# Preview API

Show preview API for:

- 442: Foreign Function & Memory API (Third Preview)
- 443: Unnamed Patterns and Variables (Preview)

## Contents

- Interfaces
- Methods
- Enum Constants

- Interfaces
  Interface
  Preview Feature
  Description
  com.sun.source.tree.AnyPatternTreePREVIEW
  Unnamed Patterns and Variables
  A tree node for a binding pattern that matches a pattern with a variable of any name and a type of the match candidate; an unnamed pattern.
  java.lang.foreign.AddressLayoutPREVIEW
  Foreign Function & Memory API
  A value layout used to model the address of some region of memory.
  java.lang.foreign.ArenaPREVIEW
  Foreign Function & Memory API
  An arena controls the lifecycle of native memory segments, providing both flexible allocation and timely deallocation.
  java.lang.foreign.FunctionDescriptorPREVIEW
  Foreign Function & Memory API
  A function descriptor models the signature of foreign functions.
  java.lang.foreign.GroupLayoutPREVIEW
  Foreign Function & Memory API
  A compound layout that aggregates multiple member layouts.
  java.lang.foreign.LinkerPREVIEW
  Foreign Function & Memory API
  A linker provides access to foreign functions from Java code, and access to Java code from foreign functions.
  java.lang.foreign.Linker.OptionPREVIEW
  Foreign Function & Memory API
  A linker option is used to indicate additional linking requirements to the linker, besides what is described by a function descriptor.
  java.lang.foreign.MemoryLayoutPREVIEW
  Foreign Function & Memory API
  A memory layout describes the contents of a memory segment.
  java.lang.foreign.MemoryLayout.PathElementPREVIEW
  Foreign Function & Memory API
  An element in a layout path.
  java.lang.foreign.MemorySegmentPREVIEW
  Foreign Function & Memory API
  A memory segment provides access to a contiguous region of memory.
  java.lang.foreign.MemorySegment.ScopePREVIEW
  Foreign Function & Memory API
  A scope models the lifetime of all the memory segments associated with it.
  java.lang.foreign.PaddingLayoutPREVIEW
  Foreign Function & Memory API
  A padding layout.
  java.lang.foreign.SegmentAllocatorPREVIEW
  Foreign Function & Memory API
  An object that may be used to allocate memory segmentsPREVIEW.
  java.lang.foreign.SequenceLayoutPREVIEW
  Foreign Function & Memory API
  A compound layout that denotes a repetition of a given element layout.
  java.lang.foreign.StructLayoutPREVIEW
  Foreign Function & Memory API
  A group layout whose member layouts are laid out one after the other.
  java.lang.foreign.SymbolLookupPREVIEW
  Foreign Function & Memory API
  A symbol lookup retrieves the address of a symbol in one or more libraries.
  java.lang.foreign.UnionLayoutPREVIEW
  Foreign Function & Memory API
  A group layout whose member layouts are laid out at the same starting offset.
  java.lang.foreign.ValueLayoutPREVIEW
  Foreign Function & Memory API
  A layout that models values of basic data types.
  java.lang.foreign.ValueLayout.OfBooleanPREVIEW
  Foreign Function & Memory API
  A value layout whose carrier is `boolean.class`.
  java.lang.foreign.ValueLayout.OfBytePREVIEW
  Foreign Function & Memory API
  A value layout whose carrier is `byte.class`.
  java.lang.foreign.ValueLayout.OfCharPREVIEW
  Foreign Function & Memory API
  A value layout whose carrier is `char.class`.
  java.lang.foreign.ValueLayout.OfDoublePREVIEW
  Foreign Function & Memory API
  A value layout whose carrier is `double.class`.
  java.lang.foreign.ValueLayout.OfFloatPREVIEW
  Foreign Function & Memory API
  A value layout whose carrier is `float.class`.
  java.lang.foreign.ValueLayout.OfIntPREVIEW
  Foreign Function & Memory API
  A value layout whose carrier is `int.class`.
  java.lang.foreign.ValueLayout.OfLongPREVIEW
  Foreign Function & Memory API
  A value layout whose carrier is `long.class`.
  java.lang.foreign.ValueLayout.OfShortPREVIEW
  Foreign Function & Memory API
  A value layout whose carrier is `short.class`.

- Methods
  Method
  Preview Feature
  Description
  com.sun.source.tree.TreeVisitor.visitAnyPattern(AnyPatternTree, P)PREVIEW
  Unnamed Patterns and Variables
  Visits a `AnyPatternTree` node.
  com.sun.source.util.SimpleTreeVisitor.visitAnyPattern(AnyPatternTree, P)PREVIEW
  Unnamed Patterns and Variables
  Visits a `AnyPatternTree` node.
  java.lang.invoke.MethodHandles.collectCoordinates(VarHandle, int, MethodHandle)PREVIEW
  Foreign Function & Memory API
  Adapts a target var handle by pre-processing a sub-sequence of its coordinate values with a filter (a method handle).
  java.lang.invoke.MethodHandles.dropCoordinates(VarHandle, int, Class<?>...)PREVIEW
  Foreign Function & Memory API
  Returns a var handle which will discard some dummy coordinates before delegating to the target var handle.
  java.lang.invoke.MethodHandles.filterCoordinates(VarHandle, int, MethodHandle...)PREVIEW
  Foreign Function & Memory API
  Adapts a target var handle by pre-processing incoming coordinate values using unary filter functions.
  java.lang.invoke.MethodHandles.filterValue(VarHandle, MethodHandle, MethodHandle)PREVIEW
  Foreign Function & Memory API
  Adapts a target var handle by pre-processing incoming and outgoing values using a pair of filter functions.
  java.lang.invoke.MethodHandles.insertCoordinates(VarHandle, int, Object...)PREVIEW
  Foreign Function & Memory API
  Provides a target var handle with one or more bound coordinates in advance of the var handle's invocation.
  java.lang.invoke.MethodHandles.memorySegmentViewVarHandle(ValueLayout)PREVIEW
  Foreign Function & Memory API
  Creates a var handle object, which can be used to dereference a memory segmentPREVIEW by viewing its contents as a sequence of the provided value layout.
  java.lang.invoke.MethodHandles.permuteCoordinates(VarHandle, List<Class<?>>, int...)PREVIEW
  Foreign Function & Memory API
  Provides a var handle which adapts the coordinate values of the target var handle, by re-arranging them so that the new coordinates match the provided ones.
  java.lang.Module.isNativeAccessEnabled()PREVIEW
  Foreign Function & Memory API
  Returns `true` if this module can access restricted methods.
  java.lang.ModuleLayer.Controller.enableNativeAccess(Module)PREVIEW
  Foreign Function & Memory API
  Enables native access for a module in the layer if the caller's module has native access.
  java.nio.channels.FileChannel.map(FileChannel.MapMode, long, long, Arena)PREVIEW
  Foreign Function & Memory API
  Maps a region of this channel's file into a new mapped memory segment, with the given offset, size and arena.
  javax.lang.model.element.VariableElement.isUnnamed()PREVIEW
  Unnamed Patterns and Variables
  Returns `true` if this is an unnamed variable and `false` otherwise.

- Enum Constants
  Enum Constant
  Preview Feature
  Description
  com.sun.source.tree.Tree.Kind.ANY_PATTERNPREVIEW
  Unnamed Patterns and Variables
  Used for instances of `BindingPatternTree`.