A modern, robust Python library for parsing and applying unified diffs with comprehensive format support and automatic error correction.

Python Patch is a comprehensive library for working with unified diff files. It provides both a command-line interface and a Python API for parsing, analyzing, and applying patches from various version control systems.

• Multi-format support: Git, Mercurial (HG), Subversion (SVN) patch formats
• Automatic error correction: Handles broken diffs, line ending issues, and path prefix problems
• Smart detection: Automatically identifies patch format and applies appropriate parsing rules

• Simple API: Easy-to-use functions for common operations
• Type hints: Full type annotation support for better IDE integration
• Comprehensive error handling: Detailed error reporting and recovery options

• Zero dependencies: Uses only Python standard library
• Cross-platform: Works on Linux, Windows, and macOS
• High test coverage: Extensively tested with real-world patch files
• Performance optimized: Efficient parsing and memory usage

• Detailed diffstat: Visual histogram showing changes per file
• Progress reporting: Track application progress for large patch sets
• Flexible output formats: JSON, plain text, and structured data

The following features are not yet supported:

• File renaming, creation, and removal operations
• Directory tree operations (mkdir, rmdir)
• Version control specific properties and metadata
• Non-unified diff formats (context diffs, ed scripts)

Install from PyPI using pip:

# Install the latest stable version
pip install patch

# Install with development dependencies
pip install "patch[dev]"

# Install specific version (recommended for production)
pip install "patch==1.*"

# Apply a patch file
patch diff.patch

# Apply with custom strip level
patch --strip=1 changes.patch

# Dry run (show what would be changed)
patch --dry-run feature.patch

# Reverse a patch
patch --reverse bugfix.patch

# Show detailed statistics
patch --verbose --stats updates.patch

import patch

# Parse and apply a patch file
patchset = patch.fromfile('changes.patch')
if patchset:
    success = patchset.apply(strip=1)
    print(f"Applied {len(patchset)} patches successfully: {success}")

# Parse patch from string
patch_content = """--- a/file.txt
+++ b/file.txt
@@ -1,3 +1,3 @@
 line1
-old line
+new line
 line3"""

patchset = patch.fromstring(patch_content)
if patchset:
    patchset.apply()

# Download and apply patch from URL
patchset = patch.fromurl('https://github.com/user/repo/commit/abc123.patch')
if patchset:
    patchset.apply(strip=1)

import patch

# Load patch with error handling
try:
    patchset = patch.fromfile('complex.patch')
    if not patchset:
        print("Failed to parse patch")
        exit(1)

    # Inspect patches before applying
    for p in patchset:
        print(f"File: {p.target}")
        print(f"Hunks: {len(p.hunks)}")
        print(f"Additions: +{p.added}, Deletions: -{p.removed}")

    # Apply with options
    success = patchset.apply(
        strip=1,           # Strip path components
        root='/path/to/project',  # Apply relative to directory
        dry_run=True       # Test without making changes
    )

    if success:
        print("All patches applied successfully!")
    else:
        print("Some patches failed to apply")

except FileNotFoundError:
    print("Patch file not found")
except PermissionError:
    print("Permission denied reading patch file")

• patch.fromfile(filename) - Parse patch from file
• patch.fromstring(content) - Parse patch from string/bytes
• patch.fromurl(url) - Download and parse patch from URL

• apply(strip=0, root=None, dry_run=False) - Apply all patches
• revert() - Reverse all patches
• findfile(filename) - Find patch for specific file
• diffstat() - Generate diffstat summary

Run the test suite to ensure everything works correctly:

# Run modern pytest tests
python -m pytest tests_pytest/ -v

# Run with coverage report
python -m pytest tests_pytest/ --cov=src/patch --cov-report=html

# Run legacy test suite
python tests/run_tests.py

# Run specific test categories
python -m pytest tests_pytest/test_api.py -v

We welcome contributions! Please see our Contributing Guide for details.

# Clone the repository
git clone https://github.com/AstroAir/python-patch.git
cd python-patch

# Create virtual environment
python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

# Install in development mode
pip install -e ".[dev]"

# Run tests
python -m pytest tests_pytest/

We maintain high code quality standards:

# Format code
black src/ tests_pytest/

# Lint code
flake8 src/ tests_pytest/

# Type checking
mypy src/

• Python: 3.10+ (see pyproject.toml for full compatibility)
• Dependencies: None (uses only Python standard library)
• Platforms: Linux, Windows, macOS

• API Documentation - Detailed API reference
• Contributing Guide - How to contribute
• Changelog - Version history and changes
• Examples - Usage examples and tutorials

This project is licensed under the MIT License - see the LICENSE file for details.

• Original Author: anatoly techtonik
• Current Maintainer: Max Qian ([email protected])
• Contributors: See CREDITS for full list

• PyPI Package: https://pypi.org/project/patch/
• Source Code: https://github.com/AstroAir/python-patch
• Issue Tracker: https://github.com/AstroAir/python-patch/issues
• CI/CD: https://github.com/AstroAir/python-patch/actions

Made with ❤️ by the Python community