class DBDB(object):
def __init__(self, f):
self._storage = Storage(f) #_storage在DBDB中只完成一个功能：检查文件有没有关闭
self._tree = BinaryTree(self._storage)
def _assert_not_close(self):
if self._storage.closed:
raise ValueError('Database closed.')
def close(self):
self._storage.close()
def commit(self):
self._assert_not_close()
self._tree.commit()
#实现__getitem__、__setitem__、__delitem__、__contains__等函数，
# 就能像操作词典一样操作DBDB对象了
def __getitem__(self, key):
'''通过 dbdb[key] 获取键值'''
self._assert_not_close()
return self._tree.get(key)
def __setitem__(self, key, value):
'''通过 dbdb[key] = value 设置键值'''
self._assert_not_close()
return self._tree.set(key, value)
def __delitem__(self, key):
'''通过 del dbdb[key] 删除键值'''
self._assert_not_close()
return self._tree.pop(key)
def __contains__(self, key):
'''通过 key in dbdb 来判断键在不在数据库中'''
try:
self[key]
except KeyError:
return False
else:
return True
def __len__(self):
return len(self._tree)
class DBDB(object):
def __init__(self, f):
self._storage = Storage(f)
self._tree = BinaryTree(self._storage)
def _assert_not_closed(self):
if self._storage.closed:
raise ValueError('Database closed.')
def close(self):
self._storage.close()
def commit(self):
self._assert_not_closed()
self._tree.commit()
def __getitem__(self, key):
#通过db[key] 获取键值
self._assert_not_closed()
return self._tree.get(key)
def __setitem__(self, key, value):
#通过db[key] =value 设置键值
self._assert_not_closed()
return self._tree.set(key, value)
def __delitem__(self, key):
#通过 del db[key] 删除键值
self._assert_not_closed()
return self._tree.pop(key)
def __contains__(self, key):
#通过key in db 来判断键在不在数据库中
try:
self[key]
except KeyError:
return False
else:
return True
def __len__(self):
return len(self._tree)
class DBDB(object):
def __init__(self, f):
self._storage = Storage(f)
self._tree = BinaryTree(self._storage)
def _assert_not_closed(self):
if self._storage.closed:
raise ValueError('Database closed.')
def close(self):
self._storage.close()
def commit(self):
self._assert_not_closed()
self._tree.commit()
#相当于重写了字典中的getitem函数
def __getitem__(self, key):
self._assert_not_closed()
return self._tree.get(key)
def __setitem__(self, key, value):
self._assert_not_closed()
return self._tree.set(key, value)
def __delitem__(self, key):
self._assert_not_closed()
return self._tree.pop(key)
def __contains__(self, key):
try:
self[key]
except KeyError:
return False
else:
return True
def __len__(self):
return len(self._tree)
class DBDB(object):
def __init__(self, f):
self._storage = Storage(f) # Reference to storage so it can enforce preconditions
self._tree = BinaryTree(self._storage)
def _assert_not_closed(self):
if self._storage.closed:
raise ValueError('Database closed.')
def close(self):
self._storage.close()
def commit(self):
self._assert_not_closed()
self._tree.commit()
# Implements dict functions
def __getitem__(self, key): # operator [<key>]
self._assert_not_closed()
return self._tree.get(key)
def __setitem__(self, key, value): # operator [<new_key>] = <value>
self._assert_not_closed()
return self._tree.set(key, value)
def __delitem__(self, key): # operator del dict[<key>]
self._assert_not_closed()
return self._tree.pop(key)
def __contains__(self, key): # operator <key> in dict
try:
self[key]
except KeyError:
return False
else:
return True
def __len__(self):
return len(self._tree)
class DBDB(object):
def __init__(self, f):
self._storage = Storage(f)
self._tree = BinaryTree(self._storage)
def _assert_not_closed(self):
if self._storage.closed:
raise ValueError("Database Closed!")
def close(self):
self._storage.close()
def commit(self):
self._assert_not_closed()
self._tree.commit()
def __getitem__(self, key):
self._assert_not_closed()
return self._tree.get(key)
def __setitem__(self, key, value):
self._assert_not_closed()
return self._tree.set(key, value)
def __delitem__(self, key):
self._assert_not_closed()
return self._tree.pop(key)
def __contains__(self, key):
try:
#self[key]的用法不懂，奇怪的用法
self[key]
except KeyError:
return False
else:
return True
def __len__(self):
return len(self._tree)
class TestBinaryTree(object):
def setup(self):
self.f = tempfile.NamedTemporaryFile(delete=False)
self.storage = Storage(self.f)
self.tree = BinaryTree(self.storage)
def teardown(self):
pass
def test_get_missing_key_raises_key_error(self):
with assert_raises(KeyError):
self.tree.get('Not A Key In The Tree')
def test_set_and_get_key(self):
self.tree.set('b', '1')
self.tree.set('a', '2')
self.tree.set('c', '3')
self.tree.commit()
eq_(self.tree.get('a'), '2')
eq_(self.tree.get('b'), '1')
eq_(self.tree.get('c'), '3')
def test_set_and_reset_key(self):
self.tree.set('a', '1')
eq_(self.tree.get('a'), '1')
self.tree.set('a', '2')
eq_(self.tree.get('a'), '2')
def test_delete_a_non_key(self):
with assert_raises(KeyError):
self.tree.pop('a')
def test_set_and_delete_key(self):
self.tree.set('a', '1')
self.tree.set('b', '2')
self.tree.set('c', '3')
self.tree.commit()
eq_(self.tree.get('a'), '1')
eq_(self.tree.get('b'), '2')
eq_(self.tree.get('c'), '3')
self.tree.pop('a')
eq_(self.tree.get('b'), '2')
eq_(self.tree.get('c'), '3')
with assert_raises(KeyError):
self.tree.get('a')
def test_set_and_delete_left_node(self):
self.tree.set('b', '2')
self.tree.set('a', '1')
self.tree.set('c', '3')
self.tree.commit()
eq_(self.tree.get('a'), '1')
eq_(self.tree.get('b'), '2')
eq_(self.tree.get('c'), '3')
self.tree.pop('a')
eq_(self.tree.get('b'), '2')
eq_(self.tree.get('c'), '3')
with assert_raises(KeyError):
self.tree.get('a')
def test_set_and_delete_right_node(self):
self.tree.set('b', '2')
self.tree.set('a', '1')
self.tree.set('c', '3')
self.tree.commit()
eq_(self.tree.get('a'), '1')
eq_(self.tree.get('b'), '2')
eq_(self.tree.get('c'), '3')
self.tree.pop('c')
eq_(self.tree.get('a'), '1')
eq_(self.tree.get('b'), '2')
with assert_raises(KeyError):
self.tree.get('c')
def test_set_and_delete_root_node(self):
self.tree.set('b', '2')
self.tree.set('a', '1')
self.tree.set('c', '3')
self.tree.commit()
eq_(self.tree.get('a'), '1')
eq_(self.tree.get('b'), '2')
eq_(self.tree.get('c'), '3')
self.tree.pop('b')
eq_(self.tree.get('a'), '1')
eq_(self.tree.get('c'), '3')
with assert_raises(KeyError):
self.tree.get('b')
def test_set_and_delete_root_node_without_its_left_node(self):
self.tree.set('b', '2')
self.tree.set('c', '3')
self.tree.commit()
eq_(self.tree.get('b'), '2')
eq_(self.tree.get('c'), '3')
self.tree.pop('b')
eq_(self.tree.get('c'), '3')
with assert_raises(KeyError):
self.tree.get('b')
def test_set_and_delete_root_node_without_its_right_node(self):
self.tree.set('b', '2')
self.tree.set('a', '1')
self.tree.commit()
eq_(self.tree.get('b'), '2')
eq_(self.tree.get('a'), '1')
self.tree.pop('b')
eq_(self.tree.get('a'), '1')
with assert_raises(KeyError):
self.tree.get('b')
def test_set_and_delete_root_node_with_its_left_part_needs_to_findmax(
self):
self.tree.set('e', '5')
self.tree.set('a', '1')
self.tree.set('b', '2')
self.tree.set('c', '3')
self.tree.set('f', '6')
self.tree.commit()
self.tree.pop('e')
with assert_raises(KeyError):
self.tree.get('e')
class TestBinaryTree(object):
def setup(self):
self.tree = BinaryTree(StubStorage())
def test_get_missing_key_raises_key_error(self):
with assert_raises(KeyError):
self.tree.get('Not A Key In The Tree')
def test_set_and_get_key(self):
self.tree.set('a', 'b')
eq_(self.tree.get('a'), 'b')
def test_random_set_and_get_keys(self):
ten_k = list(range(10000))
pairs = list(zip(random.sample(ten_k, 10), random.sample(ten_k, 10)))
for i, (k, v) in enumerate(pairs, start=1):
self.tree.set(k, v)
eq_(len(self.tree), i)
for k, v in pairs:
eq_(self.tree.get(k), v)
random.shuffle(pairs)
for i, (k, v) in enumerate(pairs, start=1):
self.tree.pop(k)
eq_(len(self.tree), len(pairs) - i)
def test_overwrite_and_get_key(self):
self.tree.set('a', 'b')
self.tree.set('a', 'c')
eq_(self.tree.get('a'), 'c')
def test_pop_non_existent_key(self):
with assert_raises(KeyError):
self.tree.pop('Not A Key In The Tree')
def test_del_leaf_key(self):
self.tree.set('b', '2')
self.tree.pop('b')
with assert_raises(KeyError):
self.tree.get('b')
def test_del_left_node_key(self):
self.tree.set('b', '2')
self.tree.set('a', '1')
self.tree.pop('b')
with assert_raises(KeyError):
self.tree.get('b')
self.tree.get('a')
def test_del_right_node_key(self):
self.tree.set('b', '2')
self.tree.set('c', '3')
self.tree.pop('b')
with assert_raises(KeyError):
self.tree.get('b')
self.tree.get('c')
def test_del_full_node_key(self):
self.tree.set('b', '2')
self.tree.set('a', '1')
self.tree.set('c', '3')
self.tree.pop('b')
with assert_raises(KeyError):
self.tree.get('b')
self.tree.get('a')
self.tree.get('c')
class TestBinaryTree(object):
def setup(self):
self.tree = BinaryTree(StubStorage())
def test_get_missing_key_raises_key_error(self):
with assert_raises(KeyError):
self.tree.get('Not A Key In The Tree')
def test_set_and_get_key(self):
self.tree.set('a', 'b')
eq_(self.tree.get('a'), 'b')
def test_random_set_and_get_keys(self):
ten_k = list(range(10000))
pairs = list(zip(random.sample(ten_k, 10), random.sample(ten_k, 10)))
for i, (k, v) in enumerate(pairs, start=1):
self.tree.set(k, v)
eq_(len(self.tree), i)
for k, v in pairs:
eq_(self.tree.get(k), v)
random.shuffle(pairs)
for i, (k, v) in enumerate(pairs, start=1):
self.tree.pop(k)
eq_(len(self.tree), len(pairs) - i)
def test_overwrite_and_get_key(self):
self.tree.set('a', 'b')
self.tree.set('a', 'c')
eq_(self.tree.get('a'), 'c')
def test_pop_non_existent_key(self):
with assert_raises(KeyError):
self.tree.pop('Not A Key In The Tree')
def test_del_leaf_key(self):
self.tree.set('b', '2')
self.tree.pop('b')
with assert_raises(KeyError):
self.tree.get('b')
def test_del_left_node_key(self):
self.tree.set('b', '2')
self.tree.set('a', '1')
self.tree.pop('b')
with assert_raises(KeyError):
self.tree.get('b')
self.tree.get('a')
def test_del_right_node_key(self):
self.tree.set('b', '2')
self.tree.set('c', '3')
self.tree.pop('b')
with assert_raises(KeyError):
self.tree.get('b')
self.tree.get('c')
def test_del_full_node_key(self):
self.tree.set('b', '2')
self.tree.set('a', '1')
self.tree.set('c', '3')
self.tree.pop('b')
with assert_raises(KeyError):
self.tree.get('b')
self.tree.get('a')
self.tree.get('c')
class TestBinaryTree:
def setup(self):
self.tree = BinaryTree(StubStorage())
def test_get_missing_key_raises_key_error(self):
with assert_raises(KeyError):
self.tree.get("Not a key in the tree")
def test_set_and_get_key(self):
self.tree.set("a", "b")
eq_(self.tree.get("a"), "b")
def test_random_set_and_get_keys(self):
ten_k = list(range(10000))
pairs = list(zip(random.sample(ten_k, 10), random.sample(ten_k, 10)))
for i, (k, v) in enumerate(pairs, start=1):
self.tree.set(k, v)
eq_(len(self.tree), i)
for k, v in pairs:
eq_(self.tree.get(k), v)
random.shuffle(pairs)
for i, (k, v) in enumerate(pairs, start=1):
self.tree.pop(k)
eq_(len(self.tree), len(pairs) - i)
def test_overwrite_and_get_key(self):
self.tree.set("a", "b")
self.tree.set("a", "c")
eq_(self.tree.get("a"), "c")
def test_pop_non_existent_key(self):
with assert_raises(KeyError):
self.tree.pop("Not a key in the tree")
def test_del_leaf_key(self):
self.tree.set("b", "2")
self.tree.pop("b")
with assert_raises(KeyError):
self.tree.get("b")
def test_del_left_node_key(self):
self.tree.set("b", "2")
self.tree.set("a", "1")
self.tree.pop("b")
with assert_raises(KeyError):
self.tree.get("b")
self.tree.get("a")
def test_del_right_node_key(self):
self.tree.set("b", "2")
self.tree.set("c", "3")
self.tree.pop("b")
with assert_raises(KeyError):
self.tree.get("b")
self.tree.get("c")
def test_del_full_node_key(self):
self.tree.set("b", "2")
self.tree.set("a", "1")
self.tree.set("c", "3")
self.tree.pop("b")
with assert_raises(KeyError):
self.tree.get("b")
self.tree.get("a")
self.tree.get("c")