⚡️ Speed up method CharacterRemover.remove_control_characters by 46%

[codeflash-ai]

📄 46% (0.46x) speedup for CharacterRemover.remove_control_characters in code_to_optimize/remove_control_chars.py

⏱️ Runtime : 574 microseconds → 394 microseconds (best of 85 runs)

📝 Explanation and details

Here’s an optimized version of your program. The main bottleneck is re.sub, which is relatively slow for simple tasks like filtering ASCII ranges, especially in tight loops. You can greatly speed this up by using str.translate with a translation table that drops the unwanted control characters. This avoids regex overhead and is much faster in practice.

Why is this faster?

• str.translate does pure C-level translation and omission in a single pass, no regex engine overhead.
• The translation table is created only once per instance.
• No function-call overhead inside loops.

Guaranteed same results: Control chars chr(0)–chr(31) and chr(127) are omitted, just as with your regex.

This will significantly reduce the time per call as shown in your profile. If you want even more speed and you're always working with ASCII, you can potentially use bytes, but str.translate is already highly efficient for this use case.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 102 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests Details

import re
import string  # for generating test data

# imports
import pytest  # used for our unit tests
from code_to_optimize.remove_control_chars import CharacterRemover

# unit tests

@pytest.fixture
def remover():
    """Fixture to provide a CharacterRemover instance."""
    return CharacterRemover()


# 1. Basic Test Cases

def test_empty_string(remover):
    """Test that an empty string returns an empty string."""
    codeflash_output = remover.remove_control_characters("")

def test_no_control_characters(remover):
    """Test that a string with no control characters is unchanged."""
    codeflash_output = remover.remove_control_characters("Hello, World!")

def test_only_control_characters(remover):
    """Test that a string with only control characters returns an empty string."""
    control_chars = "".join(chr(i) for i in list(range(0, 32)) + [127])
    codeflash_output = remover.remove_control_characters(control_chars)

def test_mixed_control_and_printable(remover):
    """Test a string with interleaved control and printable characters."""
    s = "A\x00B\x1FC\x7FD"
    expected = "ABCD"
    codeflash_output = remover.remove_control_characters(s)

def test_control_characters_at_start_end(remover):
    """Test control characters at the start and end of the string."""
    s = "\x00\x1FHello, World!\x7F\x0A"
    expected = "Hello, World!"
    codeflash_output = remover.remove_control_characters(s)

def test_control_characters_in_middle(remover):
    """Test control characters in the middle of the string."""
    s = "foo\x00bar\x1Fbaz"
    expected = "foobarbaz"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_newline_and_tab(remover):
    """Test that tabs and newlines (which are control characters) are removed."""
    s = "Line1\nLine2\tEnd"
    expected = "Line1Line2End"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_unicode_but_no_control(remover):
    """Test that non-ASCII unicode characters are preserved."""
    s = "Café 漢字 🚀"
    expected = "Café 漢字 🚀"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_unicode_and_control(remover):
    """Test that unicode is preserved and control characters are removed."""
    s = "\x00Café\x1F 漢字 🚀\x7F"
    expected = "Café 漢字 🚀"
    codeflash_output = remover.remove_control_characters(s)

# 2. Edge Test Cases

def test_none_input(remover):
    """Test that passing None returns an empty string."""
    codeflash_output = remover.remove_control_characters(None)

def test_all_ascii_printable(remover):
    """Test that all printable ASCII characters are preserved."""
    s = string.printable
    # Remove control characters from string.printable (tab, newline, carriage return, etc.)
    expected = "".join(c for c in s if c not in ''.join(chr(i) for i in list(range(0, 32)) + [127]))
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_only_del(remover):
    """Test that DEL character (ASCII 127) is removed."""
    s = "foo" + chr(127) + "bar"
    expected = "foobar"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_surrogate_pairs(remover):
    """Test that surrogate pairs (high unicode) are preserved."""
    s = "Test \U0001F600 \U0001F4A9"
    expected = s
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_extended_ascii(remover):
    """Test that extended ASCII (128-255) is preserved."""
    s = "".join(chr(i) for i in range(128, 256))
    expected = s
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_only_one_control_character(remover):
    """Test that a string with only one control character returns empty string."""
    codeflash_output = remover.remove_control_characters("\x1B")

def test_string_with_adjacent_control_characters(remover):
    """Test that adjacent control characters are all removed."""
    s = "A\x00\x01\x02B"
    expected = "AB"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_control_character_just_outside_range(remover):
    """Test that characters just outside the control range are preserved."""
    s = "A" + chr(32) + chr(126) + chr(128) + "Z"
    expected = s
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_repeated_control_characters(remover):
    """Test that multiple repeated control characters are all removed."""
    s = "\x00\x00foo\x1F\x1Fbar\x7F\x7F"
    expected = "foobar"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_mixed_line_endings(remover):
    """Test that CR, LF, and CRLF are all removed."""
    s = "A\r\nB\nC\rD"
    expected = "ABCD"
    codeflash_output = remover.remove_control_characters(s)

# 3. Large Scale Test Cases

def test_large_string_no_control_characters(remover):
    """Test a large string with no control characters (should be unchanged)."""
    s = "A" * 1000
    expected = s
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_all_control_characters(remover):
    """Test a large string composed only of control characters (should return empty)."""
    s = "".join(chr(i % 32) for i in range(1000))
    expected = ""
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_mixed(remover):
    """Test a large string with control characters every 10th character."""
    base = "abcdefghij"
    s = ""
    for i in range(100):  # 1000 characters
        s += base[:9] + chr(i % 32)
    expected = "abcdefghi" * 100
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_unicode_and_control(remover):
    """Test a large string with interleaved unicode and control characters."""
    unicode_chars = "漢字🚀"
    s = ""
    for i in range(250):
        s += unicode_chars + chr(i % 32)
    expected = unicode_chars * 250
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_with_del(remover):
    """Test a large string with DEL (ASCII 127) interleaved."""
    s = ("foo" + chr(127)) * 250
    expected = "foo" * 250
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_with_printable_and_control(remover):
    """Test a string of 1000 printable ASCII characters, each followed by a control character."""
    s = ""
    for i in range(500):
        s += chr(65 + (i % 26)) + chr(i % 32)
    expected = "".join(chr(65 + (i % 26)) for i in range(500))
    codeflash_output = remover.remove_control_characters(s)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

import re
import string  # used for generating test data

# imports
import pytest  # used for our unit tests
from code_to_optimize.remove_control_chars import CharacterRemover

# unit tests

@pytest.fixture
def remover():
    """Fixture to provide a CharacterRemover instance."""
    return CharacterRemover()

# 1. Basic Test Cases

def test_ascii_letters_and_digits_untouched(remover):
    # Letters and digits should not be removed
    s = "HelloWorld123"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_newline_and_tab(remover):
    # Newline (\n) and tab (\t) are control characters and should be removed
    s = "Hello\nWorld\t123"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_mixed_control_and_printable(remover):
    # Mix of printable and control characters
    s = "A\x00B\x1FC\x7FD"
    # \x00, \x1F, \x7F are control characters and should be removed
    codeflash_output = remover.remove_control_characters(s)

def test_no_control_characters(remover):
    # No control characters, string should be unchanged
    s = "Just a normal sentence!"
    codeflash_output = remover.remove_control_characters(s)

def test_only_control_characters(remover):
    # Only control characters, should return empty string
    s = "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F\x7F"
    codeflash_output = remover.remove_control_characters(s)

def test_empty_string(remover):
    # Empty string should return empty string
    codeflash_output = remover.remove_control_characters("")

def test_none_input(remover):
    # None input should return empty string (as per implementation)
    codeflash_output = remover.remove_control_characters(None)

def test_space_and_punctuation_untouched(remover):
    # Spaces and punctuation are not control characters and should remain
    s = "Hello, world! How are you?"
    codeflash_output = remover.remove_control_characters(s)

# 2. Edge Test Cases

def test_string_with_all_ascii_control_characters(remover):
    # String containing all ASCII control characters (0x00-0x1F and 0x7F)
    control_chars = ''.join(chr(i) for i in list(range(0x00, 0x20)) + [0x7F])
    codeflash_output = remover.remove_control_characters(control_chars)

def test_string_with_unicode_non_ascii_control(remover):
    # Unicode control characters outside ASCII range should NOT be removed
    # e.g., \u200B (zero width space), \u2028 (line separator)
    s = "A\u200BB\u2028C"
    # These are not in [\x00-\x1F\x7F], so should remain
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_surrogate_pairs(remover):
    # Surrogate pairs (e.g., emoji) should not be removed
    s = "Smile: \U0001F600"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_mixed_line_endings(remover):
    # CR (\r) and LF (\n) are both control characters and should be removed
    s = "Line1\r\nLine2\rLine3\nLine4"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_null_bytes(remover):
    # Null bytes (\x00) should be removed
    s = "abc\x00def\x00ghi"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_bell_and_escape(remover):
    # Bell (\x07) and escape (\x1B) are control characters and should be removed
    s = "Start\x07Middle\x1BEnd"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_extended_ascii(remover):
    # Extended ASCII (0x80-0xFF) are not control characters and should remain
    s = "A" + "".join(chr(i) for i in range(0x80, 0x100)) + "Z"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_only_space(remover):
    # Space is not a control character and should remain
    s = "     "
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_control_characters_at_edges(remover):
    # Control characters at start and end
    s = "\x00Hello World\x7F"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_multiple_consecutive_control_characters(remover):
    # Multiple consecutive control characters in the middle
    s = "abc\x00\x01\x02def"
    codeflash_output = remover.remove_control_characters(s)

def test_string_with_mixed_control_and_non_ascii(remover):
    # Mix of control characters and non-ASCII unicode
    s = "A\x00Bé\x1FC\u20AC\x7FD"
    codeflash_output = remover.remove_control_characters(s)

# 3. Large Scale Test Cases

def test_large_string_only_control_characters(remover):
    # Large string of only control characters should return empty string
    s = "".join(chr(i % 32) for i in range(1000))  # 1000 control chars
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_no_control_characters(remover):
    # Large string with no control characters should remain unchanged
    s = "A" * 1000 + "B" * 1000 + "C" * 1000
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_some_control_characters(remover):
    # Large string with control characters interleaved
    s = "".join("A" + chr(0x00) + "B" + chr(0x1F) + "C" + chr(0x7F) for _ in range(300))
    expected = "ABC" * 300
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_with_unicode_and_control(remover):
    # Large string with unicode and control characters mixed
    s = "".join("é" + chr(0x00) + "Ω" + chr(0x1F) + "€" + chr(0x7F) for _ in range(300))
    expected = "éΩ€" * 300
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_alternating_control_and_printable(remover):
    # Alternating control and printable characters
    s = "".join(chr(0x00 + (i % 32)) + chr(65 + (i % 26)) for i in range(500))
    expected = "".join(chr(65 + (i % 26)) for i in range(500))
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_with_spaces_and_control(remover):
    # Large string with spaces and control characters
    s = (" " * 500) + "".join(chr(i % 32) for i in range(500))
    expected = " " * 500
    codeflash_output = remover.remove_control_characters(s)

def test_large_string_with_all_ascii_characters(remover):
    # String with all ASCII characters, control characters should be removed
    s = "".join(chr(i) for i in range(128)) * 5  # 5 times all ASCII
    expected = "".join(chr(i) for i in range(32, 127)) * 5  # printable ASCII (32-126)
    codeflash_output = remover.remove_control_characters(s)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

To edit these changes git checkout codeflash/optimize-CharacterRemover.remove_control_characters-mbh6107b and push.