neo-go/pkg/core/mpt/extension.go

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package mpt
import (
"encoding/hex"
"encoding/json"
"errors"
"fmt"
2021-03-31 09:44:15 +00:00
"github.com/nspcc-dev/neo-go/pkg/core/storage"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/util"
)
const (
// maxPathLength is the max length of the extension node key.
maxPathLength = (storage.MaxStorageKeyLen + 4) * 2
// MaxKeyLength is the max length of the key to put in trie
// before transforming to nibbles.
MaxKeyLength = maxPathLength / 2
)
// ExtensionNode represents MPT's extension node.
type ExtensionNode struct {
BaseNode
key []byte
next Node
}
var _ Node = (*ExtensionNode)(nil)
// NewExtensionNode returns hash node with the specified key and next node.
// Note: because it is a part of Trie, key must be mangled, i.e. must contain only bytes with high half = 0.
func NewExtensionNode(key []byte, next Node) *ExtensionNode {
return &ExtensionNode{
key: key,
next: next,
}
}
// Type implements Node interface.
func (e ExtensionNode) Type() NodeType { return ExtensionT }
// Hash implements BaseNode interface.
func (e *ExtensionNode) Hash() util.Uint256 {
return e.getHash(e)
}
// Bytes implements BaseNode interface.
func (e *ExtensionNode) Bytes() []byte {
return e.getBytes(e)
}
// DecodeBinary implements io.Serializable.
func (e *ExtensionNode) DecodeBinary(r *io.BinReader) {
sz := r.ReadVarUint()
if sz > maxPathLength {
r.Err = fmt.Errorf("extension node key is too big: %d", sz)
return
}
e.key = make([]byte, sz)
r.ReadBytes(e.key)
no := new(NodeObject)
no.DecodeBinary(r)
e.next = no.Node
e.invalidateCache()
}
// EncodeBinary implements io.Serializable.
func (e ExtensionNode) EncodeBinary(w *io.BinWriter) {
w.WriteVarBytes(e.key)
e.next.EncodeBinaryAsChild(w)
}
// EncodeBinaryAsChild implements BaseNode interface.
func (e *ExtensionNode) EncodeBinaryAsChild(w *io.BinWriter) {
n := &NodeObject{Node: NewHashNode(e.Hash())} // with type
n.EncodeBinary(w)
}
// MarshalJSON implements json.Marshaler.
func (e *ExtensionNode) MarshalJSON() ([]byte, error) {
m := map[string]interface{}{
"key": hex.EncodeToString(e.key),
"next": e.next,
}
return json.Marshal(m)
}
// UnmarshalJSON implements json.Unmarshaler.
func (e *ExtensionNode) UnmarshalJSON(data []byte) error {
var obj NodeObject
if err := obj.UnmarshalJSON(data); err != nil {
return err
} else if u, ok := obj.Node.(*ExtensionNode); ok {
*e = *u
return nil
}
return errors.New("expected extension node")
}