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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.invoke.MethodType;
import java.lang.invoke.WrongMethodTypeException;
public class Main {
public static void main(String[] args) throws Throwable {
testThrowException();
testDropArguments();
testCatchException();
testGuardWithTest();
testArrayElementGetter();
testArrayElementSetter();
testIdentity();
testConstant();
testBindTo();
testFilterReturnValue();
testPermuteArguments();
testInvokers();
testSpreaders_reference();
testSpreaders_primitive();
testInvokeWithArguments();
testAsCollector();
testFilterArguments();
testCollectArguments();
testInsertArguments();
testFoldArguments();
}
public static void testThrowException() throws Throwable {
MethodHandle handle = MethodHandles.throwException(String.class,
IllegalArgumentException.class);
if (handle.type().returnType() != String.class) {
fail("Unexpected return type for handle: " + handle +
" [ " + handle.type() + "]");
}
final IllegalArgumentException iae = new IllegalArgumentException("boo!");
try {
handle.invoke(iae);
fail("Expected an exception of type: java.lang.IllegalArgumentException");
} catch (IllegalArgumentException expected) {
if (expected != iae) {
fail("Wrong exception: expected " + iae + " but was " + expected);
}
}
}
public static void dropArguments_delegate(String message, long message2) {
System.out.println("Message: " + message + ", Message2: " + message2);
}
public static void testDropArguments() throws Throwable {
MethodHandle delegate = MethodHandles.lookup().findStatic(Main.class,
"dropArguments_delegate",
MethodType.methodType(void.class, new Class<?>[] { String.class, long.class }));
MethodHandle transform = MethodHandles.dropArguments(delegate, 0, int.class, Object.class);
// The transformer will accept two additional arguments at position zero.
try {
transform.invokeExact("foo", 42l);
fail();
} catch (WrongMethodTypeException expected) {
}
transform.invokeExact(45, new Object(), "foo", 42l);
transform.invoke(45, new Object(), "foo", 42l);
// Additional arguments at position 1.
transform = MethodHandles.dropArguments(delegate, 1, int.class, Object.class);
transform.invokeExact("foo", 45, new Object(), 42l);
transform.invoke("foo", 45, new Object(), 42l);
// Additional arguments at position 2.
transform = MethodHandles.dropArguments(delegate, 2, int.class, Object.class);
transform.invokeExact("foo", 42l, 45, new Object());
transform.invoke("foo", 42l, 45, new Object());
// Note that we still perform argument conversions even for the arguments that
// are subsequently dropped.
try {
transform.invoke("foo", 42l, 45l, new Object());
fail();
} catch (WrongMethodTypeException expected) {
} catch (IllegalArgumentException expected) {
// TODO(narayan): We currently throw the wrong type of exception here,
// it's IAE and should be WMTE instead.
}
// Check that asType works as expected.
transform = MethodHandles.dropArguments(delegate, 0, int.class, Object.class);
transform = transform.asType(MethodType.methodType(void.class,
new Class<?>[] { short.class, Object.class, String.class, long.class }));
transform.invokeExact((short) 45, new Object(), "foo", 42l);
// Invalid argument location, should not be allowed.
try {
MethodHandles.dropArguments(delegate, -1, int.class, Object.class);
fail();
} catch (IllegalArgumentException expected) {
}
// Invalid argument location, should not be allowed.
try {
MethodHandles.dropArguments(delegate, 3, int.class, Object.class);
fail();
} catch (IllegalArgumentException expected) {
}
try {
MethodHandles.dropArguments(delegate, 1, void.class);
fail();
} catch (IllegalArgumentException expected) {
}
}
public static String testCatchException_target(String arg1, long arg2, String exceptionMessage)
throws Throwable {
if (exceptionMessage != null) {
throw new IllegalArgumentException(exceptionMessage);
}
System.out.println("Target: Arg1: " + arg1 + ", Arg2: " + arg2);
return "target";
}
public static String testCatchException_handler(IllegalArgumentException iae, String arg1, long arg2,
String exMsg) {
System.out.println("Handler: " + iae + ", Arg1: " + arg1 + ", Arg2: " + arg2 + ", ExMsg: " + exMsg);
return "handler1";
}
public static String testCatchException_handler2(IllegalArgumentException iae, String arg1) {
System.out.println("Handler: " + iae + ", Arg1: " + arg1);
return "handler2";
}
public static void testCatchException() throws Throwable {
MethodHandle target = MethodHandles.lookup().findStatic(Main.class,
"testCatchException_target",
MethodType.methodType(String.class, new Class<?>[] { String.class, long.class, String.class }));
MethodHandle handler = MethodHandles.lookup().findStatic(Main.class,
"testCatchException_handler",
MethodType.methodType(String.class, new Class<?>[] { IllegalArgumentException.class,
String.class, long.class, String.class }));
MethodHandle adapter = MethodHandles.catchException(target, IllegalArgumentException.class,
handler);
String returnVal = null;
// These two should end up calling the target always. We're passing a null exception
// message here, which means the target will not throw.
returnVal = (String) adapter.invoke("foo", 42, null);
assertEquals("target", returnVal);
returnVal = (String) adapter.invokeExact("foo", 42l, (String) null);
assertEquals("target", returnVal);
// We're passing a non-null exception message here, which means the target will throw,
// which in turn means that the handler must be called for the next two invokes.
returnVal = (String) adapter.invoke("foo", 42, "exceptionMessage");
assertEquals("handler1", returnVal);
returnVal = (String) adapter.invokeExact("foo", 42l, "exceptionMessage");
assertEquals("handler1", returnVal);
handler = MethodHandles.lookup().findStatic(Main.class,
"testCatchException_handler2",
MethodType.methodType(String.class, new Class<?>[] { IllegalArgumentException.class,
String.class }));
adapter = MethodHandles.catchException(target, IllegalArgumentException.class, handler);
returnVal = (String) adapter.invoke("foo", 42, "exceptionMessage");
assertEquals("handler2", returnVal);
returnVal = (String) adapter.invokeExact("foo", 42l, "exceptionMessage");
assertEquals("handler2", returnVal);
// Test that the type of the invoke doesn't matter. Here we call
// IllegalArgumentException.toString() on the exception that was thrown by
// the target.
handler = MethodHandles.lookup().findVirtual(IllegalArgumentException.class,
"toString", MethodType.methodType(String.class));
adapter = MethodHandles.catchException(target, IllegalArgumentException.class, handler);
returnVal = (String) adapter.invoke("foo", 42, "exceptionMessage");
assertEquals("java.lang.IllegalArgumentException: exceptionMessage", returnVal);
returnVal = (String) adapter.invokeExact("foo", 42l, "exceptionMessage2");
assertEquals("java.lang.IllegalArgumentException: exceptionMessage2", returnVal);
// Check that asType works as expected.
adapter = MethodHandles.catchException(target, IllegalArgumentException.class,
handler);
adapter = adapter.asType(MethodType.methodType(String.class,
new Class<?>[] { String.class, int.class, String.class }));
returnVal = (String) adapter.invokeExact("foo", 42, "exceptionMessage");
assertEquals("java.lang.IllegalArgumentException: exceptionMessage", returnVal);
}
public static boolean testGuardWithTest_test(String arg1, long arg2) {
return "target".equals(arg1) && 42 == arg2;
}
public static String testGuardWithTest_target(String arg1, long arg2, int arg3) {
System.out.println("target: " + arg1 + ", " + arg2 + ", " + arg3);
return "target";
}
public static String testGuardWithTest_fallback(String arg1, long arg2, int arg3) {
System.out.println("fallback: " + arg1 + ", " + arg2 + ", " + arg3);
return "fallback";
}
public static void testGuardWithTest() throws Throwable {
MethodHandle test = MethodHandles.lookup().findStatic(Main.class,
"testGuardWithTest_test",
MethodType.methodType(boolean.class, new Class<?>[] { String.class, long.class }));
final MethodType type = MethodType.methodType(String.class,
new Class<?>[] { String.class, long.class, int.class });
final MethodHandle target = MethodHandles.lookup().findStatic(Main.class,
"testGuardWithTest_target", type);
final MethodHandle fallback = MethodHandles.lookup().findStatic(Main.class,
"testGuardWithTest_fallback", type);
MethodHandle adapter = MethodHandles.guardWithTest(test, target, fallback);
String returnVal = null;
returnVal = (String) adapter.invoke("target", 42, 56);
assertEquals("target", returnVal);
returnVal = (String) adapter.invokeExact("target", 42l, 56);
assertEquals("target", returnVal);
returnVal = (String) adapter.invoke("fallback", 42l, 56);
assertEquals("fallback", returnVal);
returnVal = (String) adapter.invokeExact("target", 42l, 56);
assertEquals("target", returnVal);
// Check that asType works as expected.
adapter = adapter.asType(MethodType.methodType(String.class,
new Class<?>[] { String.class, int.class, int.class }));
returnVal = (String) adapter.invokeExact("target", 42, 56);
assertEquals("target", returnVal);
}
public static void testArrayElementGetter() throws Throwable {
MethodHandle getter = MethodHandles.arrayElementGetter(int[].class);
{
int[] array = new int[1];
array[0] = 42;
int value = (int) getter.invoke(array, 0);
if (value != 42) {
fail("Unexpected value: " + value);
}
try {
value = (int) getter.invoke(array, -1);
fail();
} catch (ArrayIndexOutOfBoundsException expected) {
}
try {
value = (int) getter.invoke(null, -1);
fail();
} catch (NullPointerException expected) {
}
}
{
getter = MethodHandles.arrayElementGetter(long[].class);
long[] array = new long[1];
array[0] = 42;
long value = (long) getter.invoke(array, 0);
if (value != 42l) {
fail("Unexpected value: " + value);
}
}
{
getter = MethodHandles.arrayElementGetter(short[].class);
short[] array = new short[1];
array[0] = 42;
short value = (short) getter.invoke(array, 0);
if (value != 42l) {
fail("Unexpected value: " + value);
}
}
{
getter = MethodHandles.arrayElementGetter(char[].class);
char[] array = new char[1];
array[0] = 42;
char value = (char) getter.invoke(array, 0);
if (value != 42l) {
fail("Unexpected value: " + value);
}
}
{
getter = MethodHandles.arrayElementGetter(byte[].class);
byte[] array = new byte[1];
array[0] = (byte) 0x8;
byte value = (byte) getter.invoke(array, 0);
if (value != (byte) 0x8) {
fail("Unexpected value: " + value);
}
}
{
getter = MethodHandles.arrayElementGetter(boolean[].class);
boolean[] array = new boolean[1];
array[0] = true;
boolean value = (boolean) getter.invoke(array, 0);
if (!value) {
fail("Unexpected value: " + value);
}
}
{
getter = MethodHandles.arrayElementGetter(float[].class);
float[] array = new float[1];
array[0] = 42.0f;
float value = (float) getter.invoke(array, 0);
if (value != 42.0f) {
fail("Unexpected value: " + value);
}
}
{
getter = MethodHandles.arrayElementGetter(double[].class);
double[] array = new double[1];
array[0] = 42.0;
double value = (double) getter.invoke(array, 0);
if (value != 42.0) {
fail("Unexpected value: " + value);
}
}
{
getter = MethodHandles.arrayElementGetter(String[].class);
String[] array = new String[3];
array[0] = "42";
array[1] = "48";
array[2] = "54";
String value = (String) getter.invoke(array, 0);
assertEquals("42", value);
value = (String) getter.invoke(array, 1);
assertEquals("48", value);
value = (String) getter.invoke(array, 2);
assertEquals("54", value);
}
}
public static void testArrayElementSetter() throws Throwable {
MethodHandle setter = MethodHandles.arrayElementSetter(int[].class);
{
int[] array = new int[2];
setter.invoke(array, 0, 42);
setter.invoke(array, 1, 43);
if (array[0] != 42) {
fail("Unexpected value: " + array[0]);
}
if (array[1] != 43) {
fail("Unexpected value: " + array[1]);
}
try {
setter.invoke(array, -1, 42);
fail();
} catch (ArrayIndexOutOfBoundsException expected) {
}
try {
setter.invoke(null, 0, 42);
fail();
} catch (NullPointerException expected) {
}
}
{
setter = MethodHandles.arrayElementSetter(long[].class);
long[] array = new long[1];
setter.invoke(array, 0, 42l);
if (array[0] != 42l) {
fail("Unexpected value: " + array[0]);
}
}
{
setter = MethodHandles.arrayElementSetter(short[].class);
short[] array = new short[1];
setter.invoke(array, 0, (short) 42);
if (array[0] != 42l) {
fail("Unexpected value: " + array[0]);
}
}
{
setter = MethodHandles.arrayElementSetter(char[].class);
char[] array = new char[1];
setter.invoke(array, 0, (char) 42);
if (array[0] != 42) {
fail("Unexpected value: " + array[0]);
}
}
{
setter = MethodHandles.arrayElementSetter(byte[].class);
byte[] array = new byte[1];
setter.invoke(array, 0, (byte) 0x8);
if (array[0] != (byte) 0x8) {
fail("Unexpected value: " + array[0]);
}
}
{
setter = MethodHandles.arrayElementSetter(boolean[].class);
boolean[] array = new boolean[1];
setter.invoke(array, 0, true);
if (!array[0]) {
fail("Unexpected value: " + array[0]);
}
}
{
setter = MethodHandles.arrayElementSetter(float[].class);
float[] array = new float[1];
setter.invoke(array, 0, 42.0f);
if (array[0] != 42.0f) {
fail("Unexpected value: " + array[0]);
}
}
{
setter = MethodHandles.arrayElementSetter(double[].class);
double[] array = new double[1];
setter.invoke(array, 0, 42.0);
if (array[0] != 42.0) {
fail("Unexpected value: " + array[0]);
}
}
{
setter = MethodHandles.arrayElementSetter(String[].class);
String[] array = new String[3];
setter.invoke(array, 0, "42");
setter.invoke(array, 1, "48");
setter.invoke(array, 2, "54");
assertEquals("42", array[0]);
assertEquals("48", array[1]);
assertEquals("54", array[2]);
}
}
public static void testIdentity() throws Throwable {
{
MethodHandle identity = MethodHandles.identity(boolean.class);
boolean value = (boolean) identity.invoke(false);
if (value) {
fail("Unexpected value: " + value);
}
}
{
MethodHandle identity = MethodHandles.identity(byte.class);
byte value = (byte) identity.invoke((byte) 0x8);
if (value != (byte) 0x8) {
fail("Unexpected value: " + value);
}
}
{
MethodHandle identity = MethodHandles.identity(char.class);
char value = (char) identity.invoke((char) -56);
if (value != (char) -56) {
fail("Unexpected value: " + value);
}
}
{
MethodHandle identity = MethodHandles.identity(short.class);
short value = (short) identity.invoke((short) -59);
if (value != (short) -59) {
fail("Unexpected value: " + Short.toString(value));
}
}
{
MethodHandle identity = MethodHandles.identity(int.class);
int value = (int) identity.invoke(52);
if (value != 52) {
fail("Unexpected value: " + value);
}
}
{
MethodHandle identity = MethodHandles.identity(long.class);
long value = (long) identity.invoke(-76l);
if (value != (long) -76) {
fail("Unexpected value: " + value);
}
}
{
MethodHandle identity = MethodHandles.identity(float.class);
float value = (float) identity.invoke(56.0f);
if (value != (float) 56.0f) {
fail("Unexpected value: " + value);
}
}
{
MethodHandle identity = MethodHandles.identity(double.class);
double value = (double) identity.invoke((double) 72.0);
if (value != (double) 72.0) {
fail("Unexpected value: " + value);
}
}
{
MethodHandle identity = MethodHandles.identity(String.class);
String value = (String) identity.invoke("bazman");
assertEquals("bazman", value);
}
}
public static void testConstant() throws Throwable {
// int constants.
{
MethodHandle constant = MethodHandles.constant(int.class, 56);
int value = (int) constant.invoke();
if (value != 56) {
fail("Unexpected value: " + value);
}
// short constant values are converted to int.
constant = MethodHandles.constant(int.class, (short) 52);
value = (int) constant.invoke();
if (value != 52) {
fail("Unexpected value: " + value);
}
// char constant values are converted to int.
constant = MethodHandles.constant(int.class, (char) 'b');
value = (int) constant.invoke();
if (value != (int) 'b') {
fail("Unexpected value: " + value);
}
// int constant values are converted to int.
constant = MethodHandles.constant(int.class, (byte) 0x1);
value = (int) constant.invoke();
if (value != 1) {
fail("Unexpected value: " + value);
}
// boolean, float, double and long primitive constants are not convertible
// to int, so the handle creation must fail with a CCE.
try {
MethodHandles.constant(int.class, false);
fail();
} catch (ClassCastException expected) {
}
try {
MethodHandles.constant(int.class, 0.1f);
fail();
} catch (ClassCastException expected) {
}
try {
MethodHandles.constant(int.class, 0.2);
fail();
} catch (ClassCastException expected) {
}
try {
MethodHandles.constant(int.class, 73l);
fail();
} catch (ClassCastException expected) {
}
}
// long constants.
{
MethodHandle constant = MethodHandles.constant(long.class, 56l);
long value = (long) constant.invoke();
if (value != 56l) {
fail("Unexpected value: " + value);
}
constant = MethodHandles.constant(long.class, (int) 56);
value = (long) constant.invoke();
if (value != 56l) {
fail("Unexpected value: " + value);
}
}
// byte constants.
{
MethodHandle constant = MethodHandles.constant(byte.class, (byte) 0x12);
byte value = (byte) constant.invoke();
if (value != (byte) 0x12) {
fail("Unexpected value: " + value);
}
}
// boolean constants.
{
MethodHandle constant = MethodHandles.constant(boolean.class, true);
boolean value = (boolean) constant.invoke();
if (!value) {
fail("Unexpected value: " + value);
}
}
// char constants.
{
MethodHandle constant = MethodHandles.constant(char.class, 'f');
char value = (char) constant.invoke();
if (value != 'f') {
fail("Unexpected value: " + value);
}
}
// short constants.
{
MethodHandle constant = MethodHandles.constant(short.class, (short) 123);
short value = (short) constant.invoke();
if (value != (short) 123) {
fail("Unexpected value: " + value);
}
}
// float constants.
{
MethodHandle constant = MethodHandles.constant(float.class, 56.0f);
float value = (float) constant.invoke();
if (value != 56.0f) {
fail("Unexpected value: " + value);
}
}
// double constants.
{
MethodHandle constant = MethodHandles.constant(double.class, 256.0);
double value = (double) constant.invoke();
if (value != 256.0) {
fail("Unexpected value: " + value);
}
}
// reference constants.
{
MethodHandle constant = MethodHandles.constant(String.class, "256.0");
String value = (String) constant.invoke();
assertEquals("256.0", value);
}
}
public static void testBindTo() throws Throwable {
MethodHandle stringCharAt = MethodHandles.lookup().findVirtual(
String.class, "charAt", MethodType.methodType(char.class, int.class));
char value = (char) stringCharAt.invoke("foo", 0);
if (value != 'f') {
fail("Unexpected value: " + value);
}
MethodHandle bound = stringCharAt.bindTo("foo");
value = (char) bound.invoke(0);
if (value != 'f') {
fail("Unexpected value: " + value);
}
try {
stringCharAt.bindTo(new Object());
fail();
} catch (ClassCastException expected) {
}
bound = stringCharAt.bindTo(null);
try {
bound.invoke(0);
fail();
} catch (NullPointerException expected) {
}
MethodHandle integerParseInt = MethodHandles.lookup().findStatic(
Integer.class, "parseInt", MethodType.methodType(int.class, String.class));
bound = integerParseInt.bindTo("78452");
int intValue = (int) bound.invoke();
if (intValue != 78452) {
fail("Unexpected value: " + intValue);
}
}
public static String filterReturnValue_target(int a) {
return "ReturnValue" + a;
}
public static boolean filterReturnValue_filter(String value) {
return value.indexOf("42") != -1;
}
public static int filterReturnValue_intTarget(String a) {
return Integer.parseInt(a);
}
public static int filterReturnValue_intFilter(int b) {
return b + 1;
}
public static void filterReturnValue_voidTarget() {
}
public static int filterReturnValue_voidFilter() {
return 42;
}
public static void testFilterReturnValue() throws Throwable {
// A target that returns a reference.
{
final MethodHandle target = MethodHandles.lookup().findStatic(Main.class,
"filterReturnValue_target", MethodType.methodType(String.class, int.class));
final MethodHandle filter = MethodHandles.lookup().findStatic(Main.class,
"filterReturnValue_filter", MethodType.methodType(boolean.class, String.class));
MethodHandle adapter = MethodHandles.filterReturnValue(target, filter);
boolean value = (boolean) adapter.invoke((int) 42);
if (!value) {
fail("Unexpected value: " + value);
}
value = (boolean) adapter.invoke((int) 43);
if (value) {
fail("Unexpected value: " + value);
}
}
// A target that returns a primitive.
{
final MethodHandle target = MethodHandles.lookup().findStatic(Main.class,
"filterReturnValue_intTarget", MethodType.methodType(int.class, String.class));
final MethodHandle filter = MethodHandles.lookup().findStatic(Main.class,
"filterReturnValue_intFilter", MethodType.methodType(int.class, int.class));
MethodHandle adapter = MethodHandles.filterReturnValue(target, filter);
int value = (int) adapter.invoke("56");
if (value != 57) {
fail("Unexpected value: " + value);
}
}
// A target that returns void.
{
final MethodHandle target = MethodHandles.lookup().findStatic(Main.class,
"filterReturnValue_voidTarget", MethodType.methodType(void.class));
final MethodHandle filter = MethodHandles.lookup().findStatic(Main.class,
"filterReturnValue_voidFilter", MethodType.methodType(int.class));
MethodHandle adapter = MethodHandles.filterReturnValue(target, filter);
int value = (int) adapter.invoke();
if (value != 42) {
fail("Unexpected value: " + value);
}
}
}
public static void permuteArguments_callee(boolean a, byte b, char c,
short d, int e, long f, float g, double h) {
if (a == true && b == (byte) 'b' && c == 'c' && d == (short) 56 &&
e == 78 && f == (long) 97 && g == 98.0f && f == 97.0) {
return;
}
fail("Unexpected arguments: " + a + ", " + b + ", " + c
+ ", " + d + ", " + e + ", " + f + ", " + g + ", " + h);
}
public static void permuteArguments_boxingCallee(boolean a, Integer b) {
if (a && b.intValue() == 42) {
return;
}
fail("Unexpected arguments: " + a + ", " + b);
}
public static void testPermuteArguments() throws Throwable {
{
final MethodHandle target = MethodHandles.lookup().findStatic(
Main.class, "permuteArguments_callee",
MethodType.methodType(void.class, new Class<?>[] {
boolean.class, byte.class, char.class, short.class, int.class,
long.class, float.class, double.class }));
final MethodType newType = MethodType.methodType(void.class, new Class<?>[] {
double.class, float.class, long.class, int.class, short.class, char.class,
byte.class, boolean.class });
final MethodHandle permutation = MethodHandles.permuteArguments(
target, newType, new int[] { 7, 6, 5, 4, 3, 2, 1, 0 });
permutation.invoke((double) 97.0, (float) 98.0f, (long) 97, 78,
(short) 56, 'c', (byte) 'b', (boolean) true);
// The permutation array was not of the right length.
try {
MethodHandles.permuteArguments(target, newType,
new int[] { 7 });
fail();
} catch (IllegalArgumentException expected) {
}
// The permutation array has an element that's out of bounds
// (there's no argument with idx == 8).
try {
MethodHandles.permuteArguments(target, newType,
new int[] { 8, 6, 5, 4, 3, 2, 1, 0 });
fail();
} catch (IllegalArgumentException expected) {
}
// The permutation array maps to an incorrect type.
try {
MethodHandles.permuteArguments(target, newType,
new int[] { 7, 7, 5, 4, 3, 2, 1, 0 });
fail();
} catch (IllegalArgumentException expected) {
}
}
// Tests for reference arguments as well as permutations that
// repeat arguments.
{
final MethodHandle target = MethodHandles.lookup().findVirtual(
String.class, "concat", MethodType.methodType(String.class, String.class));
final MethodType newType = MethodType.methodType(String.class, String.class,
String.class);
assertEquals("foobar", (String) target.invoke("foo", "bar"));
MethodHandle permutation = MethodHandles.permuteArguments(target,
newType, new int[] { 1, 0 });
assertEquals("barfoo", (String) permutation.invoke("foo", "bar"));
permutation = MethodHandles.permuteArguments(target, newType, new int[] { 0, 0 });
assertEquals("foofoo", (String) permutation.invoke("foo", "bar"));
permutation = MethodHandles.permuteArguments(target, newType, new int[] { 1, 1 });
assertEquals("barbar", (String) permutation.invoke("foo", "bar"));
}
// Tests for boxing and unboxing.
{
final MethodHandle target = MethodHandles.lookup().findStatic(
Main.class, "permuteArguments_boxingCallee",
MethodType.methodType(void.class, new Class<?>[] { boolean.class, Integer.class }));
final MethodType newType = MethodType.methodType(void.class,
new Class<?>[] { Integer.class, boolean.class });
MethodHandle permutation = MethodHandles.permuteArguments(target,
newType, new int[] { 1, 0 });
permutation.invoke(42, true);
permutation.invoke(42, Boolean.TRUE);
permutation.invoke(Integer.valueOf(42), true);
permutation.invoke(Integer.valueOf(42), Boolean.TRUE);
}
}
private static Object returnBar() {
return "bar";
}
public static void testInvokers() throws Throwable {
final MethodType targetType = MethodType.methodType(String.class, String.class);
final MethodHandle target = MethodHandles.lookup().findVirtual(
String.class, "concat", targetType);
MethodHandle invoker = MethodHandles.invoker(target.type());
assertEquals("barbar", (String) invoker.invoke(target, "bar", "bar"));
assertEquals("barbar", (String) invoker.invoke(target, (Object) returnBar(), "bar"));
try {
String foo = (String) invoker.invoke(target, "bar", "bar", 24);
fail();
} catch (WrongMethodTypeException expected) {
}
MethodHandle exactInvoker = MethodHandles.exactInvoker(target.type());
assertEquals("barbar", (String) exactInvoker.invoke(target, "bar", "bar"));
try {
String foo = (String) exactInvoker.invoke(target, (Object) returnBar(), "bar");
fail();
} catch (WrongMethodTypeException expected) {
}
try {
String foo = (String) exactInvoker.invoke(target, "bar", "bar", 24);
fail();
} catch (WrongMethodTypeException expected) {
}
}
public static int spreadReferences(String a, String b, String c) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c);
return 42;
}
public static int spreadReferences_Unbox(String a, int b) {
System.out.println("a: " + a + ", b:" + b);
return 43;
}
public static void testSpreaders_reference() throws Throwable {
MethodType methodType = MethodType.methodType(int.class,
new Class<?>[] { String.class, String.class, String.class });
MethodHandle delegate = MethodHandles.lookup().findStatic(
Main.class, "spreadReferences", methodType);
// Basic checks on array lengths.
//
// Array size = 0
MethodHandle mhAsSpreader = delegate.asSpreader(String[].class, 0);
int ret = (int) mhAsSpreader.invoke("a", "b", "c", new String[] {});
assertEquals(42, ret);
// Array size = 1
mhAsSpreader = delegate.asSpreader(String[].class, 1);
ret = (int) mhAsSpreader.invoke("a", "b", new String[] { "c" });
assertEquals(42, ret);
// Array size = 2
mhAsSpreader = delegate.asSpreader(String[].class, 2);
ret = (int) mhAsSpreader.invoke("a", new String[] { "b", "c" });
assertEquals(42, ret);
// Array size = 3
mhAsSpreader = delegate.asSpreader(String[].class, 3);
ret = (int) mhAsSpreader.invoke(new String[] { "a", "b", "c"});
assertEquals(42, ret);
// Exception case, array size = 4 is illegal.
try {
delegate.asSpreader(String[].class, 4);
fail();
} catch (IllegalArgumentException expected) {
}
// Exception case, calling with an arg of the wrong size.
// Array size = 3
mhAsSpreader = delegate.asSpreader(String[].class, 3);
try {
ret = (int) mhAsSpreader.invoke(new String[] { "a", "b"});
} catch (IllegalArgumentException expected) {
}
// Various other hijinks, pass as Object[] arrays, Object etc.
mhAsSpreader = delegate.asSpreader(Object[].class, 2);
ret = (int) mhAsSpreader.invoke("a", new String[] { "b", "c" });
assertEquals(42, ret);
mhAsSpreader = delegate.asSpreader(Object[].class, 2);
ret = (int) mhAsSpreader.invoke("a", new Object[] { "b", "c" });
assertEquals(42, ret);
mhAsSpreader = delegate.asSpreader(Object[].class, 2);
ret = (int) mhAsSpreader.invoke("a", (Object) new Object[] { "b", "c" });
assertEquals(42, ret);
// Test implicit unboxing.
MethodType methodType2 = MethodType.methodType(int.class,
new Class<?>[] { String.class, int.class });
MethodHandle delegate2 = MethodHandles.lookup().findStatic(
Main.class, "spreadReferences_Unbox", methodType2);
// .. with an Integer[] array.
mhAsSpreader = delegate2.asSpreader(Integer[].class, 1);
ret = (int) mhAsSpreader.invoke("a", new Integer[] { 43 });
assertEquals(43, ret);
// .. with an Integer[] array declared as an Object[] argument type.
mhAsSpreader = delegate2.asSpreader(Object[].class, 1);
ret = (int) mhAsSpreader.invoke("a", new Integer[] { 43 });
assertEquals(43, ret);
// .. with an Object[] array.
mhAsSpreader = delegate2.asSpreader(Object[].class, 1);
ret = (int) mhAsSpreader.invoke("a", new Object[] { Integer.valueOf(43)});
assertEquals(43, ret);
// -- Part 2--
// Run a subset of these tests on MethodHandles.spreadInvoker, which only accepts
// a trailing argument type of Object[].
MethodHandle spreadInvoker = MethodHandles.spreadInvoker(methodType2, 1);
ret = (int) spreadInvoker.invoke(delegate2, "a", new Object[] { Integer.valueOf(43)});
assertEquals(43, ret);
ret = (int) spreadInvoker.invoke(delegate2, "a", new Integer[] { 43 });
assertEquals(43, ret);
// NOTE: Annoyingly, the second argument here is leadingArgCount and not
// arrayLength.
spreadInvoker = MethodHandles.spreadInvoker(methodType, 3);
ret = (int) spreadInvoker.invoke(delegate, "a", "b", "c", new String[] {});
assertEquals(42, ret);
spreadInvoker = MethodHandles.spreadInvoker(methodType, 0);
ret = (int) spreadInvoker.invoke(delegate, new String[] { "a", "b", "c" });
assertEquals(42, ret);
// Exact invokes: Double check that the expected parameter type is
// Object[] and not T[].
try {
spreadInvoker.invokeExact(delegate, new String[] { "a", "b", "c" });
fail();
} catch (WrongMethodTypeException expected) {
}
ret = (int) spreadInvoker.invoke(delegate, new Object[] { "a", "b", "c" });
assertEquals(42, ret);
}
public static int spreadBoolean(String a, Boolean b, boolean c) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c);
return 44;
}
public static int spreadByte(String a, Byte b, byte c,
short d, int e, long f, float g, double h) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c +
", d: " + d + ", e: " + e + ", f:" + f + ", g: " + g +
", h: " + h);
return 45;
}
public static int spreadChar(String a, Character b, char c,
int d, long e, float f, double g) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c +
", d: " + d + ", e: " + e + ", f:" + f + ", g: " + g);
return 46;
}
public static int spreadShort(String a, Short b, short c,
int d, long e, float f, double g) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c +
", d: " + d + ", e: " + e + ", f:" + f + ", g:" + g);
return 47;
}
public static int spreadInt(String a, Integer b, int c,
long d, float e, double f) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c +
", d: " + d + ", e: " + e + ", f:" + f);
return 48;
}
public static int spreadLong(String a, Long b, long c, float d, double e) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c +
", d: " + d + ", e: " + e);
return 49;
}
public static int spreadFloat(String a, Float b, float c, double d) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c + ", d: " + d);
return 50;
}
public static int spreadDouble(String a, Double b, double c) {
System.out.println("a: " + a + ", b:" + b + ", c: " + c);
return 51;
}
public static void testSpreaders_primitive() throws Throwable {
// boolean[]
// ---------------------
MethodType type = MethodType.methodType(int.class,
new Class<?>[] { String.class, Boolean.class, boolean.class });
MethodHandle delegate = MethodHandles.lookup().findStatic(
Main.class, "spreadBoolean", type);
MethodHandle spreader = delegate.asSpreader(boolean[].class, 2);
int ret = (int) spreader.invokeExact("a", new boolean[] { true, false });
assertEquals(44, ret);
ret = (int) spreader.invoke("a", new boolean[] { true, false });
assertEquals(44, ret);
// boolean can't be cast to String (the first argument to the method).
try {
delegate.asSpreader(boolean[].class, 3);
fail();
} catch (WrongMethodTypeException expected) {
}
// int can't be cast to boolean to supply the last argument to the method.
try {
delegate.asSpreader(int[].class, 1);
fail();
} catch (WrongMethodTypeException expected) {
}
// byte[]
// ---------------------
type = MethodType.methodType(int.class,
new Class<?>[] {
String.class, Byte.class, byte.class,
short.class, int.class, long.class,
float.class, double.class });
delegate = MethodHandles.lookup().findStatic(Main.class, "spreadByte", type);
spreader = delegate.asSpreader(byte[].class, 7);
ret = (int) spreader.invokeExact("a",
new byte[] { 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7 });
assertEquals(45, ret);
ret = (int) spreader.invoke("a",
new byte[] { 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7 });
assertEquals(45, ret);
// char[]
// ---------------------
type = MethodType.methodType(int.class,
new Class<?>[] {
String.class, Character.class,char.class,
int.class, long.class, float.class, double.class });
delegate = MethodHandles.lookup().findStatic(Main.class, "spreadChar", type);
spreader = delegate.asSpreader(char[].class, 6);
ret = (int) spreader.invokeExact("a",
new char[] { '1', '2', '3', '4', '5', '6' });
assertEquals(46, ret);
ret = (int) spreader.invokeExact("a",
new char[] { '1', '2', '3', '4', '5', '6' });
assertEquals(46, ret);
// short[]
// ---------------------
type = MethodType.methodType(int.class,
new Class<?>[] {
String.class, Short.class, short.class,
int.class, long.class, float.class, double.class });
delegate = MethodHandles.lookup().findStatic(Main.class, "spreadShort", type);
spreader = delegate.asSpreader(short[].class, 6);
ret = (int) spreader.invokeExact("a",
new short[] { 0x1, 0x2, 0x3, 0x4, 0x5, 0x6 });
assertEquals(47, ret);
ret = (int) spreader.invoke("a",
new short[] { 0x1, 0x2, 0x3, 0x4, 0x5, 0x6 });
assertEquals(47, ret);
// int[]
// ---------------------
type = MethodType.methodType(int.class,
new Class<?>[] {
String.class, Integer.class, int.class,
long.class, float.class, double.class });
delegate = MethodHandles.lookup().findStatic(Main.class, "spreadInt", type);
spreader = delegate.asSpreader(int[].class, 5);
ret = (int) spreader.invokeExact("a", new int[] { 1, 2, 3, 4, 5 });
assertEquals(48, ret);
ret = (int) spreader.invokeExact("a", new int[] { 1, 2, 3, 4, 5 });
assertEquals(48, ret);
// long[]
// ---------------------
type = MethodType.methodType(int.class,
new Class<?>[] {
String.class, Long.class, long.class, float.class, double.class });
delegate = MethodHandles.lookup().findStatic(Main.class, "spreadLong", type);
spreader = delegate.asSpreader(long[].class, 4);
ret = (int) spreader.invokeExact("a",
new long[] { 0x1, 0x2, 0x3, 0x4 });
assertEquals(49, ret);
ret = (int) spreader.invoke("a",
new long[] { 0x1, 0x2, 0x3, 0x4 });
assertEquals(49, ret);
// float[]
// ---------------------
type = MethodType.methodType(int.class,
new Class<?>[] {
String.class, Float.class, float.class, double.class });
delegate = MethodHandles.lookup().findStatic(Main.class, "spreadFloat", type);
spreader = delegate.asSpreader(float[].class, 3);
ret = (int) spreader.invokeExact("a",
new float[] { 1.0f, 2.0f, 3.0f });
assertEquals(50, ret);
ret = (int) spreader.invokeExact("a",
new float[] { 1.0f, 2.0f, 3.0f });
assertEquals(50, ret);
// double[]
// ---------------------
type = MethodType.methodType(int.class,
new Class<?>[] { String.class, Double.class, double.class });
delegate = MethodHandles.lookup().findStatic(Main.class, "spreadDouble", type);
spreader = delegate.asSpreader(double[].class, 2);
ret = (int) spreader.invokeExact("a", new double[] { 1.0, 2.0 });
assertEquals(51, ret);
ret = (int) spreader.invokeExact("a", new double[] { 1.0, 2.0 });
assertEquals(51, ret);
}
public static void testInvokeWithArguments() throws Throwable {
MethodType methodType = MethodType.methodType(int.class,
new Class<?>[] { String.class, String.class, String.class });
MethodHandle handle = MethodHandles.lookup().findStatic(
Main.class, "spreadReferences", methodType);
Object ret = handle.invokeWithArguments(new Object[] { "a", "b", "c"});
assertEquals(42, (int) ret);
handle.invokeWithArguments(new String[] { "a", "b", "c" });
assertEquals(42, (int) ret);
// Pass in an array that's too small. Should throw an IAE.
try {
handle.invokeWithArguments(new Object[] { "a", "b" });
fail();
} catch (IllegalArgumentException expected) {
} catch (WrongMethodTypeException expected) {
}
// Test implicit unboxing.
MethodType methodType2 = MethodType.methodType(int.class,
new Class<?>[] { String.class, int.class });
MethodHandle handle2 = MethodHandles.lookup().findStatic(
Main.class, "spreadReferences_Unbox", methodType2);
ret = (int) handle2.invokeWithArguments(new Object[] { "a", 43 });
assertEquals(43, (int) ret);
}
public static int collectBoolean(String a, boolean[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 44;
}
public static int collectByte(String a, byte[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 45;
}
public static int collectChar(String a, char[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 46;
}
public static int collectShort(String a, short[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 47;
}
public static int collectInt(String a, int[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 48;
}
public static int collectLong(String a, long[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 49;
}
public static int collectFloat(String a, float[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 50;
}
public static int collectDouble(String a, double[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 51;
}
public static int collectCharSequence(String a, CharSequence[] b) {
System.out.println("a: " + a + ", b:" + b[0] + ", c: " + b[1]);
return 99;
}
public static void testAsCollector() throws Throwable {
// Reference arrays.
// -------------------
MethodHandle trailingRef = MethodHandles.lookup().findStatic(
Main.class, "collectCharSequence",
MethodType.methodType(int.class, String.class, CharSequence[].class));
// int[] is not convertible to CharSequence[].class.
try {
trailingRef.asCollector(int[].class, 1);
fail();
} catch (IllegalArgumentException expected) {
}
// Object[] is not convertible to CharSequence[].class.
try {
trailingRef.asCollector(Object[].class, 1);
fail();
} catch (IllegalArgumentException expected) {
}
// String[].class is convertible to CharSequence.class
MethodHandle collector = trailingRef.asCollector(String[].class, 2);
assertEquals(99, (int) collector.invoke("a", "b", "c"));
// Too few arguments should fail with a WMTE.
try {
collector.invoke("a", "b");
fail();
} catch (WrongMethodTypeException expected) {
}
// Too many arguments should fail with a WMTE.
try {
collector.invoke("a", "b", "c", "d");
fail();
} catch (WrongMethodTypeException expected) {
}
// Sanity checks on other array types.
MethodHandle target = MethodHandles.lookup().findStatic(
Main.class, "collectBoolean",
MethodType.methodType(int.class, String.class, boolean[].class));
assertEquals(44, (int) target.asCollector(boolean[].class, 2).invoke("a", true, false));
target = MethodHandles.lookup().findStatic(Main.class, "collectByte",
MethodType.methodType(int.class, String.class, byte[].class));
assertEquals(45, (int) target.asCollector(byte[].class, 2).invoke("a", (byte) 1, (byte) 2));
target = MethodHandles.lookup().findStatic(Main.class, "collectChar",
MethodType.methodType(int.class, String.class, char[].class));
assertEquals(46, (int) target.asCollector(char[].class, 2).invoke("a", 'a', 'b'));
target = MethodHandles.lookup().findStatic(Main.class, "collectShort",
MethodType.methodType(int.class, String.class, short[].class));
assertEquals(47, (int) target.asCollector(short[].class, 2).invoke("a", (short) 3, (short) 4));
target = MethodHandles.lookup().findStatic(Main.class, "collectInt",
MethodType.methodType(int.class, String.class, int[].class));
assertEquals(48, (int) target.asCollector(int[].class, 2).invoke("a", 42, 43));
target = MethodHandles.lookup().findStatic(Main.class, "collectLong",
MethodType.methodType(int.class, String.class, long[].class));
assertEquals(49, (int) target.asCollector(long[].class, 2).invoke("a", 100, 99));
target = MethodHandles.lookup().findStatic(Main.class, "collectFloat",
MethodType.methodType(int.class, String.class, float[].class));
assertEquals(50, (int) target.asCollector(float[].class, 2).invoke("a", 8.9f, 9.1f));
target = MethodHandles.lookup().findStatic(Main.class, "collectDouble",
MethodType.methodType(int.class, String.class, double[].class));
assertEquals(51, (int) target.asCollector(double[].class, 2).invoke("a", 6.7, 7.8));
}
public static String filter1(char a) {
return String.valueOf(a);
}
public static char filter2(String b) {
return b.charAt(0);
}
public static String badFilter1(char a, char b) {
return "bad";
}
public static int filterTarget(String a, char b, String c, char d) {
System.out.println("a: " + a + ", b: " + b + ", c:" + c + ", d:" + d);
return 56;
}
public static void testFilterArguments() throws Throwable {
MethodHandle filter1 = MethodHandles.lookup().findStatic(
Main.class, "filter1", MethodType.methodType(String.class, char.class));
MethodHandle filter2 = MethodHandles.lookup().findStatic(
Main.class, "filter2", MethodType.methodType(char.class, String.class));
MethodHandle target = MethodHandles.lookup().findStatic(
Main.class, "filterTarget", MethodType.methodType(int.class,
String.class, char.class, String.class, char.class));
// In all the cases below, the values printed will be 'a', 'b', 'c', 'd'.
// Filter arguments [0, 1] - all other arguments are passed through
// as is.
MethodHandle adapter = MethodHandles.filterArguments(
target, 0, filter1, filter2);
assertEquals(56, (int) adapter.invokeExact('a', "bXXXX", "c", 'd'));
// Filter arguments [1, 2].
adapter = MethodHandles.filterArguments(target, 1, filter2, filter1);
assertEquals(56, (int) adapter.invokeExact("a", "bXXXX", 'c', 'd'));
// Filter arguments [2, 3].
adapter = MethodHandles.filterArguments(target, 2, filter1, filter2);
assertEquals(56, (int) adapter.invokeExact("a", 'b', 'c', "dXXXXX"));
// Try out a few error cases :
// The return types of the filter doesn't align with the expected argument
// type of the target.
try {
adapter = MethodHandles.filterArguments(target, 2, filter2, filter1);
fail();
} catch (IllegalArgumentException expected) {
}
// There are more filters than arguments.
try {
adapter = MethodHandles.filterArguments(target, 3, filter2, filter1);
fail();
} catch (IllegalArgumentException expected) {
}
// We pass in an obviously bogus position.
try {
adapter = MethodHandles.filterArguments(target, -1, filter2, filter1);
fail();
} catch (ArrayIndexOutOfBoundsException expected) {
}
// We pass in a function that has more than one argument.
MethodHandle badFilter1 = MethodHandles.lookup().findStatic(
Main.class, "badFilter1",
MethodType.methodType(String.class, char.class, char.class));
try {
adapter = MethodHandles.filterArguments(target, 0, badFilter1, filter2);
fail();
} catch (IllegalArgumentException expected) {
}
}
static void voidFilter(char a, char b) {
System.out.println("voidFilter");
}
static String filter(char a, char b) {
return String.valueOf(a) + "+" + b;
}
static char badFilter(char a, char b) {
return 0;
}
static int target(String a, String b, String c) {
System.out.println("a: " + a + ", b: " + b + ", c: " + c);
return 57;
}
public static void testCollectArguments() throws Throwable {
// Test non-void filters.
MethodHandle filter = MethodHandles.lookup().findStatic(
Main.class, "filter",
MethodType.methodType(String.class, char.class, char.class));
MethodHandle target = MethodHandles.lookup().findStatic(
Main.class, "target",
MethodType.methodType(int.class, String.class, String.class, String.class));
// Filter at position 0.
MethodHandle adapter = MethodHandles.collectArguments(target, 0, filter);
assertEquals(57, (int) adapter.invokeExact('a', 'b', "c", "d"));
// Filter at position 1.
adapter = MethodHandles.collectArguments(target, 1, filter);
assertEquals(57, (int) adapter.invokeExact("a", 'b', 'c', "d"));
// Filter at position 2.
adapter = MethodHandles.collectArguments(target, 2, filter);
assertEquals(57, (int) adapter.invokeExact("a", "b", 'c', 'd'));
// Test void filters. Note that we're passing in one more argument
// than usual because the filter returns nothing - we have to invoke with
// the full set of filter args and the full set of target args.
filter = MethodHandles.lookup().findStatic(Main.class, "voidFilter",
MethodType.methodType(void.class, char.class, char.class));
adapter = MethodHandles.collectArguments(target, 0, filter);
assertEquals(57, (int) adapter.invokeExact('a', 'b', "a", "b", "c"));
adapter = MethodHandles.collectArguments(target, 1, filter);
assertEquals(57, (int) adapter.invokeExact("a", 'a', 'b', "b", "c"));
// Test out a few failure cases.
filter = MethodHandles.lookup().findStatic(
Main.class, "filter",
MethodType.methodType(String.class, char.class, char.class));
// Bogus filter position.
try {
adapter = MethodHandles.collectArguments(target, 3, filter);
fail();
} catch (IndexOutOfBoundsException expected) {
}
// Mismatch in filter return type.
filter = MethodHandles.lookup().findStatic(
Main.class, "badFilter",
MethodType.methodType(char.class, char.class, char.class));
try {
adapter = MethodHandles.collectArguments(target, 0, filter);
fail();
} catch (IllegalArgumentException expected) {
}
}
static int insertReceiver(String a, int b, Integer c, String d) {
System.out.println("a: " + a + ", b:" + b + ", c:" + c + ", d:" + d);
return 73;
}
public static void testInsertArguments() throws Throwable {
MethodHandle target = MethodHandles.lookup().findStatic(
Main.class, "insertReceiver",
MethodType.methodType(int.class,
String.class, int.class, Integer.class, String.class));
// Basic single element array inserted at position 0.
MethodHandle adapter = MethodHandles.insertArguments(
target, 0, new Object[] { "foo" });
assertEquals(73, (int) adapter.invokeExact(45, Integer.valueOf(56), "bar"));
// Exercise unboxing.
adapter = MethodHandles.insertArguments(
target, 1, new Object[] { Integer.valueOf(56), 57 });
assertEquals(73, (int) adapter.invokeExact("foo", "bar"));
// Exercise a widening conversion.
adapter = MethodHandles.insertArguments(
target, 1, new Object[] { (short) 56, Integer.valueOf(57) });
assertEquals(73, (int) adapter.invokeExact("foo", "bar"));
// Insert an argument at the last position.
adapter = MethodHandles.insertArguments(
target, 3, new Object[] { "bar" });
assertEquals(73, (int) adapter.invokeExact("foo", 45, Integer.valueOf(46)));
// Exercise a few error cases.
// A reference type that can't be cast to another reference type.
try {
MethodHandles.insertArguments(target, 3, new Object[] { new Object() });
fail();
} catch (ClassCastException expected) {
}
// A boxed type that can't be unboxed correctly.
try {
MethodHandles.insertArguments(target, 1, new Object[] { Long.valueOf(56) });
fail();
} catch (ClassCastException expected) {
}
}
public static String foldFilter(char a, char b) {
return String.valueOf(a) + "+" + b;
}
public static void voidFoldFilter(String e, char a, char b) {
System.out.println(String.valueOf(a) + "+" + b);
}
public static int foldTarget(String a, char b, char c, String d) {
System.out.println("a: " + a + " ,b:" + b + " ,c:" + c + " ,d:" + d);
return 89;
}
public static void mismatchedVoidFilter(Integer a) {
}
public static Integer mismatchedNonVoidFilter(char a, char b) {
return null;
}
public static void testFoldArguments() throws Throwable {
// Test non-void filters.
MethodHandle filter = MethodHandles.lookup().findStatic(
Main.class, "foldFilter",
MethodType.methodType(String.class, char.class, char.class));
MethodHandle target = MethodHandles.lookup().findStatic(
Main.class, "foldTarget",
MethodType.methodType(int.class, String.class,
char.class, char.class, String.class));
// Folder with a non-void type.
MethodHandle adapter = MethodHandles.foldArguments(target, filter);
assertEquals(89, (int) adapter.invokeExact('c', 'd', "e"));
// Folder with a void type.
filter = MethodHandles.lookup().findStatic(
Main.class, "voidFoldFilter",
MethodType.methodType(void.class, String.class, char.class, char.class));
adapter = MethodHandles.foldArguments(target, filter);
assertEquals(89, (int) adapter.invokeExact("a", 'c', 'd', "e"));
// Test a few erroneous cases.
filter = MethodHandles.lookup().findStatic(
Main.class, "mismatchedVoidFilter",
MethodType.methodType(void.class, Integer.class));
try {
adapter = MethodHandles.foldArguments(target, filter);
fail();
} catch (IllegalArgumentException expected) {
}
filter = MethodHandles.lookup().findStatic(
Main.class, "mismatchedNonVoidFilter",
MethodType.methodType(Integer.class, char.class, char.class));
try {
adapter = MethodHandles.foldArguments(target, filter);
fail();
} catch (IllegalArgumentException expected) {
}
}
public static void fail() {
System.out.println("FAIL");
Thread.dumpStack();
}
public static void fail(String message) {
System.out.println("fail: " + message);
Thread.dumpStack();
}
public static void assertEquals(int i1, int i2) {
if (i1 != i2) throw new AssertionError("Expected: " + i1 + " was " + i2);
}
public static void assertEquals(String s1, String s2) {
if (s1 == s2) {
return;
}
if (s1 != null && s2 != null && s1.equals(s2)) {
return;
}
throw new AssertionError("assertEquals s1: " + s1 + ", s2: " + s2);
}
}