com.xdev.jadoth.collections.Snake Maven / Gradle / Ivy

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/*
 * XDEV Application Framework - XDEV Application Framework
 * Copyright © 2003 XDEV Software (https://xdev.software)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see .
 */
package com.xdev.jadoth.collections;

import com.xdev.jadoth.util.VarChar;

/**
 * @author Thomas Muenz
 *
 */
public interface Snake //extends VarChar.Appendable
{
	E value();
	
	Snake tail();
	Snake head();
	
	Snake next();
	Snake prev();
	
	boolean hasNext();
	boolean hasPrev();
		
	Snake hop(int index);
	Snake add(E value);
	E set(E value);
	
	
	

	
	
	class Implementation implements Snake
	{
		///////////////////////////////////////////////////////////////////////////
		// instance fields  //
		/////////////////////
		
		Object value;
		Snake.Implementation next = null;
		Snake.Implementation prev = null;
		
		
		///////////////////////////////////////////////////////////////////////////
		// constructors     //
		/////////////////////	
		
		public Implementation()
		{
			super();
			this.value = null;
		}		
		public Implementation(final Object value)
		{
			super();
			this.value = value;
		}
		
		/**
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#head()
		 */
		@Override
		public Snake head()
		{
			Snake.Implementation link = this;
			while(link.next != null){
				link = link.next;
			}
			return link;
		}
		/**
		 * @param index
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#hop(int)
		 */
		@Override
		public Snake hop(int index)
		{
			Snake.Implementation link = this;
			if(index < 0){
				while(index ++> 0){
					link = link.prev;
				}
			}
			else {
				while(index --> 0){
					link = link.next;
				}
			}
			return link;
		}
		/**
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#tail()
		 */
		@Override
		public Snake tail()
		{
			Snake.Implementation link = this;
			while(link.prev != null){
				link = link.prev;
			}
			return link;
		}
		/**
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#value()
		 */
		@SuppressWarnings("unchecked")
		@Override
		public E value()
		{
			return (E)this.value;
		}
		/**
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#next()
		 */
		@Override
		public Snake next()
		{
			return this.next();
		}
		/**
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#prev()
		 */
		@Override
		public Snake prev()
		{
			return this.prev();
		}
		/**
		 * @param value
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#add(java.lang.Object)
		 */
		@Override
		public Snake add(final E value)
		{
			final Snake.Implementation newLink = new Snake.Implementation();
			newLink.value = value;
			
			newLink.prev = this;
			this.next = newLink;	
			
			return newLink;
		}
		/**
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#hasNext()
		 */
		@Override
		public boolean hasNext()
		{
			return this.next != null;
		}
		/**
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#hasPrev()
		 */
		@Override
		public boolean hasPrev()
		{
			return this.prev != null;
		}
		/**
		 * @param value
		 * @return
		 * @see com.xdev.jadoth.collections.Snake#set(java.lang.Object)
		 */
		@Override
		public E set(final E value)
		{
			final E oldValue = (E)this.value;
			this.value = value;
			return oldValue;
		}
		
		
		
		/**
		 * @return
		 * @see java.lang.Object#toString()
		 */
		@Override
		public String toString()
		{
			
			if(this.next == null){
				//head
				final VarChar vc = new VarChar().append('Ö');				
				Snake.Implementation link = this;
				do {
					vc.append('(').append(link.value).append(')');
				}
				while((link = link.prev) != null);
				return vc.append('>').toString();
			}
			if(this.prev == null){
				//tail
				final VarChar vc = new VarChar().append('<');				
				Snake.Implementation link = this;
				do {
					vc.append('(').append(link.value).append(')');
				}
				while((link = link.next) != null);
				return vc.append('Ö').toString();				
			}
			return String.valueOf(this.value);
		}
	}
}