// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
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//
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package net.hasor.utils.asm;
/**
 * A visitor to visit a Java class. The methods of this class must be called in the following order:
 * {@code visit} [ {@code visitSource} ] [ {@code visitModule} ][ {@code visitNestHost} ][ {@code
 * visitPermittedSubtype} ][ {@code visitOuterClass} ] ( {@code visitAnnotation} | {@code
 * visitTypeAnnotation} | {@code visitAttribute} )* ( {@code visitNestMember} | {@code
 * visitInnerClass} | {@code visitField} | {@code visitMethod} )* {@code visitEnd}.
 *
 * @author Eric Bruneton
 */
public abstract class ClassVisitor {
    /**
     * The ASM API version implemented by this visitor. The value of this field must be one of {@link
     * Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
     */
    protected final int          api;
    /** The class visitor to which this visitor must delegate method calls. May be {@literal null}. */
    protected       ClassVisitor cv;

    /**
     * Constructs a new {@link ClassVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of {@link
     *     Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
     */
    public ClassVisitor(final int api) {
        this(api, null);
    }

    /**
     * Constructs a new {@link ClassVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of {@link
     *     Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
     * @param classVisitor the class visitor to which this visitor must delegate method calls. May be
     *     null.
     */
    public ClassVisitor(final int api, final ClassVisitor classVisitor) {
        if (api != Opcodes.ASM7 && api != Opcodes.ASM6 && api != Opcodes.ASM5 && api != Opcodes.ASM4 && api != Opcodes.ASM8_EXPERIMENTAL) {
            throw new IllegalArgumentException("Unsupported api " + api);
        }
        if (api == Opcodes.ASM8_EXPERIMENTAL) {
            Constants.checkAsm8Experimental(this);
        }
        this.api = api;
        this.cv = classVisitor;
    }

    /**
     * Visits the header of the class.
     *
     * @param version the class version. The minor version is stored in the 16 most significant bits,
     *     and the major version in the 16 least significant bits.
     * @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()}).
     * @param signature the signature of this class. May be {@literal null} 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()}).
     *     For interfaces, the super class is {@link Object}. May be {@literal null}, but only for the
     *     {@link Object} class.
     * @param interfaces the internal names of the class's interfaces (see {@link
     *     Type#getInternalName()}). May be {@literal null}.
     */
    public void visit(final int version, final int access, final String name, final String signature, final String superName, final String[] interfaces) {
        if (cv != null) {
            cv.visit(version, access, name, signature, superName, interfaces);
        }
    }

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

    /**
     * Visit the module corresponding to the class.
     *
     * @param name the fully qualified name (using dots) of the module.
     * @param access the module access flags, among {@code ACC_OPEN}, {@code ACC_SYNTHETIC} and {@code
     *     ACC_MANDATED}.
     * @param version the module version, or {@literal null}.
     * @return a visitor to visit the module values, or {@literal null} if this visitor is not
     *     interested in visiting this module.
     */
    public ModuleVisitor visitModule(final String name, final int access, final String version) {
        if (api < Opcodes.ASM6) {
            throw new UnsupportedOperationException("This feature requires ASM6");
        }
        if (cv != null) {
            return cv.visitModule(name, access, version);
        }
        return null;
    }

    /**
     * Visits the nest host class of the class. A nest is a set of classes of the same package that
     * share access to their private members. One of these classes, called the host, lists the other
     * members of the nest, which in turn should link to the host of their nest. This method must be
     * called only once and only if the visited class is a non-host member of a nest. A class is
     * implicitly its own nest, so it's invalid to call this method with the visited class name as
     * argument.
     *
     * @param nestHost the internal name of the host class of the nest.
     */
    public void visitNestHost(final String nestHost) {
        if (api < Opcodes.ASM7) {
            throw new UnsupportedOperationException("This feature requires ASM7");
        }
        if (cv != null) {
            cv.visitNestHost(nestHost);
        }
    }

    /**
     * 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 {@literal null} if the class is
     *     not enclosed in a method of its enclosing class.
     * @param descriptor the descriptor of the method that contains the class, or {@literal null} if
     *     the class is not enclosed in a method of its enclosing class.
     */
    public void visitOuterClass(final String owner, final String name, final String descriptor) {
        if (cv != null) {
            cv.visitOuterClass(owner, name, descriptor);
        }
    }

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

    /**
     * Visits an annotation on a type in the class signature.
     *
     * @param typeRef a reference to the annotated type. The sort of this type reference must be
     *     {@link TypeReference#CLASS_TYPE_PARAMETER}, {@link
     *     TypeReference#CLASS_TYPE_PARAMETER_BOUND} or {@link TypeReference#CLASS_EXTENDS}. See
     *     {@link TypeReference}.
     * @param typePath the path to the annotated type argument, wildcard bound, array element type, or
     *     static inner type within 'typeRef'. May be {@literal null} if the annotation targets
     *     'typeRef' as a whole.
     * @param descriptor the class descriptor of the annotation class.
     * @param visible {@literal true} if the annotation is visible at runtime.
     * @return a visitor to visit the annotation values, or {@literal null} if this visitor is not
     *     interested in visiting this annotation.
     */
    public AnnotationVisitor visitTypeAnnotation(final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
        if (api < Opcodes.ASM5) {
            throw new UnsupportedOperationException("This feature requires ASM5");
        }
        if (cv != null) {
            return cv.visitTypeAnnotation(typeRef, typePath, descriptor, visible);
        }
        return null;
    }

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

    /**
     * Visits a member of the nest. A nest is a set of classes of the same package that share access
     * to their private members. One of these classes, called the host, lists the other members of the
     * nest, which in turn should link to the host of their nest. This method must be called only if
     * the visited class is the host of a nest. A nest host is implicitly a member of its own nest, so
     * it's invalid to call this method with the visited class name as argument.
     *
     * @param nestMember the internal name of a nest member.
     */
    public void visitNestMember(final String nestMember) {
        if (api < Opcodes.ASM7) {
            throw new UnsupportedOperationException("This feature requires ASM7");
        }
        if (cv != null) {
            cv.visitNestMember(nestMember);
        }
    }

    /**
     * <b>Experimental, use at your own risk. This method will be renamed when it becomes stable, this
     * will break existing code using it</b>. Visits a permitted subtypes. A permitted subtypes is one
     * of the allowed subtypes of the current class.
     *
     * @param permittedSubtype the internal name of a permitted subtype.
     * @deprecated this API is experimental.
     */
    @Deprecated
    public void visitPermittedSubtypeExperimental(final String permittedSubtype) {
        if (api != Opcodes.ASM8_EXPERIMENTAL) {
            throw new UnsupportedOperationException("This feature requires ASM8_EXPERIMENTAL");
        }
        if (cv != null) {
            cv.visitPermittedSubtypeExperimental(permittedSubtype);
        }
    }

    /**
     * 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()}).
     * @param outerName the internal name of the class to which the inner class belongs (see {@link
     *     Type#getInternalName()}). May be {@literal null} for not member classes.
     * @param innerName the (simple) name of the inner class inside its enclosing class. May be
     *     {@literal null} for anonymous inner classes.
     * @param access the access flags of the inner class as originally declared in the enclosing
     *     class.
     */
    public void visitInnerClass(final String name, final String outerName, final String innerName, final int access) {
        if (cv != null) {
            cv.visitInnerClass(name, outerName, innerName, access);
        }
    }

    /**
     * Visits a record component of the class.
     *
     * @param access the record component access flags, the only possible value is {@link
     *     Opcodes#ACC_DEPRECATED}.
     * @param name the record component name.
     * @param descriptor the record component descriptor (see {@link Type}).
     * @param signature the record component signature. May be {@literal null} if the record component
     *     type does not use generic types.
     * @return a visitor to visit this record component annotations and attributes, or {@literal null}
     *     if this class visitor is not interested in visiting these annotations and attributes.
     * @deprecated this API is experimental.
     */
    @Deprecated
    public RecordComponentVisitor visitRecordComponentExperimental(final int access, final String name, final String descriptor, final String signature) {
        if (api < Opcodes.ASM8_EXPERIMENTAL) {
            throw new UnsupportedOperationException("This feature requires ASM8_EXPERIMENTAL");
        }
        if (cv != null) {
            return cv.visitRecordComponentExperimental(access, name, descriptor, signature);
        }
        return null;
    }

    /**
     * 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 descriptor the field's descriptor (see {@link Type}).
     * @param signature the field's signature. May be {@literal null} if the field's type does not use
     *     generic types.
     * @param value the field's initial value. This parameter, which may be {@literal null} 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 {@code int}, {@code float}, {@code long}
     *     or {@code String} 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 {@literal null} if this class
     *     visitor is not interested in visiting these annotations and attributes.
     */
    public FieldVisitor visitField(final int access, final String name, final String descriptor, final String signature, final Object value) {
        if (cv != null) {
            return cv.visitField(access, name, descriptor, signature, value);
        }
        return null;
    }

    /**
     * Visits a method of the class. This method <i>must</i> return a new {@link MethodVisitor}
     * instance (or {@literal null}) 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 descriptor the method's descriptor (see {@link Type}).
     * @param signature the method's signature. May be {@literal null} 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()}). May be {@literal null}.
     * @return an object to visit the byte code of the method, or {@literal null} if this class
     *     visitor is not interested in visiting the code of this method.
     */
    public MethodVisitor visitMethod(final int access, final String name, final String descriptor, final String signature, final String[] exceptions) {
        if (cv != null) {
            return cv.visitMethod(access, name, descriptor, 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.
     */
    public void visitEnd() {
        if (cv != null) {
            cv.visitEnd();
        }
    }
}
