A high-performance Rust implementation of Python's difflib.unified_diff function with PyO3 bindings.

This package provides a Rust-based implementation of the unified diff algorithm, offering significant performance improvements over Python's built-in difflib module while maintaining API compatibility.

• 🚀 3-5x Faster: Consistently outperforms Python's difflib across all file sizes and change patterns (see Performance section for detailed benchmarks)
• 100% Compatible: Drop-in replacement for difflib.unified_diff with identical output
• Thoroughly Tested: Comprehensive test suite ensuring byte-for-byte compatibility with Python's implementation
• Easy to use: Simple Python API with PyO3 bindings

pip install difflib-rs

# Clone the repository git clone https://github.com/sweepai/difflib-rs.git cd difflib-rs # Set up virtual environment python -m venv venv source venv/bin/activate # Install build dependencies pip install maturin pytest # Build and install maturin develop --release

This is a drop-in replacement for Python's difflib.unified_diff. Simply replace your import:

- from difflib import unified_diff + from difflib_rs import unified_diff # Compare two sequences of lines a = ['line1', 'line2', 'line3'] b = ['line1', 'modified', 'line3'] diff = unified_diff( a, b, fromfile='original.txt', tofile='modified.txt', fromfiledate='2023-01-01', tofiledate='2023-01-02' ) for line in diff: print(line, end='')

Note: Currently, only unified_diff is supported. Other difflib functions are not implemented, but pull requests are welcome!

Most agents (including Sweep) can add support for any other methods if needed. A copy of the Python implementation is provided in src/difflib.py for reference.

For additional convenience, use unified_diff_str directly with (unsplit) strings:

from difflib_rs import unified_diff_str # Compare two strings directly - no need to split first! text_a = """line1 line2 line3""" text_b = """line1 modified line3""" # The function handles splitting internally (more efficient) diff = unified_diff_str( text_a, text_b, fromfile='original.txt', tofile='modified.txt', keepends=False # Whether to keep line endings in the diff ) for line in diff: print(line, end='')

The unified_diff_str function:

• Takes strings directly instead of lists
• Handles line splitting internally in Rust (faster than Python's splitlines())
• Supports \n, \r\n, and \r line endings
• Has a keepends parameter to preserve line endings in the output

The Rust implementation consistently outperforms Python's built-in difflib module while producing identical output:

Performance comparison of unified_diff_str vs unified_diff with Python splitlines():

def unified_diff(a, b, fromfile='', tofile='', fromfiledate='', tofiledate='', n=3, lineterm='\n'): """  Compare two sequences of lines; generate the unified diff.    Unified diffs are a compact way of showing line changes and a few  lines of context. The number of context lines is set by n which  defaults to three.    Parameters:  a: Sequence of lines to compare (the 'from' file)  b: Sequence of lines to compare (the 'to' file)  fromfile: Label to use for the 'from' file in the diff header  tofile: Label to use for the 'to' file in the diff header  fromfiledate: Modification date of the 'from' file  tofiledate: Modification date of the 'to' file  n: Number of context lines (default: 3)  lineterm: Line terminator to use (default: '\n')    Returns:  Generator yielding unified diff format strings    Note: This is a high-performance Rust implementation that provides  3-5x speedup over Python's difflib while maintaining 100% compatibility.  """ pass

# Activate virtual environment source venv/bin/activate # Run tests python -m pytest tests/ -v # Run benchmarks python -m pytest tests/test_benchmark.py -s # Build the package with optimizations maturin develop --release

If you want a feature or have an idea, just create a pull request! Contributions are welcome.

Everything in this project was written by Sweep AI, an AI agent for Jetbrains IDEs.