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https://github.com/dchest/fossil-delta-js
Fossil SCM delta compression in JavaScript
https://github.com/dchest/fossil-delta-js
Last synced: 24 days ago
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Fossil SCM delta compression in JavaScript
- Host: GitHub
- URL: https://github.com/dchest/fossil-delta-js
- Owner: dchest
- License: other
- Created: 2014-08-16T18:36:07.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2024-04-06T11:02:55.000Z (8 months ago)
- Last Synced: 2024-10-14T12:07:59.841Z (about 1 month ago)
- Language: TypeScript
- Homepage: https://dchest.github.io/fossil-delta-js/
- Size: 69.3 KB
- Stars: 70
- Watchers: 5
- Forks: 7
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
Fossil SCM delta compression algorithm
======================================
The cool thing about it is that plain text inputs generate plain text deltas
(binary inputs, of course, may generate binary deltas).
* [Format](http://www.fossil-scm.org/index.html/doc/tip/www/delta_format.wiki)
* [Algorithm](http://www.fossil-scm.org/index.html/doc/tip/www/delta_encoder_algorithm.wiki)
* [Original implementation](http://www.fossil-scm.org/index.html/artifact/d1b0598adcd650b3551f63b17dfc864e73775c3d)
* [Demo](https://dchest.github.io/fossil-delta-js/)
Installation
------------
$ npm install fossil-delta
Usage
-----
```javascript
import { createDelta, applyDelta } from 'fossil-delta';
```
### createDelta(source, target) -> delta
Returns a delta from source to target.
`source` and `target` must be a `Uint8Array` or an `Array` of bytes.
The same type will be returned.
### applyDelta(source, delta[, opts]) -> target
Returns the target by applying the delta to the origin.
`origin` and `delta` must be a `Uint8Array` or an `Array` of bytes.
The same type will be returned.
Throws an error if the delta fails to apply (e.g., if it is corrupted).
Optional argument `opts` can be:
```javascript
{
verifyChecksum: false
}
```
to disable checksum verification (which is enabled by default.)
### getDeltaTargetSize(delta) -> size
Returns the size of the target for this delta.
Throws an error if it cannot read the size from the delta.
## Strings
A nice property of the Fossil Delta Encoding is that it produces pure plain text deltas
if the source and target are plain text.
To simplify working with plain text strings, the library provides the following convenience functions,
which automatically encode and decode strings using `TextEncoder` and `TextDecoder` before processing:
* `createStringDelta(source: string, target: string): string`
* `applyStringDelta(origin: string, delta: string, options?: Options): string`
* `getStringDeltaTargetSize(delta: string): number`
Note that `getStringDeltaTargetSize()` will return the size of the target string in UTF-8 bytes,
not characters (that is, it's not always equal to `string` length of the resulting target).
Development
-----------
I develop with Bun.
To build the library, run:
$ bun run build
npm, yarn will also work for building.
To run tests, run:
$ bun test
Migration from v1.x.x
---------------------
fossil-delta.js is now an ES module and there is no minified version included.
API renames:
- `create` -> `createDelta`
- `apply` -> `applyDelta`
- `outputSize` -> `getDeltaTargetSize`
Important: `createDelta` and `applyDelta` now return the same type as the input (`Uint8Array` if given `Uint8Array`, `Array` if given `Array`), instead of always returning an `Array`.