Java example source code file (ScriptClassInstrumentor.java)

This example Java source code file (ScriptClassInstrumentor.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotationvisitor, checkclassadapter, classreader, classvisitor, clinit, default_init_desc, fileoutputstream, memberinfo, methodgenerator, methodvisitor, override, scriptclassinfo, scriptclassinstrumentor, string

The ScriptClassInstrumentor.java Java example source code

/*
 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * 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).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk.nashorn.internal.tools.nasgen;

import static jdk.internal.org.objectweb.asm.Opcodes.ALOAD;
import static jdk.internal.org.objectweb.asm.Opcodes.DUP;
import static jdk.internal.org.objectweb.asm.Opcodes.INVOKESPECIAL;
import static jdk.internal.org.objectweb.asm.Opcodes.INVOKESTATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.NEW;
import static jdk.internal.org.objectweb.asm.Opcodes.PUTFIELD;
import static jdk.internal.org.objectweb.asm.Opcodes.RETURN;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.$CLINIT$;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.CLINIT;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.DEFAULT_INIT_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.INIT;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.OBJECT_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTOBJECT_TYPE;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import jdk.internal.org.objectweb.asm.AnnotationVisitor;
import jdk.internal.org.objectweb.asm.Attribute;
import jdk.internal.org.objectweb.asm.ClassReader;
import jdk.internal.org.objectweb.asm.ClassVisitor;
import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.FieldVisitor;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Opcodes;
import jdk.internal.org.objectweb.asm.util.CheckClassAdapter;
import jdk.nashorn.internal.objects.annotations.Where;
import jdk.nashorn.internal.tools.nasgen.MemberInfo.Kind;

/**
 * This class instruments the java class annotated with @ScriptClass.
 *
 * Changes done are:
 *
 * 1) remove all jdk.nashorn.internal.objects.annotations.* annotations.
 * 2) static final @Property fields stay here. Other @Property fields moved to
 *    respective classes depending on 'where' value of annotation.
 * 2) add "Map" type static field named "$map".
 * 3) add static initializer block to initialize map.
 */

public class ScriptClassInstrumentor extends ClassVisitor {
    private final ScriptClassInfo scriptClassInfo;
    private final int memberCount;
    private boolean staticInitFound;

    ScriptClassInstrumentor(final ClassVisitor visitor, final ScriptClassInfo sci) {
        super(Opcodes.ASM4, visitor);
        if (sci == null) {
            throw new IllegalArgumentException("Null ScriptClassInfo, is the class annotated?");
        }
        this.scriptClassInfo = sci;
        this.memberCount = scriptClassInfo.getInstancePropertyCount();
    }

    @Override
    public AnnotationVisitor visitAnnotation(final String desc, final boolean visible) {
        if (ScriptClassInfo.annotations.containsKey(desc)) {
            // ignore @ScriptClass
            return null;
        }

        return super.visitAnnotation(desc, visible);
    }

    @Override
    public FieldVisitor visitField(final int fieldAccess, final String fieldName,
            final String fieldDesc, final String signature, final Object value) {
        final MemberInfo memInfo = scriptClassInfo.find(fieldName, fieldDesc, fieldAccess);
        if (memInfo != null && memInfo.getKind() == Kind.PROPERTY &&
                memInfo.getWhere() != Where.INSTANCE && !memInfo.isStaticFinal()) {
            // non-instance @Property fields - these have to go elsewhere unless 'static final'
            return null;
        }

        final FieldVisitor delegateFV = super.visitField(fieldAccess, fieldName, fieldDesc,
                signature, value);
        return new FieldVisitor(Opcodes.ASM4, delegateFV) {
            @Override
            public AnnotationVisitor visitAnnotation(final String desc, final boolean visible) {
                if (ScriptClassInfo.annotations.containsKey(desc)) {
                    // ignore script field annotations
                    return null;
                }

                return fv.visitAnnotation(desc, visible);
            }

            @Override
            public void visitAttribute(final Attribute attr) {
                fv.visitAttribute(attr);
            }

            @Override
            public void visitEnd() {
                fv.visitEnd();
            }
        };
    }

    @Override
    public MethodVisitor visitMethod(final int methodAccess, final String methodName,
            final String methodDesc, final String signature, final String[] exceptions) {

        final boolean isConstructor = INIT.equals(methodName);
        final boolean isStaticInit  = CLINIT.equals(methodName);

        if (isStaticInit) {
            staticInitFound = true;
        }

        final MethodGenerator delegateMV = new MethodGenerator(super.visitMethod(methodAccess, methodName, methodDesc,
                signature, exceptions), methodAccess, methodName, methodDesc);

        return new MethodVisitor(Opcodes.ASM4, delegateMV) {
            @Override
            public void visitInsn(final int opcode) {
                // call $clinit$ just before return from <clinit>
                if (isStaticInit && opcode == RETURN) {
                    super.visitMethodInsn(INVOKESTATIC, scriptClassInfo.getJavaName(),
                            $CLINIT$, DEFAULT_INIT_DESC);
                }
                super.visitInsn(opcode);
            }

            @Override
            public void visitMethodInsn(final int opcode, final String owner, final String name, final String desc) {
                if (isConstructor && opcode == INVOKESPECIAL &&
                        INIT.equals(name) && SCRIPTOBJECT_TYPE.equals(owner)) {
                    super.visitMethodInsn(opcode, owner, name, desc);

                    if (memberCount > 0) {
                        // initialize @Property fields if needed
                        for (final MemberInfo memInfo : scriptClassInfo.getMembers()) {
                            if (memInfo.isInstanceProperty() && !memInfo.getInitClass().isEmpty()) {
                                final String clazz = memInfo.getInitClass();
                                super.visitVarInsn(ALOAD, 0);
                                super.visitTypeInsn(NEW, clazz);
                                super.visitInsn(DUP);
                                super.visitMethodInsn(INVOKESPECIAL, clazz,
                                    INIT, DEFAULT_INIT_DESC);
                                super.visitFieldInsn(PUTFIELD, scriptClassInfo.getJavaName(),
                                    memInfo.getJavaName(), memInfo.getJavaDesc());
                            }

                            if (memInfo.isInstanceFunction()) {
                                super.visitVarInsn(ALOAD, 0);
                                ClassGenerator.newFunction(delegateMV, scriptClassInfo.getJavaName(), memInfo, scriptClassInfo.findSpecializations(memInfo.getJavaName()));
                                super.visitFieldInsn(PUTFIELD, scriptClassInfo.getJavaName(),
                                    memInfo.getJavaName(), OBJECT_DESC);
                            }
                        }
                    }
                } else {
                    super.visitMethodInsn(opcode, owner, name, desc);
                }
            }

            @Override
            public AnnotationVisitor visitAnnotation(final String desc, final boolean visible) {
                if (ScriptClassInfo.annotations.containsKey(desc)) {
                    // ignore script method annotations
                    return null;
                }
                return super.visitAnnotation(desc, visible);
            }
        };
    }

    @Override
    public void visitEnd() {
        emitFields();
        emitStaticInitializer();
        emitGettersSetters();
        super.visitEnd();
    }

    private void emitFields() {
        // introduce "Function" type instance fields for each
        // instance @Function in script class info
        final String className = scriptClassInfo.getJavaName();
        for (MemberInfo memInfo : scriptClassInfo.getMembers()) {
            if (memInfo.isInstanceFunction()) {
                ClassGenerator.addFunctionField(cv, memInfo.getJavaName());
                memInfo = (MemberInfo)memInfo.clone();
                memInfo.setJavaDesc(OBJECT_DESC);
                ClassGenerator.addGetter(cv, className, memInfo);
                ClassGenerator.addSetter(cv, className, memInfo);
            }
        }
        // omit addMapField() since instance classes already define a static PropertyMap field
    }

    void emitGettersSetters() {
        if (memberCount > 0) {
            for (final MemberInfo memInfo : scriptClassInfo.getMembers()) {
                final String className = scriptClassInfo.getJavaName();
                if (memInfo.isInstanceProperty()) {
                    ClassGenerator.addGetter(cv, className, memInfo);
                    if (! memInfo.isFinal()) {
                        ClassGenerator.addSetter(cv, className, memInfo);
                    }
                }
            }
        }
    }

    private void emitStaticInitializer() {
        final String className = scriptClassInfo.getJavaName();
        if (! staticInitFound) {
            // no user written <clinit> and so create one
            final MethodVisitor mv = ClassGenerator.makeStaticInitializer(this);
            mv.visitCode();
            mv.visitInsn(RETURN);
            mv.visitMaxs(Short.MAX_VALUE, 0);
            mv.visitEnd();
        }
        // Now generate $clinit$
        final MethodGenerator mi = ClassGenerator.makeStaticInitializer(this, $CLINIT$);
        ClassGenerator.emitStaticInitPrefix(mi, className, memberCount);
        if (memberCount > 0) {
            for (final MemberInfo memInfo : scriptClassInfo.getMembers()) {
                if (memInfo.isInstanceProperty() || memInfo.isInstanceFunction()) {
                    ClassGenerator.linkerAddGetterSetter(mi, className, memInfo);
                } else if (memInfo.isInstanceGetter()) {
                    final MemberInfo setter = scriptClassInfo.findSetter(memInfo);
                    ClassGenerator.linkerAddGetterSetter(mi, className, memInfo, setter);
                }
            }
        }
        ClassGenerator.emitStaticInitSuffix(mi, className);
    }

    /**
     * External entry point for ScriptClassInfoCollector if run from the command line
     *
     * @param args arguments - one argument is needed, the name of the class to collect info from
     *
     * @throws IOException if there are problems reading class
     */
    public static void main(final String[] args) throws IOException {
        if (args.length != 1) {
            System.err.println("Usage: " + ScriptClassInfoCollector.class.getName() + " <class>");
            System.exit(1);
        }

        final String fileName = args[0].replace('.', '/') + ".class";
        final ScriptClassInfo sci = ClassGenerator.getScriptClassInfo(fileName);
        if (sci == null) {
            System.err.println("No @ScriptClass in " + fileName);
            System.exit(2);
            throw new AssertionError(); //guard against warning that sci is null below
        }

        try {
            sci.verify();
        } catch (final Exception e) {
            System.err.println(e.getMessage());
            System.exit(3);
        }

        final ClassWriter writer = ClassGenerator.makeClassWriter();
        try (final BufferedInputStream bis = new BufferedInputStream(new FileInputStream(fileName))) {
            final ClassReader reader = new ClassReader(bis);
            final CheckClassAdapter checker = new CheckClassAdapter(writer);
            final ScriptClassInstrumentor instr = new ScriptClassInstrumentor(checker, sci);
            reader.accept(instr, 0);
        }

        try (FileOutputStream fos = new FileOutputStream(fileName)) {
            fos.write(writer.toByteArray());
        }
    }
}