Record Class BytePtr

java.lang.Object

java.lang.Record

club.doki7.ffm.ptr.BytePtr

All Implemented Interfaces:

IPointer, Iterable<Byte>

@ValueBasedCandidate
@UnsafeConstructor
public record BytePtr(@NotNull MemorySegment segment)
extends Record
implements IPointer, Iterable<Byte>

Represents a pointer to byte(s) in native memory.

The property segment() should always be not-null (segment != NULL && !segment.equals(MemorySegment.NULL)). To represent null pointer, you may use a Java null instead. See the documentation of IPointer.segment() for more details.

The constructor of this class is marked as UnsafeConstructor, because it does not perform any runtime check. The constructor can be useful for automatic code generators. For normal users, checked(MemorySegment) is a good safe alternative.

Constructor Summary

Constructors

Constructor	Description
BytePtr(@NotNull MemorySegment segment)	Creates an instance of a BytePtr record class.

Method Summary

Modifier and Type	Method	Description
static @NotNull BytePtr	allocate(@NotNull Arena arena)
static @NotNull BytePtr	allocate(@NotNull Arena arena, byte @NotNull [] bytes)
static @NotNull BytePtr	allocate(@NotNull Arena arena, long size)
static @NotNull BytePtr	allocate(@NotNull Arena arena, @NotNull ByteBuffer buffer)	Allocate a new BytePtr in arena and copy the contents of buffer into the newly allocated BytePtr.
static @NotNull BytePtr	allocate(@NotNull Arena arena, Collection<Byte> bytes)
static @NotNull BytePtr	allocateAligned(@NotNull Arena arena, long size, long alignment)
static @NotNull BytePtr	allocateString(@NotNull Arena arena, @NotNull String s)
static @NotNull BytePtr	allocateV(@NotNull Arena arena, byte value0, byte... values)
static @Nullable BytePtr	checked(@NotNull MemorySegment segment)	Create a new BytePtr using segment as backing storage, with argument validation.
static @NotNull BytePtr	checked(@NotNull ByteBuffer buffer)	Create a new BytePtr using the same backing storage as buffer, with argument validation.
final boolean	equals(Object o)	Indicates whether some other object is "equal to" this one.
static @NotNull BytePtr	from(@NotNull IPointer ptr)
final int	hashCode()	Returns a hash code value for this object.
@NotNull Iterator<Byte>	iterator()
@NotNull BytePtr	offset(long offset)
byte	read()
byte	read(long index)
@NotNull String	readString()	Assumes the BytePtr is a null-terminated string, reads the string from the beginning of the underlying memory segment, until the first NUL byte is encountered.
@NotNull String	readStringSafe()	Assume the BytePtr is a null-terminated string, reads the string from the beginning of the underlying memory segment, until the first NUL byte is encountered.
@NotNull BytePtr	reinterpret(long newSize)	Assume the BytePtr is capable of holding at least newSize bytes, create a new view BytePtr that uses the same backing storage as this BytePtr, but with the new size.
@NotNull MemorySegment	segment()	Returns the value of the segment record component.
long	size()
@NotNull BytePtr	slice(long end)
@NotNull BytePtr	slice(long start, long end)	Note that this function uses the List.subList(int, int) semantics (left inclusive, right exclusive interval), not MemorySegment.asSlice(long, long) semantics (offset + newSize).
final String	toString()	Returns a string representation of this record class.
void	write(byte value)
void	write(byte @NotNull [] bytes)
void	write(long index, byte value)
void	writeString(@NotNull String s)
void	writeV(byte value0, byte @NotNull ... values)

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Details

BytePtr

public BytePtr(@NotNull
 @NotNull MemorySegment segment)

Creates an instance of a BytePtr record class.

Parameters:

segment - the value for the segment record component

Method Details

size

public long size()

read

public byte read()

write

public void write(byte value)

read

public byte read(long index)

write

public void write(long index,
 byte value)

write

public void write(byte @NotNull [] bytes)

writeV

public void writeV(byte value0,
 byte @NotNull ... values)

writeString

public void writeString(@NotNull
 @NotNull String s)

readStringSafe

@NotNull
public @NotNull String readStringSafe()

Assume the BytePtr is a null-terminated string, reads the string from the beginning of the underlying memory segment, until the first NUL byte is encountered.

This function requires the size of the underlying memory segment to be set correctly. If the size is not known in advance and correctly set (for example, the BytePtr or the underlying MemorySegment is returned from some C API), you may use readString() (note that it is Unsafe) instead.

readString

@Unsafe
@NotNull
public @NotNull String readString()

Assumes the BytePtr is a null-terminated string, reads the string from the beginning of the underlying memory segment, until the first NUL byte is encountered.

This function is Unsafe because it does not check the size of the underlying memory segment. This function is suitable for the cases that the size of the underlying memory segment is not known in advance and correctly set (for example, the BytePtr or the underlying MemorySegment is returned from some C API). If the size is correctly set, you may use readStringSafe() instead.

reinterpret

@Unsafe
@NotNull
public @NotNull BytePtr reinterpret(long newSize)

Assume the BytePtr is capable of holding at least newSize bytes, create a new view BytePtr that uses the same backing storage as this BytePtr, but with the new size. Since there is actually no way to really check whether the new size is valid, while buffer overflow is undefined behavior, this method is marked as Unsafe.

This method could be useful when handling data returned from some C API, where the size of data is not known in advance.

If the size of the underlying segment is actually known in advance and correctly set, and you want to create a shrunk view, you may use slice(long) (with validation) instead.

offset

@NotNull
public @NotNull BytePtr offset(long offset)

slice

@NotNull
public @NotNull BytePtr slice(long start,
 long end)

Note that this function uses the List.subList(int, int) semantics (left inclusive, right exclusive interval), not MemorySegment.asSlice(long, long) semantics (offset + newSize). Be careful with the difference.

slice

@NotNull
public @NotNull BytePtr slice(long end)

iterator

@NotNull
public @NotNull Iterator<Byte> iterator()

Specified by:

iterator in interface Iterable<Byte>

checked

@Nullable
public static @Nullable BytePtr checked(@NotNull
 @NotNull MemorySegment segment)

Create a new BytePtr using segment as backing storage, with argument validation.

If segment is not big enough to hold at least one byte, that segment is simply considered "empty". See the documentation of IPointer.segment() for more details.

Parameters:

segment - the MemorySegment to use as the backing storage

Returns:

null if segment is MemorySegment.NULL, otherwise a new BytePtr that uses segment as backing storage

Throws:

IllegalArgumentException - if segment is not native

checked

@NotNull
public static @NotNull BytePtr checked(@NotNull
 @NotNull ByteBuffer buffer)

Create a new BytePtr using the same backing storage as buffer, with argument validation.

The main difference between this static method and the allocate(Arena, ByteBuffer) method is that this method does not copy the contents of buffer into a newly allocated MemorySegment. Instead, the newly created BytePtr will use the same backing storage as buffer. Thus, modifications from one side will be visible on the other side.

Be careful with java.nio buffer types' Buffer.position() property: only the "remaining" (from Buffer.position() to Buffer.limit()) part of buffer will be referred. If you have ever read from buffer, and you want all the contents of buffer to be referred, you may want to call Buffer.rewind().

Parameters:

buffer - the ByteBuffer to use as the backing storage

Returns:

a new BytePtr that uses buffer as its backing storage

Throws:

IllegalArgumentException - if buffer is not direct

from

@NotNull
public static @NotNull BytePtr from(@NotNull
 @NotNull IPointer ptr)

allocate

@NotNull
public static @NotNull BytePtr allocate(@NotNull
 @NotNull Arena arena)

allocate

@NotNull
public static @NotNull BytePtr allocate(@NotNull
 @NotNull Arena arena,
 long size)

allocate

@NotNull
public static @NotNull BytePtr allocate(@NotNull
 @NotNull Arena arena,
 byte @NotNull [] bytes)

allocate

@NotNull
public static @NotNull BytePtr allocate(@NotNull
 @NotNull Arena arena,
 Collection<Byte> bytes)

allocateV

@NotNull
public static @NotNull BytePtr allocateV(@NotNull
 @NotNull Arena arena,
 byte value0,
 byte... values)

allocate

@NotNull
public static @NotNull BytePtr allocate(@NotNull
 @NotNull Arena arena,
 @NotNull
 @NotNull ByteBuffer buffer)

Allocate a new BytePtr in arena and copy the contents of buffer into the newly allocated BytePtr.

Be careful with java.nio buffer types' Buffer.position() property: only the "remaining" (from Buffer.position() to Buffer.limit()) part of buffer will be copied. If you have ever read from buffer, and you want all the contents of buffer to be copied, you may want to call Buffer.rewind().

Parameters:

arena - the Arena to allocate the new BytePtr in

buffer - the ByteBuffer to copy the contents from

Returns:

a new BytePtr that contains the contents of buffer

allocateAligned

@NotNull
public static @NotNull BytePtr allocateAligned(@NotNull
 @NotNull Arena arena,
 long size,
 long alignment)

allocateString

@NotNull
public static @NotNull BytePtr allocateString(@NotNull
 @NotNull Arena arena,
 @NotNull
 @NotNull String s)

toString

public final String toString()

Returns a string representation of this record class. The representation contains the name of the class, followed by the name and value of each of the record components.

Specified by:

toString in class Record

Returns:

a string representation of this object

hashCode

public final int hashCode()

Returns a hash code value for this object. The value is derived from the hash code of each of the record components.

Specified by:

hashCode in class Record

Returns:

a hash code value for this object

equals

public final boolean equals(Object o)

Indicates whether some other object is "equal to" this one. The objects are equal if the other object is of the same class and if all the record components are equal. All components in this record class are compared with Objects::equals(Object,Object).

Specified by:

equals in class Record

Parameters:

o - the object with which to compare

Returns:

true if this object is the same as the o argument; false otherwise.

segment

@NotNull
public @NotNull MemorySegment segment()

Returns the value of the segment record component.

Specified by:

segment in interface IPointer

Returns:

the value of the segment record component