test/jdk/java/lang/Class/getSimpleName/GetSimpleNameTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 2 along with this work; if not, write to the Free Software Foundation,
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/* @test
 * @bug 8057919
 * @summary Class.getSimpleName() should work for non-JLS compliant class names
 */

import java.lang.classfile.ClassBuilder;
import java.lang.classfile.ClassFile;
import java.lang.classfile.CodeBuilder;
import java.lang.classfile.attribute.EnclosingMethodAttribute;
import java.lang.classfile.attribute.InnerClassInfo;
import java.lang.classfile.attribute.InnerClassesAttribute;
import java.lang.constant.ClassDesc;
import java.lang.reflect.AccessFlag;
import java.util.Optional;

import static java.lang.classfile.ClassFile.ACC_PUBLIC;
import static java.lang.classfile.ClassFile.ACC_STATIC;
import static java.lang.constant.ConstantDescs.CD_Object;
import static java.lang.constant.ConstantDescs.INIT_NAME;
import static java.lang.constant.ConstantDescs.MTD_void;

public class GetSimpleNameTest {
    static class NestedClass {}
    class InnerClass {}

    static Class<?> f1() {
        class LocalClass {}
        return LocalClass.class;
    }

    public static void main(String[] args) throws Exception {
        assertEquals(NestedClass.class.getSimpleName(), "NestedClass");
        assertEquals( InnerClass.class.getSimpleName(),  "InnerClass");
        assertEquals(             f1().getSimpleName(),  "LocalClass");

        java.io.Serializable anon = new java.io.Serializable() {};
        assertEquals(anon.getClass().getSimpleName(), "");

        // Java class names, prepended enclosing class name.
        testNested("p.Outer$Nested", "p.Outer", "Nested");
        testInner( "p.Outer$Inner",  "p.Inner",  "Inner");
        testLocal( "p.Outer$1Local", "p.Outer",  "Local");
        testAnon(  "p.Outer$1",      "p.Outer",       "");

        // Non-Java class names, prepended enclosing class name.
        testNested("p.$C1$Nested", "p.$C1$", "Nested");
        testInner( "p.$C1$Inner",  "p.$C1$",  "Inner");
        testLocal( "p.$C1$Local",  "p.$C1$",  "Local");
        testAnon(  "p.$C1$1",      "p.$C1$",       "");

        // Non-Java class names, unrelated class names.
        testNested("p1.$Nested$", "p2.$C1$", "Nested");
        testInner( "p1.$Inner$",  "p2.$C1$",  "Inner");
        testLocal( "p1.$Local$",  "p2.$C1$",  "Local");
        testAnon(  "p1.$anon$",   "p2.$C1$",       "");
    }

    static void testNested(String innerName, String outerName, String simpleName) throws Exception {
        BytecodeGenerator bg = new BytecodeGenerator(innerName, outerName, simpleName);
        CustomCL cl = new CustomCL(innerName, outerName, bg.getNestedClasses(true), bg.getNestedClasses(false));
        assertEquals(cl.loadClass(innerName).getSimpleName(), simpleName);
    }

    static void testInner(String innerName, String outerName, String simpleName) throws Exception {
        BytecodeGenerator bg = new BytecodeGenerator(innerName, outerName, simpleName);
        CustomCL cl = new CustomCL(innerName, outerName, bg.getInnerClasses(true), bg.getInnerClasses(false));
        assertEquals(cl.loadClass(innerName).getSimpleName(), simpleName);
    }

    static void testLocal(String innerName, String outerName, String simpleName) throws Exception {
        BytecodeGenerator bg = new BytecodeGenerator(innerName, outerName, simpleName);
        CustomCL cl = new CustomCL(innerName, outerName, bg.getLocalClasses(true), bg.getLocalClasses(false));
        assertEquals(cl.loadClass(innerName).getSimpleName(), simpleName);
    }

    static void testAnon(String innerName, String outerName, String simpleName) throws Exception {
        BytecodeGenerator bg = new BytecodeGenerator(innerName, outerName, simpleName);
        CustomCL cl = new CustomCL(innerName, outerName, bg.getAnonymousClasses(true), bg.getAnonymousClasses(false));
        assertEquals(cl.loadClass(innerName).getSimpleName(), simpleName);
    }

    static void assertEquals(Object o1, Object o2) {
        if (!java.util.Objects.equals(o1, o2)) {
            throw new AssertionError(o1 + " != " + o2);
        }
    }

    static class CustomCL extends ClassLoader {
        final String  innerName;
        final String  outerName;

        final byte[] innerClassFile;
        final byte[] outerClassFile;

        CustomCL(String innerName, String outerName, byte[] innerClassFile, byte[] outerClassFile) {
            this.innerName = innerName;
            this.outerName = outerName;
            this.innerClassFile = innerClassFile;
            this.outerClassFile = outerClassFile;
        }
        @Override
        protected Class<?> findClass(String name) throws ClassNotFoundException {
            if (innerName.equals(name)) {
                return defineClass(innerName, innerClassFile, 0, innerClassFile.length);
            } else if (outerName.equals(name)) {
                return defineClass(outerName, outerClassFile, 0, outerClassFile.length);
            } else {
                throw new ClassNotFoundException(name);
            }
        }
    }

    static class BytecodeGenerator {
        final ClassDesc innerName;
        final ClassDesc outerName;
        final String simpleName;

        BytecodeGenerator(String innerName, String outerName, String simpleName) {
            this.innerName = ClassDesc.of(innerName);
            this.outerName = ClassDesc.of(outerName);
            this.simpleName = simpleName;
        }

        static void makeDefaultCtor(ClassBuilder clb) {
            clb.withMethodBody(INIT_NAME, MTD_void, ACC_PUBLIC, cb -> {
                cb.aload(0);
                cb.invokespecial(CD_Object, INIT_NAME, MTD_void);
                cb.return_();
            });
        }

        void makeCtxk(ClassBuilder clb, boolean isInner) {
            if (isInner) {
                clb.with(EnclosingMethodAttribute.of(outerName,
                        Optional.of("f"), Optional.of(MTD_void)));
            } else {
                clb.withMethodBody("f", MTD_void, ACC_PUBLIC | ACC_STATIC,
                        CodeBuilder::return_);
            }
        }

        byte[] getNestedClasses(boolean isInner) {
            var name = (isInner ? innerName : outerName);
            return ClassFile.of().build(name, clb -> {
                clb.withSuperclass(CD_Object);
                clb.withFlags(AccessFlag.PUBLIC, AccessFlag.SUPER);
                clb.with(InnerClassesAttribute.of(
                        InnerClassInfo.of(innerName,
                                Optional.of(outerName),
                                Optional.of(simpleName))));
                makeDefaultCtor(clb);
            });
        }

        byte[] getInnerClasses(boolean isInner) {
            var name = (isInner ? innerName : outerName);
            return ClassFile.of().build(name, clb -> {
                clb.withSuperclass(CD_Object);
                clb.withFlags(AccessFlag.PUBLIC, AccessFlag.SUPER);
                clb.with(InnerClassesAttribute.of(
                        InnerClassInfo.of(innerName,
                                Optional.of(outerName),
                                Optional.of(simpleName),
                                AccessFlag.PUBLIC)));
                makeDefaultCtor(clb);
            });
        }

        byte[] getLocalClasses(boolean isInner) {
            var name = (isInner ? innerName : outerName);
            return ClassFile.of().build(name, clb -> {
                clb.withSuperclass(CD_Object);
                clb.withFlags(AccessFlag.PUBLIC, AccessFlag.SUPER);
                clb.with(InnerClassesAttribute.of(
                        InnerClassInfo.of(innerName,
                                Optional.empty(),
                                Optional.of(simpleName),
                                AccessFlag.PUBLIC, AccessFlag.STATIC)));
                makeDefaultCtor(clb);
                makeCtxk(clb, isInner);
            });
        }

        byte[] getAnonymousClasses(boolean isInner) {
            var name = (isInner ? innerName : outerName);
            return ClassFile.of().build(name, clb -> {
                clb.withSuperclass(CD_Object);
                clb.withFlags(AccessFlag.PUBLIC, AccessFlag.SUPER);
                clb.with(InnerClassesAttribute.of(
                        InnerClassInfo.of(innerName,
                                Optional.empty(),
                                Optional.empty(),
                                AccessFlag.PUBLIC, AccessFlag.STATIC)));
                makeDefaultCtor(clb);
                makeCtxk(clb, isInner);
            });
        }
    }
}