--- a/LinkedList.h	Sat Nov 06 03:59:28 2010 -0700
+++ b/LinkedList.h	Sat Nov 06 04:00:44 2010 -0700
@@ -1,69 +1,348 @@
-/*
- LinkedList
- Copyright (C) 2010  Eric Wing <ewing . public @ playcontrol.net>
- 
- This library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Library General Public
- License as published by the Free Software Foundation; either
- version 2 of the License, or (at your option) any later version.
- 
- This library 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
- Library General Public License for more details.
- 
- You should have received a copy of the GNU Library General Public
- License along with this library; if not, write to the Free
- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-*/
+#include "LinkedList.h"
+#include <stddef.h> /* for NULL */
+#include <stdlib.h> /* for malloc/free */
+#include <stdio.h> /* for debugging */
+
+struct LinkedListNode
+{
+	LinkedListNode* nextNode;
+	LinkedListNode* previousNode;
+	void* dataPtr;
+};
+
+struct LinkedList
+{
+	size_t currentSize;
+	LinkedListNode* headPtr;
+	LinkedListNode* tailPtr;
+};
+
+
+LinkedListNode* LinkedListNode_Create()
+{
+	LinkedListNode* list_node;
+	list_node = (LinkedListNode*)calloc(1, sizeof(LinkedListNode));
+	if(NULL == list_node)
+	{
+		/* Very bad, but not sure what to do here. */
+		return NULL;
+	}
+
+	return list_node;
+}
+
+
+void LinkedListNode_Free(LinkedListNode* list_node)
+{
+	if(NULL == list_node)
+	{
+		return;
+	}
+	free(list_node);
+}
+
+
+LinkedList* LinkedList_Create()
+{
+	LinkedList* linked_list;
+	linked_list = (LinkedList*)calloc(1, sizeof(LinkedList));
+	if(NULL == linked_list)
+	{
+		/* Very bad, but not sure what to do here. */
+		return NULL;
+	}
+
+	return linked_list;
+}
+
+void LinkedList_Free(LinkedList* linked_list)
+{
+	/* Both functions check for NULL */
+	LinkedList_Clear(linked_list);
+	free(linked_list);
+}
+
+
+/**
+ * Returns 1 if successful, 0 if failure.
+ */
+unsigned int LinkedList_PushFront(LinkedList* linked_list, void* new_item)
+{
+	LinkedListNode* new_node;
+	
+	if(NULL == linked_list)
+	{
+		return 0;
+	}
+
+	new_node = LinkedListNode_Create();
+	if(NULL == new_node)
+	{
+		return 0;
+	}
 
-/* I'm so sick of constantly rewriting linked lists in C. 
-So here's some initial work to write a very simple reusable implementation.
-The API could use a lot more functions, but I'll add them as I need them.
-*/
+	new_node->dataPtr = new_item;
+
+	if(0 == linked_list->currentSize)
+	{
+		linked_list->tailPtr = new_node;
+	}
+	else
+	{
+		LinkedListNode* head_node = linked_list->headPtr;
+		new_node->nextNode = head_node;
+		head_node->previousNode = new_node;
+	}
+
+	linked_list->headPtr = new_node;
+	linked_list->currentSize++;
+	return 1;
+}
+
+unsigned int LinkedList_PushBack(LinkedList* linked_list, void* new_item)
+{
+	LinkedListNode* new_node;
+	
+	if(NULL == linked_list)
+	{
+		return 0;
+	}
+
+	new_node = LinkedListNode_Create();
+	if(NULL == new_node)
+	{
+		return 0;
+	}
+
+	new_node->dataPtr = new_item;
 
-#ifndef C_LINKED_LIST_H
-#define C_LINKED_LIST_H
+	if(0 == linked_list->currentSize)
+	{
+		linked_list->headPtr = new_node;
+	}
+	else
+	{
+		LinkedListNode* tail_node = linked_list->tailPtr;
+		new_node->previousNode = tail_node;
+		tail_node->nextNode = new_node;
+	}
+
+	linked_list->tailPtr = new_node;
+	linked_list->currentSize++;
+	return 1;
+
+}
 
-/* Set up for C function definitions, even when using C++ */
-#ifdef __cplusplus
-extern "C" {
-#endif
+void* LinkedList_PopFront(LinkedList* linked_list)
+{
+	LinkedListNode* head_node;
+	void* return_data;
+	
+	if(NULL == linked_list)
+	{
+		return 0;
+	}
+	if(0 == linked_list->currentSize)
+	{
+		return NULL;
+	}
 
-#include <stddef.h>
+	head_node = linked_list->headPtr;
+	return_data = head_node->dataPtr;
+	
+	if(1 ==  linked_list->currentSize)
+	{
+		LinkedList_Clear(linked_list);
+	}
+	else
+	{
+		LinkedListNode* next_node = head_node->nextNode;
+		next_node->previousNode = NULL;
+		LinkedListNode_Free(head_node);
+		linked_list->headPtr = next_node;
+		linked_list->currentSize = linked_list->currentSize - 1;
+
+	}
+	return return_data;
+}
 
-typedef struct LinkedListNode LinkedListNode;
-typedef struct LinkedList LinkedList;
+void* LinkedList_PopBack(LinkedList* linked_list)
+{
+	LinkedListNode* tail_node;
+	void* return_data;
+	
+	if(NULL == linked_list)
+	{
+		return NULL;
+	}
+	if(0 == linked_list->currentSize)
+	{
+		return NULL;
+	}
 
-LinkedList* LinkedList_Create();
+	tail_node = linked_list->tailPtr;
+	return_data = tail_node->dataPtr;
+	
+	if(1 == linked_list->currentSize)
+	{
+		LinkedList_Clear(linked_list);
+	}
+	else
+	{
+		LinkedListNode* previous_node = tail_node->previousNode;
+		previous_node->nextNode = NULL;
+		LinkedListNode_Free(tail_node);
+		linked_list->tailPtr = previous_node;
+		linked_list->currentSize = linked_list->currentSize - 1;
+	}
+	return return_data;
+}
 
-void LinkedList_Free(LinkedList* linked_list);
 
-void* LinkedList_Front(LinkedList* linked_list);
-void* LinkedList_Back(LinkedList* linked_list);
-
-unsigned int LinkedList_PushFront(LinkedList* linked_list, void* new_item);
+void* LinkedList_Front(LinkedList* linked_list)
+{
+	LinkedListNode* head_node;
+	void* return_data;
+	
+	if(NULL == linked_list)
+	{
+		return 0;
+	}
+	if(0 == linked_list->currentSize)
+	{
+		return NULL;
+	}
+	
+	head_node = linked_list->headPtr;
+	return_data = head_node->dataPtr;
+	
+	return return_data;
+}
 
-unsigned int LinkedList_PushBack(LinkedList* linked_list, void* new_item);
+void* LinkedList_Back(LinkedList* linked_list)
+{
+	LinkedListNode* tail_node;
+	void* return_data;
+	
+	if(NULL == linked_list)
+	{
+		return NULL;
+	}
+	if(0 == linked_list->currentSize)
+	{
+		return NULL;
+	}
+	
+	tail_node = linked_list->tailPtr;
+	return_data = tail_node->dataPtr;
 
-void* LinkedList_PopFront(LinkedList* linked_list);
+	return return_data;
+}
+
 
-void* LinkedList_PopBack(LinkedList* linked_list);
+size_t LinkedList_Size(LinkedList* linked_list)
+{
+	if(NULL == linked_list)
+	{
+		return 0;
+	}
+	return linked_list->currentSize;
+}
+
+void LinkedList_Clear(LinkedList* linked_list)
+{
+	if(NULL == linked_list)
+	{
+		return;
+	}
 
-size_t LinkedList_Size(LinkedList* linked_list);
+	LinkedListNode* current_node = linked_list->headPtr;
+	LinkedListNode* next_node;
+	while(NULL != current_node)
+	{
+		next_node = current_node->nextNode;
+		LinkedListNode_Free(current_node);
+		current_node = next_node;
+	}
+	linked_list->headPtr = NULL;
+	linked_list->tailPtr = NULL;
+	linked_list->currentSize = 0;
+}
 
-void LinkedList_Clear(LinkedList* linked_list);
+void* LinkedListNode_GetData(LinkedListNode* list_node)
+{
+	if(NULL == list_node)
+	{
+		return NULL;
+	}
+	return list_node->dataPtr;
+}
 
-void* LinkedListNode_GetData(LinkedListNode* list_node);
-
-LinkedListNode* LinkedList_Find(LinkedList* linked_list, void* the_data, LinkedListNode* start_node);
+LinkedListNode* LinkedList_Find(LinkedList* linked_list, void* the_data, LinkedListNode* start_node)
+{
+	LinkedListNode* current_node;
+	if(NULL == linked_list)
+	{
+		return NULL;
+	}
+	if(NULL == start_node)
+	{
+		start_node = linked_list->headPtr;
+	}
+	
+	for(current_node = start_node; NULL != current_node; current_node = current_node->nextNode)
+	{
+		if(current_node->dataPtr == the_data)
+		{
+			return current_node;
+		}
+	}
+	return current_node;
+}
 
-unsigned int LinkedList_Remove(LinkedList* linked_list, LinkedListNode* list_node);
+/* Make sure your LinkedListNode is actually connected to the 
+ * LinkedList instance you pass.
+ */
+unsigned int LinkedList_Remove(LinkedList* linked_list, LinkedListNode* list_node)
+{
+	LinkedListNode* previous_node;
+	LinkedListNode* next_node;
+	if(NULL == linked_list)
+	{
+		return 0;
+	}
+	if(NULL == list_node)
+	{
+		return 0;
+	}
+		
+	if(1 ==  linked_list->currentSize)
+	{
+		LinkedList_Clear(linked_list);
+	}
+	else if(list_node == linked_list->headPtr)
+	{
+		LinkedList_PopFront(linked_list);
+	}
+	else if(list_node == linked_list->tailPtr)
+	{
+		LinkedList_PopBack(linked_list);
+	}
+	else
+	{
+		previous_node = list_node->previousNode;
+		next_node = list_node->nextNode;
 
-/* Ends C function definitions when using C++ */
-#ifdef __cplusplus
+		previous_node->nextNode = next_node;
+		next_node->previousNode = previous_node;
+		LinkedListNode_Free(list_node);
+
+		linked_list->currentSize = linked_list->currentSize - 1;
+	}
+
+	return 1;
+
 }
-#endif
-	
-#endif /* C_LINKED_LIST_H */
+
 
+