HashTable:

1. Fixed documentation
2. added __delitem__

Author: orenovadia

map/hashtable.py

@@ -1,21 +1,24 @@
-"""
-MAP Abstract Data Type
-Map() Create a new, empty map. It returns an empty map collection.
-put(key,val) Add a new key-value pair to the map. If the key is already in the map then replace the old value with the new value.
-get(key) Given a key, return the value stored in the map or None otherwise.
-del Delete the key-value pair from the map using a statement of the form del map[key].
-len() Return the number of key-value pairs stored in the map.
-in Return True for a statement of the form key in map, if the given key is in the map, False otherwise.
-"""
 from unittest import TestCase
 
 
 class HashTable(object):
+    """
+    HashMap Data Type
+    HashMap() Create a new, empty map. It returns an empty map collection.
+    put(key, val) Add a new key-value pair to the map. If the key is already in the map then replace
+                    the old value with the new value.
+    get(key) Given a key, return the value stored in the map or None otherwise.
+    del_(key) or del map[key] Delete the key-value pair from the map using a statement of the form del map[key].
+    len() Return the number of key-value pairs stored in the map.
+    in Return True for a statement of the form key in map, if the given key is in the map, False otherwise.
+    """
+
     _empty = object()
     _deleted = object()
 
     def __init__(self, size=11):
         self.size = size
+        self._len = 0
         self._keys = [self._empty] * size  # keys
         self._values = [self._empty] * size  # values
 
@@ -27,6 +30,7 @@ def put(self, key, value):
                 # can assign to hash_ index
                 self._keys[hash_] = key
                 self._values[hash_] = value
+                self._len += 1
                 return
             elif self._keys[hash_] == key:
                 # key already exists here, assign over
@@ -65,6 +69,7 @@ def del_(self, key):
                 # key found, assign with deleted sentinel
                 self._keys[hash_] = self._deleted
                 self._values[hash_] = self._deleted
+                self._len -= 1
                 return
 
             hash_ = self._rehash(hash_)
@@ -84,6 +89,9 @@ def _rehash(self, old_hash):
     def __getitem__(self, key):
         return self.get(key)
 
+    def __delitem__(self, key):
+        return self.del_(key)
+
     def __setitem__(self, key, value):
         self.put(key, value)
 
@@ -127,7 +135,7 @@ def test_delete_key(self):
     def test_delete_key_and_reassign(self):
         m = HashTable(10)
         m.put(1, 1)
-        m.del_(1)
+        del m[1]
         m.put(1, 2)
         self.assertEqual(2, m.get(1))