Record Class PointerPtr

java.lang.Object
java.lang.Record
club.doki7.ffm.ptr.PointerPtr
All Implemented Interfaces:
IPointer, Iterable<MemorySegment>
@ValueBasedCandidate @UnsafeConstructor public record PointerPtr(@NotNull MemorySegment segment) extends Record implements IPointer, Iterable<MemorySegment>

Reperesents a pointer to pointer(s) in native memory.

The property segment() should always be not-null (segment != NULL && !segment.equals(MemorySegment.NULL)), and properly aligned to MemoryLayout.byteAlignment() bytes. 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 Details

    • PointerPtr

      public PointerPtr(@NotNull @NotNull MemorySegment segment)
      Creates an instance of a PointerPtr record class.
      Parameters:
      segment - the value for the segment record component

  • Method Details

    • size

      public long size()

    • read

      @NotNull public @NotNull MemorySegment read()

    • write

      public void write(@NotNull @NotNull MemorySegment value)

    • write

      public void write(@Nullable @Nullable IPointer pointer)

    • read

      @NotNull public @NotNull MemorySegment read(long index)

    • write

      public void write(long index, @NotNull @NotNull MemorySegment value)

    • write

      public void write(long index, @Nullable @Nullable IPointer pointer)

    • reinterpret

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

      Assume the PointerPtr is capable of holding at least newSize pointers, create a new view PointerPtr that uses the same backing storage as this PointerPtr, 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 the 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 PointerPtr offset(long offset)

    • slice

      @NotNull public @NotNull PointerPtr 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 PointerPtr slice(long end)

    • iterator

      @NotNull public @NotNull Iterator<MemorySegment> iterator()
      Specified by:
      iterator in interface Iterable<MemorySegment>

    • checked

      @Contract("null -> null") @Nullable public static @Nullable PointerPtr checked(@Nullable @Nullable MemorySegment segment)

      Creata a new PointerPtr using segment as backing storage, with argument validation.

      This function does not ensure segment's size to be a multiple of MemoryLayout.byteSize(), since that several trailing bytes could be automatically ignored by size() method, and usually these bytes does not interfere with FFI operations. If segment is not big enough to hold at least one pointer, 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 null or MemorySegment.NULL, otherwise a new PointerPtr that uses segment as backing storage
      Throws:
      IllegalArgumentException - if segment is not native or not properly aligned

    • allocate

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

    • allocate

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

    • allocateV

      @NotNull public static @NotNull PointerPtr allocateV(@NotNull @NotNull Arena arena, @Nullable @Nullable IPointer pointer0, @Nullable @Nullable IPointer... pointers)

    • allocateV

      @NotNull public static @NotNull PointerPtr allocateV(@NotNull @NotNull Arena arena, MemorySegment segment0, MemorySegment... segments)

    • 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