Java example source code file (ClassGenerator.java)

This example Java source code file (ClassGenerator.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.

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Java - Java tags/keywords

acc_public, accessorproperty_create_desc, classgenerator, classreader, classvisitor, fieldvisitor, handle, init, memberinfo, methodgenerator, methodvisitor, scriptclassinfo, setter_prefix, string, util

The ClassGenerator.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.ACC_FINAL;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PRIVATE;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PUBLIC;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_STATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKESTATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKEVIRTUAL;
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.GETTER_PREFIX;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.GET_CLASS_NAME;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.GET_CLASS_NAME_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.INIT;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.ACCESSORPROPERTY_CREATE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.ACCESSORPROPERTY_CREATE_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.ACCESSORPROPERTY_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.LIST_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.ARRAYLIST_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.ARRAYLIST_INIT_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.COLLECTION_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.COLLECTION_ADD;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.COLLECTION_ADD_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.COLLECTIONS_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.COLLECTIONS_EMPTY_LIST;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_FIELD_NAME;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_SETISSHARED;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_SETISSHARED_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_NEWMAP;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_NEWMAP_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.OBJECT_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTIONIMPL_MAKEFUNCTION;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTIONIMPL_MAKEFUNCTION_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTIONIMPL_MAKEFUNCTION_SPECS_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTIONIMPL_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTION_SETARITY;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTION_SETARITY_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTION_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SETTER_PREFIX;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.TYPE_OBJECT;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.List;
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.Handle;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Type;
import jdk.nashorn.internal.tools.nasgen.MemberInfo.Kind;

/**
 * Base class for class generator classes.
 *
 */
public class ClassGenerator {
    /** ASM class writer used to output bytecode for this class */
    protected final ClassWriter cw;

    /**
     * Constructor
     */
    protected ClassGenerator() {
        this.cw = makeClassWriter();
    }

    MethodGenerator makeStaticInitializer() {
        return makeStaticInitializer(cw);
    }

    MethodGenerator makeConstructor() {
        return makeConstructor(cw);
    }

    MethodGenerator makeMethod(final int access, final String name, final String desc) {
        return makeMethod(cw, access, name, desc);
    }

    void addMapField() {
        addMapField(cw);
    }

    void addField(final String name, final String desc) {
        addField(cw, name, desc);
    }

    void addFunctionField(final String name) {
        addFunctionField(cw, name);
    }

    void addGetter(final String owner, final MemberInfo memInfo) {
        addGetter(cw, owner, memInfo);
    }

    void addSetter(final String owner, final MemberInfo memInfo) {
        addSetter(cw, owner, memInfo);
    }

    void emitGetClassName(final String name) {
        final MethodGenerator mi = makeMethod(ACC_PUBLIC, GET_CLASS_NAME, GET_CLASS_NAME_DESC);
        mi.loadLiteral(name);
        mi.returnValue();
        mi.computeMaxs();
        mi.visitEnd();
    }

    static ClassWriter makeClassWriter() {
        return new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS) {
            @Override
            protected String getCommonSuperClass(final String type1, final String type2) {
                try {
                    return super.getCommonSuperClass(type1, type2);
                } catch (final RuntimeException | LinkageError e) {
                    return StringConstants.OBJECT_TYPE;
                }
            }
        };
    }

    static MethodGenerator makeStaticInitializer(final ClassVisitor cv) {
        return makeStaticInitializer(cv, CLINIT);
    }

    static MethodGenerator makeStaticInitializer(final ClassVisitor cv, final String name) {
        final int access =  ACC_PUBLIC | ACC_STATIC;
        final String desc = DEFAULT_INIT_DESC;
        final MethodVisitor mv = cv.visitMethod(access, name, desc, null, null);
        return new MethodGenerator(mv, access, name, desc);
    }

    static MethodGenerator makeConstructor(final ClassVisitor cv) {
        final int access = 0;
        final String name = INIT;
        final String desc = DEFAULT_INIT_DESC;
        final MethodVisitor mv = cv.visitMethod(access, name, desc, null, null);
        return new MethodGenerator(mv, access, name, desc);
    }

    static MethodGenerator makeMethod(final ClassVisitor cv, final int access, final String name, final String desc) {
        final MethodVisitor mv = cv.visitMethod(access, name, desc, null, null);
        return new MethodGenerator(mv, access, name, desc);
    }

    static void emitStaticInitPrefix(final MethodGenerator mi, final String className, final int memberCount) {
        mi.visitCode();
        if (memberCount > 0) {
            // new ArrayList(int)
            mi.newObject(ARRAYLIST_TYPE);
            mi.dup();
            mi.push(memberCount);
            mi.invokeSpecial(ARRAYLIST_TYPE, INIT, ARRAYLIST_INIT_DESC);
            // stack: ArrayList
        } else {
            // java.util.Collections.EMPTY_LIST
            mi.getStatic(COLLECTIONS_TYPE, COLLECTIONS_EMPTY_LIST, LIST_DESC);
            // stack List
        }
    }

    static void emitStaticInitSuffix(final MethodGenerator mi, final String className) {
        // stack: Collection
        // pmap = PropertyMap.newMap(Collection<Property>);
        mi.invokeStatic(PROPERTYMAP_TYPE, PROPERTYMAP_NEWMAP, PROPERTYMAP_NEWMAP_DESC);
        // pmap.setIsShared();
        mi.invokeVirtual(PROPERTYMAP_TYPE, PROPERTYMAP_SETISSHARED, PROPERTYMAP_SETISSHARED_DESC);
        // $nasgenmap$ = pmap;
        mi.putStatic(className, PROPERTYMAP_FIELD_NAME, PROPERTYMAP_DESC);
        mi.returnVoid();
        mi.computeMaxs();
        mi.visitEnd();
    }

    @SuppressWarnings("fallthrough")
    private static Type memInfoType(final MemberInfo memInfo) {
        switch (memInfo.getJavaDesc().charAt(0)) {
            case 'I': return Type.INT_TYPE;
            case 'J': return Type.LONG_TYPE;
            case 'D': return Type.DOUBLE_TYPE;
            default:  assert false : memInfo.getJavaDesc();
            case 'L': return TYPE_OBJECT;
        }
    }

    private static String getterDesc(final MemberInfo memInfo) {
        return Type.getMethodDescriptor(memInfoType(memInfo));
    }

    private static String setterDesc(final MemberInfo memInfo) {
        return Type.getMethodDescriptor(Type.VOID_TYPE, memInfoType(memInfo));
    }

    static void addGetter(final ClassVisitor cv, final String owner, final MemberInfo memInfo) {
        final int access = ACC_PUBLIC;
        final String name = GETTER_PREFIX + memInfo.getJavaName();
        final String desc = getterDesc(memInfo);
        final MethodVisitor mv = cv.visitMethod(access, name, desc, null, null);
        final MethodGenerator mi = new MethodGenerator(mv, access, name, desc);
        mi.visitCode();
        if (memInfo.isStatic() && memInfo.getKind() == Kind.PROPERTY) {
            mi.getStatic(owner, memInfo.getJavaName(), memInfo.getJavaDesc());
        } else {
            mi.loadLocal(0);
            mi.getField(owner, memInfo.getJavaName(), memInfo.getJavaDesc());
        }
        mi.returnValue();
        mi.computeMaxs();
        mi.visitEnd();
    }

    static void addSetter(final ClassVisitor cv, final String owner, final MemberInfo memInfo) {
        final int access = ACC_PUBLIC;
        final String name = SETTER_PREFIX + memInfo.getJavaName();
        final String desc = setterDesc(memInfo);
        final MethodVisitor mv = cv.visitMethod(access, name, desc, null, null);
        final MethodGenerator mi = new MethodGenerator(mv, access, name, desc);
        mi.visitCode();
        if (memInfo.isStatic() && memInfo.getKind() == Kind.PROPERTY) {
            mi.loadLocal(1);
            mi.putStatic(owner, memInfo.getJavaName(), memInfo.getJavaDesc());
        } else {
            mi.loadLocal(0);
            mi.loadLocal(1);
            mi.putField(owner, memInfo.getJavaName(), memInfo.getJavaDesc());
        }
        mi.returnVoid();
        mi.computeMaxs();
        mi.visitEnd();
    }

    static void addMapField(final ClassVisitor cv) {
        // add a PropertyMap static field
        final FieldVisitor fv = cv.visitField(ACC_PRIVATE | ACC_STATIC | ACC_FINAL,
            PROPERTYMAP_FIELD_NAME, PROPERTYMAP_DESC, null, null);
        if (fv != null) {
            fv.visitEnd();
        }
    }

    static void addField(final ClassVisitor cv, final String name, final String desc) {
        final FieldVisitor fv = cv.visitField(ACC_PRIVATE, name, desc, null, null);
        if (fv != null) {
            fv.visitEnd();
        }
    }

    static void addFunctionField(final ClassVisitor cv, final String name) {
        addField(cv, name, OBJECT_DESC);
    }

    static void newFunction(final MethodGenerator mi, final String className, final MemberInfo memInfo, final List<MemberInfo> specs) {
        final boolean arityFound = (memInfo.getArity() != MemberInfo.DEFAULT_ARITY);

        mi.loadLiteral(memInfo.getName());
        mi.visitLdcInsn(new Handle(H_INVOKESTATIC, className, memInfo.getJavaName(), memInfo.getJavaDesc()));

        assert specs != null;
        if (!specs.isEmpty()) {
            mi.memberInfoArray(className, specs);
            mi.invokeStatic(SCRIPTFUNCTIONIMPL_TYPE, SCRIPTFUNCTIONIMPL_MAKEFUNCTION, SCRIPTFUNCTIONIMPL_MAKEFUNCTION_SPECS_DESC);
        } else {
            mi.invokeStatic(SCRIPTFUNCTIONIMPL_TYPE, SCRIPTFUNCTIONIMPL_MAKEFUNCTION, SCRIPTFUNCTIONIMPL_MAKEFUNCTION_DESC);
        }

        if (arityFound) {
            mi.dup();
            mi.push(memInfo.getArity());
            mi.invokeVirtual(SCRIPTFUNCTION_TYPE, SCRIPTFUNCTION_SETARITY, SCRIPTFUNCTION_SETARITY_DESC);
        }

    }

    static void linkerAddGetterSetter(final MethodGenerator mi, final String className, final MemberInfo memInfo) {
        final String propertyName = memInfo.getName();
        // stack: Collection
        // dup of Collection instance
        mi.dup();

        // property = AccessorProperty.create(key, flags, getter, setter);
        mi.loadLiteral(propertyName);
        // setup flags
        mi.push(memInfo.getAttributes());
        // setup getter method handle
        String javaName = GETTER_PREFIX + memInfo.getJavaName();
        mi.visitLdcInsn(new Handle(H_INVOKEVIRTUAL, className, javaName, getterDesc(memInfo)));
        // setup setter method handle
        if (memInfo.isFinal()) {
            mi.pushNull();
        } else {
            javaName = SETTER_PREFIX + memInfo.getJavaName();
            mi.visitLdcInsn(new Handle(H_INVOKEVIRTUAL, className, javaName, setterDesc(memInfo)));
        }
        mi.invokeStatic(ACCESSORPROPERTY_TYPE, ACCESSORPROPERTY_CREATE, ACCESSORPROPERTY_CREATE_DESC);
        // boolean Collection.add(property)
        mi.invokeInterface(COLLECTION_TYPE, COLLECTION_ADD, COLLECTION_ADD_DESC);
        // pop return value of Collection.add
        mi.pop();
        // stack: Collection
    }

    static void linkerAddGetterSetter(final MethodGenerator mi, final String className, final MemberInfo getter, final MemberInfo setter) {
        final String propertyName = getter.getName();
        // stack: Collection
        // dup of Collection instance
        mi.dup();

        // property = AccessorProperty.create(key, flags, getter, setter);
        mi.loadLiteral(propertyName);
        // setup flags
        mi.push(getter.getAttributes());
        // setup getter method handle
        mi.visitLdcInsn(new Handle(H_INVOKESTATIC, className,
                getter.getJavaName(), getter.getJavaDesc()));
        // setup setter method handle
        if (setter == null) {
            mi.pushNull();
        } else {
            mi.visitLdcInsn(new Handle(H_INVOKESTATIC, className,
                    setter.getJavaName(), setter.getJavaDesc()));
        }
        mi.invokeStatic(ACCESSORPROPERTY_TYPE, ACCESSORPROPERTY_CREATE, ACCESSORPROPERTY_CREATE_DESC);
        // boolean Collection.add(property)
        mi.invokeInterface(COLLECTION_TYPE, COLLECTION_ADD, COLLECTION_ADD_DESC);
        // pop return value of Collection.add
        mi.pop();
        // stack: Collection
    }

    static ScriptClassInfo getScriptClassInfo(final String fileName) throws IOException {
        try (BufferedInputStream bis = new BufferedInputStream(new FileInputStream(fileName))) {
            return getScriptClassInfo(new ClassReader(bis));
        }
    }

    static ScriptClassInfo getScriptClassInfo(final byte[] classBuf) {
        return getScriptClassInfo(new ClassReader(classBuf));
    }

    private static ScriptClassInfo getScriptClassInfo(final ClassReader reader) {
        final ScriptClassInfoCollector scic = new ScriptClassInfoCollector();
        reader.accept(scic, 0);
        return scic.getScriptClassInfo();
    }
}