dmp 2018.11.6.1
Repackaging of Google's Diff Match and Patch libraries. Offers robust algorithms to perform the operations required for synchronizing plain text.
License: Apache

# dmp

Google's [Diff Match and Patch][DMP] library, packaged for modern Python.

[![build status](https://travis-ci.org/jreese/dmp.svg?branch=master)](https://travis-ci.org/jreese/dmp)
[![version](https://img.shields.io/pypi/v/dmp.svg)](https://pypi.org/project/dmp)
[![license](https://img.shields.io/pypi/l/dmp.svg)](https://github.com/facebookincubator/dmp/blob/master/LICENSE)

## Install

dmp is supported on Python 2.7 or Python 3.4 or newer.  You can install it from PyPI:

```shell
python -m pip install dmp
```

## Usage

To make it possible to coexist with upstream diff-match-patch (and to reduce
boilerplate), this makes the normal [API][] available to import as `dmp` instead
of `diff_match_patch`. The rest of the API remains unchanged, although helper
functions may be added in future updates.

Generating a patchset (analogous to unified diff) between two texts:

```python
from dmp import diff_match_patch

dmp = diff_match_patch()
patches = dmp.patch_make(text1, text2)
diff = dmp.patch_toText(patches)
```

Applying a patchset to a text can then be done with:

```python
from dmp import diff_match_patch

dmp = diff_match_patch()
patches = dmp.patch_fromText(diff)
new_text, _ = dmp.patch_apply(patches, text)
```

## Original README
The Diff Match and Patch libraries offer robust algorithms to perform the
operations required for synchronizing plain text.

1. Diff:
   * Compare two blocks of plain text and efficiently return a list of differences.
   * [Diff Demo](https://neil.fraser.name/software/diff_match_patch/demos/diff.html)
2. Match:
   * Given a search string, find its best fuzzy match in a block of plain text. Weighted for both accuracy and location.
   * [Match Demo](https://neil.fraser.name/software/diff_match_patch/demos/match.html)
3. Patch:
   * Apply a list of patches onto plain text. Use best-effort to apply patch even when the underlying text doesn't match.
   * [Patch Demo](https://neil.fraser.name/software/diff_match_patch/demos/patch.html)

Originally built in 2006 to power Google Docs, this library is now available in C++, C#, Dart, Java, JavaScript, Lua, Objective C, and Python.

### Reference

* [API](https://github.com/google/diff-match-patch/wiki/API) - Common API across all languages.
* [Line or Word Diffs](https://github.com/google/diff-match-patch/wiki/Line-or-Word-Diffs) - Less detailed diffs.
* [Plain Text vs. Structured Content](https://github.com/google/diff-match-patch/wiki/Plain-Text-vs.-Structured-Content) - How to deal with data like XML.
* [Unidiff](https://github.com/google/diff-match-patch/wiki/Unidiff) - The patch serialization format.
* [Support](https://groups.google.com/forum/#!forum/diff-match-patch) - Newsgroup for developers.

### Languages
Although each language port of Diff Match Patch uses the same API, there are some language-specific notes.

* [C++](https://github.com/google/diff-match-patch/wiki/Language:-Cpp)
* [C#](https://github.com/google/diff-match-patch/wiki/Language:-C%23)
* [Dart](https://github.com/google/diff-match-patch/wiki/Language:-Dart)
* [Java](https://github.com/google/diff-match-patch/wiki/Language:-Java)
* [JavaScript](https://github.com/google/diff-match-patch/wiki/Language:-JavaScript)
* [Lua](https://github.com/google/diff-match-patch/wiki/Language:-Lua)
* [Objective-C](https://github.com/google/diff-match-patch/wiki/Language:-Objective-C)
* [Python](https://github.com/google/diff-match-patch/wiki/Language:-Python)

A standardized speed test tracks the [relative performance of diffs](https://docs.google.com/spreadsheets/d/1zpZccuBpjMZTvL1nGDMKJc7rWL_m_drF4XKOJvB27Kc/edit#gid=0) in each language.

### Algorithms
This library implements [Myer's diff algorithm](https://neil.fraser.name/writing/diff/myers.pdf) which is generally considered to be the best general-purpose diff. A layer of [pre-diff speedups and post-diff cleanups](https://neil.fraser.name/writing/diff/) surround the diff algorithm, improving both performance and output quality.

This library also implements a [Bitap matching algorithm](https://neil.fraser.name/writing/patch/bitap.ps) at the heart of a [flexible matching and patching strategy](https://neil.fraser.name/writing/patch/).

[DMP]: https://github.com/google/diff-match-patch
[API]: https://github.com/google/diff-match-patch/wiki/API