67 lines
2.7 KiB
Go
67 lines
2.7 KiB
Go
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// Copyright 2018 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package ethdb
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// Iterator iterates over a database's key/value pairs in ascending key order.
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//
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// When it encounters an error any seek will return false and will yield no key/
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// value pairs. The error can be queried by calling the Error method. Calling
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// Release is still necessary.
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//
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// An iterator must be released after use, but it is not necessary to read an
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// iterator until exhaustion. An iterator is not safe for concurrent use, but it
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// is safe to use multiple iterators concurrently.
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type Iterator interface {
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// Next moves the iterator to the next key/value pair. It returns whether the
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// iterator is exhausted.
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Next() bool
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// Error returns any accumulated error. Exhausting all the key/value pairs
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// is not considered to be an error.
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Error() error
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// Key returns the key of the current key/value pair, or nil if done. The caller
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// should not modify the contents of the returned slice, and its contents may
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// change on the next call to Next.
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Key() []byte
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// Value returns the value of the current key/value pair, or nil if done. The
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// caller should not modify the contents of the returned slice, and its contents
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// may change on the next call to Next.
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Value() []byte
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// Release releases associated resources. Release should always succeed and can
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// be called multiple times without causing error.
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Release()
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}
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// Iteratee wraps the NewIterator methods of a backing data store.
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type Iteratee interface {
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// NewIterator creates a binary-alphabetical iterator over the entire keyspace
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// contained within the key-value database.
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NewIterator() Iterator
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// NewIteratorWithStart creates a binary-alphabetical iterator over a subset of
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// database content starting at a particular initial key (or after, if it does
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// not exist).
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NewIteratorWithStart(start []byte) Iterator
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// NewIteratorWithPrefix creates a binary-alphabetical iterator over a subset
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// of database content with a particular key prefix.
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NewIteratorWithPrefix(prefix []byte) Iterator
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}
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