SequenceLayout is a preview API of the Java platform.
Programs can only use SequenceLayout when preview features are enabled.
Preview features may be removed in a future release, or upgraded to permanent features of the Java platform.
A compound layout that denotes a repetition of a given element layout . The repetition count is said to be the sequence layout's element count . A finite sequence can be thought of as a group layout where the sequence layout's element layout is repeated a number of times that is equal to the sequence layout's element count. In other words this layout:
Re-arrange the elements in this sequence layout into a multi-dimensional sequence layout. The resulting layout is a sequence layout where element layouts in the flattened projection of this sequence layout (see flatten()) are re-arranged into one or more nested sequence layouts according to the provided element counts. This transformation preserves the layout size; that is, multiplying the provided element counts must yield the same element count as the flattened projection of this sequence layout.
For instance, given a sequence layout of the kind:
var seq = MemoryLayout.sequenceLayout(4, MemoryLayout.sequenceLayout(3, ValueLayout.JAVA_INT));
calling 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);
Parameters:
elementCounts - an array of element counts, of which at most one can be -1.
Returns:
a sequence layout where element layouts in the flattened projection of this sequence layout (see 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.
Returns a flattened sequence layout. The element layout of the returned sequence layout is the first non-sequence element layout found by recursively traversing the element layouts of this sequence 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));
calling seq.flatten() will yield the following sequence layout:
var flattenedSeq = MemoryLayout.sequenceLayout(12, ValueLayout.JAVA_INT);
Returns:
a sequence layout with the same size as this layout (but, possibly, with different element count), whose element layout is not a sequence layout.
Throws:
UnsupportedOperationException - if this sequence layout, or one of the nested sequence layouts being flattened, does not have an element count.
Compares the specified object with this layout for equality. Returns true if and only if the specified object is also a layout, and it is equal to this layout. Two layouts are considered equal if they are of the same kind, have the same size, name and alignment constraints. Furthermore, depending on the layout kind, additional conditions must be satisfied:
two value layouts are considered equal if they have the same byte order (see ValueLayout.order()PREVIEW)
two sequence layouts are considered equal if they have the same element count (see elementCount()), and if their element layouts (see elementLayout()) are also equal
Returns the alignment constraint associated with this layout, expressed in bits. Layout alignment defines a power of two A which is the bit-wise alignment of the layout. If A <= 8 then A/8 is the number of bytes that must be aligned for any pointer that correctly points to this layout. Thus:
A=8 means unaligned (in the usual sense), which is common in packets.
A=64 means word aligned (on LP64), A=32 int aligned, A=16 short aligned, etc.
A=512 is the most strict alignment required by the x86/SV ABI (for AVX-512 data).
SequenceLayout
when preview features are enabled.