neoneo-go/pkg/core/mpt/branch.go

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package mpt
import (
"encoding/json"
"errors"
"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/util"
)
const (
// childrenCount represents a number of children of a branch node.
childrenCount = 17
// lastChild is the index of the last child.
lastChild = childrenCount - 1
)
// BranchNode represents MPT's branch node.
type BranchNode struct {
hash util.Uint256
valid bool
Children [childrenCount]Node
}
var _ Node = (*BranchNode)(nil)
// NewBranchNode returns new branch node.
func NewBranchNode() *BranchNode {
b := new(BranchNode)
for i := 0; i < childrenCount; i++ {
b.Children[i] = new(HashNode)
}
return b
}
// Type implements Node interface.
func (b *BranchNode) Type() NodeType { return BranchT }
// Hash implements Node interface.
func (b *BranchNode) Hash() util.Uint256 {
if !b.valid {
b.hash = hash.DoubleSha256(toBytes(b))
b.valid = true
}
return b.hash
}
// invalidateHash invalidates node hash.
func (b *BranchNode) invalidateHash() {
b.valid = false
}
// EncodeBinary implements io.Serializable.
func (b *BranchNode) EncodeBinary(w *io.BinWriter) {
for i := 0; i < childrenCount; i++ {
if hn, ok := b.Children[i].(*HashNode); ok {
hn.EncodeBinary(w)
continue
}
n := NewHashNode(b.Children[i].Hash())
n.EncodeBinary(w)
}
}
// DecodeBinary implements io.Serializable.
func (b *BranchNode) DecodeBinary(r *io.BinReader) {
for i := 0; i < childrenCount; i++ {
b.Children[i] = new(HashNode)
b.Children[i].DecodeBinary(r)
}
}
// MarshalJSON implements json.Marshaler.
func (b *BranchNode) MarshalJSON() ([]byte, error) {
return json.Marshal(b.Children)
}
// UnmarshalJSON implements json.Unmarshaler.
func (b *BranchNode) UnmarshalJSON(data []byte) error {
var obj NodeObject
if err := obj.UnmarshalJSON(data); err != nil {
return err
} else if u, ok := obj.Node.(*BranchNode); ok {
*b = *u
return nil
}
return errors.New("expected branch node")
}
// splitPath splits path for a branch node.
func splitPath(path []byte) (byte, []byte) {
if len(path) != 0 {
return path[0], path[1:]
}
return lastChild, path
}