Package io.substrait.relation

Class CopyOnWriteUtils

java.lang.Object

io.substrait.relation.CopyOnWriteUtils

public class CopyOnWriteUtils
extends Object

Provides common utilities for copy-on-write visitations

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	CopyOnWriteUtils.TransformFunction<T,C extends VisitationContext,E extends Exception>

Constructor Summary

Constructors

Constructor	Description
CopyOnWriteUtils()

Method Summary

Modifier and Type	Method	Description
static boolean	allEmpty(Optional<?>... optionals)	Returns true if all provided optionals are empty.
static <T> Optional<T>	or(Optional<T> left, Supplier<? extends Optional<T>> right)	Returns left if present; otherwise returns the result of right.get().
static <I, C extends VisitationContext, E extends Exception> Optional<List<I>>	transformList(List<I> items, C context, CopyOnWriteUtils.TransformFunction<I,C,E> transform)	Applies the given transformation function to each item in the list.

Methods inherited from class java.lang.Object

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

Constructor Details

CopyOnWriteUtils

public CopyOnWriteUtils()

Method Details

allEmpty

public static boolean allEmpty(Optional<?>... optionals)

Returns true if all provided optionals are empty.

Parameters:

optionals - the optionals to inspect

Returns:

true when none are present; false otherwise

or

public static <T> Optional<T> or(Optional<T> left,
 Supplier<? extends Optional<T>> right)

Returns left if present; otherwise returns the result of right.get().

Type Parameters:

T - the value type

Parameters:

left - the first optional

right - supplier of the fallback optional

Returns:

left when present; otherwise the supplied optional

transformList

public static <I,
C extends VisitationContext,
E extends Exception>
Optional<List<I>> transformList(List<I> items,
 C context,
 CopyOnWriteUtils.TransformFunction<I,C,E> transform)
                         throws E

Applies the given transformation function to each item in the list. If any of the list items are transformed, returns a new list in which each item is either

• a transformed new item replacing an old item
• the original item in the position it was in

Type Parameters:

I - the item type

C - the visitation context type

E - the exception type thrown by the transform

Parameters:

items - the list of items to transform

context - the visitation context

transform - the transformation function to apply to each item

Returns:

An empty optional if none of the items have changed. An optional containing a new list otherwise.

Throws:

E - if the transform function throws