i.Big(), nil } // Equals implements Item interface. func (i *BigInteger) Equals(s Item) bool { if i == s { return true } else if s == nil { return false } val, ok := s.(*BigInteger) return ok && i.Big().Cmp(val.Big()) == 0 } // Value implements Item interface. func (i *BigInteger) Value() interface{} { return i.Big() } func (i *BigInteger) String() string { return "BigInteger" } // Dup implements Item interface. func (i *BigInteger) Dup() Item { n := new(big.Int) return (*BigInteger)(n.Set(i.Big())) } // Type implements Item interface. func (i *BigInteger) Type() Type { return IntegerT } // Convert implements Item interface. func (i *BigInteger) Convert(typ Type) (Item, error) { return convertPrimitive(i, typ) } // MarshalJSON implements the json.Marshaler interface. func (i *BigInteger) MarshalJSON() ([]byte, error) { return json.Marshal(i.Big()) } // Bool represents a boolean Item. type Bool bool // NewBool returns an new Bool object. func NewBool(val bool) Bool { return Bool(val) } // Value implements Item interface. func (i Bool) Value() interface{} { return bool(i) } // MarshalJSON implements the json.Marshaler interface. func (i Bool) MarshalJSON() ([]byte, error) { return json.Marshal(bool(i)) } func (i Bool) String() string { return "Boolean" } // Dup implements Item interface. func (i Bool) Dup() Item { return i } // TryBool implements Item interface. func (i Bool) TryBool() (bool, error) { return bool(i), nil } // Bytes converts Bool to bytes. func (i Bool) Bytes() []byte { if i { return []byte{1} } return []byte{0} } // TryBytes implements Item interface. func (i Bool) TryBytes() ([]byte, error) { return i.Bytes(), nil } // TryInteger implements Item interface. func (i Bool) TryInteger() (*big.Int, error) { if i { return big.NewInt(1), nil } return big.NewInt(0), nil } // Equals implements Item interface. func (i Bool) Equals(s Item) bool { if i == s { return true } else if s == nil { return false } val, ok := s.(Bool) return ok && i == val } // Type implements Item interface. func (i Bool) Type() Type { return BooleanT } // Convert implements Item interface. func (i Bool) Convert(typ Type) (Item, error) { return convertPrimitive(i, typ) } // ByteArray represents a byte array on the stack. type ByteArray []byte // NewByteArray returns an new ByteArray object. func NewByteArray(b []byte) *ByteArray { return (*ByteArray)(&b) } // Value implements Item interface. func (i *ByteArray) Value() interface{} { return []byte(*i) } // MarshalJSON implements the json.Marshaler interface. func (i *ByteArray) MarshalJSON() ([]byte, error) { return json.Marshal(hex.EncodeToString(*i)) } func (i *ByteArray) String() string { return "ByteString" } // TryBool implements Item interface. func (i *ByteArray) TryBool() (bool, error) { if len(*i) > MaxBigIntegerSizeBits/8 { return false, errTooBigInteger } for _, b := range *i { if b != 0 { return true, nil } } return false, nil } // TryBytes implements Item interface. func (i ByteArray) TryBytes() ([]byte, error) { return i, nil } // TryInteger implements Item interface. func (i ByteArray) TryInteger() (*big.Int, error) { if len(i) > MaxBigIntegerSizeBits/8 { return nil, errTooBigInteger } return bigint.FromBytes(i), nil } // Equals implements Item interface. func (i *ByteArray) Equals(s Item) bool { if len(*i) > MaxByteArrayComparableSize { panic(errTooBigComparable) } if i == s { return true } else if s == nil { return false } val, ok := s.(*ByteArray) if !ok { return false } if len(*val) > MaxByteArrayComparableSize { panic(errTooBigComparable) } return bytes.Equal(*i, *val) } // Dup implements Item interface. func (i *ByteArray) Dup() Item { ba := slice.Copy(*i) return (*ByteArray)(&ba) } // Type implements Item interface. func (i *ByteArray) Type() Type { return ByteArrayT } // Convert implements Item interface. func (i *ByteArray) Convert(typ Type) (Item, error) { return convertPrimitive(i, typ) } // Array represents a new Array object. type Array struct { value []Item rc } // NewArray returns a new Array object. func NewArray(items []Item) *Array { return &Array{ value: items, } } // Value implements Item interface. func (i *Array) Value() interface{} { return i.value } // Remove removes element at `pos` index from Array value. // It will panics on bad index. func (i *Array) Remove(pos int) { i.value = append(i.value[:pos], i.value[pos+1:]...) } // Append adds Item at the end of Array value. func (i *Array) Append(item Item) { i.value = append(i.value, item) } // Clear removes all elements from Array item value. func (i *Array) Clear() { i.value = i.value[:0] } // Len returns length of Array value. func (i *Array) Len() int { return len(i.value) } // MarshalJSON implements the json.Marshaler interface. func (i *Array) MarshalJSON() ([]byte, error) { return json.Marshal(i.value) } func (i *Array) String() string { return "Array" } // TryBool implements Item interface. func (i *Array) TryBool() (bool, error) { return true, nil } // TryBytes implements Item interface. func (i *Array) TryBytes() ([]byte, error) { return nil, mkInvConversion(i, ByteArrayT) } // TryInteger implements Item interface. func (i *Array) TryInteger() (*big.Int, error) { return nil, mkInvConversion(i, IntegerT) } // Equals implements Item interface. func (i *Array) Equals(s Item) bool { return i == s } // Dup implements Item interface. func (i *Array) Dup() Item { // reference type return i } // Type implements Item interface. func (i *Array) Type() Type { return ArrayT } // Convert implements Item interface. func (i *Array) Convert(typ Type) (Item, error) { switch typ { case ArrayT: return i, nil case StructT: arr := make([]Item, len(i.value)) copy(arr, i.value) return NewStruct(arr), nil case BooleanT: return NewBool(true), nil default: return nil, mkInvConversion(i, typ) } } // MapElement is a key-value pair of StackItems. type MapElement struct { Key Item Value Item } // Map represents Map object. It's ordered, so we use slice representation // which should be fine for maps with less than 32 or so elements. Given that // our VM has quite low limit of overall stack items, it should be good enough, // but it can be extended with a real map for fast random access in the future // if need be. type Map struct { value []MapElement rc } // NewMap returns new Map object. func NewMap() *Map { return &Map{ value: make([]MapElement, 0), } } // NewMapWithValue returns new Map object filled with specified value. func NewMapWithValue(value []MapElement) *Map { if value != nil { return &Map{ value: value, } } return NewMap() } // Value implements Item interface. func (i *Map) Value() interface{} { return i.value } // Clear removes all elements from Map item value. func (i *Map) Clear() { i.value = i.value[:0] } // Len returns length of Map value. func (i *Map) Len() int { return len(i.value) } // TryBool implements Item interface. func (i *Map) TryBool() (bool, error) { return true, nil } // TryBytes implements Item interface. func (i *Map) TryBytes() ([]byte, error) { return nil, mkInvConversion(i, ByteArrayT) } // TryInteger implements Item interface. func (i *Map) TryInteger() (*big.Int, error) { return nil, mkInvConversion(i, IntegerT) } // Equals implements Item interface. func (i *Map) Equals(s Item) bool { return i == s } func (i *Map) String() string { return "Map" } // Index returns an index of the key in map. func (i *Map) Index(key Item) int { for k := range i.value { if i.value[k].Key.Equals(key) { return k } } return -1 } // Has checks if map has specified key. func (i *Map) Has(key Item) bool { return i.Index(key) >= 0 } // Dup implements Item interface. func (i *Map) Dup() Item { // reference type return i } // Type implements Item interface. func (i *Map) Type() Type { return MapT } // Convert implements Item interface. func (i *Map) Convert(typ Type) (Item, error) { switch typ { case MapT: return i, nil case BooleanT: return NewBool(true), nil default: return nil, mkInvConversion(i, typ) } } // Add adds key-value pair to the map. func (i *Map) Add(key, value Item) { if err := IsValidMapKey(key); err != nil { panic(err) } index := i.Index(key) if index >= 0 { i.value[index].Value = value } else { i.value = append(i.value, MapElement{key, value}) } } // Drop removes given index from the map (no bounds check done here). func (i *Map) Drop(index int) { copy(i.value[index:], i.value[index+1:]) i.value = i.value[:len(i.value)-1] } // IsValidMapKey checks whether it's possible to use given Item as a Map // key. func IsValidMapKey(key Item) error { switch key.(type) { case Bool, *BigInteger: return nil case *ByteArray: size := len(key.Value().([]byte)) if size > MaxKeySize { return errTooBigKey } return nil default: return fmt.Errorf("%w: %s map key", ErrInvalidType, key.Type()) } } // Interop represents interop data on the stack. type Interop struct { value interface{} } // NewInterop returns new Interop object. func NewInterop(value interface{}) *Interop { return &Interop{ value: value, } } // Value implements Item interface. func (i *Interop) Value() interface{} { return i.value } // String implements stringer interface. func (i *Interop) String() string { return "Interop" } // Dup implements Item interface. func (i *Interop) Dup() Item { // reference type return i } // TryBool implements Item interface. func (i *Interop) TryBool() (bool, error) { return true, nil } // TryBytes implements Item interface. func (i *Interop) TryBytes() ([]byte, error) { return nil, mkInvConversion(i, ByteArrayT) } // TryInteger implements Item interface. func (i *Interop) TryInteger() (*big.Int, error) { return nil, mkInvConversion(i, IntegerT) } // Equals implements Item interface. func (i *Interop) Equals(s Item) bool { if i == s { return true } else if s == nil { return false } val, ok := s.(*Interop) return ok && i.value == val.value } // Type implements Item interface. func (i *Interop) Type() Type { return InteropT } // Convert implements Item interface. func (i *Interop) Convert(typ Type) (Item, error) { switch typ { case InteropT: return i, nil case BooleanT: return NewBool(true), nil default: return nil, mkInvConversion(i, typ) } } // MarshalJSON implements the json.Marshaler interface. func (i *Interop) MarshalJSON() ([]byte, error) { return json.Marshal(i.value) } // Pointer represents VM-level instruction pointer. type Pointer struct { pos int script []byte hash util.Uint160 } // NewPointer returns new pointer on the specified position. func NewPointer(pos int, script []byte) *Pointer { return &Pointer{ pos: pos, script: script, hash: hash.Hash160(script), } } // NewPointerWithHash returns new pointer on the specified position of the // specified script. It differs from NewPointer in that the script hash is being // passed explicitly to save on hash calculcation. This hash is then being used // for pointer comparisons. func NewPointerWithHash(pos int, script []byte, h util.Uint160) *Pointer { return &Pointer{ pos: pos, script: script, hash: h, } } // String implements Item interface. func (p *Pointer) String() string { return "Pointer" } // Value implements Item interface. func (p *Pointer) Value() interface{} { return p.pos } // Dup implements Item interface. func (p *Pointer) Dup() Item { return &Pointer{ pos: p.pos, script: p.script, hash: p.hash, } } // TryBool implements Item interface. func (p *Pointer) TryBool() (bool, error) { return true, nil } // TryBytes implements Item interface. func (p *Pointer) TryBytes() ([]byte, error) { return nil, mkInvConversion(p, ByteArrayT) } // TryInteger implements Item interface. func (p *Pointer) TryInteger() (*big.Int, error) { return nil, mkInvConversion(p, IntegerT) } // Equals implements Item interface. func (p *Pointer) Equals(s Item) bool { if p == s { return true } ptr, ok := s.(*Pointer) return ok && p.pos == ptr.pos && p.hash == ptr.hash } // Type implements Item interface. func (p *Pointer) Type() Type { return PointerT } // Convert implements Item interface. func (p *Pointer) Convert(typ Type) (Item, error) { switch typ { case PointerT: return p, nil case BooleanT: return NewBool(true), nil default: return nil, mkInvConversion(p, typ) } } // ScriptHash returns pointer item hash. func (p *Pointer) ScriptHash() util.Uint160 { return p.hash } // Position returns pointer item position. func (p *Pointer) Position() int { return p.pos } // Buffer represents represents Buffer stack item. type Buffer []byte // NewBuffer returns a new Buffer object. func NewBuffer(b []byte) *Buffer { return (*Buffer)(&b) } // Value implements Item interface. func (i *Buffer) Value() interface{} { return []byte(*i) } // String implements fmt.Stringer interface. func (i *Buffer) String() string { return "Buffer" } // TryBool implements Item interface. func (i *Buffer) TryBool() (bool, error) { return true, nil } // TryBytes implements Item interface. func (i *Buffer) TryBytes() ([]byte, error) { return *i, nil } // TryInteger implements Item interface. func (i *Buffer) TryInteger() (*big.Int, error) { return nil, mkInvConversion(i, IntegerT) } // Equals implements Item interface. func (i *Buffer) Equals(s Item) bool { return i == s } // Dup implements Item interface. func (i *Buffer) Dup() Item { return i } // MarshalJSON implements the json.Marshaler interface. func (i *Buffer) MarshalJSON() ([]byte, error) { return json.Marshal(hex.EncodeToString(*i)) } // Type implements Item interface. func (i *Buffer) Type() Type { return BufferT } // Convert implements Item interface. func (i *Buffer) Convert(typ Type) (Item, error) { switch typ { case BooleanT: return NewBool(true), nil case BufferT: return i, nil case ByteArrayT: return NewByteArray(slice.Copy(*i)), nil case IntegerT: if len(*i) > MaxBigIntegerSizeBits/8 { return nil, errTooBigInteger } return NewBigInteger(bigint.FromBytes(*i)), nil default: return nil, mkInvConversion(i, typ) } } // Len returns length of Buffer value. func (i *Buffer) Len() int { return len(*i) } // DeepCopy returns new deep copy of the provided item. // Values of Interop items are not deeply copied. // It does preserve duplicates only for non-primitive types. func DeepCopy(item Item) Item { seen := make(map[Item]Item) return deepCopy(item, seen) } func deepCopy(item Item, seen map[Item]Item) Item { if it := seen[item]; it != nil { return it } switch it := item.(type) { case Null: return Null{} case *Array: arr := NewArray(make([]Item, len(it.value))) seen[item] = arr for i := range it.value { arr.value[i] = deepCopy(it.value[i], seen) } return arr case *Struct: arr := NewStruct(make([]Item, len(it.value))) seen[item] = arr for i := range it.value { arr.value[i] = deepCopy(it.value[i], seen) } return arr case *Map: m := NewMap() seen[item] = m for i := range it.value { key := deepCopy(it.value[i].Key, seen) value := deepCopy(it.value[i].Value, seen) m.Add(key, value) } return m case *BigInteger: bi := new(big.Int).Set(it.Big()) return (*BigInteger)(bi) case *ByteArray: return NewByteArray(slice.Copy(*it)) case *Buffer: return NewBuffer(slice.Copy(*it)) case Bool: return it case *Pointer: return NewPointerWithHash(it.pos, it.script, it.hash) case *Interop: return NewInterop(it.value) default: return nil } }