Tests add with collisions

02_hash_maps/hm.py

@@ -24,9 +24,7 @@ class HashMap():
 			self._size += 1
 		else: 
 			raise Exception("Collision detected at index %d", key)
-	
+		
-		# TODO: Keep implementing
-	
 	def get(self, key):
 		"""
 		Finds the element in the hash table that may contain the id for 
@@ -63,16 +61,48 @@ class HMTableCollision(HashMap):
 	each index will contain a list. This means several elements can be 
 	stored with the same index.
 	"""
+	def __init__(self, hash_size=513):
+		self._hash_size = hash_size
+		self._size = 0
+		self.hmap = [None] * self._hash_size
+		
 	def add(self, key, value):
-			"""
+		"""
-			Adds the provided value to the hashmap.
+		Adds the provided value to the hashmap.
-			Raises an Exception if a collision is detected
+		Raises an Exception if a collision is detected
-			"""
+		"""
-			my_key = self._hash(key)
+		my_key = self._hash(key)
+					
+		if self.hmap[my_key] == None:
+			self.hmap[my_key] = [value]
+		else: 
+			self.hmap[my_key].append(value)
+		self._size += 1
+	
+	def get(self, key):
+		"""
+		Finds the element in the hash table that may contain the id for 
+		the string we are looking for
+		"""
+		my_key = self._hash(key)
+		return self.hmap[my_key]		
+	
+	def size(self):
+		return self._size
+	
+	def _hash(self, value):
+		"""
+		Generates a hash for the given value.
+		The input is expected to be a String, with only ASCII characters.
+		
+		# hash function taken from HT3.
+		# We shift and add : << 4 is a *16
+		"""
+		if len(value) < 1:
+			raise Exception("Size of value must be greater than one")
+		
+		h = 0
+		for letter in value:
+			h = (h << 4) + ord(letter)
 			
-			
+		return h % self._hash_size
-			if self.hmap[my_key] == None:
-				self.hmap[my_key] = value
-				self._size += 1
-			else: 
-				raise Exception("Collision detected at index %d", key)

02_hash_maps/hm_test.py

@@ -10,16 +10,15 @@ from hm import HMTableCollision
 import unittest
 
 class test_hash_map_table_collision(unittest.TestCase):
-	
+
 	def test_add(self):
 		hm = HMTableCollision()
 		
 		hm.add("a", "Ibiza")
 		self.assertEqual(hm.size(), 1)
-
+		
-		# Tests Collision
+		hm.add("a", "Ibiza")
-		self.assertRaises(Exception, lambda x : hm.add("a", "Ibiza"))
+		self.assertEqual(hm.size(), 2)	
-		self.assertEqual(hm.size(), 1)
 
 class test_hash_map(unittest.TestCase):
 
@@ -47,6 +46,7 @@ class test_hash_map(unittest.TestCase):
 		value = ""
 		self.assertRaises(Exception, lambda x : hm._hash(value))
 
+
 	def test_add(self):
 		hm = HashMap()