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iterator.go
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iterator.go
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package sqldb
// 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 {
// IsValid return true if current element is valid.
IsValid() bool
// Next move to next
Next()
// 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() interface{}
// 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() interface{}
// 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(start interface{}) Iterator
}