class BookmarkDatabase(PersistenceLayer):
"""
A specific persistence layer implementation that uses a database in
local storage.
"""
def __init__(self):
self.table_name = "bookmarks"
print("Start connection to database")
self.db = DatabaseManager("bookmarks.db")
print("Try to create a new table")
self.db.create_table(
self.table_name,
{
"id": "INTEGER PRIMARY KEY AUTOINCREMENT",
"title": "TEXT NOT NULL",
"url": "TEXT NOT NULL",
"notes": "TEXT",
"date_added": "TEXT NOT NULL",
},
)
# All commands below are database-specific implementation for
# each of the behaviors of the interface.
def create(self, bookmark_data):
self.db.add(self.table_name, bookmark_data)
def list(self, order_by=None):
return self.db.select(self.table_name, order_by=order_by).fetchall()
def edit(self, criteria, new_data):
self.db.edit(self.table_name, criteria, new_data)
def delete(self, bookmark_id):
self.db.delete(self.table_name, {"id": bookmark_id})
class Interpreter:
def __init__(self):
self._dbm = DatabaseManager()
def interpret(self, line):
expressions = [expression for expression in line.split(';') if expression]
for expression in expressions:
tokens = self._tokenize(expression)
self._evaluate(tokens)
def _tokenize(self, expression):
return expression.replace('(', ' ( ').replace(')', ' ) ').replace('*', ' * ').replace(',', ' , ').split()
def _evaluate(self, tokens):
if (tokens[0].upper() == 'USE'):
self._dbm.select_database(tokens[1])
elif (tokens[0].upper() == 'CREATE'):
if (tokens[1].upper() == 'DATABASE'):
self._dbm.create_database(tokens[2])
elif (tokens[1].upper() == 'TABLE'):
self._dbm.create_table(tokens[2])
else:
self._syntax_error()
elif (tokens[0].upper() == 'DROP'):
if (tokens[1].upper() == 'DATABASE'):
self._dbm.drop_database(tokens[2])
elif (tokens[1].upper() == 'TABLE'):
self._dbm.drop_table(tokens[2])
else:
self._syntax_error()
elif (tokens[0].upper() == 'RENAME'):
if (tokens[1].upper() == 'DATABASE'):
self._dbm.rename_database(tokens[2], tokens[3])
elif (tokens[1].upper() == 'TABLE'):
self._dbm.rename_table(tokens[2],tokens[3])
else:
self._syntax_error()
elif (tokens[0].upper() == 'LIST'):
if (tokens[1].upper() == 'TABLES'):
self._dbm.list_tables()
else:
self._syntax_error()
elif (tokens[0].upper() == 'CLOSE'):
if (tokens[1].upper() == 'DATABASE'):
self._dbm.close_database()
else:
self._syntax_error()
elif (tokens[0].upper() == 'SELECT'):
if (tokens[1] == '*'):
print(self._dbm.select_all(tokens[3]))
else:
self._dbm.select_by_key(tokens[1], tokens[3])
elif (tokens[0].upper() == 'INSERT'):
self._dbm.insert(tokens[2], tokens[4], tokens[7])
elif (tokens[0].upper() == 'UPDATE'):
self._dbm.update_by_key(tokens[1], tokens[3], tokens[5])
elif (tokens[0].upper() == 'REMOVE'):
if (tokens[1] == '*'):
self._dbm.remove_all(tokens[3])
else:
self._dbm.remove_by_key(tokens[1], tokens[3])
else:
self._syntax_error()
def _syntax_error(self):
print("Error: Incorrect Syntax")
