The JavaDocExamplesTest.java Java example source code
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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*/
/* @test
* @summary example code used in javadoc for java.lang.invoke API
* @compile JavaDocExamplesTest.java
* @run testng/othervm test.java.lang.invoke.JavaDocExamplesTest
*/
package test.java.lang.invoke;
import java.lang.invoke.*;
import static java.lang.invoke.MethodHandles.*;
import static java.lang.invoke.MethodType.*;
import java.util.*;
import org.testng.*;
import static org.testng.AssertJUnit.*;
import org.testng.annotations.*;
/**
* @author jrose
*/
public class JavaDocExamplesTest {
/** Wrapper for running the TestNG tests in this module.
* Put TestNG on the classpath!
*/
public static void main(String... ignore) throws Throwable {
new JavaDocExamplesTest().run();
}
public void run() throws Throwable {
testMisc();
testFindStatic();
testFindConstructor();
testFindVirtual();
testFindSpecial();
testPermuteArguments();
testDropArguments();
testFilterArguments();
testFoldArguments();
testFoldArguments2();
testMethodHandlesSummary();
testAsSpreader();
testAsCollector();
testAsVarargsCollector();
testAsFixedArity();
testAsTypeCornerCases();
testMutableCallSite();
}
// How much output?
static final Class<?> THIS_CLASS = JavaDocExamplesTest.class;
static int verbosity = Integer.getInteger(THIS_CLASS.getSimpleName()+".verbosity", 0);
{}
static final private Lookup LOOKUP = lookup();
// static final private MethodHandle CONCAT_1 = LOOKUP.findVirtual(String.class,
// "concat", methodType(String.class, String.class));
// static final private MethodHandle HASHCODE_1 = LOOKUP.findVirtual(Object.class,
// "hashCode", methodType(int.class));
// form required if ReflectiveOperationException is intercepted:
static final private MethodHandle CONCAT_2, HASHCODE_2, ADD_2, SUB_2;
static {
try {
Class<?> THIS_CLASS = LOOKUP.lookupClass();
CONCAT_2 = LOOKUP.findVirtual(String.class,
"concat", methodType(String.class, String.class));
HASHCODE_2 = LOOKUP.findVirtual(Object.class,
"hashCode", methodType(int.class));
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));
} catch (ReflectiveOperationException ex) {
throw new RuntimeException(ex);
}
}
static int add(int x, int y) { return x + y; }
static int sub(int x, int y) { return x - y; }
{}
@Test public void testMisc() throws Throwable {
// Extra tests, not from javadoc:
{}
MethodHandle CONCAT_3 = LOOKUP.findVirtual(String.class,
"concat", methodType(String.class, String.class));
MethodHandle HASHCODE_3 = LOOKUP.findVirtual(Object.class,
"hashCode", methodType(int.class));
//assertEquals("xy", (String) CONCAT_1.invokeExact("x", "y"));
assertEquals("xy", (String) CONCAT_2.invokeExact("x", "y"));
assertEquals("xy", (String) CONCAT_3.invokeExact("x", "y"));
//assertEquals("xy".hashCode(), (int) HASHCODE_1.invokeExact((Object)"xy"));
assertEquals("xy".hashCode(), (int) HASHCODE_2.invokeExact((Object)"xy"));
assertEquals("xy".hashCode(), (int) HASHCODE_3.invokeExact((Object)"xy"));
{}
}
@Test public void testFindStatic() throws Throwable {
{}
MethodHandle MH_asList = publicLookup().findStatic(Arrays.class,
"asList", methodType(List.class, Object[].class));
assertEquals("[x, y]", MH_asList.invoke("x", "y").toString());
{}
}
@Test public void testFindVirtual() throws Throwable {
{}
MethodHandle MH_concat = publicLookup().findVirtual(String.class,
"concat", methodType(String.class, String.class));
MethodHandle MH_hashCode = publicLookup().findVirtual(Object.class,
"hashCode", methodType(int.class));
MethodHandle MH_hashCode_String = publicLookup().findVirtual(String.class,
"hashCode", methodType(int.class));
assertEquals("xy", (String) MH_concat.invokeExact("x", "y"));
assertEquals("xy".hashCode(), (int) MH_hashCode.invokeExact((Object)"xy"));
assertEquals("xy".hashCode(), (int) MH_hashCode_String.invokeExact("xy"));
// interface method:
MethodHandle MH_subSequence = publicLookup().findVirtual(CharSequence.class,
"subSequence", methodType(CharSequence.class, int.class, int.class));
assertEquals("def", MH_subSequence.invoke("abcdefghi", 3, 6).toString());
// constructor "internal method" must be accessed differently:
MethodType MT_newString = methodType(void.class); //()V for new String()
try { assertEquals("impossible", lookup()
.findVirtual(String.class, "<init>", MT_newString));
} catch (NoSuchMethodException ex) { } // OK
MethodHandle MH_newString = publicLookup()
.findConstructor(String.class, MT_newString);
assertEquals("", (String) MH_newString.invokeExact());
{}
}
@Test public void testFindConstructor() throws Throwable {
{}
MethodHandle MH_newArrayList = publicLookup().findConstructor(
ArrayList.class, methodType(void.class, Collection.class));
Collection orig = Arrays.asList("x", "y");
Collection copy = (ArrayList) MH_newArrayList.invokeExact(orig);
assert(orig != copy);
assertEquals(orig, copy);
// a variable-arity constructor:
MethodHandle MH_newProcessBuilder = publicLookup().findConstructor(
ProcessBuilder.class, methodType(void.class, String[].class));
ProcessBuilder pb = (ProcessBuilder)
MH_newProcessBuilder.invoke("x", "y", "z");
assertEquals("[x, y, z]", pb.command().toString());
{}
}
// for testFindSpecial
{}
static class Listie extends ArrayList {
public String toString() { return "[wee Listie]"; }
static Lookup lookup() { return MethodHandles.lookup(); }
}
{}
@Test public void testFindSpecial() throws Throwable {
{}
// no access to constructor via invokeSpecial:
MethodHandle MH_newListie = Listie.lookup()
.findConstructor(Listie.class, methodType(void.class));
Listie l = (Listie) MH_newListie.invokeExact();
try { assertEquals("impossible", Listie.lookup().findSpecial(
Listie.class, "<init>", methodType(void.class), Listie.class));
} catch (NoSuchMethodException ex) { } // OK
// access to super and self methods via invokeSpecial:
MethodHandle MH_super = Listie.lookup().findSpecial(
ArrayList.class, "toString" , methodType(String.class), Listie.class);
MethodHandle MH_this = Listie.lookup().findSpecial(
Listie.class, "toString" , methodType(String.class), Listie.class);
MethodHandle MH_duper = Listie.lookup().findSpecial(
Object.class, "toString" , methodType(String.class), Listie.class);
assertEquals("[]", (String) MH_super.invokeExact(l));
assertEquals(""+l, (String) MH_this.invokeExact(l));
assertEquals("[]", (String) MH_duper.invokeExact(l)); // ArrayList method
try { assertEquals("inaccessible", Listie.lookup().findSpecial(
String.class, "toString", methodType(String.class), Listie.class));
} catch (IllegalAccessException ex) { } // OK
Listie subl = new Listie() { public String toString() { return "[subclass]"; } };
assertEquals(""+l, (String) MH_this.invokeExact(subl)); // Listie method
{}
}
@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 testDropArguments() throws Throwable {
{{
{} /// JAVADOC
MethodHandle cat = lookup().findVirtual(String.class,
"concat", methodType(String.class, String.class));
assertEquals("xy", (String) cat.invokeExact("x", "y"));
MethodType bigType = cat.type().insertParameterTypes(0, int.class, String.class);
MethodHandle d0 = dropArguments(cat, 0, bigType.parameterList().subList(0,2));
assertEquals(bigType, d0.type());
assertEquals("yz", (String) d0.invokeExact(123, "x", "y", "z"));
}}
{{
{} /// 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 testFilterArguments() throws Throwable {
{{
{} /// JAVADOC
MethodHandle cat = lookup().findVirtual(String.class,
"concat", methodType(String.class, String.class));
MethodHandle upcase = lookup().findVirtual(String.class,
"toUpperCase", methodType(String.class));
assertEquals("xy", (String) cat.invokeExact("x", "y"));
MethodHandle f0 = filterArguments(cat, 0, upcase);
assertEquals("Xy", (String) f0.invokeExact("x", "y")); // Xy
MethodHandle f1 = filterArguments(cat, 1, upcase);
assertEquals("xY", (String) f1.invokeExact("x", "y")); // xY
MethodHandle f2 = filterArguments(cat, 0, upcase, upcase);
assertEquals("XY", (String) f2.invokeExact("x", "y")); // XY
}}
}
@Test public void testCollectArguments() throws Throwable {
{{
{} /// JAVADOC
MethodHandle deepToString = publicLookup()
.findStatic(Arrays.class, "deepToString", methodType(String.class, Object[].class));
MethodHandle ts1 = deepToString.asCollector(String[].class, 1);
assertEquals("[strange]", (String) ts1.invokeExact("strange"));
MethodHandle ts2 = deepToString.asCollector(String[].class, 2);
assertEquals("[up, down]", (String) ts2.invokeExact("up", "down"));
MethodHandle ts3 = deepToString.asCollector(String[].class, 3);
MethodHandle ts3_ts2 = collectArguments(ts3, 1, ts2);
assertEquals("[top, [up, down], strange]",
(String) ts3_ts2.invokeExact("top", "up", "down", "strange"));
MethodHandle ts3_ts2_ts1 = collectArguments(ts3_ts2, 3, ts1);
assertEquals("[top, [up, down], [strange]]",
(String) ts3_ts2_ts1.invokeExact("top", "up", "down", "strange"));
MethodHandle ts3_ts2_ts3 = collectArguments(ts3_ts2, 1, ts3);
assertEquals("[top, [[up, down, strange], charm], bottom]",
(String) ts3_ts2_ts3.invokeExact("top", "up", "down", "strange", "charm", "bottom"));
}}
}
@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"));
}}
}
static void assertEquals(Object exp, Object act) {
if (verbosity > 0)
System.out.println("result: "+act);
Assert.assertEquals(exp, act);
}
@Test public void testMethodHandlesSummary() throws Throwable {
{{
{} /// JAVADOC
Object x, y; String s; int i;
MethodType mt; MethodHandle mh;
MethodHandles.Lookup lookup = MethodHandles.lookup();
// mt is (char,char)String
mt = MethodType.methodType(String.class, char.class, char.class);
mh = lookup.findVirtual(String.class, "replace", mt);
s = (String) mh.invokeExact("daddy",'d','n');
// invokeExact(Ljava/lang/String;CC)Ljava/lang/String;
assertEquals(s, "nanny");
// weakly typed invocation (using MHs.invoke)
s = (String) mh.invokeWithArguments("sappy", 'p', 'v');
assertEquals(s, "savvy");
// mt is (Object[])List
mt = MethodType.methodType(java.util.List.class, Object[].class);
mh = lookup.findStatic(java.util.Arrays.class, "asList", mt);
assert(mh.isVarargsCollector());
x = mh.invoke("one", "two");
// invoke(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;
assertEquals(x, java.util.Arrays.asList("one","two"));
// mt is (Object,Object,Object)Object
mt = MethodType.genericMethodType(3);
mh = mh.asType(mt);
x = mh.invokeExact((Object)1, (Object)2, (Object)3);
// invokeExact(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
assertEquals(x, java.util.Arrays.asList(1,2,3));
// mt is ()int
mt = MethodType.methodType(int.class);
mh = lookup.findVirtual(java.util.List.class, "size", mt);
i = (int) mh.invokeExact(java.util.Arrays.asList(1,2,3));
// invokeExact(Ljava/util/List;)I
assert(i == 3);
mt = MethodType.methodType(void.class, String.class);
mh = lookup.findVirtual(java.io.PrintStream.class, "println", mt);
mh.invokeExact(System.out, "Hello, world.");
// invokeExact(Ljava/io/PrintStream;Ljava/lang/String;)V
{}
}}
}
@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" }));
// try to spread from anything but a 2-array:
for (int n = 0; n <= 10; n++) {
Object[] badArityArgs = (n == 2 ? null : new Object[n]);
try { assert((boolean) eq2.invokeExact(badArityArgs) && false); }
catch (IllegalArgumentException ex) { } // OK
}
// 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));
}}
}
@SuppressWarnings("rawtypes")
@Test public void testAsVarargsCollector() throws Throwable {
{{
{} /// JAVADOC
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:
MethodHandle asList = publicLookup()
.findStatic(Arrays.class, "asList", methodType(List.class, Object[].class));
assertEquals(methodType(List.class, Object[].class), asList.type());
assert(asList.isVarargsCollector());
assertEquals("[]", asList.invoke().toString());
assertEquals("[1]", asList.invoke(1).toString());
assertEquals("[two, too]", asList.invoke("two", "too").toString());
String[] argv = { "three", "thee", "tee" };
assertEquals("[three, thee, tee]", asList.invoke(argv).toString());
assertEquals("[three, thee, tee]", asList.invoke((Object[])argv).toString());
List ls = (List) asList.invoke((Object)argv);
assertEquals(1, ls.size());
assertEquals("[three, thee, tee]", Arrays.toString((Object[])ls.get(0)));
}}
}
@Test public void testAsFixedArity() throws Throwable {
{{
{} /// JAVADOC
MethodHandle asListVar = publicLookup()
.findStatic(Arrays.class, "asList", methodType(List.class, Object[].class))
.asVarargsCollector(Object[].class);
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>
* <p>
* The same call site may be used in several places at once.
* <blockquote> */
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.hasBeenInvalidated());
// 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.hasBeenInvalidated());
assertEquals("hodmet", (String) worker.invokeExact("met", "hod"));
{}
}}
}
@Test public void testFoldArguments2() throws Throwable {
{{
{} /// JAVADOC
// argument-based dispatch for methods of the form boolean x.___(y: String)
Lookup lookup = publicLookup();
// first, a tracing hack:
MethodHandle println = lookup.findVirtual(java.io.PrintStream.class, "println", methodType(void.class, String.class));
MethodHandle arrayToString = lookup.findStatic(Arrays.class, "toString", methodType(String.class, Object[].class));
MethodHandle concat = lookup.findVirtual(String.class, "concat", methodType(String.class, String.class));
MethodHandle arrayToString_DIS = filterReturnValue(arrayToString, concat.bindTo("DIS:"));
MethodHandle arrayToString_INV = filterReturnValue(arrayToString, concat.bindTo("INV:"));
MethodHandle printArgs_DIS = filterReturnValue(arrayToString_DIS, println.bindTo(System.out)).asVarargsCollector(Object[].class);
MethodHandle printArgs_INV = filterReturnValue(arrayToString_INV, println.bindTo(System.out)).asVarargsCollector(Object[].class);
// metaobject protocol:
MethodType mtype = methodType(boolean.class, String.class);
MethodHandle findVirtual = lookup.findVirtual(Lookup.class,
"findVirtual", methodType(MethodHandle.class, Class.class, String.class, MethodType.class));
MethodHandle getClass = lookup.findVirtual(Object.class,
"getClass", methodType(Class.class));
MethodHandle dispatch = findVirtual;
dispatch = filterArguments(dispatch, 1, getClass);
dispatch = insertArguments(dispatch, 3, mtype);
dispatch = dispatch.bindTo(lookup);
assertEquals(methodType(MethodHandle.class, Object.class, String.class), dispatch.type());
MethodHandle invoker = invoker(mtype.insertParameterTypes(0, Object.class));
// wrap tracing around the dispatch and invoke steps:
dispatch = foldArguments(dispatch, printArgs_DIS.asType(dispatch.type().changeReturnType(void.class)));
invoker = foldArguments(invoker, printArgs_INV.asType(invoker.type().changeReturnType(void.class)));
invoker = dropArguments(invoker, 2, String.class); // ignore selector
// compose the dispatcher and the invoker:
MethodHandle invokeDispatched = foldArguments(invoker, dispatch);
Object x = "football", y = new java.util.Scanner("bar");
assert( (boolean) invokeDispatched.invokeExact(x, "startsWith", "foo"));
assert(!(boolean) invokeDispatched.invokeExact(x, "startsWith", "#"));
assert( (boolean) invokeDispatched.invokeExact(x, "endsWith", "all"));
assert(!(boolean) invokeDispatched.invokeExact(x, "endsWith", "foo"));
assert( (boolean) invokeDispatched.invokeExact(y, "hasNext", "[abc]+[rst]"));
assert(!(boolean) invokeDispatched.invokeExact(y, "hasNext", "[123]+[789]"));
}}
}
/* ---- TEMPLATE ----
@Test public void testFoo() throws Throwable {
{{
{} /// JAVADOC
{}
}}
}
*/
}
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