diff & diff3 in Python

A simple implementation of Myers' diff algorithm and a three-way merge algorithm (diff3) in Python. This library enables you to compare two sequences efficiently and perform three-way merging for version control or conflict resolution.

Features

• Implements Myers' diff algorithm for calculating differences between two sequences.
• Implements diff3 algorithm for three-way merging based on the following reference:
  • https://www.cis.upenn.edu/~bcpierce/papers/diff3-short.pdf
• Lightweight and dependency-free, making it easy to integrate into any project.
• Compatible with Python 3.9+.
• No guarantees on correctness or robustness – use at your own risk.
• MIT License – free to use and modify.

Installation

You can install the package via pip:

pip install git+https://github.com/nagaokayuji/diff3.git

Or, clone the repository and install locally:

git clone https://github.com/nagaokayuji/diff3.git
cd diff3
pip install .

Usage

diff

from diff3 import diff

original = list("ABCABBA")
target = list("CBABAC")
diff_result = diff(original, target)
print(diff_result)
# Output:
# [- A, - B,   C, + B,   A,   B, - B,   A, + C]

diff3 (Three-way Merge)

from diff3 import merge

base = ['a', 'b', 'c', 'd', 'e']
a = ['a', 'b', 'c', 'cc', 'd', 'e']
b = ['a', 'c', 'd', 'dd', 'e', 'f']

merged = merge(base, a, b)
print(merged)
# Output:
# a
# c
# cc
# d
# dd
# e
# f

Running Tests

Unit tests are included. To run all tests, use:

PYTHONPATH=src python -m unittest discover test

License

This project is licensed under the MIT License.