Java tutorial
// ASM: a very small and fast Java bytecode manipulation framework // Copyright (c) 2000-2011 INRIA, France Telecom // All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions // are met: // 1. Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // 2. Redistributions in binary form must reproduce the above copyright // notice, this list of conditions and the following disclaimer in the // documentation and/or other materials provided with the distribution. // 3. Neither the name of the copyright holders nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF // THE POSSIBILITY OF SUCH DAMAGE. package org.objectweb.asm.util; import java.io.PrintWriter; import org.objectweb.asm.AnnotationVisitor; import org.objectweb.asm.Attribute; import org.objectweb.asm.ClassVisitor; import org.objectweb.asm.FieldVisitor; import org.objectweb.asm.MethodVisitor; import org.objectweb.asm.ModuleVisitor; import org.objectweb.asm.Opcodes; import org.objectweb.asm.RecordComponentVisitor; import org.objectweb.asm.TypePath; /** * A {@link ClassVisitor} that prints the classes it visits with a {@link Printer}. This class * visitor can be used in the middle of a class visitor chain to trace the class that is visited at * a given point in this chain. This may be useful for debugging purposes. * * <p>When used with a {@link Textifier}, the trace printed when visiting the {@code Hello} class is * the following: * * <pre> * // class version 49.0 (49) // access flags 0x21 public class Hello { * * // compiled from: Hello.java * * // access flags 0x1 * public <init> ()V * ALOAD 0 * INVOKESPECIAL java/lang/Object <init> ()V * RETURN * MAXSTACK = 1 MAXLOCALS = 1 * * // access flags 0x9 * public static main ([Ljava/lang/String;)V * GETSTATIC java/lang/System out Ljava/io/PrintStream; * LDC "hello" * INVOKEVIRTUAL java/io/PrintStream println (Ljava/lang/String;)V * RETURN * MAXSTACK = 2 MAXLOCALS = 1 * } * </pre> * * <p>where {@code Hello} is defined by: * * <pre> * public class Hello { * * public static void main(String[] args) { * System.out.println("hello"); * } * } * </pre> * * @author Eric Bruneton * @author Eugene Kuleshov */ public final class TraceClassVisitor extends ClassVisitor { /** The print writer to be used to print the class. May be {@literal null}. */ private final PrintWriter printWriter; /** The printer to convert the visited class into text. */ // DontCheck(MemberName): can't be renamed (for backward binary compatibility). public final Printer p; /** * Constructs a new {@link TraceClassVisitor}. * * @param printWriter the print writer to be used to print the class. May be {@literal null}. */ public TraceClassVisitor(final PrintWriter printWriter) { this(null, printWriter); } /** * Constructs a new {@link TraceClassVisitor}. * * @param classVisitor the class visitor to which to delegate calls. May be {@literal null}. * @param printWriter the print writer to be used to print the class. May be {@literal null}. */ public TraceClassVisitor(final ClassVisitor classVisitor, final PrintWriter printWriter) { this(classVisitor, new Textifier(), printWriter); } /** * Constructs a new {@link TraceClassVisitor}. * * @param classVisitor the class visitor to which to delegate calls. May be {@literal null}. * @param printer the printer to convert the visited class into text. * @param printWriter the print writer to be used to print the class. May be {@literal null}. */ public TraceClassVisitor(final ClassVisitor classVisitor, final Printer printer, final PrintWriter printWriter) { super(/* latest api = */ Opcodes.ASM8_EXPERIMENTAL, classVisitor); this.printWriter = printWriter; this.p = printer; } @Override public void visit(final int version, final int access, final String name, final String signature, final String superName, final String[] interfaces) { p.visit(version, access, name, signature, superName, interfaces); super.visit(version, access, name, signature, superName, interfaces); } @Override public void visitSource(final String file, final String debug) { p.visitSource(file, debug); super.visitSource(file, debug); } @Override public ModuleVisitor visitModule(final String name, final int flags, final String version) { Printer modulePrinter = p.visitModule(name, flags, version); return new TraceModuleVisitor(super.visitModule(name, flags, version), modulePrinter); } @Override public void visitNestHost(final String nestHost) { p.visitNestHost(nestHost); super.visitNestHost(nestHost); } @Override public void visitOuterClass(final String owner, final String name, final String descriptor) { p.visitOuterClass(owner, name, descriptor); super.visitOuterClass(owner, name, descriptor); } @Override public AnnotationVisitor visitAnnotation(final String descriptor, final boolean visible) { Printer annotationPrinter = p.visitClassAnnotation(descriptor, visible); return new TraceAnnotationVisitor(super.visitAnnotation(descriptor, visible), annotationPrinter); } @Override public AnnotationVisitor visitTypeAnnotation(final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) { Printer annotationPrinter = p.visitClassTypeAnnotation(typeRef, typePath, descriptor, visible); return new TraceAnnotationVisitor(super.visitTypeAnnotation(typeRef, typePath, descriptor, visible), annotationPrinter); } @Override public void visitAttribute(final Attribute attribute) { p.visitClassAttribute(attribute); super.visitAttribute(attribute); } @Override public void visitNestMember(final String nestMember) { p.visitNestMember(nestMember); super.visitNestMember(nestMember); } @Override public void visitPermittedSubtypeExperimental(final String permittedSubtype) { p.visitPermittedSubtypeExperimental(permittedSubtype); super.visitPermittedSubtypeExperimental(permittedSubtype); } @Override public void visitInnerClass(final String name, final String outerName, final String innerName, final int access) { p.visitInnerClass(name, outerName, innerName, access); super.visitInnerClass(name, outerName, innerName, access); } @Override public RecordComponentVisitor visitRecordComponentExperimental(final int access, final String name, final String descriptor, final String signature) { Printer recordComponentPrinter = p.visitRecordComponentExperimental(access, name, descriptor, signature); return new TraceRecordComponentVisitor( super.visitRecordComponentExperimental(access, name, descriptor, signature), recordComponentPrinter); } @Override public FieldVisitor visitField(final int access, final String name, final String descriptor, final String signature, final Object value) { Printer fieldPrinter = p.visitField(access, name, descriptor, signature, value); return new TraceFieldVisitor(super.visitField(access, name, descriptor, signature, value), fieldPrinter); } @Override public MethodVisitor visitMethod(final int access, final String name, final String descriptor, final String signature, final String[] exceptions) { Printer methodPrinter = p.visitMethod(access, name, descriptor, signature, exceptions); return new TraceMethodVisitor(super.visitMethod(access, name, descriptor, signature, exceptions), methodPrinter); } @Override public void visitEnd() { p.visitClassEnd(); if (printWriter != null) { p.print(printWriter); printWriter.flush(); } super.visitEnd(); } }