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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * 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
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 */
package jdk.internal.org.objectweb.asm.util;

import java.io.PrintWriter;

import jdk.internal.org.objectweb.asm.AnnotationVisitor;
import jdk.internal.org.objectweb.asm.Attribute;
import jdk.internal.org.objectweb.asm.ClassVisitor;
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.TypePath;

A ClassVisitor that prints the classes it visits with a 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.

The trace printed when visiting the Hello class is the following:

// 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 }
where Hello is defined by:

public class Hello {
    public static void main(String[] args) {
        System.out.println("hello");
    }
}
Author:Eric Bruneton, Eugene Kuleshov
/** * 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> * The trace printed when visiting the <tt>Hello</tt> class is the following: * <p> * <blockquote> * * <pre> * // class version 49.0 (49) // access flags 0x21 public class Hello { * * // compiled from: Hello.java * * // access flags 0x1 public &lt;init&gt; ()V ALOAD 0 INVOKESPECIAL * java/lang/Object &lt;init&gt; ()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 &quot;hello&quot; * INVOKEVIRTUAL java/io/PrintStream println (Ljava/lang/String;)V RETURN * MAXSTACK = 2 MAXLOCALS = 1 } * </pre> * * </blockquote> where <tt>Hello</tt> is defined by: * <p> * <blockquote> * * <pre> * public class Hello { * * public static void main(String[] args) { * System.out.println(&quot;hello&quot;); * } * } * </pre> * * </blockquote> * * @author Eric Bruneton * @author Eugene Kuleshov */
public final class TraceClassVisitor extends ClassVisitor {
The print writer to be used to print the class. May be null.
/** * The print writer to be used to print the class. May be null. */
private final PrintWriter pw;
The object that actually converts visit events into text.
/** * The object that actually converts visit events into text. */
public final Printer p;
Constructs a new TraceClassVisitor.
Params:
  • pw – the print writer to be used to print the class.
/** * Constructs a new {@link TraceClassVisitor}. * * @param pw * the print writer to be used to print the class. */
public TraceClassVisitor(final PrintWriter pw) { this(null, pw); }
Constructs a new TraceClassVisitor.
Params:
  • cv – the ClassVisitor to which this visitor delegates calls. May be null.
  • pw – the print writer to be used to print the class.
/** * Constructs a new {@link TraceClassVisitor}. * * @param cv * the {@link ClassVisitor} to which this visitor delegates * calls. May be <tt>null</tt>. * @param pw * the print writer to be used to print the class. */
public TraceClassVisitor(final ClassVisitor cv, final PrintWriter pw) { this(cv, new Textifier(), pw); }
Constructs a new TraceClassVisitor.
Params:
  • cv – the ClassVisitor to which this visitor delegates calls. May be null.
  • p – the object that actually converts visit events into text.
  • pw – the print writer to be used to print the class. May be null if you simply want to use the result via Printer.getText(), instead of printing it.
/** * Constructs a new {@link TraceClassVisitor}. * * @param cv * the {@link ClassVisitor} to which this visitor delegates * calls. May be <tt>null</tt>. * @param p * the object that actually converts visit events into text. * @param pw * the print writer to be used to print the class. May be null if * you simply want to use the result via * {@link Printer#getText()}, instead of printing it. */
public TraceClassVisitor(final ClassVisitor cv, final Printer p, final PrintWriter pw) { super(Opcodes.ASM5, cv); this.pw = pw; this.p = p; } @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 void visitOuterClass(final String owner, final String name, final String desc) { p.visitOuterClass(owner, name, desc); super.visitOuterClass(owner, name, desc); } @Override public AnnotationVisitor visitAnnotation(final String desc, final boolean visible) { Printer p = this.p.visitClassAnnotation(desc, visible); AnnotationVisitor av = cv == null ? null : cv.visitAnnotation(desc, visible); return new TraceAnnotationVisitor(av, p); } @Override public AnnotationVisitor visitTypeAnnotation(int typeRef, TypePath typePath, String desc, boolean visible) { Printer p = this.p.visitClassTypeAnnotation(typeRef, typePath, desc, visible); AnnotationVisitor av = cv == null ? null : cv.visitTypeAnnotation( typeRef, typePath, desc, visible); return new TraceAnnotationVisitor(av, p); } @Override public void visitAttribute(final Attribute attr) { p.visitClassAttribute(attr); super.visitAttribute(attr); } @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 FieldVisitor visitField(final int access, final String name, final String desc, final String signature, final Object value) { Printer p = this.p.visitField(access, name, desc, signature, value); FieldVisitor fv = cv == null ? null : cv.visitField(access, name, desc, signature, value); return new TraceFieldVisitor(fv, p); } @Override public MethodVisitor visitMethod(final int access, final String name, final String desc, final String signature, final String[] exceptions) { Printer p = this.p.visitMethod(access, name, desc, signature, exceptions); MethodVisitor mv = cv == null ? null : cv.visitMethod(access, name, desc, signature, exceptions); return new TraceMethodVisitor(mv, p); } @Override public void visitEnd() { p.visitClassEnd(); if (pw != null) { p.print(pw); pw.flush(); } super.visitEnd(); } }