Package gov.nasa.jpl.aerie.merlin.framework

Class Scoped<T>

java.lang.Object

gov.nasa.jpl.aerie.merlin.framework.Scoped<T>

All Implemented Interfaces:

Supplier<T>

public final class Scoped<T>
extends Object
implements Supplier<T>

A dynamically-scoped cell. Values pushed into the cell are strictly popped in the same order, and the lifetime of each value is tied to the call stack. See the related concept of scoped variables in Project Loom.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Scoped.EmptyDynamicCellException
static final record	Scoped.UndoToken<T>

Method Summary

Modifier and Type	Method	Description
static <T> Scoped<T>	create()	Create a dynamically-scoped cell containing values of type Scoped.
T	get()	Gets the current value of the dynamic cell.
Scoped.UndoToken<T>	set(T newValue)	Set a value in this cell, returning an AutoCloseable resource restoring the previous value on close.

Methods inherited from class java.lang.Object

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

Method Details

create

public static <T> Scoped<T> create()

Create a dynamically-scoped cell containing values of type Scoped.

Type Parameters:

T - The type of value this cell will contain.

Returns:

A new cell that can contain values of type Scoped.

get

public T get()
      throws Scoped.EmptyDynamicCellException

Gets the current value of the dynamic cell. Throws an exception if nobody up-stack is currently serving this cell.

Specified by:

get in interface Supplier<T>

Throws:

Scoped.EmptyDynamicCellException

set

public Scoped.UndoToken<T> set(T newValue)

Set a value in this cell, returning an AutoCloseable resource restoring the previous value on close.

This method should always be used in a try-with-resources statement:

 try (final var scope = cell.set(value)) {
   // ...
 }