mirror of https://github.com/poanetwork/gecko.git
59 lines
2.2 KiB
Go
59 lines
2.2 KiB
Go
// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
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// See the file LICENSE for licensing terms.
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// For ease of implementation, our database's interface matches Ethereum's
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// database implementation. This was to allow use to use Geth code as is for the
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// EVM chain.
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package database
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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
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// the 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.
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Key() []byte
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// Value returns the value of the current key/value pair, or nil if done.
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Value() []byte
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// Release releases associated resources. Release should always succeed and
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// can 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
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// keyspace 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
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// of database content starting at a particular initial key (or after, if it
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// does not exist).
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NewIteratorWithStart(start []byte) Iterator
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// NewIteratorWithPrefix creates a binary-alphabetical iterator over a
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// subset of database content with a particular key prefix.
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NewIteratorWithPrefix(prefix []byte) Iterator
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// NewIteratorWithStartAndPrefix creates a binary-alphabetical iterator over
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// a subset of database content with a particular key prefix starting at a
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// specified key.
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NewIteratorWithStartAndPrefix(start, prefix []byte) Iterator
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}
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