neoneo-go/pkg/vm/stackitem/item.go

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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 a 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 a ByteArray for Equals method.
// It is set to be the maximum uint16 value.
MaxByteArrayComparableSize = math.MaxUint16
// MaxKeySize is the maximum size of a map key.
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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 upon an attempt to make an incorrect
// conversion between item types.
ErrInvalidConversion = errors.New("invalid conversion")
// ErrTooBig is returned when an item exceeds some size constraints, like
// the maximum allowed integer value of the number of elements in an array. It
// can also be returned by serialization functions if the 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 a 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 an appropriate stack item from the 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 an Item to a 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 a primitive item to the 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 a new Struct object.
func NewStruct(items []Item) *Struct {
return &Struct{
value: items,
}
}
// Value implements the Item interface.
func (i *Struct) Value() interface{} {
return i.value
}
// Remove removes the element at `pos` index from the Struct value.
// It will panic if a bad index given.
func (i *Struct) Remove(pos int) {
i.value = append(i.value[:pos], i.value[pos+1:]...)
}
// Append adds an Item to the end of the Struct value.
func (i *Struct) Append(item Item) {
i.value = append(i.value, item)
}
// Clear removes all elements from the Struct item value.
func (i *Struct) Clear() {
i.value = i.value[:0]
}
// Len returns the length of the Struct value.
func (i *Struct) Len() int {
return len(i.value)
}
// String implements the Item interface.
func (i *Struct) String() string {
return "Struct"
}
// Dup implements the Item interface.
func (i *Struct) Dup() Item {
// it's a reference type, so no copying here.
return i
}
// TryBool implements the Item interface.
func (i *Struct) TryBool() (bool, error) { return true, nil }
// TryBytes implements the Item interface.
func (i *Struct) TryBytes() ([]byte, error) {
return nil, mkInvConversion(i, ByteArrayT)
}
// TryInteger implements the Item interface.
func (i *Struct) TryInteger() (*big.Int, error) {
return nil, mkInvConversion(i, IntegerT)
}
// Equals implements the 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 the Item interface.
func (i *Struct) Type() Type { return StructT }
// Convert implements the 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 the 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 the Item interface.
func (i Null) String() string {
return "Null"
}
// Value implements the Item interface.
func (i Null) Value() interface{} {
return nil
}
// Dup implements the Item interface.
// There is no need to perform a real copy here
// since Null has no internal state.
func (i Null) Dup() Item {
return i
}
// TryBool implements the Item interface.
func (i Null) TryBool() (bool, error) { return false, nil }
// TryBytes implements the Item interface.
func (i Null) TryBytes() ([]byte, error) {
return nil, mkInvConversion(i, ByteArrayT)
}
// TryInteger implements the Item interface.
func (i Null) TryInteger() (*big.Int, error) {
return nil, mkInvConversion(i, IntegerT)
}
// Equals implements the Item interface.
func (i Null) Equals(s Item) bool {
_, ok := s.(Null)
return ok
}
// Type implements the Item interface.
func (i Null) Type() Type { return AnyT }
// Convert implements the 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 {
if err := CheckIntegerSize(value); err != nil {
panic(err)
}
return (*BigInteger)(value)
}
// CheckIntegerSize checks that the value size doesn't exceed the VM limit for Interer.
func CheckIntegerSize(value *big.Int) error {
// There are 2 cases when `BitLen` differs from the actual size:
// 1. Positive integer with the highest bit on byte boundary = 1.
// 2. Negative integer with the highest bit on byte boundary = 1
// minus some value. (-0x80 -> 0x80, -0x7F -> 0x81, -0x81 -> 0x7FFF).
sz := value.BitLen()
// This check is not required, just an optimization for the common case.
if sz < MaxBigIntegerSizeBits {
return nil
}
if sz > MaxBigIntegerSizeBits {
return errTooBigInteger
}
if value.Sign() == 1 || value.TrailingZeroBits() != MaxBigIntegerSizeBits-1 {
return errTooBigInteger
}
return nil
}
// 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 the Item interface.
func (i *BigInteger) TryBool() (bool, error) {
return i.Big().Sign() != 0, nil
}
// TryBytes implements the Item interface.
func (i *BigInteger) TryBytes() ([]byte, error) {
return i.Bytes(), nil
}
// TryInteger implements the Item interface.
func (i *BigInteger) TryInteger() (*big.Int, error) {
return i.Big(), nil
}
// Equals implements the 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 the Item interface.
func (i *BigInteger) Value() interface{} {
return i.Big()
}
func (i *BigInteger) String() string {
return "BigInteger"
}
// Dup implements the Item interface.
func (i *BigInteger) Dup() Item {
n := new(big.Int)
return (*BigInteger)(n.Set(i.Big()))
}
// Type implements the Item interface.
func (i *BigInteger) Type() Type { return IntegerT }
// Convert implements the 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 the 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 the Item interface.
func (i Bool) Dup() Item {
return i
}
// TryBool implements the 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 the Item interface.
func (i Bool) TryBytes() ([]byte, error) {
return i.Bytes(), nil
}
// TryInteger implements the Item interface.
func (i Bool) TryInteger() (*big.Int, error) {
if i {
return big.NewInt(1), nil
}
return big.NewInt(0), nil
}
// Equals implements the 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 the Item interface.
func (i Bool) Type() Type { return BooleanT }
// Convert implements the 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 the 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 the 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 the Item interface.
func (i ByteArray) TryBytes() ([]byte, error) {
return i, nil
}
// TryInteger implements the Item interface.
func (i ByteArray) TryInteger() (*big.Int, error) {
if len(i) > MaxBigIntegerSizeBits/8 {
return nil, errTooBigInteger
}
return bigint.FromBytes(i), nil
}
// Equals implements the 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 the Item interface.
func (i *ByteArray) Dup() Item {
ba := slice.Copy(*i)
return (*ByteArray)(&ba)
}
// Type implements the Item interface.
func (i *ByteArray) Type() Type { return ByteArrayT }
// Convert implements the 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 the Item interface.
func (i *Array) Value() interface{} {
return i.value
}
// Remove removes the 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 an Item to the end of the Array value.
func (i *Array) Append(item Item) {
i.value = append(i.value, item)
}
// Clear removes all elements from the 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 the Item interface.
func (i *Array) TryBool() (bool, error) { return true, nil }
// TryBytes implements the Item interface.
func (i *Array) TryBytes() ([]byte, error) {
return nil, mkInvConversion(i, ByteArrayT)
}
// TryInteger implements the Item interface.
func (i *Array) TryInteger() (*big.Int, error) {
return nil, mkInvConversion(i, IntegerT)
}
// Equals implements the Item interface.
func (i *Array) Equals(s Item) bool {
return i == s
}
// Dup implements the Item interface.
func (i *Array) Dup() Item {
// reference type
return i
}
// Type implements the Item interface.
func (i *Array) Type() Type { return ArrayT }
// Convert implements the 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 a 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 needed.
type Map struct {
value []MapElement
rc
}
// NewMap returns a new Map object.
func NewMap() *Map {
return &Map{
value: make([]MapElement, 0),
}
}
// NewMapWithValue returns a new Map object filled with the specified value.
func NewMapWithValue(value []MapElement) *Map {
if value != nil {
return &Map{
value: value,
}
}
return NewMap()
}
// Value implements the Item interface.
func (i *Map) Value() interface{} {
return i.value
}
// Clear removes all elements from the Map item value.
func (i *Map) Clear() {
i.value = i.value[:0]
}
// Len returns the length of the Map value.
func (i *Map) Len() int {
return len(i.value)
}
// TryBool implements the Item interface.
func (i *Map) TryBool() (bool, error) { return true, nil }
// TryBytes implements the Item interface.
func (i *Map) TryBytes() ([]byte, error) {
return nil, mkInvConversion(i, ByteArrayT)
}
// TryInteger implements the Item interface.
func (i *Map) TryInteger() (*big.Int, error) {
return nil, mkInvConversion(i, IntegerT)
}
// Equals implements the 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 the map has the specified key.
func (i *Map) Has(key Item) bool {
return i.Index(key) >= 0
}
// Dup implements the Item interface.
func (i *Map) Dup() Item {
// reference type
return i
}
// Type implements the Item interface.
func (i *Map) Type() Type { return MapT }
// Convert implements the 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 a key-value pair to the map.
func (i *Map) Add(key, value Item) {
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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 the 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 the given Item as a Map
// key.
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func IsValidMapKey(key Item) error {
switch key.(type) {
case Bool, *BigInteger:
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return nil
case *ByteArray:
size := len(key.Value().([]byte))
if size > MaxKeySize {
return errTooBigKey
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}
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 a new Interop object.
func NewInterop(value interface{}) *Interop {
return &Interop{
value: value,
}
}
// Value implements the Item interface.
func (i *Interop) Value() interface{} {
return i.value
}
// String implements stringer interface.
func (i *Interop) String() string {
return "Interop"
}
// Dup implements the Item interface.
func (i *Interop) Dup() Item {
// reference type
return i
}
// TryBool implements the Item interface.
func (i *Interop) TryBool() (bool, error) { return true, nil }
// TryBytes implements the Item interface.
func (i *Interop) TryBytes() ([]byte, error) {
return nil, mkInvConversion(i, ByteArrayT)
}
// TryInteger implements the Item interface.
func (i *Interop) TryInteger() (*big.Int, error) {
return nil, mkInvConversion(i, IntegerT)
}
// Equals implements the 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 the Item interface.
func (i *Interop) Type() Type { return InteropT }
// Convert implements the 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 a VM-level instruction pointer.
type Pointer struct {
pos int
script []byte
hash util.Uint160
}
// NewPointer returns a 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 a 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 calculation. 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 the Item interface.
func (p *Pointer) String() string {
return "Pointer"
}
// Value implements the Item interface.
func (p *Pointer) Value() interface{} {
return p.pos
}
// Dup implements the Item interface.
func (p *Pointer) Dup() Item {
return &Pointer{
pos: p.pos,
script: p.script,
hash: p.hash,
}
}
// TryBool implements the Item interface.
func (p *Pointer) TryBool() (bool, error) {
return true, nil
}
// TryBytes implements the Item interface.
func (p *Pointer) TryBytes() ([]byte, error) {
return nil, mkInvConversion(p, ByteArrayT)
}
// TryInteger implements the Item interface.
func (p *Pointer) TryInteger() (*big.Int, error) {
return nil, mkInvConversion(p, IntegerT)
}
// Equals implements the 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 the Item interface.
func (p *Pointer) Type() Type {
return PointerT
}
// Convert implements the 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 the pointer item hash.
func (p *Pointer) ScriptHash() util.Uint160 {
return p.hash
}
// Position returns the pointer item position.
func (p *Pointer) Position() int {
return p.pos
}
// Buffer represents represents a Buffer stack item.
type Buffer []byte
// NewBuffer returns a new Buffer object.
func NewBuffer(b []byte) *Buffer {
return (*Buffer)(&b)
}
// Value implements the Item interface.
func (i *Buffer) Value() interface{} {
return []byte(*i)
}
// String implements the fmt.Stringer interface.
func (i *Buffer) String() string {
return "Buffer"
}
// TryBool implements the Item interface.
func (i *Buffer) TryBool() (bool, error) {
return true, nil
}
// TryBytes implements the Item interface.
func (i *Buffer) TryBytes() ([]byte, error) {
return *i, nil
}
// TryInteger implements the Item interface.
func (i *Buffer) TryInteger() (*big.Int, error) {
return nil, mkInvConversion(i, IntegerT)
}
// Equals implements the Item interface.
func (i *Buffer) Equals(s Item) bool {
return i == s
}
// Dup implements the 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 the Item interface.
func (i *Buffer) Type() Type { return BufferT }
// Convert implements the 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 the length of the Buffer value.
func (i *Buffer) Len() int {
return len(*i)
}
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// DeepCopy returns a new deep copy of the provided item.
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// 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, typicalNumOfItems)
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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)
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case *ByteArray:
return NewByteArray(slice.Copy(*it))
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case *Buffer:
return NewBuffer(slice.Copy(*it))
case Bool:
return it
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case *Pointer:
return NewPointerWithHash(it.pos, it.script, it.hash)
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case *Interop:
return NewInterop(it.value)
default:
return nil
}
}