- All Implemented Interfaces:
Constable
,MemoryLayout
MemoryLayout.sequenceLayout(3, MemoryLayout.valueLayout(32, ByteOrder.BIG_ENDIAN));
is equivalent to the following layout:
MemoryLayout.structLayout(
MemoryLayout.valueLayout(32, ByteOrder.BIG_ENDIAN),
MemoryLayout.valueLayout(32, ByteOrder.BIG_ENDIAN),
MemoryLayout.valueLayout(32, ByteOrder.BIG_ENDIAN));
This is a value-based
class; programmers should treat instances that are
equal as interchangeable and should not
use instances for synchronization, or unpredictable behavior may
occur. For example, in a future release, synchronization may fail.
The equals
method should be used for comparisons.
Unless otherwise specified, passing a null
argument, or an array argument containing one or more null
elements to a method in this class causes a NullPointerException
to be thrown.
- Implementation Requirements:
- This class is immutable and thread-safe.
-
Nested Class Summary
Nested classes/interfaces declared in interface jdk.incubator.foreign.MemoryLayout
MemoryLayout.PathElement
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Field Summary
Fields declared in interface jdk.incubator.foreign.MemoryLayout
LAYOUT_NAME
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Method Summary
Modifier and TypeMethodDescriptionReturns the attribute with the given name (if it exists).Returns a stream of the attribute names associated with this layout.final long
Returns the alignment constraint associated with this layout, expressed in bits.long
bitSize()
Computes the layout size, in bits.Returns the element count of this sequence layout (if any).Returns the element layout associated with this sequence layout.boolean
Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.flatten()
Returns a new, flattened sequence layout whose element layout is the first non-sequence element layout found by recursively traversing the element layouts of this sequence layout.int
hashCode()
Answers an integer hash code for the receiver.boolean
hasSize()
Does this layout have a specified size?boolean
Is this a padding layout (e.g. a layout created fromMemoryLayout.paddingLayout(long)
) ?name()
Return the name (if any) associated with this layout.reshape
(long... elementCounts) Returns a new sequence layout where element layouts in the flattened projection of this sequence layout (seeflatten()
) are re-arranged into one or more nested sequence layouts according to the provided element counts.toString()
Answers a string containing a concise, human-readable description of the receiver.withAttribute
(String name, Constable value) Returns a new memory layout which features the same attributes as this layout, plus the newly specified attribute.withBitAlignment
(long alignmentBits) Creates a new layout which features the desired alignment constraint.withElementCount
(long elementCount) Obtains a new sequence layout with same element layout, alignment constraints and name as this sequence layout but with the new specified element count.Creates a new layout which features the desired layout name.Methods declared in class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
Methods declared in interface jdk.incubator.foreign.MemoryLayout
attribute, attributes, bitAlignment, bitOffset, bitOffsetHandle, bitSize, byteAlignment, byteOffset, byteOffsetHandle, byteSize, hasSize, isPadding, map, name, select, sliceHandle, varHandle
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Method Details
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elementLayout
Returns the element layout associated with this sequence layout.- Returns:
- The element layout associated with this sequence layout.
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elementCount
Returns the element count of this sequence layout (if any).- Returns:
- the element count of this sequence layout (if any).
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withElementCount
Obtains a new sequence layout with same element layout, alignment constraints and name as this sequence layout but with the new specified element count.- Parameters:
elementCount
- the new element count.- Returns:
- a new sequence with given element count.
- Throws:
IllegalArgumentException
- ifelementCount < 0
.
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reshape
Returns a new sequence layout where element layouts in the flattened projection of this sequence layout (seeflatten()
) 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:
callingvar seq = MemoryLayout.sequenceLayout(4, MemoryLayout.sequenceLayout(3, MemoryLayouts.JAVA_INT));
seq.reshape(2, 6)
will yield the following sequence layout:var reshapeSeq = MemoryLayout.sequenceLayout(2, MemoryLayout.sequenceLayout(6, MemoryLayouts.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 abovereshapeSeq
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 new 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. - Throws:
UnsupportedOperationException
- if this sequence layout does not have an element count.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.
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flatten
Returns a new, flattened sequence layout whose element 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:
callingvar seq = MemoryLayout.sequenceLayout(4, MemoryLayout.sequenceLayout(3, MemoryLayouts.JAVA_INT));
seq.flatten()
will yield the following sequence layout:var flattenedSeq = MemoryLayout.sequenceLayout(12, MemoryLayouts.JAVA_INT);
- Returns:
- a new 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.
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toString
Description copied from class:Object
Answers a string containing a concise, human-readable description of the receiver.- Specified by:
toString
in interfaceMemoryLayout
- Overrides:
toString
in classObject
- Returns:
- String a printable representation for the receiver.
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equals
Description copied from class:Object
Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison. The implementation in Object answers true only if the argument is the exact same object as the receiver (==).- Specified by:
equals
in interfaceMemoryLayout
- Parameters:
other
- Object the object to compare with this object.- Returns:
- boolean
true
if the object is the same as this objectfalse
if it is different from this object. - See Also:
-
hashCode
public int hashCode()Description copied from class:Object
Answers an integer hash code for the receiver. Any two objects which answertrue
when passed to.equals
must answer the same value for this method.- Specified by:
hashCode
in interfaceMemoryLayout
- Returns:
- the receiver's hash.
- See Also:
-
describeConstable
Description copied from interface:MemoryLayout
Returns anOptional
containing the nominal descriptor for this layout, if one can be constructed, or an emptyOptional
if one cannot be constructed.- Specified by:
describeConstable
in interfaceConstable
- Specified by:
describeConstable
in interfaceMemoryLayout
- Returns:
- An
Optional
containing the resulting nominal descriptor, or an emptyOptional
if one cannot be constructed.
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withName
Creates a new layout which features the desired layout name.This is equivalent to the following code:
withAttribute(LAYOUT_NAME, name);
- Specified by:
withName
in interfaceMemoryLayout
- Parameters:
name
- the layout name.- Returns:
- a new layout which is the same as this layout, except for the name associated with it.
- See Also:
-
withBitAlignment
Creates a new layout which features the desired alignment constraint.- Specified by:
withBitAlignment
in interfaceMemoryLayout
- Parameters:
alignmentBits
- the layout alignment constraint, expressed in bits.- Returns:
- a new layout which is the same as this layout, except for the alignment constraint associated with it.
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withAttribute
Returns a new memory layout which features the same attributes as this layout, plus the newly specified attribute. If this layout already contains an attribute with the same name, the existing attribute value is overwritten in the returned layout.- Specified by:
withAttribute
in interfaceMemoryLayout
- Parameters:
name
- the attribute name.value
- the attribute value.- Returns:
- a new memory layout which features the same attributes as this layout, plus the newly specified attribute.
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name
Description copied from interface:MemoryLayout
Return the name (if any) associated with this layout.This is equivalent to the following code:
attribute(LAYOUT_NAME).map(String.class::cast);
- Specified by:
name
in interfaceMemoryLayout
- Returns:
- the layout name (if any).
- See Also:
-
attribute
Description copied from interface:MemoryLayout
Returns the attribute with the given name (if it exists).- Specified by:
attribute
in interfaceMemoryLayout
- Parameters:
name
- the attribute name- Returns:
- the attribute with the given name (if it exists).
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attributes
Description copied from interface:MemoryLayout
Returns a stream of the attribute names associated with this layout.- Specified by:
attributes
in interfaceMemoryLayout
- Returns:
- a stream of the attribute names associated with this layout.
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bitAlignment
public final long bitAlignment()Description copied from interface:MemoryLayout
Returns the alignment constraint associated with this layout, expressed in bits. Layout alignment defines a power of twoA
which is the bit-wise alignment of the layout. IfA <= 8
thenA/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).
MemoryLayout.withBitAlignment(long)
), then this method returns the natural alignment constraint (in bits) associated with this layout.- Specified by:
bitAlignment
in interfaceMemoryLayout
- Returns:
- the layout alignment constraint, in bits.
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hasSize
public boolean hasSize()Description copied from interface:MemoryLayout
Does this layout have a specified size? A layout does not have a specified size if it is (or contains) a sequence layout whose size is unspecified (seeelementCount()
). Value layouts (seeValueLayout
) and padding layouts (seeMemoryLayout.paddingLayout(long)
) always have a specified size, therefore this method always returnstrue
in these cases.- Specified by:
hasSize
in interfaceMemoryLayout
- Returns:
true
, if this layout has a specified size.
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bitSize
public long bitSize()Description copied from interface:MemoryLayout
Computes the layout size, in bits.- Specified by:
bitSize
in interfaceMemoryLayout
- Returns:
- the layout size, in bits.
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isPadding
public boolean isPadding()Description copied from interface:MemoryLayout
Is this a padding layout (e.g. a layout created fromMemoryLayout.paddingLayout(long)
) ?- Specified by:
isPadding
in interfaceMemoryLayout
- Returns:
- true, if this layout is a padding layout.
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