use of org.objectweb.asm.Opcodes.ACC_SUPER in project LanternServer by LanternPowered.
the class FieldAccessFactory method createSetter.
/**
* Creates a setter {@link BiConsumer} for the given {@link Field}.
*
* @param field The field
* @param <T> The target object type
* @param <V> The field value type
* @return The bi consumer
*/
public static <T, V> BiConsumer<T, V> createSetter(Field field) {
checkNotNull(field, "field");
field.setAccessible(true);
boolean isFinal = Modifier.isFinal(field.getModifiers());
// Better check is somebody changed the final modifier already
if (!isFinal) {
final Field[] fields = field.getDeclaringClass().getDeclaredFields();
boolean isFound = false;
for (Field field1 : fields) {
// The same signature, now check if somebody tinkered with the field
if (field.getName().equals(field1.getName()) && field.getType().equals(field1.getType())) {
isFinal = Modifier.isFinal(field1.getModifiers());
isFound = true;
break;
}
}
if (!isFound) {
throw new IllegalStateException("Something funky happened with: " + field.getName());
}
} else {
try {
modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
} catch (IllegalAccessException e) {
throw new IllegalStateException(e);
}
}
// Final fields don't allow direct access, so MethodHandles will do the trick.
if (isFinal) {
try {
final MethodHandle methodHandle = MethodHandleMagic.trustedLookup().in(field.getDeclaringClass()).unreflectSetter(field).asType(setterMethodType);
return (a, b) -> {
try {
methodHandle.invokeExact(a, b);
} catch (Throwable throwable) {
throw new IllegalStateException(throwable);
}
};
} catch (IllegalAccessException e) {
throw new IllegalStateException(e);
}
}
final ClassWriter cw = new ClassWriter(0);
final String className = field.getName().replace('.', '/') + "$$LanternSetter$" + setterCounter.incrementAndGet();
cw.visit(V1_8, ACC_PUBLIC + ACC_SUPER, className, "Ljava/lang/Object;Ljava/util/function/BiConsumer<Ljava/lang/Object;Ljava/lang/Object;>;", "java/lang/Object", new String[] { "java/util/function/BiConsumer" });
// Add a empty constructor
BytecodeUtils.visitEmptyConstructor(cw);
// Generate the apply method
final MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "accept", "(Ljava/lang/Object;Ljava/lang/Object;)V", null, null);
mv.visitCode();
final String descriptor = Type.getDescriptor(field.getType());
final String targetName = Type.getInternalName(field.getDeclaringClass());
final boolean isStatic = Modifier.isStatic(field.getModifiers());
if (!isStatic) {
// Load the target parameter
mv.visitVarInsn(ALOAD, 1);
// Cast it
mv.visitTypeInsn(CHECKCAST, targetName);
}
// Load the value parameter
mv.visitVarInsn(ALOAD, 2);
// Unbox the values in case they are primitives, otherwise cast
GeneratorUtils.visitUnboxingMethod(mv, Type.getType(field.getType()));
// Put the value into the field
if (isStatic) {
mv.visitFieldInsn(PUTSTATIC, targetName, field.getName(), descriptor);
} else {
mv.visitFieldInsn(PUTFIELD, targetName, field.getName(), descriptor);
}
// Return
mv.visitInsn(RETURN);
mv.visitMaxs(2, 3);
mv.visitEnd();
// Finish class generation
cw.visitEnd();
// Define the class and create a function instance
final MethodHandles.Lookup lookup = MethodHandleMagic.trustedLookup().in(field.getDeclaringClass());
final Class<?> functionClass = MethodHandleMagic.defineNestmateClass(lookup, cw.toByteArray());
try {
return (BiConsumer<T, V>) functionClass.newInstance();
} catch (Exception e) {
throw new IllegalStateException("Something went wrong!", e);
}
}
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