forked from TrueCloudLab/neoneo-go
339 lines
8.6 KiB
Go
339 lines
8.6 KiB
Go
package stackitem
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import (
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"errors"
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"fmt"
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"math/big"
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"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
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"github.com/nspcc-dev/neo-go/pkg/io"
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)
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// MaxDeserialized is the maximum number one deserialized item can contain
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// (including itself).
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const MaxDeserialized = 2048
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// typicalNumOfItems is the number of items covering most serialization needs.
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// It's a hint used for map creation, so it does not limit anything, it's just
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// a microoptimization to avoid excessive reallocations. Most of the serialized
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// items are structs, so there is at least one of them.
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const typicalNumOfItems = 4
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// ErrRecursive is returned upon an attempt to serialize some recursive stack item
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// (like an array including an item with the reference to the same array).
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var ErrRecursive = errors.New("recursive item")
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// ErrUnserializable is returned upon an attempt to serialize some item that can't
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// be serialized (like Interop item or Pointer).
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var ErrUnserializable = errors.New("unserializable")
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// SerializationContext is a serialization context.
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type SerializationContext struct {
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uv [9]byte
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data []byte
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allowInvalid bool
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seen map[Item]sliceNoPointer
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}
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// deserContext is an internal deserialization context.
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type deserContext struct {
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*io.BinReader
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allowInvalid bool
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limit int
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}
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// Serialize encodes the given Item into a byte slice.
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func Serialize(item Item) ([]byte, error) {
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sc := SerializationContext{
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allowInvalid: false,
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seen: make(map[Item]sliceNoPointer, typicalNumOfItems),
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}
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err := sc.serialize(item)
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if err != nil {
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return nil, err
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}
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return sc.data, nil
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}
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// EncodeBinary encodes the given Item into the given BinWriter. It's
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// similar to io.Serializable's EncodeBinary but works with Item
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// interface.
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func EncodeBinary(item Item, w *io.BinWriter) {
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data, err := Serialize(item)
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if err != nil {
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w.Err = err
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return
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}
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w.WriteBytes(data)
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}
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// EncodeBinaryProtected encodes the given Item into the given BinWriter. It's
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// similar to EncodeBinary but allows to encode interop items (only type,
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// value is lost) and doesn't return any errors in the w. Instead, if an error
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// (like recursive array) is encountered, it just writes the special InvalidT
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// type of an element to the w.
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func EncodeBinaryProtected(item Item, w *io.BinWriter) {
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sc := SerializationContext{
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allowInvalid: true,
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seen: make(map[Item]sliceNoPointer, typicalNumOfItems),
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}
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err := sc.serialize(item)
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if err != nil {
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w.WriteBytes([]byte{byte(InvalidT)})
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return
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}
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w.WriteBytes(sc.data)
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}
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func (w *SerializationContext) writeArray(item Item, arr []Item, start int) error {
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w.seen[item] = sliceNoPointer{}
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w.appendVarUint(uint64(len(arr)))
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for i := range arr {
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if err := w.serialize(arr[i]); err != nil {
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return err
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}
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}
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w.seen[item] = sliceNoPointer{start, len(w.data)}
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return nil
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}
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// NewSerializationContext returns reusable stack item serialization context.
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func NewSerializationContext() *SerializationContext {
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return &SerializationContext{
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seen: make(map[Item]sliceNoPointer, typicalNumOfItems),
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}
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}
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// Serialize returns flat slice of bytes with the given item. The process can be protected
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// from bad elements if appropriate flag is given (otherwise an error is returned on
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// encountering any of them). The buffer returned is only valid until the call to Serialize.
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func (w *SerializationContext) Serialize(item Item, protected bool) ([]byte, error) {
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w.allowInvalid = protected
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if w.data != nil {
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w.data = w.data[:0]
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}
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for k := range w.seen {
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delete(w.seen, k)
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}
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err := w.serialize(item)
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if err != nil && protected {
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if w.data == nil {
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w.data = make([]byte, 0, 1)
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}
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w.data = append(w.data[:0], byte(InvalidT))
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err = nil
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}
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return w.data, err
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}
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func (w *SerializationContext) serialize(item Item) error {
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if v, ok := w.seen[item]; ok {
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if v.start == v.end {
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return ErrRecursive
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}
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if len(w.data)+v.end-v.start > MaxSize {
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return ErrTooBig
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}
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w.data = append(w.data, w.data[v.start:v.end]...)
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return nil
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}
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start := len(w.data)
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switch t := item.(type) {
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case *ByteArray:
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w.data = append(w.data, byte(ByteArrayT))
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w.appendVarUint(uint64(len(*t)))
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w.data = append(w.data, *t...)
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case *Buffer:
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w.data = append(w.data, byte(BufferT))
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w.appendVarUint(uint64(len(*t)))
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w.data = append(w.data, *t...)
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case Bool:
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w.data = append(w.data, byte(BooleanT))
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if t {
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w.data = append(w.data, 1)
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} else {
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w.data = append(w.data, 0)
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}
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case *BigInteger:
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w.data = append(w.data, byte(IntegerT))
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ln := len(w.data)
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w.data = append(w.data, 0)
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data := bigint.ToPreallocatedBytes((*big.Int)(t), w.data[len(w.data):])
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w.data[ln] = byte(len(data))
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w.data = append(w.data, data...)
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case *Interop:
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if w.allowInvalid {
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w.data = append(w.data, byte(InteropT))
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} else {
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return fmt.Errorf("%w: Interop", ErrUnserializable)
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}
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case *Array:
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w.data = append(w.data, byte(ArrayT))
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if err := w.writeArray(item, t.value, start); err != nil {
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return err
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}
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case *Struct:
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w.data = append(w.data, byte(StructT))
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if err := w.writeArray(item, t.value, start); err != nil {
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return err
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}
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case *Map:
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w.seen[item] = sliceNoPointer{}
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elems := t.value
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w.data = append(w.data, byte(MapT))
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w.appendVarUint(uint64(len(elems)))
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for i := range elems {
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if err := w.serialize(elems[i].Key); err != nil {
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return err
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}
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if err := w.serialize(elems[i].Value); err != nil {
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return err
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}
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}
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w.seen[item] = sliceNoPointer{start, len(w.data)}
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case Null:
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w.data = append(w.data, byte(AnyT))
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case nil:
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if w.allowInvalid {
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w.data = append(w.data, byte(InvalidT))
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} else {
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return fmt.Errorf("%w: nil", ErrUnserializable)
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}
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}
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if len(w.data) > MaxSize {
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return errTooBigSize
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}
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return nil
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}
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func (w *SerializationContext) appendVarUint(val uint64) {
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n := io.PutVarUint(w.uv[:], val)
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w.data = append(w.data, w.uv[:n]...)
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}
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// Deserialize decodes the Item from the given byte slice.
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func Deserialize(data []byte) (Item, error) {
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r := io.NewBinReaderFromBuf(data)
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item := DecodeBinary(r)
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if r.Err != nil {
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return nil, r.Err
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}
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return item, nil
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}
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// DecodeBinary decodes the previously serialized Item from the given
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// reader. It's similar to the io.Serializable's DecodeBinary() but implemented
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// as a function because Item itself is an interface. Caveat: always check
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// reader's error value before using the returned Item.
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func DecodeBinary(r *io.BinReader) Item {
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dc := deserContext{
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BinReader: r,
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allowInvalid: false,
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limit: MaxDeserialized,
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}
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return dc.decodeBinary()
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}
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// DecodeBinaryProtected is similar to DecodeBinary but allows Interop and
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// Invalid values to be present (making it symmetric to EncodeBinaryProtected).
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func DecodeBinaryProtected(r *io.BinReader) Item {
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dc := deserContext{
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BinReader: r,
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allowInvalid: true,
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limit: MaxDeserialized,
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}
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return dc.decodeBinary()
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}
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func (r *deserContext) decodeBinary() Item {
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var t = Type(r.ReadB())
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if r.Err != nil {
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return nil
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}
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r.limit--
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if r.limit < 0 {
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r.Err = errTooBigElements
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return nil
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}
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switch t {
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case ByteArrayT, BufferT:
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data := r.ReadVarBytes(MaxSize)
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if t == ByteArrayT {
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return NewByteArray(data)
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}
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return NewBuffer(data)
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case BooleanT:
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var b = r.ReadBool()
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return NewBool(b)
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case IntegerT:
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data := r.ReadVarBytes(bigint.MaxBytesLen)
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num := bigint.FromBytes(data)
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return NewBigInteger(num)
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case ArrayT, StructT:
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size := int(r.ReadVarUint())
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if size > MaxDeserialized {
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r.Err = errTooBigElements
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return nil
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}
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arr := make([]Item, size)
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for i := 0; i < size; i++ {
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arr[i] = r.decodeBinary()
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}
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if t == ArrayT {
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return NewArray(arr)
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}
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return NewStruct(arr)
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case MapT:
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size := int(r.ReadVarUint())
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if size > MaxDeserialized {
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r.Err = errTooBigElements
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return nil
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}
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m := NewMap()
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for i := 0; i < size; i++ {
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key := r.decodeBinary()
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value := r.decodeBinary()
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if r.Err != nil {
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break
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}
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m.Add(key, value)
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}
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return m
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case AnyT:
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return Null{}
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case InteropT:
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if r.allowInvalid {
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return NewInterop(nil)
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}
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fallthrough
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default:
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if t == InvalidT && r.allowInvalid {
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return nil
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}
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r.Err = fmt.Errorf("%w: %v", ErrInvalidType, t)
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return nil
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}
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}
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// SerializeConvertible serializes Convertible into a slice of bytes.
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func SerializeConvertible(conv Convertible) ([]byte, error) {
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item, err := conv.ToStackItem()
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if err != nil {
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return nil, err
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}
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return Serialize(item)
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}
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// DeserializeConvertible deserializes Convertible from a slice of bytes.
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func DeserializeConvertible(data []byte, conv Convertible) error {
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item, err := Deserialize(data)
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if err != nil {
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return err
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}
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return conv.FromStackItem(item)
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}
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