Package com.apple.foundationdb.tuple

Class TupleHelpers

java.lang.Object

com.apple.foundationdb.tuple.TupleHelpers

@API(UNSTABLE)
public class TupleHelpers
extends Object

Helper methods for working with Tuples.

Field Summary

Fields

Modifier and Type	Field	Description
static final Tuple	EMPTY

Method Summary

Modifier and Type	Method	Description
static int	compare(Tuple t1, Tuple t2)	Compare two tuples lexicographically, that is, the same way they would sort when used as keys.
static boolean	equals(Tuple t1, Tuple t2)	Determine if two Tuples have the same contents.
static boolean	isPrefix(Tuple t1, Tuple t2)	Get whether one tuple is a prefix of another.
static Number	negate(Number number)	Negate a number used as an element of a Tuple.
static int	packedSizeAsTupleItem(Object item)	Get the number of bytes that an object would occupy as an element of an encoded Tuple.
static int	prefixLengthOfSize(byte[] bytes, int size)	Get the index of a prefix of an encoded tuple that decodes as a sub-tuple of the given size.
static Tuple	set(Tuple src, int index, Object value)
static Tuple	subTuple(Tuple src, int start, int end)

Methods inherited from class java.lang.Object

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

Field Details

EMPTY

@Nonnull
public static final Tuple EMPTY

Method Details

set

@Nonnull
public static Tuple set(@Nonnull
 Tuple src,
 int index,
 Object value)

subTuple

@Nonnull
public static Tuple subTuple(@Nonnull
 Tuple src,
 int start,
 int end)

compare

@API(UNSTABLE)
public static int compare(@Nonnull
 Tuple t1,
 @Nonnull
 Tuple t2)

Compare two tuples lexicographically, that is, the same way they would sort when used as keys. Note that this is currently WAY more efficient than calling Tuple.equals(java.lang.Object), and slightly more efficient than calling Tuple.compareTo(com.apple.foundationdb.tuple.Tuple).

Parameters:

t1 - the first Tuple to compare

t2 - the second Tuple to compare

Returns:

0 if t1 and t2 are equal a value less than 0 if t1 would sort before t2 a value greater than 0 if t1 would sort after t2

equals

public static boolean equals(@Nullable
 Tuple t1,
 @Nullable
 Tuple t2)

Determine if two Tuples have the same contents. Unfortunately, the implementation of Tuple.equals() serializes both Tuples to byte arrays, so it is fairly expensive. This method avoids serializing either Tuple, and it also adds a short-circuit to return early if the two Tuples are pointer-equal.

Parameters:

t1 - the first Tuple to compare

t2 - the second Tuple to compare

Returns:

true if the two Tuples would serialize to the same array and false otherwise

negate

public static Number negate(@Nonnull
 Number number)

Negate a number used as an element of a Tuple.

Parameters:

number - the number to be negated

Returns:

a negated number suitable for use in a new Tuple

packedSizeAsTupleItem

public static int packedSizeAsTupleItem(Object item)

Get the number of bytes that an object would occupy as an element of an encoded Tuple. Unlike Tuple.getPackedSize(), this does not include the extra space an incomplete Versionstamp would add to the end to record its position.

Parameters:

item - an item of a tuple

Returns:

the number of bytes in the encoded form of the item

isPrefix

public static boolean isPrefix(@Nonnull
 Tuple t1,
 @Nonnull
 Tuple t2)

Get whether one tuple is a prefix of another.

Parameters:

t1 - the potential prefix

t2 - the whole tuple

Returns:

true if t1 is a prefix of t2

prefixLengthOfSize

public static int prefixLengthOfSize(@Nonnull
 byte[] bytes,
 int size)

Get the index of a prefix of an encoded tuple that decodes as a sub-tuple of the given size.

Parameters:

bytes - encoded tuple

size - size of desired subtuple

Returns:

the index into bytes that ends the sub-tuple or -1 if bytes is too short or decoding fails