class DB:
"""A simple in-memory key-value store with nested transactional blocks."""
# Commands are implicity mapped to methods of the same name, but lowercased.
_commands_ = ['SET', 'GET', 'UNSET', 'NUMEQUALTO', 'BEGIN', 'ROLLBACK', 'COMMIT', 'END']
def __init__(self):
self._store_ = NestedStore()
def run(self, query):
"""Runs the provided query and returns the result."""
tokens = query.split(' ')
command, args = tokens[0], (self._parse_token_(token) for token in tokens[1:])
if command in DB._commands_:
try:
return DB.__dict__[command.lower()](self, *args)
except TypeError:
return '[ERROR] Probably incorrect arguments for command: {}'.format(command)
else:
return '[ERROR] Unrecognized command: {}'.format(command)
def set(self, key, value):
"""SET [name] [value]: Set a variable [name] to the value [value].
Neither variable names or values will ever contain spaces.
"""
self._store_.set(key, value)
def get(self, key):
"""GET [name]: Print out the value stored under the variable [name].
Print NULL if that variable name hasn't been set.
"""
return self._store_.get(key) if self._store_.has_key(key) else 'NULL'
def unset(self, key):
"""UNSET [name]: Unset the variable [name]."""
self._store_.delete(key)
def numequalto(self, value):
"""NUMEQUALTO [value]: Return the number of variables equal to [value].
If no values are equal, this should output 0.
"""
return self._store_.numequalto(value)
def begin(self):
"""BEGIN: Open a transactional block."""
self._store_.nest()
def rollback(self):
"""ROLLBACK: Rollback all of the commands from the most recent transaction block.
If no transactional block is open, print out INVALID ROLLBACK.
"""
if self._store_.is_flat():
return 'INVALID ROLLBACK'
else:
self._store_.pop_nest()
def commit(self):
"""COMMIT: Closes all open transactional blocks."""
self._store_.flatten()
def end(self):
"""END: Exit the program."""
sys.exit()
def _parse_token_(self, token):
"""Converts the token into an int or float if applicable.
token - the string to parse
Returns the token as is, or as an int or float if possible.
"""
try:
return int(token)
except ValueError:
try:
return float(token)
except ValueError:
return token
class DB:
"""A simple in-memory key-value store with nested transactional blocks."""
# Commands are implicity mapped to methods of the same name, but lowercased.
_commands_ = ["SET", "GET", "UNSET", "NUMEQUALTO", "BEGIN", "ROLLBACK", "COMMIT", "END"]
def __init__(self):
self._store_ = NestedStore()
def run(self, query):
"""Runs the provided query and returns the result."""
tokens = query.split(" ")
command, args = tokens[0], (self._parse_token_(token) for token in tokens[1:])
if command in DB._commands_:
try:
return DB.__dict__[command.lower()](self, *args)
except TypeError:
return "[ERROR] Probably incorrect arguments for command: {}".format(command)
else:
return "[ERROR] Unrecognized command: {}".format(command)
def set(self, key, value):
"""SET [name] [value]: Set a variable [name] to the value [value].
Neither variable names or values will ever contain spaces.
"""
self._store_.set(key, value)
def get(self, key):
"""GET [name]: Print out the value stored under the variable [name].
Print NULL if that variable name hasn't been set.
"""
return self._store_.get(key) if self._store_.has_key(key) else "NULL"
def unset(self, key):
"""UNSET [name]: Unset the variable [name]."""
self._store_.delete(key)
def numequalto(self, value):
"""NUMEQUALTO [value]: Return the number of variables equal to [value].
If no values are equal, this should output 0.
"""
return self._store_.numequalto(value)
def begin(self):
"""BEGIN: Open a transactional block."""
self._store_.nest()
def rollback(self):
"""ROLLBACK: Rollback all of the commands from the most recent transaction block.
If no transactional block is open, print out INVALID ROLLBACK.
"""
if self._store_.is_flat():
return "INVALID ROLLBACK"
else:
self._store_.pop_nest()
def commit(self):
"""COMMIT: Closes all open transactional blocks."""
self._store_.flatten()
def end(self):
"""END: Exit the program."""
sys.exit()
def _parse_token_(self, token):
"""Converts the token into an int or float if applicable.
token - the string to parse
Returns the token as is, or as an int or float if possible.
"""
try:
return int(token)
except ValueError:
try:
return float(token)
except ValueError:
return token
def __init__(self):
self._store_ = NestedStore()
def __init__(self):
self._store_ = NestedStore()
