org.iq80.leveldb.iterator

Class ASeekingIterator<K,V>

java.lang.Object

org.iq80.leveldb.iterator.ASeekingIterator<K,V>

Type Parameters:

K - type of the key

V - type of the value

All Implemented Interfaces:

Closeable, AutoCloseable, SeekingIterator<K,V>

Direct Known Subclasses:

BlockIterator, MemTableIterator, MergingIterator, SnapshotSeekingIterator

public abstract class ASeekingIterator<K,V>
extends Object
implements SeekingIterator<K,V>

Seeking Iterator base implementation that ensure proper state validation before each call and implement shared direction management between iterator implementations.

Constructor Summary

Constructors

Constructor and Description
ASeekingIterator()

Method Summary

Modifier and Type	Method and Description
void	close()
protected abstract void	internalClose()
protected abstract K	internalKey()
protected abstract boolean	internalNext(boolean switchDirection)
protected abstract boolean	internalPrev(boolean switchDirection)
protected abstract boolean	internalSeek(K key)
protected abstract boolean	internalSeekToFirst()
protected abstract boolean	internalSeekToLast()
protected abstract V	internalValue()
K	key() Return the key for the current entry.
boolean	next() Moves to the next entry in the source.
boolean	prev() Moves to the previous entry in the source.
boolean	seek(K key) Position at the first key in the source that is at or past target.
boolean	seekToFirst() Position at the first key in the source.
boolean	seekToLast() Position at the last key in the source.
boolean	valid() An iterator is either positioned at a key/value pair, or not valid.
V	value() Return the value for the current entry.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ASeekingIterator

public ASeekingIterator()

Method Detail

valid

public final boolean valid()

Description copied from interface: SeekingIterator

An iterator is either positioned at a key/value pair, or not valid.

Specified by:

valid in interface SeekingIterator<K,V>

Returns:

true if the iterator is valid.

seekToFirst

public final boolean seekToFirst()

Description copied from interface: SeekingIterator

Position at the first key in the source. The iterator is SeekingIterator.valid() after this call if the source is not empty.

Specified by:

seekToFirst in interface SeekingIterator<K,V>

Returns:

true if iterator is valid, same value will be return by SeekingIterator.valid() after this call

seekToLast

public final boolean seekToLast()

Description copied from interface: SeekingIterator

Position at the last key in the source. The iterator is SeekingIterator.valid() after this call if the source is not empty.

Specified by:

seekToLast in interface SeekingIterator<K,V>

Returns:

true if iterator is valid, same value will be return by SeekingIterator.valid() after this call

seek

public final boolean seek(K key)

Description copied from interface: SeekingIterator

Position at the first key in the source that is at or past target. The iterator is SeekingIterator.valid() after this call if the source contains an entry that comes at or past target.

Specified by:

seek in interface SeekingIterator<K,V>

Returns:

true if iterator is valid, same value will be return by SeekingIterator.valid() after this call

next

public final boolean next()

Description copied from interface: SeekingIterator

Moves to the next entry in the source. After this call, SeekingIterator.valid() is true if the iterator was not positioned at the last entry in the source. In the case SeekingIterator.seek(Object), SeekingIterator.seekToLast() or SeekingIterator.seekToLast() where not called first call to this method should position iterator on the first entry.

Specified by:

next in interface SeekingIterator<K,V>

Returns:

true if iterator is valid, same value will be return by SeekingIterator.valid() after this call

prev

public final boolean prev()

Description copied from interface: SeekingIterator

Moves to the previous entry in the source. Return true if the iterator was not positioned at the first entry in source.

Specified by:

prev in interface SeekingIterator<K,V>

Returns:

true if iterator is valid, same value will be return by SeekingIterator.valid() after this call

key

public final K key()

Description copied from interface: SeekingIterator

Return the key for the current entry. The underlying storage for the returned slice is valid only until the next modification of the iterator.

Specified by:

key in interface SeekingIterator<K,V>

Returns:

current position key

value

public final V value()

Description copied from interface: SeekingIterator

Return the value for the current entry. The underlying storage for the returned slice is valid only until the next modification of the iterator.

Specified by:

value in interface SeekingIterator<K,V>

Returns:

current position value

close

public final void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

internalClose

protected abstract void internalClose()
                               throws IOException

Throws:

IOException

internalSeek

protected abstract boolean internalSeek(K key)

internalNext

protected abstract boolean internalNext(boolean switchDirection)

internalPrev

protected abstract boolean internalPrev(boolean switchDirection)

internalSeekToFirst

protected abstract boolean internalSeekToFirst()

internalSeekToLast

protected abstract boolean internalSeekToLast()

internalValue

protected abstract V internalValue()

internalKey

protected abstract K internalKey()