add other session providers (#5963)

vendor/github.com/lunny/nodb/scan.go

@@ -0,0 +1,144 @@
+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
+}