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package db
import (
"bytes"
"crypto/sha256"
"errors"
)
// ErrNotFound is used by the implementations of the interface db.Storage for
// when a key is not found in the storage
var ErrNotFound = errors.New("key not found")
// Storage is the interface that defines the methods for the storage used in
// the merkletree. Examples of the interface implementation can be found at
// db/memory and db/leveldb directories.
type Storage interface {
NewTx() (Tx, error)
WithPrefix(prefix []byte) Storage
Get([]byte) ([]byte, error)
List(int) ([]KV, error)
Close()
Info() string
Iterate(func([]byte, []byte) (bool, error)) error
}
// Tx is the interface that defines the methods for the db transaction used in
// the merkletree storage. Examples of the interface implementation can be
// found at db/memory and db/leveldb directories.
type Tx interface {
Get([]byte) ([]byte, error)
Put(k, v []byte)
Add(Tx)
Commit() error
Close()
}
// KV contains a key (K) and a value (V)
type KV struct {
K []byte
V []byte
}
// KvMap is a key-value map between a sha256 byte array hash, and a KV struct
type KvMap map[[sha256.Size]byte]KV
// Get retreives the value respective to a key from the KvMap
func (m KvMap) Get(k []byte) ([]byte, bool) {
v, ok := m[sha256.Sum256(k)]
return v.V, ok
}
// Put stores a key and a value in the KvMap
func (m KvMap) Put(k, v []byte) {
m[sha256.Sum256(k)] = KV{k, v}
}
// Concat concatenates arrays of bytes
func Concat(vs ...[]byte) []byte {
var b bytes.Buffer
for _, v := range vs {
b.Write(v)
}
return b.Bytes()
}
// Clone clones a byte array into a new byte array
func Clone(b0 []byte) []byte {
b1 := make([]byte, len(b0))
copy(b1, b0)
return b1
}