⚡️ Speed up function parse_diff_header by 36%

[misrasaurabh1]

📄 36% (0.36x) speedup for parse_diff_header in openhands/resolver/patching/patch.py

⏱️ Runtime : 649 microseconds → 478 microseconds (best of 1434 runs)

📝 Explanation and details

Optimizations Applied.

• Early Exit Strategy: By replacing the list comprehension with any() in parse_diff_header, the function can stop iterating as soon as a match is found, which is beneficial for performance.
• Regex Matching and Conditional Assignment: Used the := operator (walrus operator) for regex matching, which allows assignment directly within an if condition. This reduces multiple evaluations and is a bit more efficient.
• Loop Simplification: Removed redundant findall_regex calls which iterated over lists multiple times. Now, regex patterns are checked inline where necessary, reducing overhead.
• Line Popping: Directly pops lines when needed to clearly indicate processing order and removal, making the code simpler and easier to follow.

This set of changes should improve the performance of the parsing functions, especially when handling large lists of lines.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 23 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	✅ 2 Passed
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests Details

import re
from collections import namedtuple

# imports
import pytest  # used for our unit tests
from openhands.resolver.patching.patch import parse_diff_header

# function to test
# -*- coding: utf-8 -*-


header = namedtuple(
    'header',
    'index_path old_path old_version new_path new_version',
)

file_timestamp_str = '(.+?)(?:\t|:|  +)(.*)'

# general diff regex
diffcmd_header = re.compile('^diff.* (.+) (.+))
unified_header_new_line = re.compile(r'^\+\+\+ ' + file_timestamp_str + ')

context_header_old_line = re.compile(r'^\*\*\* ' + file_timestamp_str + ')
git_header_new_line = re.compile(r'^\+\+\+ (.+))
from openhands.resolver.patching.patch import parse_diff_header

# unit tests

def test_empty_input():
    # Test with empty input
    codeflash_output = parse_diff_header("")
    codeflash_output = parse_diff_header([])

def test_no_matching_header():
    # Test with input that doesn't match any header
    codeflash_output = parse_diff_header("random text\nanother line")

def test_unified_diff_header():
    # Test with a simple unified diff header
    text = "--- old_file.txt\t2023-10-01 12:34:56\n+++ new_file.txt\t2023-10-01 12:34:56"
    expected = header(index_path=None, old_path="old_file.txt", old_version="2023-10-01 12:34:56", new_path="new_file.txt", new_version="2023-10-01 12:34:56")
    codeflash_output = parse_diff_header(text)

def test_context_diff_header():
    # Test with a simple context diff header
    text = "*** old_file.txt\t2023-10-01 12:34:56\n--- new_file.txt\t2023-10-01 12:34:56"
    expected = header(index_path=None, old_path="old_file.txt", old_version="2023-10-01 12:34:56", new_path="new_file.txt", new_version="2023-10-01 12:34:56")
    codeflash_output = parse_diff_header(text)

def test_git_diff_header():
    # Test with a simple git diff header
    text = "diff --git a/old_file.txt b/new_file.txt\nindex abcdef1..1234567\n--- old_file.txt\n+++ new_file.txt"
    expected = header(index_path=None, old_path="old_file.txt", old_version="abcdef1", new_path="new_file.txt", new_version="1234567")
    codeflash_output = parse_diff_header(text)

def test_git_diff_header_with_dev_null():
    # Test with a git diff header indicating file creation
    text = "diff --git a/old_file.txt b/new_file.txt\nindex 0000000..1234567\n--- /dev/null\n+++ new_file.txt"
    expected = header(index_path=None, old_path="/dev/null", old_version="0000000", new_path="new_file.txt", new_version="1234567")
    codeflash_output = parse_diff_header(text)

def test_git_diff_header_with_binary_files():
    # Test with a git diff header indicating binary files
    text = "Binary files old_file.bin and new_file.bin differ"
    expected = header(index_path=None, old_path="old_file.bin", old_version=None, new_path="new_file.bin", new_version=None)
    codeflash_output = parse_diff_header(text)

def test_large_unified_diff():
    # Test with a large unified diff
    text = "\n".join([f"--- old_file_{i}.txt\t2023-10-01 12:34:56\n+++ new_file_{i}.txt\t2023-10-01 12:34:56" for i in range(100)])
    expected = header(index_path=None, old_path="old_file_0.txt", old_version="2023-10-01 12:34:56", new_path="new_file_0.txt", new_version="2023-10-01 12:34:56")
    codeflash_output = parse_diff_header(text)

def test_unicode_characters_in_paths():
    # Test with unicode characters in file paths
    text = "--- old_文件.txt\t2023-10-01 12:34:56\n+++ new_文件.txt\t2023-10-01 12:34:56"
    expected = header(index_path=None, old_path="old_文件.txt", old_version="2023-10-01 12:34:56", new_path="new_文件.txt", new_version="2023-10-01 12:34:56")
    codeflash_output = parse_diff_header(text)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

import re
from collections import namedtuple

# imports
import pytest  # used for our unit tests
from openhands.resolver.patching.patch import parse_diff_header

# function to test
# -*- coding: utf-8 -*-


header = namedtuple(
    'header',
    'index_path old_path old_version new_path new_version',
)

file_timestamp_str = '(.+?)(?:\t|:|  +)(.*)'

# general diff regex
diffcmd_header = re.compile('^diff.* (.+) (.+))
unified_header_new_line = re.compile(r'^\+\+\+ ' + file_timestamp_str + ')

context_header_old_line = re.compile(r'^\*\*\* ' + file_timestamp_str + ')
git_header_new_line = re.compile(r'^\+\+\+ (.+))
from openhands.resolver.patching.patch import parse_diff_header

# unit tests

def test_empty_input():
    # Test with an empty string
    codeflash_output = parse_diff_header("")
    # Test with an empty list
    codeflash_output = parse_diff_header([])

def test_basic_unified_diff():
    # Test with a simple unified diff
    text = "--- old_file.txt\n+++ new_file.txt\n"
    expected = header(index_path=None, old_path='old_file.txt', old_version=None, new_path='new_file.txt', new_version=None)
    codeflash_output = parse_diff_header(text)

def test_basic_context_diff():
    # Test with a simple context diff
    text = "*** old_file.txt\n--- new_file.txt\n"
    expected = header(index_path=None, old_path='old_file.txt', old_version=None, new_path='new_file.txt', new_version=None)
    codeflash_output = parse_diff_header(text)

def test_basic_git_diff():
    # Test with a simple git diff
    text = "diff --git a/old_file.txt b/new_file.txt\nindex 1234567..89abcde\n--- a/old_file.txt\n+++ b/new_file.txt\n"
    expected = header(index_path=None, old_path='old_file.txt', old_version='1234567', new_path='new_file.txt', new_version='89abcde')
    codeflash_output = parse_diff_header(text)

def test_malformed_header():
    # Test with a malformed header
    text = "diff --git a/ b/\n"
    codeflash_output = parse_diff_header(text)

def test_non_diff_text():
    # Test with random text
    text = "This is just some random text."
    codeflash_output = parse_diff_header(text)

def test_special_characters_in_paths():
    # Test with special characters in file paths
    text = "--- old file.txt\n+++ new file.txt\n"
    expected = header(index_path=None, old_path='old file.txt', old_version=None, new_path='new file.txt', new_version=None)
    codeflash_output = parse_diff_header(text)

def test_multiple_diffs_in_one_input():
    # Test with multiple diffs in one input
    text = "--- old_file1.txt\n+++ new_file1.txt\n--- old_file2.txt\n+++ new_file2.txt\n"
    expected = header(index_path=None, old_path='old_file1.txt', old_version=None, new_path='new_file1.txt', new_version=None)
    codeflash_output = parse_diff_header(text)

def test_git_binary_file():
    # Test with a git diff indicating a binary file
    text = "diff --git a/file1.bin b/file2.bin\nBinary files a/file1.bin and b/file2.bin differ\n"
    expected = header(index_path=None, old_path='file1.bin', old_version=None, new_path='file2.bin', new_version=None)
    codeflash_output = parse_diff_header(text)

def test_large_input():
    # Test with a large input
    text = "--- old_file.txt\n+++ new_file.txt\n" * 500
    expected = header(index_path=None, old_path='old_file.txt', old_version=None, new_path='new_file.txt', new_version=None)
    codeflash_output = parse_diff_header(text)

def test_unusual_line_endings():
    # Test with mixed line endings
    text = "--- old_file.txt\r\n+++ new_file.txt\n"
    expected = header(index_path=None, old_path='old_file.txt', old_version=None, new_path='new_file.txt', new_version=None)
    codeflash_output = parse_diff_header(text)

def test_large_version_numbers():
    # Test with large version numbers
    text = "--- old_file.txt\t12345678901234567890\n+++ new_file.txt\t09876543210987654321\n"
    expected = header(index_path=None, old_path='old_file.txt', old_version='12345678901234567890', new_path='new_file.txt', new_version='09876543210987654321')
    codeflash_output = parse_diff_header(text)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

from openhands.resolver.patching.patch import parse_diff_header

def test_parse_diff_header():
    parse_diff_header(['', '+++ \x00\x00'])

def test_parse_diff_header_2():
    parse_diff_header('')