/*
 * Copyright  2000-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); 
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License. 
 *
 */
package org.apache.bcel.classfile;

import java.util.Stack;

/**
 * Traverses a JavaClass with another Visitor object 'piggy-backed' that is
 * applied to all components of a JavaClass object. I.e. this class supplies the
 * traversal strategy, other classes can make use of it.
 * 
 * @version $Id: DescendingVisitor.java 388707 2006-03-25 05:40:28Z tcurdt $
 * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
 */
public class DescendingVisitor implements Visitor {

	private JavaClass clazz;
	private Visitor visitor;
	private Stack<Cloneable> stack = new Stack<Cloneable>();

	/**
	 * @return container of current entitity, i.e., predecessor during traversal
	 */
	public Object predecessor() {
		return predecessor(0);
	}

	/**
	 * @param level
	 *            nesting level, i.e., 0 returns the direct predecessor
	 * @return container of current entitity, i.e., predecessor during traversal
	 */
	public Object predecessor(int level) {
		int size = stack.size();
		if ((size < 2) || (level < 0)) {
			return null;
		} else {
			return stack.elementAt(size - (level + 2)); // size - 1 == current
		}
	}

	/**
	 * @return current object
	 */
	public Object current() {
		return stack.peek();
	}

	/**
	 * @param clazz
	 *            Class to traverse
	 * @param visitor
	 *            visitor object to apply to all components
	 */
	public DescendingVisitor(JavaClass clazz, Visitor visitor) {
		this.clazz = clazz;
		this.visitor = visitor;
	}

	/**
	 * Start traversal.
	 */
	public void visit() {
		clazz.accept(this);
	}

	@Override
	public void visitJavaClass(JavaClass _clazz) {
		stack.push(_clazz);
		_clazz.accept(visitor);
		Field[] fields = _clazz.getFields();
		for (int i = 0; i < fields.length; i++) {
			fields[i].accept(this);
		}
		Method[] methods = _clazz.getMethods();
		for (int i = 0; i < methods.length; i++) {
			methods[i].accept(this);
		}
		Attribute[] attributes = _clazz.getAttributes();
		for (int i = 0; i < attributes.length; i++) {
			attributes[i].accept(this);
		}
		_clazz.getConstantPool().accept(this);
		stack.pop();
	}

	@Override
	public void visitField(Field field) {
		stack.push(field);
		field.accept(visitor);
		Attribute[] attributes = field.getAttributes();
		for (int i = 0; i < attributes.length; i++) {
			attributes[i].accept(this);
		}
		stack.pop();
	}

	@Override
	public void visitConstantValue(ConstantValue cv) {
		stack.push(cv);
		cv.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitMethod(Method method) {
		stack.push(method);
		method.accept(visitor);
		Attribute[] attributes = method.getAttributes();
		for (int i = 0; i < attributes.length; i++) {
			attributes[i].accept(this);
		}
		stack.pop();
	}

	@Override
	public void visitExceptionTable(ExceptionTable table) {
		stack.push(table);
		table.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitCode(Code code) {
		stack.push(code);
		code.accept(visitor);
		CodeException[] table = code.getExceptionTable();
		for (int i = 0; i < table.length; i++) {
			table[i].accept(this);
		}
		Attribute[] attributes = code.getAttributes();
		for (int i = 0; i < attributes.length; i++) {
			attributes[i].accept(this);
		}
		stack.pop();
	}

	@Override
	public void visitCodeException(CodeException ce) {
		stack.push(ce);
		ce.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitLineNumberTable(LineNumberTable table) {
		stack.push(table);
		table.accept(visitor);
		LineNumber[] numbers = table.getLineNumberTable();
		for (int i = 0; i < numbers.length; i++) {
			numbers[i].accept(this);
		}
		stack.pop();
	}

	@Override
	public void visitLineNumber(LineNumber number) {
		stack.push(number);
		number.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitLocalVariableTable(LocalVariableTable table) {
		stack.push(table);
		table.accept(visitor);
		LocalVariable[] vars = table.getLocalVariableTable();
		for (int i = 0; i < vars.length; i++) {
			vars[i].accept(this);
		}
		stack.pop();
	}

	@Override
	public void visitStackMap(StackMap table) {
		stack.push(table);
		table.accept(visitor);
		StackMapEntry[] vars = table.getStackMap();
		for (int i = 0; i < vars.length; i++) {
			vars[i].accept(this);
		}
		stack.pop();
	}

	@Override
	public void visitStackMapEntry(StackMapEntry var) {
		stack.push(var);
		var.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitLocalVariable(LocalVariable var) {
		stack.push(var);
		var.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantPool(ConstantPool cp) {
		stack.push(cp);
		cp.accept(visitor);
		Constant[] constants = cp.getConstantPool();
		for (int i = 1; i < constants.length; i++) {
			if (constants[i] != null) {
				constants[i].accept(this);
			}
		}
		stack.pop();
	}

	@Override
	public void visitConstantClass(ConstantClass constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantDouble(ConstantDouble constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantFieldref(ConstantFieldref constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantFloat(ConstantFloat constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantInteger(ConstantInteger constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantInterfaceMethodref(
			ConstantInterfaceMethodref constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantLong(ConstantLong constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantMethodref(ConstantMethodref constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantNameAndType(ConstantNameAndType constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantString(ConstantString constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitConstantUtf8(ConstantUtf8 constant) {
		stack.push(constant);
		constant.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitInnerClasses(InnerClasses ic) {
		stack.push(ic);
		ic.accept(visitor);
		InnerClass[] ics = ic.getInnerClasses();
		for (int i = 0; i < ics.length; i++) {
			ics[i].accept(this);
		}
		stack.pop();
	}

	@Override
	public void visitInnerClass(InnerClass inner) {
		stack.push(inner);
		inner.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitDeprecated(Deprecated attribute) {
		stack.push(attribute);
		attribute.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitSignature(Signature attribute) {
		stack.push(attribute);
		attribute.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitSourceFile(SourceFile attribute) {
		stack.push(attribute);
		attribute.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitSynthetic(Synthetic attribute) {
		stack.push(attribute);
		attribute.accept(visitor);
		stack.pop();
	}

	@Override
	public void visitUnknown(Unknown attribute) {
		stack.push(attribute);
		attribute.accept(visitor);
		stack.pop();
	}
}
