예제 #1
0
 /**
  * Adapts the return type of the method handle with {@code explicitCastArguments} when it is an
  * unboxing conversion. This will ensure that nulls are unwrapped to false or 0.
  *
  * @param target the target method handle
  * @param newType the desired new type. Note that this method does not adapt the method handle
  *     completely to the new type, it only adapts the return type; this is allowed as per {@link
  *     DynamicLinkerFactory#setAutoConversionStrategy(MethodTypeConversionStrategy)}, which is
  *     what this method is used for.
  * @return the method handle with adapted return type, if it required an unboxing conversion.
  */
 private static MethodHandle unboxReturnType(final MethodHandle target, final MethodType newType) {
   final MethodType targetType = target.type();
   final Class<?> oldReturnType = targetType.returnType();
   final Class<?> newReturnType = newType.returnType();
   if (TypeUtilities.isWrapperType(oldReturnType)) {
     if (newReturnType.isPrimitive()) {
       // The contract of setAutoConversionStrategy is such that the difference between newType and
       // targetType
       // can only be JLS method invocation conversions.
       assert TypeUtilities.isMethodInvocationConvertible(oldReturnType, newReturnType);
       return MethodHandles.explicitCastArguments(
           target, targetType.changeReturnType(newReturnType));
     }
   } else if (oldReturnType == void.class && newReturnType == Object.class) {
     return MethodHandles.filterReturnValue(target, VOID_TO_OBJECT);
   }
   return target;
 }
 private static boolean canWiden(final Class<?> type) {
   return TypeUtilities.isWrapperType(type) && type != Boolean.class && type != Character.class;
 }