122 lines
2.0 KiB
Go
122 lines
2.0 KiB
Go
package leveldb
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import (
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"bytes"
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"github.com/jmhodges/levigo"
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)
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const forward uint8 = 0
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const backward uint8 = 1
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type Iterator struct {
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it *levigo.Iterator
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start []byte
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stop []byte
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limit int
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step int
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//0 for forward, 1 for backward
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direction uint8
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}
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func newIterator(db *DB, opts *levigo.ReadOptions, start []byte, stop []byte, limit int, direction uint8) *Iterator {
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it := new(Iterator)
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it.it = db.db.NewIterator(opts)
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it.start = start
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it.stop = stop
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it.limit = limit
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it.direction = direction
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it.step = 0
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if start == nil {
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if direction == forward {
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it.it.SeekToFirst()
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} else {
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it.it.SeekToLast()
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}
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} else {
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it.it.Seek(start)
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if it.Valid() && !bytes.Equal(it.Key(), start) {
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//for forward, key is the next bigger than start
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//for backward, key is the next bigger than start, so must go prev
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if direction == backward {
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it.it.Prev()
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}
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}
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}
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return it
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}
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func (it *Iterator) Valid() bool {
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if !it.it.Valid() {
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return false
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}
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if it.limit > 0 && it.step >= it.limit {
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return false
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}
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if it.direction == forward {
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if it.stop != nil && bytes.Compare(it.Key(), it.stop) > 0 {
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return false
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}
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} else {
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if it.stop != nil && bytes.Compare(it.Key(), it.stop) < 0 {
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return false
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}
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}
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return true
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}
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func (it *Iterator) GetError() error {
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return it.it.GetError()
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}
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func (it *Iterator) Next() {
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it.step++
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if it.direction == forward {
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it.it.Next()
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} else {
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it.it.Prev()
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}
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}
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func (it *Iterator) Key() []byte {
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return it.it.Key()
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}
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func (it *Iterator) Value() []byte {
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return it.it.Value()
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}
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func (it *Iterator) Close() {
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it.it.Close()
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}
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func (it *Iterator) IntValue() (int64, error) {
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return Int(it.Value(), nil)
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}
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func (it *Iterator) UintValue() (uint64, error) {
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return Uint(it.Value(), nil)
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}
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func (it *Iterator) FloatValue() (float64, error) {
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return Float(it.Value(), nil)
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}
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func (it *Iterator) StringValue() (string, error) {
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return String(it.Value(), nil)
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}
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func (it *Iterator) SliceValue() ([]byte, error) {
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return Slice(it.Value(), nil)
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}
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