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82 lines
1.5 KiB
82 lines
1.5 KiB
package db
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import "bytes"
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// A wrapper around itr that tries to keep the iterator
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// within the bounds as defined by `prefix`
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type prefixIterator struct {
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itr Iterator
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prefix []byte
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invalid bool
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}
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func (pi *prefixIterator) Seek(key []byte) {
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if !bytes.HasPrefix(key, pi.prefix) {
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pi.invalid = true
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return
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}
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pi.itr.Seek(key)
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pi.checkInvalid()
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}
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func (pi *prefixIterator) checkInvalid() {
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if !pi.itr.Valid() {
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pi.invalid = true
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}
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}
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func (pi *prefixIterator) Valid() bool {
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if pi.invalid {
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return false
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}
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key := pi.itr.Key()
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ok := bytes.HasPrefix(key, pi.prefix)
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if !ok {
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pi.invalid = true
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return false
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}
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return true
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}
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func (pi *prefixIterator) Next() {
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if pi.invalid {
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panic("prefixIterator Next() called when invalid")
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}
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pi.itr.Next()
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pi.checkInvalid()
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}
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func (pi *prefixIterator) Prev() {
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if pi.invalid {
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panic("prefixIterator Prev() called when invalid")
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}
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pi.itr.Prev()
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pi.checkInvalid()
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}
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func (pi *prefixIterator) Key() []byte {
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if pi.invalid {
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panic("prefixIterator Key() called when invalid")
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}
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return pi.itr.Key()
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}
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func (pi *prefixIterator) Value() []byte {
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if pi.invalid {
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panic("prefixIterator Value() called when invalid")
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}
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return pi.itr.Value()
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}
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func (pi *prefixIterator) Close() { pi.itr.Close() }
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func (pi *prefixIterator) GetError() error { return pi.itr.GetError() }
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func IteratePrefix(db DB, prefix []byte) Iterator {
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itr := db.Iterator()
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pi := &prefixIterator{
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itr: itr,
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prefix: prefix,
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}
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pi.Seek(prefix)
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return pi
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}
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