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// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package iterator
import (
"github.com/syndtr/goleveldb/leveldb/errors"
"github.com/syndtr/goleveldb/leveldb/util"
)
// IteratorIndexer is the interface that wraps CommonIterator and basic Get
// method. IteratorIndexer provides index for indexed iterator.
type IteratorIndexer interface {
CommonIterator
// Get returns a new data iterator for the current position, or nil if
// done.
Get() Iterator
}
type indexedIterator struct {
util.BasicReleaser
index IteratorIndexer
strict bool
data Iterator
err error
errf func(err error)
closed bool
}
func (i *indexedIterator) setData() {
if i.data != nil {
i.data.Release()
}
i.data = i.index.Get()
}
func (i *indexedIterator) clearData() {
if i.data != nil {
i.data.Release()
}
i.data = nil
}
func (i *indexedIterator) indexErr() {
if err := i.index.Error(); err != nil {
if i.errf != nil {
i.errf(err)
}
i.err = err
}
}
func (i *indexedIterator) dataErr() bool {
if err := i.data.Error(); err != nil {
if i.errf != nil {
i.errf(err)
}
if i.strict || !errors.IsCorrupted(err) {
i.err = err
return true
}
}
return false
}
func (i *indexedIterator) Valid() bool {
return i.data != nil && i.data.Valid()
}
func (i *indexedIterator) First() bool {
if i.err != nil {
return false
} else if i.Released() {
i.err = ErrIterReleased
return false
}
if !i.index.First() {
i.indexErr()
i.clearData()
return false
}
i.setData()
return i.Next()
}
func (i *indexedIterator) Last() bool {
if i.err != nil {
return false
} else if i.Released() {
i.err = ErrIterReleased
return false
}
if !i.index.Last() {
i.indexErr()
i.clearData()
return false
}
i.setData()
if !i.data.Last() {
if i.dataErr() {
return false
}
i.clearData()
return i.Prev()
}
return true
}
func (i *indexedIterator) Seek(key []byte) bool {
if i.err != nil {
return false
} else if i.Released() {
i.err = ErrIterReleased
return false
}
if !i.index.Seek(key) {
i.indexErr()
i.clearData()
return false
}
i.setData()
if !i.data.Seek(key) {
if i.dataErr() {
return false
}
i.clearData()
return i.Next()
}
return true
}
func (i *indexedIterator) Next() bool {
if i.err != nil {
return false
} else if i.Released() {
i.err = ErrIterReleased
return false
}
switch {
case i.data != nil && !i.data.Next():
if i.dataErr() {
return false
}
i.clearData()
fallthrough
case i.data == nil:
if !i.index.Next() {
i.indexErr()
return false
}
i.setData()
return i.Next()
}
return true
}
func (i *indexedIterator) Prev() bool {
if i.err != nil {
return false
} else if i.Released() {
i.err = ErrIterReleased
return false
}
switch {
case i.data != nil && !i.data.Prev():
if i.dataErr() {
return false
}
i.clearData()
fallthrough
case i.data == nil:
if !i.index.Prev() {
i.indexErr()
return false
}
i.setData()
if !i.data.Last() {
if i.dataErr() {
return false
}
i.clearData()
return i.Prev()
}
}
return true
}
func (i *indexedIterator) Key() []byte {
if i.data == nil {
return nil
}
return i.data.Key()
}
func (i *indexedIterator) Value() []byte {
if i.data == nil {
return nil
}
return i.data.Value()
}
func (i *indexedIterator) Release() {
i.clearData()
i.index.Release()
i.BasicReleaser.Release()
}
func (i *indexedIterator) Error() error {
if i.err != nil {
return i.err
}
if err := i.index.Error(); err != nil {
return err
}
return nil
}
func (i *indexedIterator) SetErrorCallback(f func(err error)) {
i.errf = f
}
// NewIndexedIterator returns an 'indexed iterator'. An index is iterator
// that returns another iterator, a 'data iterator'. A 'data iterator' is the
// iterator that contains actual key/value pairs.
//
// If strict is true the any 'corruption errors' (i.e errors.IsCorrupted(err) == true)
// won't be ignored and will halt 'indexed iterator', otherwise the iterator will
// continue to the next 'data iterator'. Corruption on 'index iterator' will not be
// ignored and will halt the iterator.
func NewIndexedIterator(index IteratorIndexer, strict bool) Iterator {
return &indexedIterator{index: index, strict: strict}
}
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