⚡️ Speed up function get_diff_lines_count by 19% in PR #274 (skip-formatting-for-large-diffs)

[codeflash-ai]

⚡️ This pull request contains optimizations for PR #274

If you approve this dependent PR, these changes will be merged into the original PR branch skip-formatting-for-large-diffs.

This PR will be automatically closed if the original PR is merged.

---

📄 19% (0.19x) speedup for get_diff_lines_count in codeflash/code_utils/formatter.py

⏱️ Runtime : 3.13 milliseconds → 2.62 milliseconds (best of 279 runs)

📝 Explanation and details

Here is a much faster rewrite. The biggest bottleneck was constructing the entire diff_lines list just to count its length. Instead, loop directly through the lines and count matching lines, avoiding extra memory and function call overhead. This also removes the small overhead of the nested function.

Optimizations made.

• No internal list allocation: Now iterating and counting in one pass with no extra list.
• No inner function call: Faster, via direct string checks.
• Short-circuit on empty: Avoids string indexing on empty lines.
• Direct char compare for '+', '-': Faster than using tuple membership or startswith with a tuple.

This reduces both runtime and memory usage by avoiding unnecessary data structures!

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 57 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	✅ 1 Passed
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests Details

from __future__ import annotations

# imports
import pytest  # used for our unit tests
from codeflash.code_utils.formatter import get_diff_lines_count

# unit tests

# ------------------- Basic Test Cases -------------------

def test_empty_string():
    # No lines at all
    codeflash_output = get_diff_lines_count('')

def test_no_diff_lines():
    # Only context lines, no diff markers
    diff = " context line 1\n context line 2"
    codeflash_output = get_diff_lines_count(diff)

def test_single_added_line():
    # One added line
    diff = "+added line"
    codeflash_output = get_diff_lines_count(diff)

def test_single_removed_line():
    # One removed line
    diff = "-removed line"
    codeflash_output = get_diff_lines_count(diff)

def test_multiple_added_and_removed_lines():
    # Several added and removed lines
    diff = "+foo\n-bar\n+bar\n-baz\n context"
    codeflash_output = get_diff_lines_count(diff)

def test_ignore_file_headers():
    # Should ignore file header lines starting with '+++' or '---'
    diff = "+++ b/file.txt\n--- a/file.txt\n+added\n-removed"
    codeflash_output = get_diff_lines_count(diff)

def test_mixed_diff_and_context_lines():
    # Mix of diff and context lines
    diff = " context\n+add1\n context2\n-remove1\n context3"
    codeflash_output = get_diff_lines_count(diff)

# ------------------- Edge Test Cases -------------------

def test_only_file_headers():
    # Only file header lines
    diff = "+++ b/foo.txt\n--- a/foo.txt"
    codeflash_output = get_diff_lines_count(diff)

def test_lines_with_plus_minus_in_middle():
    # Lines with + or - not at the start
    diff = "foo+bar\nbaz-qux"
    codeflash_output = get_diff_lines_count(diff)

def test_lines_starting_with_multiple_plus_minus():
    # Lines starting with multiple + or - (should only skip '+++' and '---')
    diff = "++not header\n--not header\n+++ header\n--- header\n+real add\n-real remove"
    codeflash_output = get_diff_lines_count(diff)  # only '+real add' and '-real remove' count

def test_lines_with_leading_spaces():
    # Lines with leading spaces before + or - are not counted
    diff = " +should not count\n -should not count\n+should count\n-should count"
    codeflash_output = get_diff_lines_count(diff)

def test_empty_lines_and_whitespace():
    # Empty lines and lines with only whitespace
    diff = "\n\n   \n+foo\n-bar\n"
    codeflash_output = get_diff_lines_count(diff)

def test_lines_with_only_plus_or_minus():
    # Lines that are just '+' or '-'
    diff = "+\n-\n context"
    codeflash_output = get_diff_lines_count(diff)

def test_unicode_characters_in_lines():
    # Lines with unicode characters
    diff = "+Añadido\n-Удалено\n context"
    codeflash_output = get_diff_lines_count(diff)

def test_no_trailing_newline():
    # No trailing newline at end of input
    diff = "+add\n-remove"
    codeflash_output = get_diff_lines_count(diff)

def test_windows_line_endings():
    # Handle \r\n line endings
    diff = "+foo\r\n-bar\r\n context\r\n+++ header\r\n"
    codeflash_output = get_diff_lines_count(diff.replace('\r\n', '\n'))

def test_only_context_lines():
    # Only context lines
    diff = " context1\n context2\n context3"
    codeflash_output = get_diff_lines_count(diff)

def test_line_that_is_just_plus_plus_plus():
    # Line that is exactly '+++'
    diff = "+++"
    codeflash_output = get_diff_lines_count(diff)

def test_line_that_is_just_minus_minus_minus():
    # Line that is exactly '---'
    diff = "---"
    codeflash_output = get_diff_lines_count(diff)

def test_line_that_is_just_plus_plus_plus_and_more():
    # Line that starts with '+++' but has more content
    diff = "+++ some file"
    codeflash_output = get_diff_lines_count(diff)

def test_line_that_is_just_minus_minus_minus_and_more():
    # Line that starts with '---' but has more content
    diff = "--- some file"
    codeflash_output = get_diff_lines_count(diff)

def test_line_with_plus_minus_but_not_at_start():
    # Lines with + or - not at the start
    diff = "foo+bar\nbaz-qux"
    codeflash_output = get_diff_lines_count(diff)

def test_lines_starting_with_other_symbols():
    # Lines starting with other symbols
    diff = "*not diff\n#not diff\n!not diff"
    codeflash_output = get_diff_lines_count(diff)

def test_line_with_multiple_plus_minus():
    # Lines with multiple + or - at start but not exactly three
    diff = "++++extra\n----extra\n+add\n-remove"
    codeflash_output = get_diff_lines_count(diff)  # only '+add' and '-remove' count

# ------------------- Large Scale Test Cases -------------------

def test_large_number_of_added_lines():
    # 1000 added lines
    diff = '\n'.join(['+line{}'.format(i) for i in range(1000)])
    codeflash_output = get_diff_lines_count(diff)

def test_large_number_of_removed_lines():
    # 1000 removed lines
    diff = '\n'.join(['-line{}'.format(i) for i in range(1000)])
    codeflash_output = get_diff_lines_count(diff)

def test_large_mixed_diff():
    # 500 added, 500 removed, 500 context, 2 headers
    added = ['+add{}'.format(i) for i in range(500)]
    removed = ['-rem{}'.format(i) for i in range(500)]
    context = [' context{}'.format(i) for i in range(500)]
    headers = ['+++ file1', '--- file2']
    lines = headers + added + removed + context
    diff = '\n'.join(lines)
    codeflash_output = get_diff_lines_count(diff)

def test_large_with_noise():
    # 333 added, 333 removed, 333 context, 1 header, 1 line with leading space, 1 line with only '+'
    added = ['+add{}'.format(i) for i in range(333)]
    removed = ['-rem{}'.format(i) for i in range(333)]
    context = [' context{}'.format(i) for i in range(333)]
    lines = ['+++ file'] + added + removed + context + [' +notdiff', '+']
    diff = '\n'.join(lines)
    # '+notdiff' (with space) does not count; '+' (only plus) does count
    codeflash_output = get_diff_lines_count(diff)

def test_large_all_types():
    # 250 added, 250 removed, 250 context, 250 lines with just whitespace, 2 headers
    added = ['+add{}'.format(i) for i in range(250)]
    removed = ['-rem{}'.format(i) for i in range(250)]
    context = [' context{}'.format(i) for i in range(250)]
    whitespace = ['   ' for _ in range(250)]
    headers = ['+++ file1', '--- file2']
    lines = headers + added + removed + context + whitespace
    diff = '\n'.join(lines)
    codeflash_output = get_diff_lines_count(diff)

def test_large_no_diff_lines():
    # 1000 context lines, no diff lines
    context = [' context{}'.format(i) for i in range(1000)]
    diff = '\n'.join(context)
    codeflash_output = get_diff_lines_count(diff)

def test_large_headers_only():
    # 500 '+++' and 500 '---' lines
    headers = ['+++ file{}'.format(i) for i in range(500)] + ['--- file{}'.format(i) for i in range(500)]
    diff = '\n'.join(headers)
    codeflash_output = get_diff_lines_count(diff)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

from __future__ import annotations

# imports
import pytest  # used for our unit tests
from codeflash.code_utils.formatter import get_diff_lines_count

# unit tests

# ------------------------------
# Basic Test Cases
# ------------------------------

def test_empty_string_returns_zero():
    # Empty diff should return 0
    codeflash_output = get_diff_lines_count("")

def test_no_diff_lines_returns_zero():
    # Diff with only context lines
    diff = " context line\n another context"
    codeflash_output = get_diff_lines_count(diff)

def test_single_added_line():
    # Single added line
    diff = "+added line"
    codeflash_output = get_diff_lines_count(diff)

def test_single_removed_line():
    # Single removed line
    diff = "-removed line"
    codeflash_output = get_diff_lines_count(diff)

def test_multiple_added_and_removed_lines():
    # Multiple added and removed lines
    diff = "+a\n-b\n context\n+c\n-d"
    codeflash_output = get_diff_lines_count(diff)

def test_ignores_file_header_lines():
    # Should ignore lines starting with '+++' or '---'
    diff = "+++ b/file.txt\n--- a/file.txt\n+added\n-removed"
    codeflash_output = get_diff_lines_count(diff)

def test_mixed_with_blank_lines():
    # Should count only non-header diff lines, skip blanks
    diff = "+foo\n\n-bar\n\n"
    codeflash_output = get_diff_lines_count(diff)

# ------------------------------
# Edge Test Cases
# ------------------------------

def test_line_with_only_plus_or_minus():
    # Lines with only '+' or '-' should count
    diff = "+\n-\n context"
    codeflash_output = get_diff_lines_count(diff)

def test_line_with_leading_spaces():
    # Lines with leading spaces before + or - should not count
    diff = " +not diff\n -not diff"
    codeflash_output = get_diff_lines_count(diff)

def test_line_with_triple_plus_or_minus():
    # Lines starting with '+++' or '---' should not count
    diff = "+++ file.txt\n--- file.txt\n+++not counted\n---not counted"
    codeflash_output = get_diff_lines_count(diff)

def test_line_with_double_plus_or_minus():
    # Lines starting with '++' or '--' should count as diff lines
    diff = "++double plus\n--double minus"
    codeflash_output = get_diff_lines_count(diff)

def test_line_with_multiple_plus_minus_but_not_header():
    # Lines like '+-mixed' should count as diff lines
    diff = "+-mixed\n-+mixed"
    codeflash_output = get_diff_lines_count(diff)

def test_diff_with_only_headers_and_context():
    # Only headers and context lines
    diff = "--- a.txt\n+++ b.txt\n context"
    codeflash_output = get_diff_lines_count(diff)

def test_diff_with_only_headers():
    # Only headers
    diff = "--- a.txt\n+++ b.txt"
    codeflash_output = get_diff_lines_count(diff)

def test_diff_with_blank_lines_only():
    # Only blank lines
    diff = "\n\n\n"
    codeflash_output = get_diff_lines_count(diff)

def test_diff_with_carriage_returns():
    # Lines with \r\n endings
    diff = "+foo\r\n-bar\r\n context\r\n"
    codeflash_output = get_diff_lines_count(diff.replace('\r\n', '\n'))

def test_diff_with_unicode_characters():
    # Diff lines with unicode
    diff = "+áéíóú\n-ßΩ≈ç√∫˜µ≤≥÷"
    codeflash_output = get_diff_lines_count(diff)

def test_diff_with_tabs():
    # Diff lines with tabs
    diff = "+\tadded\n-\tremoved"
    codeflash_output = get_diff_lines_count(diff)

# ------------------------------
# Large Scale Test Cases
# ------------------------------

def test_large_diff_all_added():
    # Large diff with only added lines
    diff = '\n'.join(['+added line {}'.format(i) for i in range(1000)])
    codeflash_output = get_diff_lines_count(diff)

def test_large_diff_all_removed():
    # Large diff with only removed lines
    diff = '\n'.join(['-removed line {}'.format(i) for i in range(1000)])
    codeflash_output = get_diff_lines_count(diff)

def test_large_diff_mixed_lines():
    # Large diff with mixed added, removed, context, and header lines
    lines = []
    for i in range(250):
        lines.append('+++ file{}'.format(i))
        lines.append('--- file{}'.format(i))
        lines.append(' context {}'.format(i))
        lines.append('+added {}'.format(i))
        lines.append('-removed {}'.format(i))
        lines.append(' context2 {}'.format(i))
    diff = '\n'.join(lines)
    # Only '+added' and '-removed' lines should count: 250*2 = 500
    codeflash_output = get_diff_lines_count(diff)

def test_large_diff_with_blank_and_header_lines():
    # Large diff with many blank and header lines mixed in
    lines = []
    for i in range(500):
        lines.append('')
        lines.append('+++ file{}'.format(i))
        lines.append('-removed {}'.format(i))
        lines.append('')
        lines.append(' context')
        lines.append('+added {}'.format(i))
    diff = '\n'.join(lines)
    # Only '+added' and '-removed' lines should count: 500*2 = 1000
    codeflash_output = get_diff_lines_count(diff)

def test_large_diff_with_edge_cases():
    # Large diff with edge-case lines
    lines = []
    for i in range(300):
        lines.append('++not header {}'.format(i))   # should count
        lines.append('--not header {}'.format(i))   # should count
        lines.append('+++ header {}'.format(i))     # should not count
        lines.append('--- header {}'.format(i))     # should not count
        lines.append('+')                           # should count
        lines.append('-')                           # should count
        lines.append(' context {}'.format(i))       # should not count
    diff = '\n'.join(lines)
    # For each group: 2 (++,--) + 2 (+,-) = 4 per group, 300 groups = 1200
    codeflash_output = get_diff_lines_count(diff)

# ------------------------------
# Mutation-Resistant Tests
# ------------------------------

def test_mutation_resistant_plus_minus_only_at_start():
    # If implementation checks for '+' or '-' anywhere, it will fail this test
    diff = "not+added\nnot-removed\n+added\n-removed"
    codeflash_output = get_diff_lines_count(diff)

def test_mutation_resistant_header_prefix():
    # If implementation fails to exclude '+++' or '---', will fail this test
    diff = "+++file\n---file\n++notheader\n--notheader\n+added\n-removed"
    # Only '++notheader', '--notheader', '+added', '-removed' should count
    codeflash_output = get_diff_lines_count(diff)

def test_mutation_resistant_whitespace():
    # If implementation strips whitespace, will fail this test
    diff = " +added\n -removed\n+added\n-removed"
    # Only '+added' and '-removed' should count
    codeflash_output = get_diff_lines_count(diff)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

from codeflash.code_utils.formatter import get_diff_lines_count

def test_get_diff_lines_count():
    get_diff_lines_count('')

To edit these changes git checkout codeflash/optimize-pr274-2025-06-03T21.03.54 and push.

[codeflash-ai]

This PR has been automatically closed because the original PR #274 by mohammedahmed18 was closed.