neoneo-go/pkg/vm/stackitem/item.go
Roman Khimov 9d2712573f *: enable godot linter and fix all its warnings
It's important for NeoGo to have clean documentation. No functional changes.
2021-05-12 23:17:03 +03:00

1135 lines
25 KiB
Go

package stackitem
import (
"bytes"
"encoding/binary"
"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"
)
const (
// MaxBigIntegerSizeBits is the maximum size of BigInt item in bits.
MaxBigIntegerSizeBits = 32 * 8
// MaxArraySize is the maximum array size allowed in the VM.
MaxArraySize = 1024
// MaxSize is the maximum item size allowed in the VM.
MaxSize = 1024 * 1024
// 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)
}
var (
errInvalidConversion = errors.New("invalid conversion type")
errExceedingMaxComparableSize = errors.New("the operand exceeds the maximum comparable size")
)
// 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{
value: big.NewInt(int64(val)),
}
case int64:
return &BigInteger{
value: big.NewInt(val),
}
case uint8:
return &BigInteger{
value: big.NewInt(int64(val)),
}
case uint16:
return &BigInteger{
value: big.NewInt(int64(val)),
}
case uint32:
return &BigInteger{
value: big.NewInt(int64(val)),
}
case uint64:
b := make([]byte, 8)
binary.BigEndian.PutUint64(b, val)
bigInt := big.NewInt(0)
bigInt.SetBytes(b)
return &BigInteger{
value: bigInt,
}
case []byte:
return &ByteArray{
value: val,
}
case string:
return &ByteArray{
value: []byte(val),
}
case bool:
return &Bool{
value: 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 "", errors.New("not a valid UTF-8")
}
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 {
newb := make([]byte, len(b))
copy(newb, b)
return NewBuffer(newb), 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, errInvalidConversion
}
}
// Struct represents a struct on the stack.
type Struct struct {
value []Item
}
// 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, errors.New("can't convert Struct to ByteString")
}
// TryInteger implements Item interface.
func (i *Struct) TryInteger() (*big.Int, error) {
return nil, errors.New("can't convert Struct to Integer")
}
// Equals implements Item interface.
func (i *Struct) Equals(s Item) bool {
if i == s {
return true
} else if s == nil {
return false
}
val, ok := s.(*Struct)
if !ok || len(i.value) != len(val.value) {
return false
}
for j := range i.value {
if !i.value[j].Equals(val.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, errInvalidConversion
}
}
// Clone returns a Struct with all Struct fields copied by value.
// Array fields are still copied by reference.
func (i *Struct) Clone() *Struct {
ret := &Struct{make([]Item, len(i.value))}
for j := range i.value {
switch t := i.value[j].(type) {
case *Struct:
ret.value[j] = t.Clone()
default:
ret.value[j] = t
}
}
return ret
}
// 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, errors.New("can't convert Null to ByteString")
}
// TryInteger implements Item interface.
func (i Null) TryInteger() (*big.Int, error) {
return nil, errors.New("can't convert Null to Integer")
}
// 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, errInvalidConversion
}
return i, nil
}
// BigInteger represents a big integer on the stack.
type BigInteger struct {
value *big.Int
}
// NewBigInteger returns an new BigInteger object.
func NewBigInteger(value *big.Int) *BigInteger {
const tooBigErrMsg = "integer is too big"
// 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(tooBigErrMsg)
} else if sz == MaxBigIntegerSizeBits {
if value.Sign() == 1 || value.TrailingZeroBits() != MaxBigIntegerSizeBits-1 {
panic(tooBigErrMsg)
}
}
return &BigInteger{
value: value,
}
}
// Bytes converts i to a slice of bytes.
func (i *BigInteger) Bytes() []byte {
return bigint.ToBytes(i.value)
}
// TryBool implements Item interface.
func (i *BigInteger) TryBool() (bool, error) {
return i.value.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.value, 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.value.Cmp(val.value) == 0
}
// Value implements Item interface.
func (i *BigInteger) Value() interface{} {
return i.value
}
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.value)}
}
// 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.value)
}
// Bool represents a boolean Item.
type Bool struct {
value bool
}
// NewBool returns an new Bool object.
func NewBool(val bool) *Bool {
return &Bool{
value: val,
}
}
// Value implements Item interface.
func (i *Bool) Value() interface{} {
return i.value
}
// MarshalJSON implements the json.Marshaler interface.
func (i *Bool) MarshalJSON() ([]byte, error) {
return json.Marshal(i.value)
}
func (i *Bool) String() string {
return "Boolean"
}
// Dup implements Item interface.
func (i *Bool) Dup() Item {
return &Bool{i.value}
}
// TryBool implements Item interface.
func (i *Bool) TryBool() (bool, error) { return i.value, nil }
// Bytes converts Bool to bytes.
func (i *Bool) Bytes() []byte {
if i.value {
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.value {
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.value == val.value
}
// 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 struct {
value []byte
}
// NewByteArray returns an new ByteArray object.
func NewByteArray(b []byte) *ByteArray {
return &ByteArray{
value: b,
}
}
// Value implements Item interface.
func (i *ByteArray) Value() interface{} {
return i.value
}
// MarshalJSON implements the json.Marshaler interface.
func (i *ByteArray) MarshalJSON() ([]byte, error) {
return json.Marshal(hex.EncodeToString(i.value))
}
func (i *ByteArray) String() string {
return "ByteString"
}
// TryBool implements Item interface.
func (i *ByteArray) TryBool() (bool, error) {
if len(i.value) > MaxBigIntegerSizeBits/8 {
return false, errors.New("too big byte string")
}
for _, b := range i.value {
if b != 0 {
return true, nil
}
}
return false, nil
}
// TryBytes implements Item interface.
func (i *ByteArray) TryBytes() ([]byte, error) {
return i.value, nil
}
// TryInteger implements Item interface.
func (i *ByteArray) TryInteger() (*big.Int, error) {
if len(i.value) > MaxBigIntegerSizeBits/8 {
return nil, errors.New("integer is too big")
}
return bigint.FromBytes(i.value), nil
}
// Equals implements Item interface.
func (i *ByteArray) Equals(s Item) bool {
if len(i.value) > MaxByteArrayComparableSize {
panic(errExceedingMaxComparableSize)
}
if i == s {
return true
} else if s == nil {
return false
}
val, ok := s.(*ByteArray)
if !ok {
return false
}
if len(val.value) > MaxByteArrayComparableSize {
panic(errExceedingMaxComparableSize)
}
return bytes.Equal(i.value, val.value)
}
// Dup implements Item interface.
func (i *ByteArray) Dup() Item {
a := make([]byte, len(i.value))
copy(a, i.value)
return &ByteArray{a}
}
// 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
}
// 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, errors.New("can't convert Array to ByteString")
}
// TryInteger implements Item interface.
func (i *Array) TryInteger() (*big.Int, error) {
return nil, errors.New("can't convert Array to Integer")
}
// 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, errInvalidConversion
}
}
// 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
}
// 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, errors.New("can't convert Map to ByteString")
}
// TryInteger implements Item interface.
func (i *Map) TryInteger() (*big.Int, error) {
return nil, errors.New("can't convert Map to Integer")
}
// 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, errInvalidConversion
}
}
// 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 fmt.Errorf("invalid map key size: %d", size)
}
return nil
default:
return fmt.Errorf("invalid map key of type %s", 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, errors.New("can't convert Interop to ByteString")
}
// TryInteger implements Item interface.
func (i *Interop) TryInteger() (*big.Int, error) {
return nil, errors.New("can't convert Interop to Integer")
}
// 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, errInvalidConversion
}
}
// 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, errors.New("can't convert Pointer to ByteString")
}
// TryInteger implements Item interface.
func (p *Pointer) TryInteger() (*big.Int, error) {
return nil, errors.New("can't convert Pointer to Integer")
}
// 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, errInvalidConversion
}
}
// 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 struct {
value []byte
}
// NewBuffer returns a new Buffer object.
func NewBuffer(b []byte) *Buffer {
return &Buffer{
value: b,
}
}
// Value implements Item interface.
func (i *Buffer) Value() interface{} {
return i.value
}
// 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.value, nil
}
// TryInteger implements Item interface.
func (i *Buffer) TryInteger() (*big.Int, error) {
return nil, errors.New("can't convert Buffer to Integer")
}
// 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.value))
}
// 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:
val := make([]byte, len(i.value))
copy(val, i.value)
return NewByteArray(val), nil
case IntegerT:
if len(i.value) > MaxBigIntegerSizeBits/8 {
return nil, errInvalidConversion
}
return NewBigInteger(bigint.FromBytes(i.value)), nil
default:
return nil, errInvalidConversion
}
}
// Len returns length of Buffer value.
func (i *Buffer) Len() int {
return len(i.value)
}
// 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).SetBytes(it.value.Bytes())
if it.value.Sign() == -1 {
bi.Neg(bi)
}
return NewBigInteger(bi)
case *ByteArray:
val := make([]byte, len(it.value))
copy(val, it.value)
return NewByteArray(val)
case *Buffer:
val := make([]byte, len(it.value))
copy(val, it.value)
return NewBuffer(val)
case *Bool:
return NewBool(it.value)
case *Pointer:
return NewPointerWithHash(it.pos, it.script, it.hash)
case *Interop:
return NewInterop(it.value)
default:
return nil
}
}