Record Class WCharPtr

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

Represents a pointer to C wchar_t element(s) in native memory.

The property segment() should always be not-null (segment != NULL && !segment.equals(MemorySegment.NULL)), and properly aligned to NativeLayout.WCHAR_T.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

    • WCharPtr

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

  • Method Details

    • size

      public long size()

    • read

      public int read()

    • write

      public void write(int value)

    • read

      public int read(long index)

    • write

      public void write(long index, int value)

    • readWStringSafe

      @NotNull public @NotNull String readWStringSafe()

      (Windows only) Assume the WCharPtr is a Windows wide character string, reads the string from the beginning of the underlying memory segment, until the first NUL byte is encountered or the end of the segment is reached.

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

    • readWString

      @Unsafe @NotNull public @NotNull String readWString()

      (Windows only) Assume the WCharPtr is a Windows wide character string, reads the wide 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 now known in advance or correctly set (for example, the WCharPtr or the underlying MemorySegment is returned from some C API). If the size is correctly set, you may use readWStringSafe() instead.

    • reinterpret

      @NotNull public @NotNull WCharPtr reinterpret(long newSize)

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

    • slice

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

    • iterator

      @NotNull public PrimitiveIterator.OfInt iterator()
      Specified by:
      iterator in interface Iterable<Integer>

    • checked

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

      Create a new WCharPtr with the given MemorySegment as the backing storage, with argument validation.

      This function does not ensure segment's size to be a multiple of NativeLayout.WCHAR_SIZE, 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 element, 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 WCharPtr that uses segment as backing storage
      Throws:
      IllegalArgumentException - if segment is not native or not properly aligned

    • allocate

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

    • allocate

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

    • allocateWString

      @NotNull public static @NotNull WCharPtr allocateWString(@NotNull @NotNull Arena arena, @NotNull @NotNull String string)
      (Windows only) allocate a new WCharPtr with the given string as the content.

    • 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