diff-patch

Introduction

diff-patch is a library that exposes two functions, diff and patch.

The library does not have any dependencies.

The diff function takes two objects (obj1 and obj2) and deep compares them, returning an object that represents the difference between the two (the diffData). diffData is an object that can be used to apply the diff to obj1 to get an object that is the same as obj2.

The patch function takes an obj and a diffData object and applies the diff to the object, returning a new object.

The diff and patch functions are implemented in the following languages:

• TypeScript
• Python3
• Dart

The diffData object can be used interchangeably between the languages.
This makes this library very useful for networked applications, where the client and server are written in different languages.

diffData can be serialized to JSON and deserialized back to an object. It aims to be as small as possible, and is designed to be used in a networked environment.

More languages will be added in the future, contributions are welcome.

Usage

TypeScript

To install the TypeScript version of diff-patch, run:

npm install @fsoft/diff-patch

Then, in your TypeScript code:

import { diff, patch } from '@fsoft/diff-patch';

const obj1 = {
  a: 1,
  b: 2,
  c: {
    d: 3,
    e: 4,
  },
};

const obj2 = {
  a: 1,
  b: 2,
  c: {
    d: 3,
    e: 5,   // changed
  },
};

// create the diff data
const diffData = diff(obj1, obj2);

// show the diff data for debugging
console.log( "diffData: ", diffData);

// apply the diff data to obj1 to get an object that is the same as obj2
const obj3 = patch(obj1, diffData);

// show the result for debugging
console.log( "obj3: ", obj3);

Python3

To install the Python3 version of diff-patch, run:

pip install fsoft-diff-patch

Then, in your Python code:

from fsoft_diff_patch import diff, patch

obj1 = {
  'a': 1,
  'b': 2,
  'c': {
    'd': 3,
    'e': 4,
  },
}

obj2 = {
  'a': 1,
  'b': 2,
  'c': {
    'd': 3,
    'e': 5,   # changed
  },
}

# create the diff data
diff_data = diff(obj1, obj2)

# show the diff data for debugging
print("diff_data: ", diff_data)

# apply the diff data to obj1 to get an object that is the same as obj2
obj3 = patch(obj1, diff_data)

# show the result for debugging
print("obj3: ", obj3)

Dart

To install the Dart version of diff-patch, run:

dart pub add fsoft_diff_patch

Then, in your Dart code:

import 'package:fsoft_diff_patch/fsoft_diff_patch.dart';

void main() {
  final a = {
    "a": 1,
    "b": 2,
    "c": {
      "d": 3,
      "e": 4,
      "f": {
        "g": 5,
        "h": 6,
      },
    },
  };
  final b = {
    "a": 1,
    // "b": 2, // b is deleted
    "c": {
      "d": 9, // d is changed
      "e": 4,
      "f": {
        "g": 5,
        "h": 7, // h is changed
        "i": 10, // i is added
      },
    },
  };
  // diff a and b and create a diffData object
  final diffData = diff(a, b);
  // print diffData in the console
  print("DIFF DATA\n${json.encode(diffData)}");
  // apply diffData to a and create a new object
  final patched_a = patch(a, diffData);
  // print patched_a in the console
  print("\n\nPATCHED OBJ\n${json.encode(patched_a)}");
  // check if patched_a is equal to b
  print("\n\nSAME OBJECT: ${json.encode(patched_a) == json.encode(b)}");
}

Hint

The diff function can be used to see if two objects are the same, by comparing the result of diff to an empty object.

from diff_patch import diff

obj1 = {
  'a': 1,
  'b': 2,
  'c': {
    'd': 3,
    'e': 4,
  },
}

obj2 = {
  'a': 1,
  'b': 2,
  'c': {
    'd': 3,
    'e': 4,
  },
}

diff_data = diff(obj1, obj2)

# if the objects are the same, diff_data will be an empty object
if not diff_data:
  print("The objects are the same")

Contributors

This library was created by Fabio Rotondo.

New language implementations are more than welcome.
Please open an issue or a pull request if you want to contribute.

Collaborators:

• Nikola Gluhovic

The official repository for this library is here.

License

This library is licensed under the MIT License.
See the LICENSE file for details.