neoneo-go/pkg/vm/serialization.go

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package vm
import (
"errors"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
)
type stackItemType byte
const (
byteArrayT stackItemType = 0x00
booleanT stackItemType = 0x01
integerT stackItemType = 0x02
arrayT stackItemType = 0x80
structT stackItemType = 0x81
mapT stackItemType = 0x82
)
// SerializeItem encodes given StackItem into the byte slice.
func SerializeItem(item StackItem) ([]byte, error) {
w := io.NewBufBinWriter()
EncodeBinaryStackItem(item, w.BinWriter)
if w.Err != nil {
return nil, w.Err
}
return w.Bytes(), nil
}
// EncodeBinaryStackItem encodes given StackItem into the given BinWriter. It's
// similar to io.Serializable's EncodeBinary, but works with StackItem
// interface.
func EncodeBinaryStackItem(item StackItem, w *io.BinWriter) {
serializeItemTo(item, w, make(map[StackItem]bool))
}
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func serializeItemTo(item StackItem, w *io.BinWriter, seen map[StackItem]bool) {
if seen[item] {
w.Err = errors.New("recursive structures can't be serialized")
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return
}
switch t := item.(type) {
case *ByteArrayItem:
w.WriteBytes([]byte{byte(byteArrayT)})
w.WriteVarBytes(t.value)
case *BoolItem:
w.WriteBytes([]byte{byte(booleanT)})
w.WriteBool(t.value)
case *BigIntegerItem:
w.WriteBytes([]byte{byte(integerT)})
w.WriteVarBytes(emit.IntToBytes(t.value))
case *InteropItem:
w.Err = errors.New("interop item can't be serialized")
case *ArrayItem, *StructItem:
seen[item] = true
_, isArray := t.(*ArrayItem)
if isArray {
w.WriteBytes([]byte{byte(arrayT)})
} else {
w.WriteBytes([]byte{byte(structT)})
}
arr := t.Value().([]StackItem)
w.WriteVarUint(uint64(len(arr)))
for i := range arr {
serializeItemTo(arr[i], w, seen)
}
case *MapItem:
seen[item] = true
w.WriteBytes([]byte{byte(mapT)})
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w.WriteVarUint(uint64(len(t.value)))
for k, v := range t.value {
serializeItemTo(v, w, seen)
serializeItemTo(makeStackItem(k), w, seen)
}
}
}
// DeserializeItem decodes StackItem from the given byte slice.
func DeserializeItem(data []byte) (StackItem, error) {
r := io.NewBinReaderFromBuf(data)
item := DecodeBinaryStackItem(r)
if r.Err != nil {
return nil, r.Err
}
return item, nil
}
// DecodeBinaryStackItem decodes previously serialized StackItem from the given
// reader. It's similar to the io.Serializable's DecodeBinary(), but implemented
// as a function because StackItem itself is an interface. Caveat: always check
// reader's error value before using the returned StackItem.
func DecodeBinaryStackItem(r *io.BinReader) StackItem {
var t = r.ReadB()
if r.Err != nil {
return nil
}
switch stackItemType(t) {
case byteArrayT:
data := r.ReadVarBytes()
return NewByteArrayItem(data)
case booleanT:
var b = r.ReadBool()
return NewBoolItem(b)
case integerT:
data := r.ReadVarBytes()
num := emit.BytesToInt(data)
return &BigIntegerItem{
value: num,
}
case arrayT, structT:
size := int(r.ReadVarUint())
arr := make([]StackItem, size)
for i := 0; i < size; i++ {
arr[i] = DecodeBinaryStackItem(r)
}
if stackItemType(t) == arrayT {
return &ArrayItem{value: arr}
}
return &StructItem{value: arr}
case mapT:
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size := int(r.ReadVarUint())
m := NewMapItem()
for i := 0; i < size; i++ {
value := DecodeBinaryStackItem(r)
key := DecodeBinaryStackItem(r)
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if r.Err != nil {
break
}
m.Add(key, value)
}
return m
default:
r.Err = errors.New("unknown type")
return nil
}
}