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:

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:

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

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