ASM: a very small and fast Java bytecode manipulation framework
Copyright (c) 2000-2011 INRIA, France Telecom
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/***
 * 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;

A visitor to visit a Java class. The methods of this class must be called in
the following order: visit [ visitSource ] [
visitOuterClass ] ( visitAnnotation |
visitAttribute )* ( visitInnerClass | visitField |
visitMethod )* visitEnd.
Author:
Eric Bruneton/**
 * A visitor to visit a Java class. The methods of this class must be called in
 * the following order: <tt>visit</tt> [ <tt>visitSource</tt> ] [
 * <tt>visitOuterClass</tt> ] ( <tt>visitAnnotation</tt> |
 * <tt>visitAttribute</tt> )* ( <tt>visitInnerClass</tt> | <tt>visitField</tt> |
 * <tt>visitMethod</tt> )* <tt>visitEnd</tt>.
 * 
 * @author Eric Bruneton
 */
public abstract class ClassVisitor {

    
The ASM API version implemented by this visitor. The value of this field must be one of Opcodes.ASM4. /**
     * The ASM API version implemented by this visitor. The value of this field
     * must be one of {@link Opcodes#ASM4}.
     */
    protected final int api;

    
The class visitor to which this visitor must delegate method calls. May
be null.
/**
     * The class visitor to which this visitor must delegate method calls. May
     * be null.
     */
    protected ClassVisitor cv;

    
Constructs a new ClassVisitor. 
Params:
api –  the ASM API version implemented by this visitor. Must be one of Opcodes.ASM4./**
     * Constructs a new {@link ClassVisitor}.
     * 
     * @param api
     *            the ASM API version implemented by this visitor. Must be one
     *            of {@link Opcodes#ASM4}.
     */
    public ClassVisitor(final int api) {
        this(api, null);
    }

    
Constructs a new ClassVisitor. 
Params:
api –  the ASM API version implemented by this visitor. Must be one of Opcodes.ASM4.
cv – 
           the class visitor to which this visitor must delegate method
           calls. May be null./**
     * Constructs a new {@link ClassVisitor}.
     * 
     * @param api
     *            the ASM API version implemented by this visitor. Must be one
     *            of {@link Opcodes#ASM4}.
     * @param cv
     *            the class visitor to which this visitor must delegate method
     *            calls. May be null.
     */
    public ClassVisitor(final int api, final ClassVisitor cv) {
        if (api != Opcodes.ASM4) {
            throw new IllegalArgumentException();
        }
        this.api = api;
        this.cv = cv;
    }

    
Visits the header of the class.
Params:
version – 
           the class version.
access –  the class's access flags (see Opcodes). This parameter also indicates if the class is deprecated.
name –  the internal name of the class (see getInternalName).
signature – 
           the signature of this class. May be null if the class
           is not a generic one, and does not extend or implement generic
           classes or interfaces.
superName –  the internal of name of the super class (see getInternalName). For interfaces, the super class is Object. May be null, but only for the Object class.
interfaces –  the internal names of the class's interfaces (see getInternalName). May be null./**
     * Visits the header of the class.
     * 
     * @param version
     *            the class version.
     * @param access
     *            the class's access flags (see {@link Opcodes}). This parameter
     *            also indicates if the class is deprecated.
     * @param name
     *            the internal name of the class (see
     *            {@link Type#getInternalName() getInternalName}).
     * @param signature
     *            the signature of this class. May be <tt>null</tt> if the class
     *            is not a generic one, and does not extend or implement generic
     *            classes or interfaces.
     * @param superName
     *            the internal of name of the super class (see
     *            {@link Type#getInternalName() getInternalName}). For
     *            interfaces, the super class is {@link Object}. May be
     *            <tt>null</tt>, but only for the {@link Object} class.
     * @param interfaces
     *            the internal names of the class's interfaces (see
     *            {@link Type#getInternalName() getInternalName}). May be
     *            <tt>null</tt>.
     */
    public void visit(int version, int access, String name, String signature,
            String superName, String[] interfaces) {
        if (cv != null) {
            cv.visit(version, access, name, signature, superName, interfaces);
        }
    }

    
Visits the source of the class.
Params:
source – 
           the name of the source file from which the class was compiled.
           May be null.
debug – 
           additional debug information to compute the correspondance
           between source and compiled elements of the class. May be
           null./**
     * Visits the source of the class.
     * 
     * @param source
     *            the name of the source file from which the class was compiled.
     *            May be <tt>null</tt>.
     * @param debug
     *            additional debug information to compute the correspondance
     *            between source and compiled elements of the class. May be
     *            <tt>null</tt>.
     */
    public void visitSource(String source, String debug) {
        if (cv != null) {
            cv.visitSource(source, debug);
        }
    }

    
Visits the enclosing class of the class. This method must be called only
if the class has an enclosing class.
Params:
owner – 
           internal name of the enclosing class of the class.
name – 
           the name of the method that contains the class, or
           null if the class is not enclosed in a method of its
           enclosing class.
desc – 
           the descriptor of the method that contains the class, or
           null if the class is not enclosed in a method of its
           enclosing class./**
     * Visits the enclosing class of the class. This method must be called only
     * if the class has an enclosing class.
     * 
     * @param owner
     *            internal name of the enclosing class of the class.
     * @param name
     *            the name of the method that contains the class, or
     *            <tt>null</tt> if the class is not enclosed in a method of its
     *            enclosing class.
     * @param desc
     *            the descriptor of the method that contains the class, or
     *            <tt>null</tt> if the class is not enclosed in a method of its
     *            enclosing class.
     */
    public void visitOuterClass(String owner, String name, String desc) {
        if (cv != null) {
            cv.visitOuterClass(owner, name, desc);
        }
    }

    
Visits an annotation of the class.
Params:
desc – 
           the class descriptor of the annotation class.
visible – 
           true if the annotation is visible at runtime.
Returns:
a visitor to visit the annotation values, or null if
        this visitor is not interested in visiting this annotation./**
     * Visits an annotation of the class.
     * 
     * @param desc
     *            the class descriptor of the annotation class.
     * @param visible
     *            <tt>true</tt> if the annotation is visible at runtime.
     * @return a visitor to visit the annotation values, or <tt>null</tt> if
     *         this visitor is not interested in visiting this annotation.
     */
    public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
        if (cv != null) {
            return cv.visitAnnotation(desc, visible);
        }
        return null;
    }

    
Visits a non standard attribute of the class.
Params:
attr – 
           an attribute./**
     * Visits a non standard attribute of the class.
     * 
     * @param attr
     *            an attribute.
     */
    public void visitAttribute(Attribute attr) {
        if (cv != null) {
            cv.visitAttribute(attr);
        }
    }

    
Visits information about an inner class. This inner class is not
necessarily a member of the class being visited.
Params:
name –  the internal name of an inner class (see getInternalName).
outerName –  the internal name of the class to which the inner class belongs (see getInternalName). May be null for not member classes.
innerName – 
           the (simple) name of the inner class inside its enclosing
           class. May be null for anonymous inner classes.
access – 
           the access flags of the inner class as originally declared in
           the enclosing class./**
     * Visits information about an inner class. This inner class is not
     * necessarily a member of the class being visited.
     * 
     * @param name
     *            the internal name of an inner class (see
     *            {@link Type#getInternalName() getInternalName}).
     * @param outerName
     *            the internal name of the class to which the inner class
     *            belongs (see {@link Type#getInternalName() getInternalName}).
     *            May be <tt>null</tt> for not member classes.
     * @param innerName
     *            the (simple) name of the inner class inside its enclosing
     *            class. May be <tt>null</tt> for anonymous inner classes.
     * @param access
     *            the access flags of the inner class as originally declared in
     *            the enclosing class.
     */
    public void visitInnerClass(String name, String outerName,
            String innerName, int access) {
        if (cv != null) {
            cv.visitInnerClass(name, outerName, innerName, access);
        }
    }

    
Visits a field of the class.
Params:
access –  the field's access flags (see Opcodes). This parameter also indicates if the field is synthetic and/or deprecated.
name – 
           the field's name.
desc –  the field's descriptor (see Type).
signature – 
           the field's signature. May be null if the field's
           type does not use generic types.
value – 
           the field's initial value. This parameter, which may be
           null if the field does not have an initial value, must be an Integer, a Float, a Long, a Double or a String (for int,
           float, long or String fields
           respectively). This parameter is only used for static
           fields. Its value is ignored for non static fields, which
           must be initialized through bytecode instructions in
           constructors or methods.
Returns:
a visitor to visit field annotations and attributes, or
        null if this class visitor is not interested in visiting
        these annotations and attributes./**
     * Visits a field of the class.
     * 
     * @param access
     *            the field's access flags (see {@link Opcodes}). This parameter
     *            also indicates if the field is synthetic and/or deprecated.
     * @param name
     *            the field's name.
     * @param desc
     *            the field's descriptor (see {@link Type Type}).
     * @param signature
     *            the field's signature. May be <tt>null</tt> if the field's
     *            type does not use generic types.
     * @param value
     *            the field's initial value. This parameter, which may be
     *            <tt>null</tt> if the field does not have an initial value,
     *            must be an {@link Integer}, a {@link Float}, a {@link Long}, a
     *            {@link Double} or a {@link String} (for <tt>int</tt>,
     *            <tt>float</tt>, <tt>long</tt> or <tt>String</tt> fields
     *            respectively). <i>This parameter is only used for static
     *            fields</i>. Its value is ignored for non static fields, which
     *            must be initialized through bytecode instructions in
     *            constructors or methods.
     * @return a visitor to visit field annotations and attributes, or
     *         <tt>null</tt> if this class visitor is not interested in visiting
     *         these annotations and attributes.
     */
    public FieldVisitor visitField(int access, String name, String desc,
            String signature, Object value) {
        if (cv != null) {
            return cv.visitField(access, name, desc, signature, value);
        }
        return null;
    }

    
Visits a method of the class. This method must return a new MethodVisitor instance (or null) each time it is called,
i.e., it should not return a previously returned visitor.
Params:
access –  the method's access flags (see Opcodes). This parameter also indicates if the method is synthetic and/or deprecated.
name – 
           the method's name.
desc –  the method's descriptor (see Type).
signature – 
           the method's signature. May be null if the method
           parameters, return type and exceptions do not use generic
           types.
exceptions –  the internal names of the method's exception classes (see getInternalName). May be null.
Returns:
an object to visit the byte code of the method, or null
        if this class visitor is not interested in visiting the code of
        this method./**
     * Visits a method of the class. This method <i>must</i> return a new
     * {@link MethodVisitor} instance (or <tt>null</tt>) each time it is called,
     * i.e., it should not return a previously returned visitor.
     * 
     * @param access
     *            the method's access flags (see {@link Opcodes}). This
     *            parameter also indicates if the method is synthetic and/or
     *            deprecated.
     * @param name
     *            the method's name.
     * @param desc
     *            the method's descriptor (see {@link Type Type}).
     * @param signature
     *            the method's signature. May be <tt>null</tt> if the method
     *            parameters, return type and exceptions do not use generic
     *            types.
     * @param exceptions
     *            the internal names of the method's exception classes (see
     *            {@link Type#getInternalName() getInternalName}). May be
     *            <tt>null</tt>.
     * @return an object to visit the byte code of the method, or <tt>null</tt>
     *         if this class visitor is not interested in visiting the code of
     *         this method.
     */
    public MethodVisitor visitMethod(int access, String name, String desc,
            String signature, String[] exceptions) {
        if (cv != null) {
            return cv.visitMethod(access, name, desc, signature, exceptions);
        }
        return null;
    }

    
Visits the end of the class. This method, which is the last one to be
called, is used to inform the visitor that all the fields and methods of
the class have been visited.
/**
     * Visits the end of the class. This method, which is the last one to be
     * called, is used to inform the visitor that all the fields and methods of
     * the class have been visited.
     */
    public void visitEnd() {
        if (cv != null) {
            cv.visitEnd();
        }
    }
}