Added linked list

Author: devangrose

dataStructures.py

@@ -0,0 +1,133 @@
+#!/usr/bin/env python
+
+
+class Linked_List_Node:
+
+    def __init__(self, payload, parent = None, child = None):
+        self.payload = payload
+        self.parent = parent
+        self.child = child
+
+    def has_child(self):
+        return not self.child == None
+
+    def has_parent(self):
+        return  not self.parent == None
+
+    def get_child(self):
+        if self.has_child():
+            return self.child
+        else: return None
+
+    def set_child(self, child):
+        self.child = child
+
+    def get_parent(self):
+        if self.has_parent():
+            return self.parent
+        else: return None
+
+    def set_parent(self, parent):
+        self.parent = parent
+    
+    def get_payload(self):
+        return self.payload
+
+    def set_payload(self, payload):
+        self.payload = payload
+
+class Linked_List:
+    
+    def __init__(self):
+        self.head = None
+
+    def __len__(self):
+        toReturn = 0
+        current_node = self.head
+        while not current_node == None:
+            toReturn += 1
+            current_node = current_node.get_child()
+        return toReturn
+
+    def add(self, data):
+
+        # make new node
+        newNode = Linked_List_Node(data)
+        # case - List is empty
+        if self.head == None:
+            self.head = newNode
+        # case - List is not empty
+        else: 
+            current_node = self.head
+            
+            # traverse through list to end
+            while current_node.has_child():
+                current_node = current_node.get_child()
+            
+            # insert into list
+            current_node.set_child(newNode)
+            newNode.set_parent(current_node)
+
+    def find_in_list(self,term):
+        current_node = self.head
+        # traverse the list until end or match
+        while (not current_node.get_payload() == term) and current_node.has_child():
+            print "checking {} vs {}".format(current_node.get_payload(),term)
+            current_node = current_node.get_child()
+            print current_node.get_payload()
+        if current_node.get_payload() == term:
+            return current_node
+        else: return None
+
+    def delete(self, term):
+        
+        # find the node in the list
+        node = self.find_in_list(term) 
+        if not node == None:    
+            parent = node.get_parent()
+            child = node.get_child()
+            
+            # top of list
+            if parent == None:
+
+                # last in list
+                if child == None:
+                    self.head = None
+                else:
+                    self.head = child
+            else: 
+                
+                # last in list
+                if child == None:
+                    parent.set_child(None)
+                else:
+                    child.set_parent(parent)
+                    parent.set_child(child)
+        else: print "Item not in list"
+
+    def get_item(self,term):
+        node = self.find_in_list(term)
+
+        if node == None: 
+            return  None
+        else: return node.get_payload()
+
+    def print_list(self):
+        current_node = self.head
+        if not current_node == None:
+            print current_node.get_payload(),
+            current_node = current_node.get_child()
+        while not current_node == None:
+            print ", ",
+            print current_node.get_payload(),
+            
+            current_node = current_node.get_child()
+    
+    def pop(self):
+        if not self.head == None:
+            toReturn = self.head.get_payload()
+            self.head = self.head.get_child()
+            return toReturn
+        else: return None
+
+