MemoryLayoutPREVIEW
public sealed interface SequenceLayout extends MemoryLayoutPREVIEW
SequenceLayout
is a preview API of the Java platform. MemoryLayout.sequenceLayout(3, ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN));
MemoryLayout.structLayout(
ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN),
ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN),
ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN));
MemoryLayout.PathElementPREVIEW
Modifier and Type | Method | Description |
---|---|---|
long |
elementCount() |
Returns the element count of this sequence layout. |
MemoryLayoutPREVIEW |
elementLayout() |
Returns the element layout of this sequence layout. |
SequenceLayoutPREVIEW |
flatten() |
Returns a flattened sequence layout. |
SequenceLayoutPREVIEW |
reshape |
Rearranges the elements in this sequence layout into a multi-dimensional sequence layout. |
SequenceLayoutPREVIEW |
withByteAlignment |
Returns a memory layout with the same characteristics as this layout, but with the given alignment constraint (in bytes). |
SequenceLayoutPREVIEW |
withElementCount |
Returns a sequence layout with the same characteristics of this layout, but with the given element count. |
SequenceLayoutPREVIEW |
withName |
Returns a memory layout with the same characteristics as this layout, but with the given name. |
byteAlignment, byteOffset, byteOffsetHandle, byteSize, equals, hashCode, name, select, sliceHandle, toString, varHandle, withoutName
MemoryLayoutPREVIEW elementLayout()
long elementCount()
SequenceLayoutPREVIEW withElementCount(long elementCount)
elementCount
- the new element count.IllegalArgumentException
- if elementCount
is negative.IllegalArgumentException
- if elementLayout.bitSize() * elementCount
overflows.SequenceLayoutPREVIEW reshape(long... elementCounts)
For instance, given a sequence layout of the kind:
var seq = MemoryLayout.sequenceLayout(4, MemoryLayout.sequenceLayout(3, ValueLayout.JAVA_INT));
seq.reshape(2, 6)
will yield the following sequence layout: var reshapeSeq = MemoryLayout.sequenceLayout(2, MemoryLayout.sequenceLayout(6, ValueLayout.JAVA_INT));
If one of the provided element count is the special value -1
, then the element count in that position will be inferred from the remaining element counts and the element count of the flattened projection of this layout. For instance, a layout equivalent to the above reshapeSeq
can also be computed in the following ways:
var reshapeSeqImplicit1 = seq.reshape(-1, 6);
var reshapeSeqImplicit2 = seq.reshape(2, -1);
elementCounts
- an array of element counts, of which at most one can be -1
.flatten()
) are re-arranged into one or more nested sequence layouts.IllegalArgumentException
- if two or more element counts are set to -1
, or if one or more element count is <= 0
(but other than -1
) or, if, after any required inference, multiplying the element counts does not yield the same element count as the flattened projection of this sequence layout.SequenceLayoutPREVIEW flatten()
MemoryLayout flatElementLayout(SequenceLayout sequenceLayout) {
return switch (sequenceLayout.elementLayout()) {
case SequenceLayout nestedSequenceLayout -> flatElementLayout(nestedSequenceLayout);
case MemoryLayout layout -> layout;
};
}
This transformation preserves the layout size; nested sequence layout in this sequence layout will be dropped and their element counts will be incorporated into that of the returned sequence layout. For instance, given a sequence layout of the kind:
var seq = MemoryLayout.sequenceLayout(4, MemoryLayout.sequenceLayout(3, ValueLayout.JAVA_INT));
seq.flatten()
will yield the following sequence layout: var flattenedSeq = MemoryLayout.sequenceLayout(12, ValueLayout.JAVA_INT);
SequenceLayoutPREVIEW withName(String name)
withName
in interface MemoryLayoutPREVIEW
name
- the layout name.SequenceLayoutPREVIEW withByteAlignment(long byteAlignment)
withByteAlignment
in interface MemoryLayoutPREVIEW
byteAlignment
- the layout alignment constraint, expressed in bytes.IllegalArgumentException
- if byteAlignment
is not a power of two.IllegalArgumentException
- if byteAlignment < elementLayout().byteAlignment()
.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/foreign/SequenceLayout.html
SequenceLayout
when preview features are enabled.