-DJavaDocExamplesTest.verbosity=1 \

    public static void main(String... ignore) throws Throwable {

        System.out.println("can run this as:");

        System.out.println("$ java org.junit.runner.JUnitCore "+JavaDocExamplesTest.class.getName());

        new JavaDocExamplesTest().run();

    }

    public void run() throws Throwable {

        testFindVirtual();

        testPermuteArguments();

        testDropArguments();

        testFilterArguments();

        testFoldArguments();

        testMethodHandlesSummary();

        testAsSpreader();

        testAsCollector();

        testAsVarargsCollector();

        testAsFixedArity();

        testAsTypeCornerCases();

        testMutableCallSite();

    static final Class<?> THIS_CLASS = JavaDocExamplesTest.class;

    static int verbosity = Integer.getInteger(THIS_CLASS.getSimpleName()+".verbosity", 0);

    static final private MethodHandle CONCAT_2, HASHCODE_2, ADD_2, SUB_2;

    Class<?> THIS_CLASS = LOOKUP.lookupClass();

    ADD_2 = LOOKUP.findStatic(THIS_CLASS, "add", methodType(int.class, int.class, int.class));

    SUB_2 = LOOKUP.findStatic(THIS_CLASS, "sub", methodType(int.class, int.class, int.class));

    static int add(int x, int y) { return x + y; }

    static int sub(int x, int y) { return x - y; }

    @Test public void testPermuteArguments() throws Throwable {

        {{

{} /// JAVADOC

MethodType intfn1 = methodType(int.class, int.class);

MethodType intfn2 = methodType(int.class, int.class, int.class);

MethodHandle sub = SUB_2;// ... {int x, int y => x-y} ...;

assert(sub.type().equals(intfn2));

MethodHandle sub1 = permuteArguments(sub, intfn2, 0, 1);

MethodHandle rsub = permuteArguments(sub, intfn2, 1, 0);

assert((int)rsub.invokeExact(1, 100) == 99);

MethodHandle add = ADD_2;// ... {int x, int y => x+y} ...;

assert(add.type().equals(intfn2));

MethodHandle twice = permuteArguments(add, intfn1, 0, 0);

assert(twice.type().equals(intfn1));

assert((int)twice.invokeExact(21) == 42);

            }}

        {{

{} /// JAVADOC

MethodHandle cat = lookup().findVirtual(String.class,

  "concat", methodType(String.class, String.class));

assertEquals("xy", (String) cat.invokeExact("x", "y"));

MethodHandle d0 = dropArguments(cat, 0, String.class);

assertEquals("yz", (String) d0.invokeExact("x", "y", "z"));

MethodHandle d1 = dropArguments(cat, 1, String.class);

assertEquals("xz", (String) d1.invokeExact("x", "y", "z"));

MethodHandle d2 = dropArguments(cat, 2, String.class);

assertEquals("xy", (String) d2.invokeExact("x", "y", "z"));

MethodHandle d12 = dropArguments(cat, 1, int.class, boolean.class);

assertEquals("xz", (String) d12.invokeExact("x", 12, true, "z"));

            }}

    }

    @Test public void testFoldArguments() throws Throwable {

        {{

{} /// JAVADOC

MethodHandle trace = publicLookup().findVirtual(java.io.PrintStream.class,

  "println", methodType(void.class, String.class))

    .bindTo(System.out);

MethodHandle cat = lookup().findVirtual(String.class,

  "concat", methodType(String.class, String.class));

assertEquals("boojum", (String) cat.invokeExact("boo", "jum"));

MethodHandle catTrace = foldArguments(cat, trace);

// also prints "boo":

assertEquals("boojum", (String) catTrace.invokeExact("boo", "jum"));

            }}

    }

assertEquals(s, "nanny");

assertEquals(s, "savvy");

assertEquals(x, java.util.Arrays.asList("one","two"));

assertEquals(x, java.util.Arrays.asList(1,2,3));

// mt is ()int

    @Test public void testAsSpreader() throws Throwable {

        {{

{} /// JAVADOC

MethodHandle equals = publicLookup()

  .findVirtual(String.class, "equals", methodType(boolean.class, Object.class));

assert( (boolean) equals.invokeExact("me", (Object)"me"));

assert(!(boolean) equals.invokeExact("me", (Object)"thee"));

// spread both arguments from a 2-array:

MethodHandle eq2 = equals.asSpreader(Object[].class, 2);

assert( (boolean) eq2.invokeExact(new Object[]{ "me", "me" }));

assert(!(boolean) eq2.invokeExact(new Object[]{ "me", "thee" }));

// spread both arguments from a String array:

MethodHandle eq2s = equals.asSpreader(String[].class, 2);

assert( (boolean) eq2s.invokeExact(new String[]{ "me", "me" }));

assert(!(boolean) eq2s.invokeExact(new String[]{ "me", "thee" }));

// spread second arguments from a 1-array:

MethodHandle eq1 = equals.asSpreader(Object[].class, 1);

assert( (boolean) eq1.invokeExact("me", new Object[]{ "me" }));

assert(!(boolean) eq1.invokeExact("me", new Object[]{ "thee" }));

// spread no arguments from a 0-array or null:

MethodHandle eq0 = equals.asSpreader(Object[].class, 0);

assert( (boolean) eq0.invokeExact("me", (Object)"me", new Object[0]));

assert(!(boolean) eq0.invokeExact("me", (Object)"thee", (Object[])null));

// asSpreader and asCollector are approximate inverses:

for (int n = 0; n <= 2; n++) {

    for (Class<?> a : new Class<?>[]{Object[].class, String[].class, CharSequence[].class}) {

        MethodHandle equals2 = equals.asSpreader(a, n).asCollector(a, n);

        assert( (boolean) equals2.invokeWithArguments("me", "me"));

        assert(!(boolean) equals2.invokeWithArguments("me", "thee"));

    }

}

MethodHandle caToString = publicLookup()

  .findStatic(Arrays.class, "toString", methodType(String.class, char[].class));

assertEquals("[A, B, C]", (String) caToString.invokeExact("ABC".toCharArray()));

MethodHandle caString3 = caToString.asCollector(char[].class, 3);

assertEquals("[A, B, C]", (String) caString3.invokeExact('A', 'B', 'C'));

MethodHandle caToString2 = caString3.asSpreader(char[].class, 2);

assertEquals("[A, B, C]", (String) caToString2.invokeExact('A', "BC".toCharArray()));

            }}

    }

    @Test public void testAsCollector() throws Throwable {

        {{

{} /// JAVADOC

MethodHandle deepToString = publicLookup()

  .findStatic(Arrays.class, "deepToString", methodType(String.class, Object[].class));

assertEquals("[won]",   (String) deepToString.invokeExact(new Object[]{"won"}));

MethodHandle ts1 = deepToString.asCollector(Object[].class, 1);

assertEquals(methodType(String.class, Object.class), ts1.type());

//assertEquals("[won]", (String) ts1.invokeExact(         new Object[]{"won"})); //FAIL

assertEquals("[[won]]", (String) ts1.invokeExact((Object) new Object[]{"won"}));

// arrayType can be a subtype of Object[]

MethodHandle ts2 = deepToString.asCollector(String[].class, 2);

assertEquals(methodType(String.class, String.class, String.class), ts2.type());

assertEquals("[two, too]", (String) ts2.invokeExact("two", "too"));

MethodHandle ts0 = deepToString.asCollector(Object[].class, 0);

assertEquals("[]", (String) ts0.invokeExact());

// collectors can be nested, Lisp-style

MethodHandle ts22 = deepToString.asCollector(Object[].class, 3).asCollector(String[].class, 2);

assertEquals("[A, B, [C, D]]", ((String) ts22.invokeExact((Object)'A', (Object)"B", "C", "D")));

// arrayType can be any primitive array type

MethodHandle bytesToString = publicLookup()

  .findStatic(Arrays.class, "toString", methodType(String.class, byte[].class))

  .asCollector(byte[].class, 3);

assertEquals("[1, 2, 3]", (String) bytesToString.invokeExact((byte)1, (byte)2, (byte)3));

MethodHandle longsToString = publicLookup()

  .findStatic(Arrays.class, "toString", methodType(String.class, long[].class))

  .asCollector(long[].class, 1);

assertEquals("[123]", (String) longsToString.invokeExact((long)123));

            }}

    }

MethodHandle deepToString = publicLookup()

  .findStatic(Arrays.class, "deepToString", methodType(String.class, Object[].class));

MethodHandle ts1 = deepToString.asVarargsCollector(Object[].class);

assertEquals("[won]",   (String) ts1.invokeExact(    new Object[]{"won"}));

assertEquals("[won]",   (String) ts1.invoke(         new Object[]{"won"}));

assertEquals("[won]",   (String) ts1.invoke(                      "won" ));

assertEquals("[[won]]", (String) ts1.invoke((Object) new Object[]{"won"}));

// findStatic of Arrays.asList(...) produces a variable arity method handle:

  .findStatic(Arrays.class, "asList", methodType(List.class, Object[].class));

assertEquals(methodType(List.class, Object[].class), asList.type());

assert(asList.isVarargsCollector());

String[] argv = { "three", "thee", "tee" };

assertEquals("[three, thee, tee]", asList.invoke((Object[])argv).toString());

    @Test public void testAsFixedArity() throws Throwable {

MethodHandle asListVar = publicLookup()

MethodHandle asListFix = asListVar.asFixedArity();

assertEquals("[1]", asListVar.invoke(1).toString());

Exception caught = null;

try { asListFix.invoke((Object)1); }

catch (Exception ex) { caught = ex; }

assert(caught instanceof ClassCastException);

assertEquals("[two, too]", asListVar.invoke("two", "too").toString());

try { asListFix.invoke("two", "too"); }

catch (Exception ex) { caught = ex; }

assert(caught instanceof WrongMethodTypeException);

Object[] argv = { "three", "thee", "tee" };

assertEquals("[three, thee, tee]", asListVar.invoke(argv).toString());

assertEquals("[three, thee, tee]", asListFix.invoke(argv).toString());

assertEquals(1, ((List) asListVar.invoke((Object)argv)).size());

assertEquals("[three, thee, tee]", asListFix.invoke((Object)argv).toString());

            }}

    }

    @Test public void testAsTypeCornerCases() throws Throwable {

        {{

{} /// JAVADOC

MethodHandle i2s = publicLookup()

  .findVirtual(Integer.class, "toString", methodType(String.class));

i2s = i2s.asType(i2s.type().unwrap());

MethodHandle l2s = publicLookup()

  .findVirtual(Long.class, "toString", methodType(String.class));

l2s = l2s.asType(l2s.type().unwrap());

Exception caught = null;

try { i2s.asType(methodType(String.class, String.class)); }

catch (Exception ex) { caught = ex; }

assert(caught instanceof WrongMethodTypeException);

i2s.asType(methodType(String.class, byte.class));

i2s.asType(methodType(String.class, Byte.class));

i2s.asType(methodType(String.class, Character.class));

i2s.asType(methodType(String.class, Integer.class));

l2s.asType(methodType(String.class, byte.class));

l2s.asType(methodType(String.class, Byte.class));

l2s.asType(methodType(String.class, Character.class));

l2s.asType(methodType(String.class, Integer.class));

l2s.asType(methodType(String.class, Long.class));

caught = null;

try { i2s.asType(methodType(String.class, Long.class)); }

catch (Exception ex) { caught = ex; }

assert(caught instanceof WrongMethodTypeException);

MethodHandle i2sGen = i2s.asType(methodType(String.class, Object.class));

MethodHandle l2sGen = l2s.asType(methodType(String.class, Object.class));

i2sGen.invoke(42);  // int -> Integer -> Object -> Integer -> int

i2sGen.invoke((byte)4);  // byte -> Byte -> Object -> Byte -> byte -> int

l2sGen.invoke(42);  // int -> Integer -> Object -> Integer -> int

l2sGen.invoke((byte)4);  // byte -> Byte -> Object -> Byte -> byte -> int

l2sGen.invoke(0x420000000L);

caught = null;

try { i2sGen.invoke(0x420000000L); } // long -> Long -> Object -> Integer CCE

catch (Exception ex) { caught = ex; }

assert(caught instanceof ClassCastException);

caught = null;

try { i2sGen.invoke("asdf"); } // String -> Object -> Integer CCE

catch (Exception ex) { caught = ex; }

assert(caught instanceof ClassCastException);

    @Test public void testMutableCallSite() throws Throwable {

        {{

{} /// JAVADOC

MutableCallSite name = new MutableCallSite(MethodType.methodType(String.class));

MethodHandle MH_name = name.dynamicInvoker();

MethodType MT_str1 = MethodType.methodType(String.class);

MethodHandle MH_upcase = MethodHandles.lookup()

    .findVirtual(String.class, "toUpperCase", MT_str1);

MethodHandle worker1 = MethodHandles.filterReturnValue(MH_name, MH_upcase);

name.setTarget(MethodHandles.constant(String.class, "Rocky"));

assertEquals("ROCKY", (String) worker1.invokeExact());

name.setTarget(MethodHandles.constant(String.class, "Fred"));

assertEquals("FRED", (String) worker1.invokeExact());

// (mutation can be continued indefinitely)

/*

 * </pre></blockquote>

 * <p>

 * The same call site may be used in several places at once.

 * <blockquote><pre>

 */

MethodType MT_str2 = MethodType.methodType(String.class, String.class);

MethodHandle MH_cat = lookup().findVirtual(String.class,

  "concat", methodType(String.class, String.class));

MethodHandle MH_dear = MethodHandles.insertArguments(MH_cat, 1, ", dear?");

MethodHandle worker2 = MethodHandles.filterReturnValue(MH_name, MH_dear);

assertEquals("Fred, dear?", (String) worker2.invokeExact());

name.setTarget(MethodHandles.constant(String.class, "Wilma"));

assertEquals("WILMA", (String) worker1.invokeExact());

assertEquals("Wilma, dear?", (String) worker2.invokeExact());

{}

            }}

    }

    @Test public void testSwitchPoint() throws Throwable {

        {{

{} /// JAVADOC

MethodHandle MH_strcat = MethodHandles.lookup()

    .findVirtual(String.class, "concat", MethodType.methodType(String.class, String.class));

SwitchPoint spt = new SwitchPoint();

assert(spt.isValid());

// the following steps may be repeated to re-use the same switch point:

MethodHandle worker1 = MH_strcat;

MethodHandle worker2 = MethodHandles.permuteArguments(MH_strcat, MH_strcat.type(), 1, 0);

MethodHandle worker = spt.guardWithTest(worker1, worker2);

assertEquals("method", (String) worker.invokeExact("met", "hod"));

SwitchPoint.invalidateAll(new SwitchPoint[]{ spt });

assert(!spt.isValid());

assertEquals("hodmet", (String) worker.invokeExact("met", "hod"));

{}

            }}

    }

    /* ---- TEMPLATE ----

    @Test public void testFoo() throws Throwable {

        {{