Looking for a Simple Doubly Linked List Implementation

[Ron Tarrant]

Sorry. I posted the wrong file. This is the one that works:

```
import std.stdio;
import std.conv;

class TabList
{
	private:
	Tab _head;
	int _lastUniqueID = 0;
	string labelText;
	
	this()
	{
		append();
	}
	
	
	void append()
	{
		string labelText = "Tab " ~ _lastUniqueID.to!string();
		Tab current;
		
		if(_head is null)
		{
			_head = new Tab(_lastUniqueID, labelText);
			_head.setPrev(null);
			_head.setNext(null);
		}
		else
		{
			current = _head;
//writeln("before the while loop");
//current.showThings();

			while(current.getNext() !is null)
			{
//				writeln("in the while loop...");
//				current.showThings();
				
//				if(current.getPrev() !is null)
//				{
//					writeln("prev = ", current.getPrev().getTabID());
//				}
//				else
//				{
//					writeln("prev = null");
//				}
				current = current.getNext();
			}
//writeln("out of the while loop\n");
			Tab tab = new Tab(_lastUniqueID, labelText);
			current.setNext(tab);
			tab.setPrev(current);
		}
		
		_lastUniqueID++;
		
	} // append()


	Tab getHead()
	{
		return(_head);
		
	} // getHead()
	
	
	void removeTab(int uniqueID)
	{
		// get the head
		Tab current = _head;

		// walk the list to find the Tab with the uniqueID
		while(current.getNext() !is null)
		{
			// if the uniqueID matches the head's ID
			if(current.getTabID() is uniqueID)
			{
				// destroy the Tab object
				current.destroy(uniqueID);
				break;
			}

			// go to the next Tab
			current = current.getNext();
		}
		

	} // removeTab()
	
} // class TabList


class Tab
{
	private:
	int _tabID;
	string _label;
	Tab _prev = null, _next = null;
	
	public:
	this(int uniqueID, string labelText)
	{
		_tabID = uniqueID;
		_label = labelText;
		
	} // this()
	
	
	void showThings()
	{
		writeln("Tab = ", getTabID());
		
		if(getPrev() !is null)
		{
			writeln("Tab.prev = ", getPrev().getTabID());
		}
		else
		{
			writeln("Tab.prev is null");
		}
		
		if(getNext() !is null)
		{
			writeln("Tab.next = ", getNext().getTabID());
		}
		else
		{
			writeln("Tab.next = null");
		}
		
	} // showThings()
	

	void destroy(int id)
	{
		if(_tabID is id)
		{
			// destroy the TextView
			// destroy the Label
			_prev.setNext(_next);
			_next.setPrev(_prev);
		}
		
	} // destroy()


	Tab getNext()
	{
		return(_next);
		
	} // getNext()
	
	
	Tab getPrev()
	{
		return(_prev);
		
	} // getPrev()
	
	
	int getTabID()
	{
		return(_tabID);
		
	} // getTabID()
	
	
	void setNext(Tab tab)
	{
		_next = tab;
		
	} // setNext()
	

	void setPrev(Tab tab)
	{
		_prev = tab;
		
	} // setPrev()	
	
} // class Tab


void main(string[] args)
{
	TabList tabList;
	
	tabList = new TabList();
	
	for(int i = 0; i < 7; i++)
	{
//		writeln("building Tab #", i);
		tabList.append();
//		writeln("------------------------------");
	}

	writeln();
	
	Tab tab = tabList.getHead();
	
	while(tab !is null)
	{
		tab.showThings();
		tab = tab.getNext();
		writeln("-----");
	}
writeln("------------------------------");
	
	// delete one
	tabList.removeTab(3);

	tab = tabList.getHead();

	while(tab !is null)
	{
		tab.showThings();
		tab = tab.getNext();
		writeln("-----");
	}
	
} // main()

```