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- // Copyright 2018 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 ethdb
- // Iterator iterates over a database's key/value pairs in ascending key order.
- //
- // When it encounters an error any seek will return false and will yield no key/
- // value pairs. The error can be queried by calling the Error method. Calling
- // Release is still necessary.
- //
- // An iterator must be released after use, but it is not necessary to read an
- // iterator until exhaustion. An iterator is not safe for concurrent use, but it
- // is safe to use multiple iterators concurrently.
- type Iterator interface {
- // Next moves the iterator to the next key/value pair. It returns whether the
- // iterator is exhausted.
- Next() bool
- // Error returns any accumulated error. Exhausting all the key/value pairs
- // is not considered to be an error.
- Error() error
- // Key returns the key of the current key/value pair, or nil if done. The caller
- // should not modify the contents of the returned slice, and its contents may
- // change on the next call to Next.
- Key() []byte
- // Value returns the value of the current key/value pair, or nil if done. The
- // caller should not modify the contents of the returned slice, and its contents
- // may change on the next call to Next.
- Value() []byte
- // Release releases associated resources. Release should always succeed and can
- // be called multiple times without causing error.
- Release()
- }
- // Iteratee wraps the NewIterator methods of a backing data store.
- type Iteratee interface {
- // NewIterator creates a binary-alphabetical iterator over a subset
- // of database content with a particular key prefix, starting at a particular
- // initial key (or after, if it does not exist).
- //
- // Note: This method assumes that the prefix is NOT part of the start, so there's
- // no need for the caller to prepend the prefix to the start
- NewIterator(prefix []byte, start []byte) Iterator
- }
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