plugeth/core/rawdb/key_length_iterator.go

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// Copyright 2022 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rawdb
import "github.com/ethereum/go-ethereum/ethdb"
// KeyLengthIterator is a wrapper for a database iterator that ensures only key-value pairs
// with a specific key length will be returned.
type KeyLengthIterator struct {
requiredKeyLength int
ethdb.Iterator
}
// NewKeyLengthIterator returns a wrapped version of the iterator that will only return key-value
// pairs where keys with a specific key length will be returned.
func NewKeyLengthIterator(it ethdb.Iterator, keyLen int) ethdb.Iterator {
return &KeyLengthIterator{
Iterator: it,
requiredKeyLength: keyLen,
}
}
func (it *KeyLengthIterator) Next() bool {
// Return true as soon as a key with the required key length is discovered
for it.Iterator.Next() {
if len(it.Iterator.Key()) == it.requiredKeyLength {
return true
}
}
// Return false when we exhaust the keys in the underlying iterator.
return false
}