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iterator.go
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iterator.go
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package goleveldb
import (
"bytes"
"github.com/syndtr/goleveldb/leveldb/iterator"
tmdb "github.com/tendermint/tm-db"
)
type goLevelDBIterator struct {
source iterator.Iterator
start []byte
end []byte
isReverse bool
isInvalid bool
}
var _ tmdb.Iterator = (*goLevelDBIterator)(nil)
func newGoLevelDBIterator(source iterator.Iterator, start, end []byte, isReverse bool) *goLevelDBIterator {
if isReverse {
if end == nil {
source.Last()
} else {
valid := source.Seek(end)
if valid {
eoakey := source.Key() // end or after key
if bytes.Compare(end, eoakey) <= 0 {
source.Prev()
}
} else {
source.Last()
}
}
} else {
if start == nil {
source.First()
} else {
source.Seek(start)
}
}
return &goLevelDBIterator{
source: source,
start: start,
end: end,
isReverse: isReverse,
isInvalid: false,
}
}
// Domain implements Iterator.
func (itr *goLevelDBIterator) Domain() ([]byte, []byte) {
return itr.start, itr.end
}
// Valid implements Iterator.
func (itr *goLevelDBIterator) Valid() bool {
// Once invalid, forever invalid.
if itr.isInvalid {
return false
}
// If source errors, invalid.
if err := itr.Error(); err != nil {
itr.isInvalid = true
return false
}
// If source is invalid, invalid.
if !itr.source.Valid() {
itr.isInvalid = true
return false
}
// If key is end or past it, invalid.
var start = itr.start
var end = itr.end
var key = itr.source.Key()
if itr.isReverse {
if start != nil && bytes.Compare(key, start) < 0 {
itr.isInvalid = true
return false
}
} else {
if end != nil && bytes.Compare(end, key) <= 0 {
itr.isInvalid = true
return false
}
}
// Valid
return true
}
// Key implements Iterator.
func (itr *goLevelDBIterator) Key() []byte {
// Key returns a copy of the current key.
// See https://github.com/syndtr/goleveldb/blob/52c212e6c196a1404ea59592d3f1c227c9f034b2/leveldb/iterator/iter.go#L88
itr.assertIsValid()
return cp(itr.source.Key())
}
// Value implements Iterator.
func (itr *goLevelDBIterator) Value() []byte {
// Value returns a copy of the current value.
// See https://github.com/syndtr/goleveldb/blob/52c212e6c196a1404ea59592d3f1c227c9f034b2/leveldb/iterator/iter.go#L88
itr.assertIsValid()
return cp(itr.source.Value())
}
func cp(bz []byte) (ret []byte) {
ret = make([]byte, len(bz))
copy(ret, bz)
return ret
}
// Next implements Iterator.
func (itr *goLevelDBIterator) Next() {
itr.assertIsValid()
if itr.isReverse {
itr.source.Prev()
} else {
itr.source.Next()
}
}
// Error implements Iterator.
func (itr *goLevelDBIterator) Error() error {
return itr.source.Error()
}
// Close implements Iterator.
func (itr *goLevelDBIterator) Close() error {
itr.source.Release()
return nil
}
func (itr goLevelDBIterator) assertIsValid() {
if !itr.Valid() {
panic("iterator is invalid")
}
}