953 lines
42 KiB
Java
953 lines
42 KiB
Java
/*
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* Copyright (c) 2009, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/* @test
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* @summary example code used in javadoc for java.lang.invoke API
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* @compile JavaDocExamplesTest.java
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* @run testng/othervm test.java.lang.invoke.JavaDocExamplesTest
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*/
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package test.java.lang.invoke;
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import java.io.StringWriter;
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import java.lang.invoke.*;
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import static java.lang.invoke.MethodHandles.*;
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import static java.lang.invoke.MethodType.*;
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import java.util.*;
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import org.testng.*;
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import org.testng.annotations.*;
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/**
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* @author jrose
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*/
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public class JavaDocExamplesTest {
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/** Wrapper for running the TestNG tests in this module.
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* Put TestNG on the classpath!
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*/
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public static void main(String... ignore) throws Throwable {
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new JavaDocExamplesTest().run();
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}
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public void run() throws Throwable {
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testMisc();
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testFindStatic();
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testFindConstructor();
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testFindVirtual();
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testFindSpecial();
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testPermuteArguments();
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testZero();
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testDropArguments();
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testDropArgumentsToMatch();
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testFilterArguments();
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testFoldArguments();
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testFoldArguments2();
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testMethodHandlesSummary();
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testAsSpreader();
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testAsCollector();
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testAsVarargsCollector();
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testAsFixedArity();
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testAsTypeCornerCases();
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testMutableCallSite();
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}
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// How much output?
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static final Class<?> THIS_CLASS = JavaDocExamplesTest.class;
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static int verbosity = Integer.getInteger(THIS_CLASS.getSimpleName()+".verbosity", 0);
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{}
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private static final Lookup LOOKUP = lookup();
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// static final private MethodHandle CONCAT_1 = LOOKUP.findVirtual(String.class,
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// "concat", methodType(String.class, String.class));
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// static final private MethodHandle HASHCODE_1 = LOOKUP.findVirtual(Object.class,
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// "hashCode", methodType(int.class));
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// form required if ReflectiveOperationException is intercepted:
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private static final MethodHandle CONCAT_2, HASHCODE_2, ADD_2, SUB_2;
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static {
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try {
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Class<?> THIS_CLASS = LOOKUP.lookupClass();
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CONCAT_2 = LOOKUP.findVirtual(String.class,
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"concat", methodType(String.class, String.class));
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HASHCODE_2 = LOOKUP.findVirtual(Object.class,
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"hashCode", methodType(int.class));
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ADD_2 = LOOKUP.findStatic(THIS_CLASS, "add", methodType(int.class, int.class, int.class));
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SUB_2 = LOOKUP.findStatic(THIS_CLASS, "sub", methodType(int.class, int.class, int.class));
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} catch (ReflectiveOperationException ex) {
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throw new RuntimeException(ex);
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}
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}
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static int add(int x, int y) { return x + y; }
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static int sub(int x, int y) { return x - y; }
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{}
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@Test public void testMisc() throws Throwable {
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// Extra tests, not from javadoc:
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{}
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MethodHandle CONCAT_3 = LOOKUP.findVirtual(String.class,
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"concat", methodType(String.class, String.class));
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MethodHandle HASHCODE_3 = LOOKUP.findVirtual(Object.class,
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"hashCode", methodType(int.class));
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//assertEquals("xy", (String) CONCAT_1.invokeExact("x", "y"));
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assertEquals("xy", (String) CONCAT_2.invokeExact("x", "y"));
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assertEquals("xy", (String) CONCAT_3.invokeExact("x", "y"));
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//assertEquals("xy".hashCode(), (int) HASHCODE_1.invokeExact((Object)"xy"));
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assertEquals("xy".hashCode(), (int) HASHCODE_2.invokeExact((Object)"xy"));
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assertEquals("xy".hashCode(), (int) HASHCODE_3.invokeExact((Object)"xy"));
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{}
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}
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@Test public void testFindStatic() throws Throwable {
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{}
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MethodHandle MH_asList = publicLookup().findStatic(Arrays.class,
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"asList", methodType(List.class, Object[].class));
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assertEquals("[x, y]", MH_asList.invoke("x", "y").toString());
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{}
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}
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@Test public void testFindVirtual() throws Throwable {
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{}
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MethodHandle MH_concat = publicLookup().findVirtual(String.class,
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"concat", methodType(String.class, String.class));
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MethodHandle MH_hashCode = publicLookup().findVirtual(Object.class,
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"hashCode", methodType(int.class));
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MethodHandle MH_hashCode_String = publicLookup().findVirtual(String.class,
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"hashCode", methodType(int.class));
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assertEquals("xy", (String) MH_concat.invokeExact("x", "y"));
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assertEquals("xy".hashCode(), (int) MH_hashCode.invokeExact((Object)"xy"));
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assertEquals("xy".hashCode(), (int) MH_hashCode_String.invokeExact("xy"));
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// interface method:
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MethodHandle MH_subSequence = publicLookup().findVirtual(CharSequence.class,
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"subSequence", methodType(CharSequence.class, int.class, int.class));
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assertEquals("def", MH_subSequence.invoke("abcdefghi", 3, 6).toString());
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// constructor "internal method" must be accessed differently:
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MethodType MT_newString = methodType(void.class); //()V for new String()
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try { assertEquals("impossible", lookup()
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.findVirtual(String.class, "<init>", MT_newString));
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} catch (NoSuchMethodException ex) { } // OK
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MethodHandle MH_newString = publicLookup()
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.findConstructor(String.class, MT_newString);
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assertEquals("", (String) MH_newString.invokeExact());
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{}
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}
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@Test public void testFindConstructor() throws Throwable {
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{}
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MethodHandle MH_newArrayList = publicLookup().findConstructor(
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ArrayList.class, methodType(void.class, Collection.class));
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Collection orig = Arrays.asList("x", "y");
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Collection copy = (ArrayList) MH_newArrayList.invokeExact(orig);
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assert(orig != copy);
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assertEquals(orig, copy);
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// a variable-arity constructor:
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MethodHandle MH_newProcessBuilder = publicLookup().findConstructor(
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ProcessBuilder.class, methodType(void.class, String[].class));
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ProcessBuilder pb = (ProcessBuilder)
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MH_newProcessBuilder.invoke("x", "y", "z");
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assertEquals("[x, y, z]", pb.command().toString());
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{}
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}
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// for testFindSpecial
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{}
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static class Listie extends ArrayList {
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public String toString() { return "[wee Listie]"; }
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static Lookup lookup() { return MethodHandles.lookup(); }
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}
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{}
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@Test public void testFindSpecial() throws Throwable {
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{}
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// no access to constructor via invokeSpecial:
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MethodHandle MH_newListie = Listie.lookup()
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.findConstructor(Listie.class, methodType(void.class));
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Listie l = (Listie) MH_newListie.invokeExact();
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try { assertEquals("impossible", Listie.lookup().findSpecial(
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Listie.class, "<init>", methodType(void.class), Listie.class));
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} catch (NoSuchMethodException ex) { } // OK
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// access to super and self methods via invokeSpecial:
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MethodHandle MH_super = Listie.lookup().findSpecial(
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ArrayList.class, "toString" , methodType(String.class), Listie.class);
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MethodHandle MH_this = Listie.lookup().findSpecial(
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Listie.class, "toString" , methodType(String.class), Listie.class);
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MethodHandle MH_duper = Listie.lookup().findSpecial(
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Object.class, "toString" , methodType(String.class), Listie.class);
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assertEquals("[]", (String) MH_super.invokeExact(l));
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assertEquals(""+l, (String) MH_this.invokeExact(l));
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assertEquals("[]", (String) MH_duper.invokeExact(l)); // ArrayList method
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try { assertEquals("inaccessible", Listie.lookup().findSpecial(
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String.class, "toString", methodType(String.class), Listie.class));
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} catch (IllegalAccessException ex) { } // OK
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Listie subl = new Listie() { public String toString() { return "[subclass]"; } };
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assertEquals(""+l, (String) MH_this.invokeExact(subl)); // Listie method
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{}
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}
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@Test public void testPermuteArguments() throws Throwable {
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{{
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{} /// JAVADOC
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MethodType intfn1 = methodType(int.class, int.class);
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MethodType intfn2 = methodType(int.class, int.class, int.class);
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MethodHandle sub = SUB_2;// ... {int x, int y => x-y} ...;
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assert(sub.type().equals(intfn2));
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MethodHandle sub1 = permuteArguments(sub, intfn2, 0, 1);
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MethodHandle rsub = permuteArguments(sub, intfn2, 1, 0);
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assert((int)rsub.invokeExact(1, 100) == 99);
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MethodHandle add = ADD_2;// ... {int x, int y => x+y} ...;
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assert(add.type().equals(intfn2));
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MethodHandle twice = permuteArguments(add, intfn1, 0, 0);
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assert(twice.type().equals(intfn1));
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assert((int)twice.invokeExact(21) == 42);
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}}
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{{
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{} /// JAVADOC
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MethodHandle cat = lookup().findVirtual(String.class,
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"concat", methodType(String.class, String.class));
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assertEquals("xy", (String) cat.invokeExact("x", "y"));
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MethodHandle d0 = dropArguments(cat, 0, String.class);
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assertEquals("yz", (String) d0.invokeExact("x", "y", "z"));
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MethodHandle d1 = dropArguments(cat, 1, String.class);
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assertEquals("xz", (String) d1.invokeExact("x", "y", "z"));
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MethodHandle d2 = dropArguments(cat, 2, String.class);
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assertEquals("xy", (String) d2.invokeExact("x", "y", "z"));
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MethodHandle d12 = dropArguments(cat, 1, int.class, boolean.class);
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assertEquals("xz", (String) d12.invokeExact("x", 12, true, "z"));
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}}
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}
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@Test public void testZero() throws Throwable {
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{{
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{} /// JAVADOC
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Class<?> type = Double.class;
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MethodHandle mh1 = MethodHandles.explicitCastArguments(MethodHandles.constant(Object.class, null), methodType(type));
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assertEquals("()Double", mh1.type().toString());
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MethodHandle mh2 = MethodHandles.empty(methodType(type));
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assertEquals("()Double", mh2.type().toString());
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}}
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}
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@Test public void testDropArguments() throws Throwable {
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{{
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{} /// JAVADOC
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MethodHandle cat = lookup().findVirtual(String.class,
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"concat", methodType(String.class, String.class));
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assertEquals("xy", (String) cat.invokeExact("x", "y"));
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MethodType bigType = cat.type().insertParameterTypes(0, int.class, String.class);
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MethodHandle d0 = dropArguments(cat, 0, bigType.parameterList().subList(0,2));
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assertEquals(bigType, d0.type());
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assertEquals("yz", (String) d0.invokeExact(123, "x", "y", "z"));
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}}
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{{
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{} /// JAVADOC
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MethodHandle cat = lookup().findVirtual(String.class,
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"concat", methodType(String.class, String.class));
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assertEquals("xy", (String) cat.invokeExact("x", "y"));
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MethodHandle d0 = dropArguments(cat, 0, String.class);
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assertEquals("yz", (String) d0.invokeExact("x", "y", "z"));
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MethodHandle d1 = dropArguments(cat, 1, String.class);
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assertEquals("xz", (String) d1.invokeExact("x", "y", "z"));
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MethodHandle d2 = dropArguments(cat, 2, String.class);
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assertEquals("xy", (String) d2.invokeExact("x", "y", "z"));
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MethodHandle d12 = dropArguments(cat, 1, int.class, boolean.class);
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assertEquals("xz", (String) d12.invokeExact("x", 12, true, "z"));
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}}
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}
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@Test public void testDropArgumentsToMatch() throws Throwable {
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{{
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{} /// JAVADOC
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MethodHandle h0= constant(boolean.class, true);
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MethodHandle h1 = lookup().findVirtual(String.class, "concat", methodType(String.class, String.class));
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MethodType bigType = h1.type().insertParameterTypes(1, String.class, int.class);
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MethodHandle h2 = dropArguments(h1, 0, bigType.parameterList());
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if (h1.type().parameterCount() < h2.type().parameterCount()) {
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h1 = dropArgumentsToMatch(h1, 0, h2.type().parameterList(), 0); // lengthen h1
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}
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else {
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h2 = dropArgumentsToMatch(h2, 0, h1.type().parameterList(), 0); // lengthen h2
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}
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MethodHandle h3 = guardWithTest(h0, h1, h2);
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assertEquals("xy", h3.invoke("x", "y", 1, "a", "b", "c"));
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}}
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}
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@Test public void testFilterArguments() throws Throwable {
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{{
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{} /// JAVADOC
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MethodHandle cat = lookup().findVirtual(String.class,
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"concat", methodType(String.class, String.class));
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MethodHandle upcase = lookup().findVirtual(String.class,
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"toUpperCase", methodType(String.class));
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assertEquals("xy", (String) cat.invokeExact("x", "y"));
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MethodHandle f0 = filterArguments(cat, 0, upcase);
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assertEquals("Xy", (String) f0.invokeExact("x", "y")); // Xy
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MethodHandle f1 = filterArguments(cat, 1, upcase);
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assertEquals("xY", (String) f1.invokeExact("x", "y")); // xY
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MethodHandle f2 = filterArguments(cat, 0, upcase, upcase);
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assertEquals("XY", (String) f2.invokeExact("x", "y")); // XY
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}}
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}
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@Test public void testCollectArguments() throws Throwable {
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{{
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{} /// JAVADOC
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MethodHandle deepToString = publicLookup()
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.findStatic(Arrays.class, "deepToString", methodType(String.class, Object[].class));
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MethodHandle ts1 = deepToString.asCollector(String[].class, 1);
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assertEquals("[strange]", (String) ts1.invokeExact("strange"));
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MethodHandle ts2 = deepToString.asCollector(String[].class, 2);
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assertEquals("[up, down]", (String) ts2.invokeExact("up", "down"));
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MethodHandle ts3 = deepToString.asCollector(String[].class, 3);
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MethodHandle ts3_ts2 = collectArguments(ts3, 1, ts2);
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assertEquals("[top, [up, down], strange]",
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(String) ts3_ts2.invokeExact("top", "up", "down", "strange"));
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MethodHandle ts3_ts2_ts1 = collectArguments(ts3_ts2, 3, ts1);
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assertEquals("[top, [up, down], [strange]]",
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(String) ts3_ts2_ts1.invokeExact("top", "up", "down", "strange"));
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MethodHandle ts3_ts2_ts3 = collectArguments(ts3_ts2, 1, ts3);
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assertEquals("[top, [[up, down, strange], charm], bottom]",
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(String) ts3_ts2_ts3.invokeExact("top", "up", "down", "strange", "charm", "bottom"));
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}}
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}
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@Test public void testFoldArguments() throws Throwable {
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{{
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{} /// JAVADOC
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MethodHandle trace = publicLookup().findVirtual(java.io.PrintStream.class,
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"println", methodType(void.class, String.class))
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.bindTo(System.out);
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MethodHandle cat = lookup().findVirtual(String.class,
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"concat", methodType(String.class, String.class));
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assertEquals("boojum", (String) cat.invokeExact("boo", "jum"));
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MethodHandle catTrace = foldArguments(cat, trace);
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// also prints "boo":
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assertEquals("boojum", (String) catTrace.invokeExact("boo", "jum"));
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}}
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}
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static void assertEquals(Object exp, Object act) {
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if (verbosity > 0)
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System.out.println("result: "+act);
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Assert.assertEquals(exp, act);
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}
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static void assertTrue(boolean b) {
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if (verbosity > 0) {
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System.out.println("result: " + b);
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}
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Assert.assertTrue(b);
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}
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@Test public void testMethodHandlesSummary() throws Throwable {
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{{
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{} /// JAVADOC
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Object x, y; String s; int i;
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MethodType mt; MethodHandle mh;
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MethodHandles.Lookup lookup = MethodHandles.lookup();
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// mt is (char,char)String
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mt = MethodType.methodType(String.class, char.class, char.class);
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mh = lookup.findVirtual(String.class, "replace", mt);
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s = (String) mh.invokeExact("daddy",'d','n');
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// invokeExact(Ljava/lang/String;CC)Ljava/lang/String;
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assertEquals(s, "nanny");
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// weakly typed invocation (using MHs.invoke)
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s = (String) mh.invokeWithArguments("sappy", 'p', 'v');
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assertEquals(s, "savvy");
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// mt is (Object[])List
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mt = MethodType.methodType(java.util.List.class, Object[].class);
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mh = lookup.findStatic(java.util.Arrays.class, "asList", mt);
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assert(mh.isVarargsCollector());
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x = mh.invoke("one", "two");
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// invoke(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;
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assertEquals(x, java.util.Arrays.asList("one","two"));
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// mt is (Object,Object,Object)Object
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mt = MethodType.genericMethodType(3);
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mh = mh.asType(mt);
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x = mh.invokeExact((Object)1, (Object)2, (Object)3);
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// invokeExact(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
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assertEquals(x, java.util.Arrays.asList(1,2,3));
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// mt is ()int
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mt = MethodType.methodType(int.class);
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mh = lookup.findVirtual(java.util.List.class, "size", mt);
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i = (int) mh.invokeExact(java.util.Arrays.asList(1,2,3));
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// invokeExact(Ljava/util/List;)I
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assert(i == 3);
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mt = MethodType.methodType(void.class, String.class);
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mh = lookup.findVirtual(java.io.PrintStream.class, "println", mt);
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mh.invokeExact(System.out, "Hello, world.");
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// invokeExact(Ljava/io/PrintStream;Ljava/lang/String;)V
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{}
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}}
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}
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@Test public void testAsSpreader() throws Throwable {
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{{
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{} /// JAVADOC
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MethodHandle equals = publicLookup()
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.findVirtual(String.class, "equals", methodType(boolean.class, Object.class));
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assert( (boolean) equals.invokeExact("me", (Object)"me"));
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assert(!(boolean) equals.invokeExact("me", (Object)"thee"));
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// spread both arguments from a 2-array:
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MethodHandle eq2 = equals.asSpreader(Object[].class, 2);
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assert( (boolean) eq2.invokeExact(new Object[]{ "me", "me" }));
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assert(!(boolean) eq2.invokeExact(new Object[]{ "me", "thee" }));
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// try to spread from anything but a 2-array:
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for (int n = 0; n <= 10; n++) {
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Object[] badArityArgs = (n == 2 ? new Object[0] : new Object[n]);
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try { assert((boolean) eq2.invokeExact(badArityArgs) && false); }
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catch (IllegalArgumentException ex) { } // OK
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}
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// 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></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.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]"));
|
|
}}
|
|
}
|
|
|
|
static int one(int k) { return 1; }
|
|
static int inc(int i, int acc, int k) { return i + 1; }
|
|
static int mult(int i, int acc, int k) { return i * acc; }
|
|
static boolean pred(int i, int acc, int k) { return i < k; }
|
|
static int fin(int i, int acc, int k) { return acc; }
|
|
|
|
@Test public void testLoop() throws Throwable {
|
|
MethodHandle MH_inc, MH_one, MH_mult, MH_pred, MH_fin;
|
|
Class<?> I = int.class;
|
|
MH_inc = LOOKUP.findStatic(THIS_CLASS, "inc", methodType(I, I, I, I));
|
|
MH_one = LOOKUP.findStatic(THIS_CLASS, "one", methodType(I, I));
|
|
MH_mult = LOOKUP.findStatic(THIS_CLASS, "mult", methodType(I, I, I, I));
|
|
MH_pred = LOOKUP.findStatic(THIS_CLASS, "pred", methodType(boolean.class, I, I, I));
|
|
MH_fin = LOOKUP.findStatic(THIS_CLASS, "fin", methodType(I, I, I, I));
|
|
{{
|
|
{} /// JAVADOC
|
|
// iterative implementation of the factorial function as a loop handle
|
|
// null initializer for counter, should initialize to 0
|
|
MethodHandle[] counterClause = new MethodHandle[]{null, MH_inc};
|
|
MethodHandle[] accumulatorClause = new MethodHandle[]{MH_one, MH_mult, MH_pred, MH_fin};
|
|
MethodHandle loop = MethodHandles.loop(counterClause, accumulatorClause);
|
|
assertEquals(120, loop.invoke(5));
|
|
{}
|
|
}}
|
|
}
|
|
|
|
static int inc(int i) { return i + 1; } // drop acc, k
|
|
static int mult(int i, int acc) { return i * acc; } //drop k
|
|
static boolean cmp(int i, int k) { return i < k; }
|
|
|
|
@Test public void testSimplerLoop() throws Throwable {
|
|
MethodHandle MH_inc, MH_mult, MH_cmp;
|
|
Class<?> I = int.class;
|
|
MH_inc = LOOKUP.findStatic(THIS_CLASS, "inc", methodType(I, I));
|
|
MH_mult = LOOKUP.findStatic(THIS_CLASS, "mult", methodType(I, I, I));
|
|
MH_cmp = LOOKUP.findStatic(THIS_CLASS, "cmp", methodType(boolean.class, I, I));
|
|
{{
|
|
{} /// JAVADOC
|
|
// simplified implementation of the factorial function as a loop handle
|
|
// null initializer for counter, should initialize to 0
|
|
MethodHandle MH_one = MethodHandles.constant(int.class, 1);
|
|
MethodHandle MH_pred = MethodHandles.dropArguments(MH_cmp, 1, int.class); // drop acc
|
|
MethodHandle MH_fin = MethodHandles.dropArguments(MethodHandles.identity(int.class), 0, int.class); // drop i
|
|
MethodHandle[] counterClause = new MethodHandle[]{null, MH_inc};
|
|
MethodHandle[] accumulatorClause = new MethodHandle[]{MH_one, MH_mult, MH_pred, MH_fin};
|
|
MethodHandle loop = MethodHandles.loop(counterClause, accumulatorClause);
|
|
assertEquals(720, loop.invoke(6));
|
|
{}
|
|
}}
|
|
}
|
|
|
|
// for testFacLoop
|
|
{}
|
|
static class FacLoop {
|
|
final int k;
|
|
FacLoop(int k) { this.k = k; }
|
|
int inc(int i) { return i + 1; }
|
|
int mult(int i, int acc) { return i * acc; }
|
|
boolean pred(int i) { return i < k; }
|
|
int fin(int i, int acc) { return acc; }
|
|
}
|
|
{}
|
|
|
|
// assume MH_inc, MH_mult, and MH_pred are handles to the above methods
|
|
@Test public void testFacLoop() throws Throwable {
|
|
MethodHandle MH_FacLoop, MH_inc, MH_mult, MH_pred, MH_fin;
|
|
Class<?> I = int.class;
|
|
MH_FacLoop = LOOKUP.findConstructor(FacLoop.class, methodType(void.class, I));
|
|
MH_inc = LOOKUP.findVirtual(FacLoop.class, "inc", methodType(I, I));
|
|
MH_mult = LOOKUP.findVirtual(FacLoop.class, "mult", methodType(I, I, I));
|
|
MH_pred = LOOKUP.findVirtual(FacLoop.class, "pred", methodType(boolean.class, I));
|
|
MH_fin = LOOKUP.findVirtual(FacLoop.class, "fin", methodType(I, I, I));
|
|
{{
|
|
{} /// JAVADOC
|
|
// instance-based implementation of the factorial function as a loop handle
|
|
// null initializer for counter, should initialize to 0
|
|
MethodHandle MH_one = MethodHandles.constant(int.class, 1);
|
|
MethodHandle[] instanceClause = new MethodHandle[]{MH_FacLoop};
|
|
MethodHandle[] counterClause = new MethodHandle[]{null, MH_inc};
|
|
MethodHandle[] accumulatorClause = new MethodHandle[]{MH_one, MH_mult, MH_pred, MH_fin};
|
|
MethodHandle loop = MethodHandles.loop(instanceClause, counterClause, accumulatorClause);
|
|
assertEquals(5040, loop.invoke(7));
|
|
{}
|
|
}}
|
|
}
|
|
|
|
static List<String> initZip(Iterator<String> a, Iterator<String> b) { return new ArrayList<>(); }
|
|
static boolean zipPred(List<String> zip, Iterator<String> a, Iterator<String> b) { return a.hasNext() && b.hasNext(); }
|
|
static List<String> zipStep(List<String> zip, Iterator<String> a, Iterator<String> b) {
|
|
zip.add(a.next());
|
|
zip.add(b.next());
|
|
return zip;
|
|
}
|
|
|
|
@Test public void testWhileLoop() throws Throwable {
|
|
MethodHandle MH_initZip, MH_zipPred, MH_zipStep;
|
|
Class<?> IT = Iterator.class;
|
|
Class<?> L = List.class;
|
|
MH_initZip = LOOKUP.findStatic(THIS_CLASS, "initZip", methodType(L, IT, IT));
|
|
MH_zipPred = LOOKUP.findStatic(THIS_CLASS, "zipPred", methodType(boolean.class, L, IT, IT));
|
|
MH_zipStep = LOOKUP.findStatic(THIS_CLASS, "zipStep", methodType(L, L, IT, IT));
|
|
{{
|
|
{} /// JAVADOC
|
|
// implement the zip function for lists as a loop handle
|
|
MethodHandle loop = MethodHandles.whileLoop(MH_initZip, MH_zipPred, MH_zipStep);
|
|
List<String> a = Arrays.asList("a", "b", "c", "d");
|
|
List<String> b = Arrays.asList("e", "f", "g", "h");
|
|
List<String> zipped = Arrays.asList("a", "e", "b", "f", "c", "g", "d", "h");
|
|
assertEquals(zipped, (List<String>) loop.invoke(a.iterator(), b.iterator()));
|
|
{}
|
|
}}
|
|
}
|
|
|
|
static int zero(int limit) { return 0; }
|
|
static int step(int i, int limit) { return i + 1; }
|
|
static boolean pred(int i, int limit) { return i < limit; }
|
|
|
|
@Test public void testDoWhileLoop() throws Throwable {
|
|
MethodHandle MH_zero, MH_step, MH_pred;
|
|
Class<?> I = int.class;
|
|
MH_zero = LOOKUP.findStatic(THIS_CLASS, "zero", methodType(I, I));
|
|
MH_step = LOOKUP.findStatic(THIS_CLASS, "step", methodType(I, I, I));
|
|
MH_pred = LOOKUP.findStatic(THIS_CLASS, "pred", methodType(boolean.class, I, I));
|
|
{{
|
|
{} /// JAVADOC
|
|
// int i = 0; while (i < limit) { ++i; } return i; => limit
|
|
MethodHandle loop = MethodHandles.doWhileLoop(MH_zero, MH_step, MH_pred);
|
|
assertEquals(23, loop.invoke(23));
|
|
{}
|
|
}}
|
|
}
|
|
|
|
static String step(String v, int counter, String start_) { return "na " + v; } //#0
|
|
static String step(String v, int counter ) { return "na " + v; } //#1
|
|
static String step(String v, int counter, int iterations_, String pre, String start_) { return pre + " " + v; } //#2
|
|
static String step3(String v, int counter, String pre) { return pre + " " + v; } //#3
|
|
|
|
@Test public void testCountedLoop() throws Throwable {
|
|
MethodHandle MH_step;
|
|
Class<?> S = String.class, I = int.class;
|
|
// Theme:
|
|
MH_step = LOOKUP.findStatic(THIS_CLASS, "step", methodType(S, S, I, S));
|
|
{{
|
|
{} /// JAVADOC
|
|
// String s = "Lambdaman!"; for (int i = 0; i < 13; ++i) { s = "na " + s; } return s;
|
|
// => a variation on a well known theme
|
|
MethodHandle fit13 = MethodHandles.constant(int.class, 13);
|
|
MethodHandle start = MethodHandles.identity(String.class);
|
|
MethodHandle loop = MethodHandles.countedLoop(fit13, start, MH_step); // (v, i, _) -> "na " + v
|
|
assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke("Lambdaman!"));
|
|
{}
|
|
}}
|
|
// Variation #1:
|
|
MH_step = LOOKUP.findStatic(THIS_CLASS, "step", methodType(S, S, I));
|
|
{{
|
|
{} /// JAVADOC
|
|
// String s = "Lambdaman!"; for (int i = 0; i < 13; ++i) { s = "na " + s; } return s;
|
|
// => a variation on a well known theme
|
|
MethodHandle count = MethodHandles.dropArguments(MethodHandles.identity(int.class), 1, String.class);
|
|
MethodHandle start = MethodHandles.dropArguments(MethodHandles.identity(String.class), 0, int.class);
|
|
MethodHandle loop = MethodHandles.countedLoop(count, start, MH_step); // (v, i) -> "na " + v
|
|
assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke(13, "Lambdaman!"));
|
|
{}
|
|
assertEquals("na na Lambdaman!", loop.invoke(2, "Lambdaman!"));
|
|
assertEquals("Lambdaman!", loop.invoke(0, "Lambdaman!"));
|
|
assertEquals("Lambdaman!", loop.invoke(-1, "Lambdaman!"));
|
|
assertEquals("Lambdaman!", loop.invoke(Integer.MIN_VALUE, "Lambdaman!"));
|
|
}}
|
|
// Variation #2:
|
|
MH_step = LOOKUP.findStatic(THIS_CLASS, "step", methodType(S, S, I, I, S, S));
|
|
{{
|
|
{} /// JAVADOC
|
|
// String s = "Lambdaman!", t = "na"; for (int i = 0; i < 13; ++i) { s = t + " " + s; } return s;
|
|
// => a variation on a well known theme
|
|
MethodHandle count = MethodHandles.identity(int.class);
|
|
MethodHandle start = MethodHandles.dropArguments(MethodHandles.identity(String.class), 0, int.class, String.class);
|
|
MethodHandle loop = MethodHandles.countedLoop(count, start, MH_step); // (v, i, _, pre, _) -> pre + " " + v
|
|
assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke(13, "na", "Lambdaman!"));
|
|
{}
|
|
}}
|
|
// Variation #3:
|
|
MH_step = LOOKUP.findStatic(THIS_CLASS, "step3", methodType(S, S, I, S));
|
|
{{
|
|
{} /// JAVADOC
|
|
// String s = "Lambdaman!", t = "na"; for (int i = 0; i < 13; ++i) { s = t + " " + s; } return s;
|
|
// => a variation on a well known theme
|
|
MethodType loopType = methodType(String.class, String.class, int.class, String.class);
|
|
MethodHandle count = MethodHandles.dropArgumentsToMatch(MethodHandles.identity(int.class), 0, loopType.parameterList(), 1);
|
|
MethodHandle start = MethodHandles.dropArgumentsToMatch(MethodHandles.identity(String.class), 0, loopType.parameterList(), 2);
|
|
MethodHandle body = MethodHandles.dropArgumentsToMatch(MH_step, 2, loopType.parameterList(), 0);
|
|
MethodHandle loop = MethodHandles.countedLoop(count, start, body); // (v, i, pre, _, _) -> pre + " " + v
|
|
assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke("na", 13, "Lambdaman!"));
|
|
{}
|
|
}}
|
|
}
|
|
|
|
static List<String> reverseStep(List<String> r, String e) {
|
|
r.add(0, e);
|
|
return r;
|
|
}
|
|
static List<String> newArrayList() { return new ArrayList<>(); }
|
|
|
|
@Test public void testIteratedLoop() throws Throwable {
|
|
MethodHandle MH_newArrayList, MH_reverseStep;
|
|
Class<?> L = List.class, S = String.class;
|
|
MH_newArrayList = LOOKUP.findStatic(THIS_CLASS, "newArrayList", methodType(L));
|
|
MH_reverseStep = LOOKUP.findStatic(THIS_CLASS, "reverseStep", methodType(L, L, S));
|
|
{{
|
|
{} /// JAVADOC
|
|
// reverse a list
|
|
MethodHandle loop = MethodHandles.iteratedLoop(null, MH_newArrayList, MH_reverseStep);
|
|
List<String> list = Arrays.asList("a", "b", "c", "d", "e");
|
|
List<String> reversedList = Arrays.asList("e", "d", "c", "b", "a");
|
|
assertEquals(reversedList, (List<String>) loop.invoke(list));
|
|
{}
|
|
}}
|
|
}
|
|
|
|
@Test public void testFoldArguments3() 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, 1, trace);
|
|
// also prints "jum":
|
|
assertEquals("boojum", (String) catTrace.invokeExact("boo", "jum"));
|
|
{}
|
|
}}
|
|
}
|
|
|
|
@Test public void testAsCollector2() throws Throwable {
|
|
{{
|
|
{} /// JAVADOC
|
|
StringWriter swr = new StringWriter();
|
|
MethodHandle swWrite = LOOKUP.findVirtual(StringWriter.class, "write", methodType(void.class, char[].class, int.class, int.class)).bindTo(swr);
|
|
MethodHandle swWrite4 = swWrite.asCollector(0, char[].class, 4);
|
|
swWrite4.invoke('A', 'B', 'C', 'D', 1, 2);
|
|
assertEquals("BC", swr.toString());
|
|
swWrite4.invoke('P', 'Q', 'R', 'S', 0, 4);
|
|
assertEquals("BCPQRS", swr.toString());
|
|
swWrite4.invoke('W', 'X', 'Y', 'Z', 3, 1);
|
|
assertEquals("BCPQRSZ", swr.toString());
|
|
{}
|
|
}}
|
|
}
|
|
|
|
@Test public void testAsSpreader2() throws Throwable {
|
|
{{
|
|
{} /// JAVADOC
|
|
MethodHandle compare = LOOKUP.findStatic(Objects.class, "compare", methodType(int.class, Object.class, Object.class, Comparator.class));
|
|
MethodHandle compare2FromArray = compare.asSpreader(0, Object[].class, 2);
|
|
Object[] ints = new Object[]{3, 9, 7, 7};
|
|
Comparator<Integer> cmp = (a, b) -> a - b;
|
|
assertTrue((int) compare2FromArray.invoke(Arrays.copyOfRange(ints, 0, 2), cmp) < 0);
|
|
assertTrue((int) compare2FromArray.invoke(Arrays.copyOfRange(ints, 1, 3), cmp) > 0);
|
|
assertTrue((int) compare2FromArray.invoke(Arrays.copyOfRange(ints, 2, 4), cmp) == 0);
|
|
{}
|
|
}}
|
|
}
|
|
|
|
/* ---- TEMPLATE ----
|
|
@Test public void testFoo() throws Throwable {
|
|
{{
|
|
{} /// JAVADOC
|
|
{}
|
|
}}
|
|
}
|
|
*/
|
|
}
|