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package nodb
import (
"bytes"
"errors"
"regexp"
"github.com/lunny/nodb/store"
)
var errDataType = errors.New("error data type")
var errMetaKey = errors.New("error meta key")
// Seek search the prefix key
func (db *DB) Seek(key []byte) (*store.Iterator, error) {
return db.seek(KVType, key)
}
func (db *DB) seek(dataType byte, key []byte) (*store.Iterator, error) {
var minKey []byte
var err error
if len(key) > 0 {
if err = checkKeySize(key); err != nil {
return nil, err
}
if minKey, err = db.encodeMetaKey(dataType, key); err != nil {
return nil, err
}
} else {
if minKey, err = db.encodeMinKey(dataType); err != nil {
return nil, err
}
}
it := db.bucket.NewIterator()
it.Seek(minKey)
return it, nil
}
func (db *DB) MaxKey() ([]byte, error) {
return db.encodeMaxKey(KVType)
}
func (db *DB) Key(it *store.Iterator) ([]byte, error) {
return db.decodeMetaKey(KVType, it.Key())
}
func (db *DB) scan(dataType byte, key []byte, count int, inclusive bool, match string) ([][]byte, error) {
var minKey, maxKey []byte
var err error
var r *regexp.Regexp
if len(match) > 0 {
if r, err = regexp.Compile(match); err != nil {
return nil, err
}
}
if len(key) > 0 {
if err = checkKeySize(key); err != nil {
return nil, err
}
if minKey, err = db.encodeMetaKey(dataType, key); err != nil {
return nil, err
}
} else {
if minKey, err = db.encodeMinKey(dataType); err != nil {
return nil, err
}
}
if maxKey, err = db.encodeMaxKey(dataType); err != nil {
return nil, err
}
if count <= 0 {
count = defaultScanCount
}
v := make([][]byte, 0, count)
it := db.bucket.NewIterator()
it.Seek(minKey)
if !inclusive {
if it.Valid() && bytes.Equal(it.RawKey(), minKey) {
it.Next()
}
}
for i := 0; it.Valid() && i < count && bytes.Compare(it.RawKey(), maxKey) < 0; it.Next() {
if k, err := db.decodeMetaKey(dataType, it.Key()); err != nil {
continue
} else if r != nil && !r.Match(k) {
continue
} else {
v = append(v, k)
i++
}
}
it.Close()
return v, nil
}
func (db *DB) encodeMinKey(dataType byte) ([]byte, error) {
return db.encodeMetaKey(dataType, nil)
}
func (db *DB) encodeMaxKey(dataType byte) ([]byte, error) {
k, err := db.encodeMetaKey(dataType, nil)
if err != nil {
return nil, err
}
k[len(k)-1] = dataType + 1
return k, nil
}
func (db *DB) encodeMetaKey(dataType byte, key []byte) ([]byte, error) {
switch dataType {
case KVType:
return db.encodeKVKey(key), nil
case LMetaType:
return db.lEncodeMetaKey(key), nil
case HSizeType:
return db.hEncodeSizeKey(key), nil
case ZSizeType:
return db.zEncodeSizeKey(key), nil
case BitMetaType:
return db.bEncodeMetaKey(key), nil
case SSizeType:
return db.sEncodeSizeKey(key), nil
default:
return nil, errDataType
}
}
func (db *DB) decodeMetaKey(dataType byte, ek []byte) ([]byte, error) {
if len(ek) < 2 || ek[0] != db.index || ek[1] != dataType {
return nil, errMetaKey
}
return ek[2:], nil
}
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