- 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
Indicates whether some other object is "equal to" this one.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()
Returns a hash code value for the object.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()
Returns a string representation of the object.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
Returns a string representation of the object.- Specified by:
toString
in interfaceMemoryLayout
- Overrides:
toString
in classObject
- Returns:
- a string representation of the object.
-
equals
Description copied from class:Object
Indicates whether some other object is "equal to" this one.The
equals
method implements an equivalence relation on non-null object references:- It is reflexive: for any non-null reference value
x
,x.equals(x)
should returntrue
. - It is symmetric: for any non-null reference values
x
andy
,x.equals(y)
should returntrue
if and only ify.equals(x)
returnstrue
. - It is transitive: for any non-null reference values
x
,y
, andz
, ifx.equals(y)
returnstrue
andy.equals(z)
returnstrue
, thenx.equals(z)
should returntrue
. - It is consistent: for any non-null reference values
x
andy
, multiple invocations ofx.equals(y)
consistently returntrue
or consistently returnfalse
, provided no information used inequals
comparisons on the objects is modified. - For any non-null reference value
x
,x.equals(null)
should returnfalse
.
An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.
- Specified by:
equals
in interfaceMemoryLayout
- Parameters:
other
- the reference object with which to compare.- Returns:
true
if this object is the same as the obj argument;false
otherwise.- See Also:
- It is reflexive: for any non-null reference value
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hashCode
public int hashCode()Description copied from class:Object
Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided byHashMap
.The general contract of
hashCode
is:- Whenever it is invoked on the same object more than once during
an execution of a Java application, the
hashCode
method must consistently return the same integer, provided no information used inequals
comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. - If two objects are equal according to the
equals
method, then calling thehashCode
method on each of the two objects must produce the same integer result. - It is not required that if two objects are unequal
according to the
equals
method, then calling thehashCode
method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
- Specified by:
hashCode
in interfaceMemoryLayout
- Returns:
- a hash code value for this object.
- See Also:
- Whenever it is invoked on the same object more than once during
an execution of a Java application, the
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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).
-
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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