Interface GroupLayout

All Superinterfaces:

MemoryLayout

All Known Subinterfaces:

StructLayout, UnionLayout

public sealed interface GroupLayout
extends MemoryLayout
permits StructLayout, UnionLayout

A compound layout that is an aggregation of multiple, heterogeneous member layouts. There are two ways in which member layouts can be combined: if member layouts are laid out one after the other, the resulting group layout is a struct layout; conversely, if all member layouts are laid out at the same starting offset, the resulting group layout is a union layout.

Implementation Requirements:

This class is immutable, thread-safe and value-based.

Sealed Class Hierarchy Graph:

Since:

22

Nested Class Summary

Nested classes/interfaces declared in interface MemoryLayout

MemoryLayout.PathElement

Modifier and Type	Interface	Description
static interface	MemoryLayout.PathElement	An element in a layout path.

Method Summary

Modifier and Type	Method	Description
List<MemoryLayout>	memberLayouts()	Returns the member layouts of this group layout.
GroupLayout	withByteAlignment(long byteAlignment)	Returns a memory layout with the same characteristics as this layout, but with the given alignment constraint (in bytes).
GroupLayout	withName(String name)	Returns a memory layout with the same characteristics as this layout, but with the given name.
GroupLayout	withoutName()	Returns a memory layout with the same characteristics as this layout, but with no name.

Methods declared in interface MemoryLayout

arrayElementVarHandle, byteAlignment, byteOffset, byteOffsetHandle, byteSize, equals, hashCode, name, scale, scaleHandle, select, sliceHandle, toString, varHandle

Modifier and Type	Method	Description
VarHandle	arrayElementVarHandle(MemoryLayout.PathElement... elements)	Creates a var handle that accesses adjacent elements in a memory segment at offsets selected by the given layout path, where the accessed elements have this layout, and where the initial layout in the path is this layout.
long	byteAlignment()	Returns the alignment constraint associated with this layout, expressed in bytes.
long	byteOffset(MemoryLayout.PathElement... elements)	Computes the offset, in bytes, of the layout selected by the given layout path, where the initial layout in the path is this layout.
MethodHandle	byteOffsetHandle(MemoryLayout.PathElement... elements)	Creates a method handle that computes the offset, in bytes, of the layout selected by the given layout path, where the initial layout in the path is this layout.
long	byteSize()	Returns the layout size, in bytes.
boolean	equals(Object other)	Compares the specified object with this layout for equality.
int	hashCode()	Returns the hash code value for this layout.
Optional<String>	name()	Returns the name (if any) associated with this layout.
long	scale(long offset, long index)	Returns offset + (byteSize() * index).
MethodHandle	scaleHandle()	Returns a method handle that can be used to invoke MemoryLayout.scale(long, long) on this layout.
MemoryLayout	select(MemoryLayout.PathElement... elements)	Returns the layout selected from the provided path, where the initial layout in the path is this layout.
MethodHandle	sliceHandle(MemoryLayout.PathElement... elements)	Creates a method handle which, given a memory segment, returns a slice corresponding to the layout selected by the given layout path, where the initial layout in the path is this layout.
String	toString()	Returns the string representation of this layout.
VarHandle	varHandle(MemoryLayout.PathElement... elements)	Creates a var handle that accesses a memory segment at the offset selected by the given layout path, where the initial layout in the path is this layout.

Method Details

memberLayouts

List<MemoryLayout> memberLayouts()

Returns the member layouts of this group layout.

API Note:

the order in which member layouts are returned is the same order in which member layouts have been passed to one of the group layout factory methods (see MemoryLayout.structLayout(MemoryLayout...) and MemoryLayout.unionLayout(MemoryLayout...)).

Returns:

the member layouts of this group layout

withName

GroupLayout withName(String name)

Returns a memory layout with the same characteristics as this layout, but with the given name.

Specified by:

withName in interface MemoryLayout

Parameters:

name - the layout name

Returns:

a memory layout with the same characteristics as this layout, but with the given name

See Also:

• MemoryLayout.name()

withoutName

GroupLayout withoutName()

Returns a memory layout with the same characteristics as this layout, but with no name.

Specified by:

withoutName in interface MemoryLayout

Returns:

a memory layout with the same characteristics as this layout, but with no name

See Also:

• MemoryLayout.name()

withByteAlignment

GroupLayout withByteAlignment(long byteAlignment)

Returns a memory layout with the same characteristics as this layout, but with the given alignment constraint (in bytes).

Specified by:

withByteAlignment in interface MemoryLayout

Parameters:

byteAlignment - the layout alignment constraint, expressed in bytes

Returns:

a memory layout with the same characteristics as this layout, but with the given alignment constraint (in bytes)

Throws:

IllegalArgumentException - if byteAlignment is not a power of two

IllegalArgumentException - if byteAlignment is less than M, where M is the maximum alignment constraint in any of the member layouts associated with this group layout