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#!/usr/bin/python
# CodeQ: an online programming tutor.
# Copyright (C) 2015 UL FRI
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option) any
# later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import io
import re
from tokenize import tokenize, TokenError
import ast
def get_tokens(code):
""" Gets a list of tokens. """
try:
stream = io.BytesIO(code.encode('utf-8'))
return [t.string for t in tokenize(stream.readline) if t.string]
except TokenError:
return []
def all_tokens(code):
try:
stream = io.BytesIO(code.encode('utf-8'))
return [t for t in tokenize(stream.readline)]
except TokenError:
return []
# Check if tokens contain a sequence of tokens (given as a list of strings).
def has_token_sequence(tokens, sequence):
for i in range(len(tokens)-len(sequence)+1):
if tokens[i:i+len(sequence)] == sequence:
return True
return False
def almost_equal(a, b, prec):
""" Compares values a and b
using prec if value < 1 or
prec most significant numbers otherwise.
"""
return abs(a-b) <= max(abs(a), abs(b), 1) * 10**(-prec)
def get_numbers(s):
""" Extracts numbers from string s. """
str_vals = re.findall(r'''
[-+]? # optional sign
(?:
(?: \d* \. \d+ ) # .1 .12 .123 etc 9.1 etc 98.1 etc
|
(?: \d+ \.? ) # 1. 12. 123. etc 1 12 123 etc
)
# followed by optional exponent part if desired
(?: [Ee] [+-]? \d+ ) ?
''', s, re.VERBOSE)
return [float(v) for v in str_vals]
def string_almost_equal(s, a, prec=3):
""" Searches string s for a value that is almost equal to a. """
for v in get_numbers(s):
if almost_equal(v, a, prec):
return True
return False
def string_contains_number(s, a):
""" Searches string s for a value that is equal to a. """
return a in get_numbers(s)
def get_exception_desc(exc):
# if have an exception!
if exc:
if 'EOFError' in exc:
return [{'id':'eof_error'}]
if 'timed out' in exc:
return [{'id':'timed_out'}]
if 'sandbox violation' in exc:
return [{'id': 'sandbox_violation'}]
if 'NameError' in exc:
return [{'id':'name_error', 'args': {'message': exc}}]
elif 'TypeError' in exc:
return [{'id':'type_error', 'args': {'message': exc}}]
else:
return [{'id':'error', 'args': {'message': exc}}]
return None
def get_ast(code):
"""
Turn code into ast; use it when regular expressions on strings
are not enjoyable enough.
"""
return ast.parse(code)
def has_comprehension(tree):
""" Searches code for comprehensions and generators. """
for n in ast.walk(tree):
if isinstance(n, ast.comprehension):
return True
return False
def has_loop(tree):
""" Searches abstract syntax tree for loops (for and while). """
for n in ast.walk(tree):
if isinstance(n, ast.For) or isinstance(n, ast.While):
return True
return False
if __name__ == '__main__':
print(has_token_sequence(get_tokens('x + y >= 0'), ['>=', '0']))
print(has_token_sequence(get_tokens('x + y > 0'), ['>=', '0']))
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