Java MethodType.insertParameterTypes方法代碼示例

import java.lang.invoke.MethodType; //導入方法依賴的package包/類
@Test
public static void testCountedLoopVoidInit() throws Throwable {
    MethodHandle fit5 = MethodHandles.constant(int.class, 5);
    for (int i = 0; i < 8; i++) {
        MethodHandle zero = MethodHandles.zero(void.class);
        MethodHandle init = fit5;
        MethodHandle body = Counted.MH_printHello;
        boolean useNull = (i & 1) != 0, addInitArg = (i & 2) != 0, addBodyArg = (i & 4) != 0;
        if (useNull)    zero = null;
        if (addInitArg) init = MethodHandles.dropArguments(init, 0, int.class);
        if (addBodyArg) body = MethodHandles.dropArguments(body, 1, int.class);
        System.out.println("testCountedLoopVoidInit i="+i+" : "+Arrays.asList(init, zero, body));
        MethodHandle loop = MethodHandles.countedLoop(init, zero, body);
        MethodType expectedType = Counted.MT_countedPrinting;
        if (addInitArg || addBodyArg)
            expectedType = expectedType.insertParameterTypes(0, int.class);
        assertEquals(expectedType, loop.type());
        if (addInitArg || addBodyArg)
            loop.invoke(99);
        else
            loop.invoke();
    }
}
 

import java.lang.invoke.MethodType; //導入方法依賴的package包/類
private static MethodType getMethodType(final AccessibleObject ao) {
    final boolean isMethod = ao instanceof Method;
    final Class<?> rtype = isMethod ? ((Method)ao).getReturnType() : ((Constructor<?>)ao).getDeclaringClass();
    final Class<?>[] ptypes = isMethod ? ((Method)ao).getParameterTypes() : ((Constructor<?>)ao).getParameterTypes();
    final MethodType type = MethodType.methodType(rtype, ptypes);
    final Member m = (Member)ao;
    return type.insertParameterTypes(0,
            isMethod ?
                    Modifier.isStatic(m.getModifiers()) ?
                            Object.class :
                            m.getDeclaringClass() :
                    StaticClass.class);
}
 

import java.lang.invoke.MethodType; //導入方法依賴的package包/類
@Test(dataProvider = "countedLoopBodyParameters")
public static void testCountedLoopBodyParameters(MethodType countType, MethodType initType, MethodType bodyType) throws Throwable {
    MethodHandle loop = MethodHandles.countedLoop(
            MethodHandles.empty(countType),
            initType == null ? null : MethodHandles.empty(initType),
            MethodHandles.empty(bodyType));
    // The rule:  If body takes the minimum number of parameters, then take what countType offers.
    // The initType has to just roll with whatever the other two agree on.
    int innerParams = (bodyType.returnType() == void.class ? 1 : 2);
    MethodType expectType = bodyType.dropParameterTypes(0, innerParams);
    if (expectType.parameterCount() == 0)
        expectType = expectType.insertParameterTypes(0, countType.parameterList());
    assertEquals(expectType, loop.type());
}
 

import java.lang.invoke.MethodType; //導入方法依賴的package包/類
Binder(final LinkerServices linkerServices, final MethodType methodType, final Object fixedKey) {
    this.linkerServices = linkerServices;
    this.methodType = fixedKey == null ? methodType : methodType.insertParameterTypes(1, fixedKey.getClass());
    this.fixedKey = fixedKey;
}
 

import java.lang.invoke.MethodType; //導入方法依賴的package包/類
@Override
public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {
    final Object objBoundCallable = linkRequest.getReceiver();
    if(!(objBoundCallable instanceof BoundCallable)) {
        return null;
    }

    final CallSiteDescriptor descriptor = linkRequest.getCallSiteDescriptor();
    final Operation operation = NamedOperation.getBaseOperation(descriptor.getOperation());
    // We need to distinguish NEW from CALL because CALL sites have parameter list of the form
    // "callee, this, args", while NEW sites have "callee, args" -- they lack the "this" parameter.
    final boolean isCall;
    if (operation == StandardOperation.NEW) {
        isCall = false;
    } else if (operation == StandardOperation.CALL) {
        isCall = true;
    } else {
        // Only CALL and NEW are supported.
        return null;
    }
    final BoundCallable boundCallable = (BoundCallable)objBoundCallable;
    final Object callable = boundCallable.getCallable();
    final Object boundThis = boundCallable.getBoundThis();

    // We need to ask the linker services for a delegate invocation on the target callable.

    // Replace arguments (boundCallable[, this], args) => (callable[, boundThis], boundArgs, args) when delegating
    final Object[] args = linkRequest.getArguments();
    final Object[] boundArgs = boundCallable.getBoundArgs();
    final int argsLen = args.length;
    final int boundArgsLen = boundArgs.length;
    final Object[] newArgs = new Object[argsLen + boundArgsLen];
    newArgs[0] = callable;
    final int firstArgIndex;
    if (isCall) {
        newArgs[1] = boundThis;
        firstArgIndex = 2;
    } else {
        firstArgIndex = 1;
    }
    System.arraycopy(boundArgs, 0, newArgs, firstArgIndex, boundArgsLen);
    System.arraycopy(args, firstArgIndex, newArgs, firstArgIndex + boundArgsLen, argsLen - firstArgIndex);

    // Use R(T0, T1, T2, ...) => R(callable.class, boundThis.class, boundArg0.class, ..., boundArgn.class, T2, ...)
    // call site type when delegating to underlying linker (for NEW, there's no this).
    final MethodType type = descriptor.getMethodType();
    // Use R(T0, ...) => R(callable.class, ...)
    MethodType newMethodType = descriptor.getMethodType().changeParameterType(0, callable.getClass());
    if (isCall) {
        // R(callable.class, T1, ...) => R(callable.class, boundThis.class, ...)
        newMethodType = newMethodType.changeParameterType(1, boundThis == null? Object.class : boundThis.getClass());
    }
    // R(callable.class[, boundThis.class], T2, ...) => R(callable.class[, boundThis.class], boundArg0.class, ..., boundArgn.class, T2, ...)
    for(int i = boundArgs.length; i-- > 0;) {
        newMethodType = newMethodType.insertParameterTypes(firstArgIndex, boundArgs[i] == null ? Object.class : boundArgs[i].getClass());
    }
    final CallSiteDescriptor newDescriptor = descriptor.changeMethodType(newMethodType);

    // Delegate to target's linker
    final GuardedInvocation inv = linkerServices.getGuardedInvocation(linkRequest.replaceArguments(newDescriptor, newArgs));
    if(inv == null) {
        return null;
    }

    // Bind (callable[, boundThis], boundArgs) to the delegate handle
    final MethodHandle boundHandle = MethodHandles.insertArguments(inv.getInvocation(), 0,
            Arrays.copyOf(newArgs, firstArgIndex + boundArgs.length));
    final Class<?> p0Type = type.parameterType(0);
    final MethodHandle droppingHandle;
    if (isCall) {
        // Ignore incoming boundCallable and this
        droppingHandle = MethodHandles.dropArguments(boundHandle, 0, p0Type, type.parameterType(1));
    } else {
        // Ignore incoming boundCallable
        droppingHandle = MethodHandles.dropArguments(boundHandle, 0, p0Type);
    }
    // Identity guard on boundCallable object
    final MethodHandle newGuard = Guards.getIdentityGuard(boundCallable);
    return inv.replaceMethods(droppingHandle, newGuard.asType(newGuard.type().changeParameterType(0, p0Type)));
}