neo-go/pkg/core/mpt/extension.go
Evgenii Stratonikov 861a1638e8 mpt: implement MPT trie
MPT is a trie with a branching factor = 16, i.e. it consists of sequences in
16-element alphabet.
2020-06-01 18:14:19 +03:00

70 lines
1.6 KiB
Go

package mpt
import (
"fmt"
"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"
)
// MaxKeyLength is the max length of the extension node key.
const MaxKeyLength = 1125
// ExtensionNode represents MPT's extension node.
type ExtensionNode struct {
hash util.Uint256
valid bool
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 Node interface.
func (e *ExtensionNode) Hash() util.Uint256 {
if !e.valid {
e.hash = hash.DoubleSha256(toBytes(e))
e.valid = true
}
return e.hash
}
// invalidateHash invalidates node hash.
func (e *ExtensionNode) invalidateHash() {
e.valid = false
}
// DecodeBinary implements io.Serializable.
func (e *ExtensionNode) DecodeBinary(r *io.BinReader) {
sz := r.ReadVarUint()
if sz > MaxKeyLength {
r.Err = fmt.Errorf("extension node key is too big: %d", sz)
return
}
e.valid = false
e.key = make([]byte, sz)
r.ReadBytes(e.key)
e.next = new(HashNode)
e.next.DecodeBinary(r)
}
// EncodeBinary implements io.Serializable.
func (e ExtensionNode) EncodeBinary(w *io.BinWriter) {
w.WriteVarBytes(e.key)
n := NewHashNode(e.next.Hash())
n.EncodeBinary(w)
}