java.lang.Object
jdk.incubator.foreign.ValueLayout
- All Implemented Interfaces:
Constable
,MemoryLayout
A value layout. A value layout is used to model the memory layout associated with values of basic data types, such as integral types
(either signed or unsigned) and floating-point types. Each value layout has a size and a byte order (see
ByteOrder
).
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.
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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.boolean
Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.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.order()
Returns the value's byte order.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.Creates a new layout which features the desired layout name.Returns a new value layout with given byte order.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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order
Returns the value's byte order.- Returns:
- the value's byte order.
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withOrder
Returns a new value layout with given byte order.- Parameters:
order
- the desired byte order.- Returns:
- a new value layout with given byte order.
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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:
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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:
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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:
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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:
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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 (seeSequenceLayout.elementCount()
). 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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