com.google.java.contract.core.agent.ContractFixingClassAdapter.java Source code

Introduction

Here is the source code for com.google.java.contract.core.agent.ContractFixingClassAdapter.java

Source

/*
 * Copyright 2007 Johannes Rieken
 * Copyright 2010 Google Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */
package com.google.java.contract.core.agent;

import com.google.java.contract.Requires;
import com.google.java.contract.core.util.JavaUtils;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.Handle;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

/**
 * A class adapter that transforms injected contract methods to remove
 * contract compilation artefacts:
 *
 * <ul>
 * <li>fix calls to {@code access$n} synthetic methods for inner/nested
 * classes.
 * </ul>
 *
 * @author nhat.minh.le@huoc.org (Nhat Minh L)
 */
class ContractFixingClassAdapter extends ClassVisitor {
    /**
     * A method adapter that amends calls to {@code access$n} synthetic
     * methods. These methods are generated for access to members from
     * inner/nested classes. Contract compilation may generate some of
     * these, which are renamed and injected into the original class
     * bytecode during instrumentation. Calls to these methods need to
     * be fixed to use the new names.
     */
    protected static class AccessMethodAdapter extends MethodVisitor {
        /**
         * Constructs a new AccessMethodAdapter.
         *
         * @param mv the MethodVisitor this adapter delegates to
         */
        @Requires("mv != null")
        public AccessMethodAdapter(MethodVisitor mv) {
            super(Opcodes.ASM5, mv);
        }

        /**
         * Converts calls to {@code access$n} synthetic methods to the
         * equivalent injected methods.
         */
        @Override
        public void visitMethodInsn(int opcode, String owner, String name, String desc, boolean itf) {
            if (!name.startsWith("access$")) {
                mv.visitMethodInsn(opcode, owner, name, desc, itf);
            } else {
                String newName = JavaUtils.SYNTHETIC_MEMBER_PREFIX + name;
                mv.visitMethodInsn(opcode, owner, newName, desc, itf);
            }
        }

        /**
         * Converts calls to {@code lambda$n} synthetic methods to the
         * equivalent injected methods.
         */
        @Override
        public void visitInvokeDynamicInsn(String name, String desc, Handle bsm, Object... bsmArgs) {
            for (int i = 0; i < bsmArgs.length; ++i) {
                if (!(bsmArgs[i] instanceof Handle)) {
                    continue;
                }
                Handle h = (Handle) bsmArgs[i];
                if (!h.getName().startsWith("lambda$")) {
                    continue;
                }
                String newName = JavaUtils.SYNTHETIC_MEMBER_PREFIX + h.getName();
                bsmArgs[i] = new Handle(h.getTag(), h.getOwner(), newName, h.getDesc());
            }
            mv.visitInvokeDynamicInsn(name, desc, bsm, bsmArgs);
        }
    }

    /**
     * Constructs a new ContractFixingClassAdapter.
     *
     * @param cv the ClassVisitor this adapter delegates to
     */
    @Requires("cv != null")
    public ContractFixingClassAdapter(ClassVisitor cv) {
        super(Opcodes.ASM5, cv);
    }

    /**
     * Visits the specified method fixing method calls.
     */
    @Override
    public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
        MethodVisitor mv = cv.visitMethod(access | Opcodes.ACC_SYNTHETIC, name, desc, signature, exceptions);
        return new AccessMethodAdapter(mv);
    }
}