⚡️ Speed up function _calculate_lines_mappings by 6% in src/black/ranges.py

[codeflash-ai]

📄 _calculate_lines_mappings in src/black/ranges.py

✨ Performance Summary:

• Speed Increase: 📈 6% (0.06x faster)
• Runtime Reduction: ⏱️ From 63.1 microseconds down to 59.6 microseconds (best of 72 runs)

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📝 Explanation and details

Here is the optimized version of the program.

Optimizations Made.

1. Split Lines Early: Rather than calling splitlines inside SequenceMatcher, we do it once at the beginning and reuse the split line lists.
2. Avoid Multiple if and else Statements: By checking for previous_block only once at the start of the loop, we avoid redundant if checks inside the loop.
3. Direct _LinesMapping Object Appends: Append the _LinesMapping objects directly inside the loop without needing an additional if statement for the first block.
4. Reuse previous_block: Store and reuse previous_block to avoid recalculating or reiterating over previous blocks.

Note.

The optimized code maintains the same logic but avoids unnecessary splits, rechecks, and leverages straightforward list operations to enhance performance and clarity.

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✅ Correctness verification

The new optimized code was tested for correctness. The results are listed below:

Test	Status	Details
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 6 Passed	See below
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Coverage	100.0%

🌀 Generated Regression Tests Details

Click to view details

import difflib
from collections.abc import Sequence
from dataclasses import dataclass

# imports
import pytest  # used for our unit tests
from black.ranges import _calculate_lines_mappings

# unit tests



def test_empty_files():
    codeflash_output = _calculate_lines_mappings("", "")
    codeflash_output = _calculate_lines_mappings("line1\nline2\n", "")
    codeflash_output = _calculate_lines_mappings("", "line1\nline2\n")

def test_single_line_files():
    codeflash_output = _calculate_lines_mappings("line1\n", "line1\n")
    codeflash_output = _calculate_lines_mappings("line1\n", "line2\n")














import difflib
from collections.abc import Sequence
from dataclasses import dataclass

# imports
import pytest  # used for our unit tests
from black.ranges import _calculate_lines_mappings

# unit tests



def test_empty_sources():
    original_source = ""
    modified_source = ""
    expected = []
    codeflash_output = _calculate_lines_mappings(original_source, modified_source)

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