Module java.base
Package java.lang.foreign

Class FunctionDescriptor

java.lang.Object
java.lang.foreign.FunctionDescriptor
public sealed class FunctionDescriptor extends Object
FunctionDescriptor is a preview API of the Java platform.
Programs can only use FunctionDescriptor when preview features are enabled.
Preview features may be removed in a future release, or upgraded to permanent features of the Java platform.
A function descriptor is made up of zero or more argument layouts and zero or one return layout. A function descriptor is used to model the signature of foreign functions when creating downcall method handlesPREVIEW or upcall stubsPREVIEW.
Implementation Requirements:
This class is immutable, thread-safe and value-based.
Since:
19
See Also:

  • Method Details

    • returnLayout

      public Optional<MemoryLayoutPREVIEW> returnLayout()
      Returns the return layout (if any) associated with this function descriptor.
      Returns:
      the return layout (if any) associated with this function descriptor

    • argumentLayouts

      public List<MemoryLayoutPREVIEW> argumentLayouts()
      Returns the argument layouts associated with this function descriptor (as an immutable list)..
      Returns:
      the argument layouts associated with this function descriptor (as an immutable list)

    • of

      public static FunctionDescriptorPREVIEW of(MemoryLayoutPREVIEW resLayout, MemoryLayoutPREVIEW... argLayouts)
      Creates a function descriptor with the given return and argument layouts.
      Parameters:
      resLayout - the return layout.
      argLayouts - the argument layouts.
      Returns:
      the new function descriptor.

    • ofVoid

      public static FunctionDescriptorPREVIEW ofVoid(MemoryLayoutPREVIEW... argLayouts)
      Creates a function descriptor with the given argument layouts and no return layout.
      Parameters:
      argLayouts - the argument layouts.
      Returns:
      the new function descriptor.

    • asVariadic

      public FunctionDescriptorPREVIEW asVariadic(MemoryLayoutPREVIEW... variadicLayouts)
      Creates a specialized variadic function descriptor, by appending given variadic layouts to this function descriptor argument layouts. The resulting function descriptor can report the position of the first variadic argument, and cannot be altered in any way: for instance, calling changeReturnLayout(MemoryLayout) on the resulting descriptor will throw an UnsupportedOperationException.
      Parameters:
      variadicLayouts - the variadic argument layouts to be appended to this descriptor argument layouts.
      Returns:
      a variadic function descriptor, or this descriptor if variadicLayouts.length == 0.

    • firstVariadicArgumentIndex

      public int firstVariadicArgumentIndex()
      The index of the first variadic argument layout (where defined).
      Returns:
      The index of the first variadic argument layout, or -1 if this is not a variadic layout.

    • appendArgumentLayouts

      public FunctionDescriptorPREVIEW appendArgumentLayouts(MemoryLayoutPREVIEW... addedLayouts)
      Returns a function descriptor with the given argument layouts appended to the argument layout array of this function descriptor.
      Parameters:
      addedLayouts - the argument layouts to append.
      Returns:
      the new function descriptor.

    • insertArgumentLayouts

      public FunctionDescriptorPREVIEW insertArgumentLayouts(int index, MemoryLayoutPREVIEW... addedLayouts)
      Returns a function descriptor with the given argument layouts inserted at the given index, into the argument layout array of this function descriptor.
      Parameters:
      index - the index at which to insert the arguments
      addedLayouts - the argument layouts to insert at given index.
      Returns:
      the new function descriptor.
      Throws:
      IllegalArgumentException - if index < 0 || index > argumentLayouts().size().

    • changeReturnLayout

      public FunctionDescriptorPREVIEW changeReturnLayout(MemoryLayoutPREVIEW newReturn)
      Returns a function descriptor with the given memory layout as the new return layout.
      Parameters:
      newReturn - the new return layout.
      Returns:
      the new function descriptor.

    • dropReturnLayout

      public FunctionDescriptorPREVIEW dropReturnLayout()
      Returns a function descriptor with the return layout dropped. This is useful to model functions which return no values.
      Returns:
      the new function descriptor.

    • toString

      public String toString()
      Returns the string representation of this function descriptor.
      Overrides:
      toString in class Object
      Returns:
      the string representation of this function descriptor

    • equals

      public boolean equals(Object other)
      Compares the specified object with this function descriptor for equality. Returns true if and only if the specified object is also a function descriptor, and all the following conditions are met:
      Overrides:
      equals in class Object
      Parameters:
      other - the object to be compared for equality with this function descriptor.
      Returns:
      true if the specified object is equal to this function descriptor.
      See Also:

    • hashCode

      public int hashCode()
      Returns the hash code value for this function descriptor.
      Overrides:
      hashCode in class Object
      Returns:
      the hash code value for this function descriptor
      See Also: