Open linked list (meaning you can pull it apart; useful for big data that means manual organization)

LinusListorCp.cpp

/*
Name: Linus Listor for C++
(Linus Listor C Plus / Linus Listor Cp )

(C) Nic Anderson

Date: June 15, 2011

See LinusListorCp.h for copyright details.

Desc: This is a simple linked list for C++ programs.
*/

#ifndef _LLISTOR_
#define _LLISTOR_

// include the header
#include "LinusListorCp.h"

namespace Linus
{
	template<class Unk>
	LListor<Unk>::LListor()
	{
			// indicate this link has neither prior nor post links
			possession_state = s_none;
	}

	// for the item being stored

	template<class Unk>
	Unk* LListor<Unk>::getThisItemAddress()
	{
		return &ThisItem;
	}

	template<class Unk>
	Unk LListor<Unk>::getThisItemCopy()
	{
		return ThisItem;
	}

	template<class Unk>
	void LListor<Unk>::setThisItem(Unk newItem)
	{
		ThisItem = newItem;
	}


	// for the prior and post links

	template<class Unk>
	LListor<Unk>* LListor<Unk>::getPriorLink()
	{
		if ( possession_state == s_prior || possession_state == s_both )
			return PriorLink;
		else return 0;
	}

	template<class Unk>
	void LListor<Unk>::setPriorLink( LListor<Unk>* newPrior )
	{
		// set the new link (NOTE: Does not delete the old one in case it is needed)
		PriorLink = newPrior;

		// adjust the possession state if necessary
		switch ( possession_state )
		{
		case s_none: possession_state = s_prior; break;
		case s_prior: break;
		case s_post: possession_state = s_both; break;
		case s_both: break;
		}
	}

	template<class Unk>
	LListor<Unk>* LListor<Unk>::getPostLink()
	{
		if ( possession_state == s_post || possession_state == s_both )
			return PostLink;
		else return 0;
	}

	template<class Unk>
	void LListor<Unk>::setPostLink( LListor<Unk>* newPost )
	{
		// set the new link (NOTE: Does not delete the old one in case it is needed)
		PostLink = newPost;

		// adjust the possession state if necessary
		switch ( possession_state )
		{
		case s_none: possession_state = s_post; break;
		case s_prior: possession_state = s_both; break;
		case s_post: break;
		case s_both: break;
		}
	}


	// possession state
	template<class Unk>
	si32 LListor<Unk>::hasWhat()
	{
		switch ( possession_state )
		{
		case s_none: return 0;
		case s_prior: return 1;
		case s_post: return 2;
		case s_both: return 3;
		}
	}


	// for adding on new links onto the chain

	template<class Unk>
	LListor<Unk>* LListor<Unk>::addNewLink( Unk item , bool head )
	{
		// save the location of the new link, based on whether it is the prior or post
		if (head) // prior
		{
			// determine if this link has a prior link already
			switch ( possession_state )
			{
			case s_none:
				// create a new link - use "new" to ensure it isn't deleted from the stack
				PriorLink = new LListor<Unk>;

				// assign it the new item
				PriorLink->setThisItem(item);

				// indicate the prior link now has a post link
				PriorLink->setPostLink(this);

				// indicate that this now has a prior link
				possession_state = s_prior;
				break;

			case s_prior:
					// considering this has a prior, send the item to that link to be added
				return PriorLink->addNewLink( item, true );
				//break; - unnecessary after a "return" statement

			case s_post:
				// create a new link - use "new" to ensure it isn't deleted from the stack
				PriorLink = new LListor<Unk>;

				// assign it the new item
				PriorLink->setThisItem(item);

				// indicate the prior link now has a post link
				PriorLink->setPostLink(this);

				// indicate this link now has both links
				possession_state = s_both;
				break;

			case s_both:
				// considering this has a prior, send the item to that link to be added
				return PriorLink->addNewLink( item, true );
				//break; - unnecessary after a return statement
			}

			// return the pointer to the link of the new object
			return PriorLink;

		} else {

			// indicate that this link now has a new post link
			switch ( possession_state )
			{
			case s_none:
				// create a new link - use "new" to ensure it isn't deleted from the stack
				PostLink = new LListor<Unk>;

				// assign it the new item
				PostLink->setThisItem(item);

				// indicate the post link now has a prior link
				PostLink->setPriorLink(this);

				// indicate this link now has a post link
				possession_state = s_post;
				break;

			case s_prior:
				// create a new link - use "new" to ensure it isn't deleted from the stack
				PostLink = new LListor<Unk>;

				// assign it the new item
				PostLink->setThisItem(item);

				// indicate the post link now has a prior link
				PostLink->setPriorLink(this);

				// indicate this link now has both links
				possession_state = s_both;
				break;

			case s_post:
				// considering this has a post, send the item to that link to be added
				return PostLink->addNewLink( item, false );
				//break; - unnecessary after a return statement

			case s_both:
				// considering this has a post, send the item to that link to be added
				return PostLink->addNewLink( item, false );
				//break; - unnecessary after a return statement
			}

			// return the pointer to the link of the new object
			return PostLink;
		}
	}


	// for removing the current link from its current chain without deleting it
	template<class Unk>
	void LListor<Unk>::extractCurrLink() const
	{
		// check for whether this link has a prior and a post link
		if ( possession_state == s_both )
		{
			PriorLink->setPostLink( PostLink );
			PostLink->setPriorLink( PriorLink );
		}

		switch( possession_state )
		{
		case s_prior:
			switch ( PriorLink->possession_state )
			{
			case s_post: PriorLink->possession_state = s_none; break;
			case s_both: PriorLink->possession_state = s_prior; break;
			default: break;
			}
			break;

		case s_post: // flag that the prior link has been dropped
			switch ( PostLink->possession_state )
			{
			case s_prior: PostLink->possession_state = s_none; break;
			case s_both: PostLink->possession_state = s_post; break;
			default: break;
			}
			break;

		case s_both: // bridge the chain
			PriorLink->setPostLink( PostLink );
			PostLink->setPriorLink( PriorLink );
			break;

		default: break;
		}
	}


	// for properly deleting the current link in the chain
	template<class Unk>
	void LListor<Unk>::delCurrLink() const
	{
		// check for whether this link has a prior and a post link
		extractCurrLink();

		// finally, delete this link
		delete this;
	}


	// for scanning the chain

	template<class Unk>
	LListor<Unk>* LListor<Unk>::getFirstLink()
	{
		// if this link itself has a prior link, call it
		if ( possession_state == s_prior || possession_state == s_both )
			return PriorLink->getFirstLink();
		else
			return this; // otherwise, this (the current) link is the one to return
	}


	template<class Unk>
	LListor<Unk>* LListor<Unk>::getLastLink()
	{
		// if this link itself has a prior link, call it
		if ( possession_state == s_post || possession_state == s_both )
			return PostLink->getLastLink();
		else
			return this; // otherwise, this (the current) link is the one to return
	}

}

#endif

LinusListorCp.h

/*
This is the header file for LinusListorCp.cpp
(C) Nic Anderson
Date: June 15, 2011

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/

// don't double define this
	// if "_Linus_INCLUDED" is not defined...
#ifndef _Linus_INCLUDED_
	// ... define it (and define the namespace as well)
#define _Linus_INCLUDED_

// simple definitions for usage with this list
#ifdef _MSC_VER
typedef __int32                 si32;
#else
typedef signed int              si32;
#endif

namespace Linus
{

	// The main class in Linus - the actual linked list
	template<class Unk>
	class LListor
	{

	private:
		// pointers to the prior link and post link (links before and after this one)
		LListor<Unk>* PriorLink;
		LListor<Unk>* PostLink;

		/* indicates the posession state:
			if this link has a link before it, after it, or both */
		enum {
			s_none = 0,
			s_prior,
			s_post,
			s_both
		} possession_state;

	public:
		// object being pointed to
		Unk ThisItem;

			//! Default constructor
		/** Sets the possession state to zero, indicating this link
		has neither a link that preceeds it nor one that follows. */
		LListor();

		// Dealing with the user's item being stored in the list

			//! Return item address
		/** This returns the address of the item/object
		being pointed to by this class's pointer. */
		virtual Unk* getThisItemAddress();

			//! Return item copy
		/** This returns a copy of the item/object
		being pointed to by this class's pointer. */
		virtual Unk getThisItemCopy();

			//! Set/replace item
		/** This sets a new item for this pointer or
		replaces the current one. */
		virtual void setThisItem(Unk newItem);



		// Dealing with the chain

			//! Return prior link
		/** This returns a pointer to the link that
		comes before this one in the chain. */
		virtual LListor<Unk>* getPriorLink();

			//! Set prior link
		/** This sets a pointer to the link that is
		now to precede this one. */
		virtual void setPriorLink( LListor<Unk>* newPrior );

			//! Return post link
		/** This returns a pointer to the link that
		follows this one in the chain. */
		virtual LListor<Unk>* getPostLink();

			//! Set post link
		/** This sets a pointer to the link that is
		now to follow this one. */
		virtual void setPostLink( LListor<Unk>* newPost );

			//! Get possession state
		/** This returns one of four values, indicating what links
		it has:
		0 if it has neither a preceeding/prior link nor a following/post, 
		1 if it has a prior link, 
		2 if it has a post link, 
		3 if it has both a prior and a post link. */
		virtual si32 hasWhat();

			//! Add new link
		/** Generate an entirely new link, assign it
		the given object, and append it to this link.
		\param item = new object being added
		\param head = if this link is the new prior */
		virtual LListor<Unk>* addNewLink( Unk item , bool head );

			//! Extract the current link
		/** Takes a link out of the chain it currently belongs to
		without deleting it. The gap in the old chain is linked
		by the linking of the former post and prior links of the
		extracted link. */
		virtual void extractCurrLink() const;

			//! Delete the current link
		/** Removes the current link in the chain by assigning
		the post link and previous link to each other, returning
		one of the two (post takes precedence over prior) if
		available. The removed link is then deleted. */
		virtual void delCurrLink() const;

			//! Delete the next link
		/** Removes the next link in the chain, if it exists,
		and by calling delCurrLink() on its post link. */
		void delPostLink() const
		{
			if ( possession_state == s_post || possession_state == s_both )
			{
				this->getPostLink()->delCurrLink();
			}
		}

			//! Delete the previous link
		/** Removes the previous link in the chain, if it exists,
		and by calling delCurrLink() on its post link. */
		void delPriorLink() const
		{
			if ( possession_state == s_prior || possession_state == s_both )
			{
				this->getPriorLink()->delCurrLink();
			}
		}

			//! Get the first link in the chain
		/** This returns the first link whose possession state
		indicates it does not have a prior link. */
		virtual LListor<Unk>* getFirstLink();

			//! Get the last link in the chain
		/** This returns the last link whose possession state
		indicates it does not have a post link. */
		virtual LListor<Unk>* getLastLink();


			//! Compare items
		/** Apply greater-than comparison operation to the
		items pointed to by the links. */
		void operator> ( LListor<Unk>* ll_out )
		{
			return ( ThisItem > ll_out->getThisItemCopy() );
		}

			//! Compare items
		/** Apply less-than comparison operation to the
		items pointed to by the links. */
		void operator< ( LListor<Unk>* ll_out )
		{
			return ( ThisItem < ll_out->getThisItemCopy() );
		}

			//! Compare items
		/** Apply greater-than-or-equal-to comparison operation
		to the items pointed to by the links. */
		void operator>= ( LListor<Unk>* ll_out )
		{
			return ( ThisItem >= ll_out->getThisItemCopy() );
		}

			//! Compare items
		/** Apply less-than-or-equal-to comparison operation
		to the items pointed to by the links. */
		void operator<= ( LListor<Unk>* ll_out )
		{
			return ( ThisItem <= ll_out->getThisItemCopy() );
		}

			//! Compare items
		/** Apply not-equal-to comparison operation to the
		items pointed to by the links. */
		void operator!= ( LListor<Unk>* ll_out )
		{
			return ( ThisItem != ll_out->getThisItemCopy() );
		}

			//! Compare items
		/** Apply the equal-to comparison operations to the
		items pointed to by the links. */
		void operator== ( LListor<Unk>* ll_out )
		{
			return ( ThisItem == ll_out->getThisItemCopy() );
		}

	};


	// type definitions (essentially just shortcuts)
	//typedef LListor<int> LLii;
	//typedef LListor<float> LLif;
}

	// end the definition
#endif

LL_test_main.cpp

/*
Test program for testing Linus Listor for C++

Author: Nic Anderson
Date: June 15, 2011
*/

#include <iostream> // search the system directory for iostream and add it
#include <string>
#include "LinusListorCp.cpp" // search the locale directory for LinusListorCp.cpp and add it

using namespace std;
using namespace Linus;


void main()
{
	cout << "\nThis program is meant to test a linked list program.";

	// user input
	string answer;

	// the start of the linked list
	LListor<string> lls;
	LListor<string> * lsp;

	lls.setThisItem( "List start" );

	do {
		// Request user input
		cout << "\nPlease enter a value: ";
		cin >> answer;

		// add a new link to the linked list
		lsp = lls.addNewLink( answer, false );

		// ask if the user wants to continue inputting values to be added to the list
		cout << "\nContinue? (y/n): ";
		cin >> answer;
	} while ( answer == "y" );

	// output the final list
	cout << "\n\nFinal List:\n";

	int count = 0;
	LListor<string> * lsi;

	// start at this address - point to the list with the pointer "lsi"
	lsi = &lls;
	lsp = lls.getLastLink();

	// get the first link
	lsi = lsi->getFirstLink();

	
	do {
		// obtain the string
		answer = lsi->getThisItemCopy();

		// print the contents
		cout << count << ") " << answer << endl;

		count++;

		// if possible, get the post link
		if ( lsi->hasWhat() == 2 || lsi->hasWhat() == 3 )
			lsi = lsi->getPostLink();
		else break;

	} while ( 1 );

	// For debug
	cout << "\nlsp copy = " << ( lsp->getThisItemCopy() )
		<< "\nlsp addr = " << ( lsp->getThisItemAddress() )
		<< "\nlls copy = " << ( lls.getThisItemCopy() ) << endl;

	// get the first link
	lsi = lsi->getFirstLink();

	// remove from the chain and delete the last link
	//lsp->extractCurrLink();
	//delete lsp;

	// delete the last link
	lsp->delCurrLink();

	do {
		// obtain the string
		answer = lsi->getThisItemCopy();

		// print the contents
		cout << count << ") " << answer << endl;

		count++;

		// if possible, get the post link
		if ( lsi->hasWhat() == 2 || lsi->hasWhat() == 3 )
			lsi = lsi->getPostLink();
		else break;

	} while ( 1 );

	// prevent closing
	cin >> answer;

}