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Fix #13654, improve performance of auto match for quotes...
Fix #13654, improve performance of auto match for quotes As pointed out in #13654, auto matching of quotes may take a long time if the prefix is long. To be more precise, the longer the text before the first quote, the slower it is. This is all caused by the regex pattern used: `r'^([^"]+|"[^"]*")*$'`, which I suspect is O(2^N) slow. ```python In [1]: text = "function_with_long_nameeee('arg" In [2]: import re In [3]: pattern = re.compile(r"^([^']+|'[^']*')*$") In [4]: %timeit pattern.match(text) 10.3 s ± 67.2 ms per loop (mean ± std. dev. of 7 runs, 1 loop each) In [5]: %timeit pattern.match("1'") 312 ns ± 0.775 ns per loop (mean ± std. dev. of 7 runs, 1,000,000 loops each) In [6]: %timeit pattern.match("12'") 462 ns ± 1.95 ns per loop (mean ± std. dev. of 7 runs, 1,000,000 loops each) In [7]: %timeit pattern.match("123'") 766 ns ± 6.32 ns per loop (mean ± std. dev. of 7 runs, 1,000,000 loops each) In [8]: %timeit pattern.match("1234'") 1.59 µs ± 20.9 ns per loop (mean ± std. dev. of 7 runs, 1,000,000 loops each) ``` But the pattern we want here can actually be detected with a Python implemention in O(N) time.

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test_io.py
61 lines | 1.4 KiB | text/x-python | PythonLexer
# encoding: utf-8
"""Tests for io.py"""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
import sys
from io import StringIO
from subprocess import Popen, PIPE
import unittest
from IPython.utils.io import Tee, capture_output
def test_tee_simple():
"Very simple check with stdout only"
chan = StringIO()
text = 'Hello'
tee = Tee(chan, channel='stdout')
print(text, file=chan)
assert chan.getvalue() == text + "\n"
class TeeTestCase(unittest.TestCase):
def tchan(self, channel):
trap = StringIO()
chan = StringIO()
text = 'Hello'
std_ori = getattr(sys, channel)
setattr(sys, channel, trap)
tee = Tee(chan, channel=channel)
print(text, end='', file=chan)
trap_val = trap.getvalue()
self.assertEqual(chan.getvalue(), text)
tee.close()
setattr(sys, channel, std_ori)
assert getattr(sys, channel) == std_ori
def test(self):
for chan in ['stdout', 'stderr']:
self.tchan(chan)
class TestIOStream(unittest.TestCase):
def test_capture_output(self):
"""capture_output() context works"""
with capture_output() as io:
print("hi, stdout")
print("hi, stderr", file=sys.stderr)
self.assertEqual(io.stdout, "hi, stdout\n")
self.assertEqual(io.stderr, "hi, stderr\n")