Package nginx.clojure.asm.util

Source Code of nginx.clojure.asm.util.TraceClassVisitor

/***
* 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 nginx.clojure.asm.util;

import java.io.PrintWriter;

import nginx.clojure.asm.AnnotationVisitor;
import nginx.clojure.asm.Attribute;
import nginx.clojure.asm.ClassVisitor;
import nginx.clojure.asm.FieldVisitor;
import nginx.clojure.asm.MethodVisitor;
import nginx.clojure.asm.Opcodes;

/**
* 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.
     */
    private final PrintWriter pw;

    /**
     * The object that actually converts visit events into text.
     */
    public final Printer p;

    /**
     * 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 {@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 {@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.ASM4, 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 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();
    }
}
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