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https://github.com/discord/erlpack
High Performance Erlang Term Format Packer
https://github.com/discord/erlpack
electron elixir erlang etf nodejs python
Last synced: 3 days ago
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High Performance Erlang Term Format Packer
- Host: GitHub
- URL: https://github.com/discord/erlpack
- Owner: discord
- License: mit
- Created: 2015-12-16T02:03:44.000Z (almost 9 years ago)
- Default Branch: master
- Last Pushed: 2023-11-02T22:55:16.000Z (about 1 year ago)
- Last Synced: 2024-12-08T11:46:34.663Z (4 days ago)
- Topics: electron, elixir, erlang, etf, nodejs, python
- Language: Cython
- Size: 1.36 MB
- Stars: 225
- Watchers: 150
- Forks: 66
- Open Issues: 24
-
Metadata Files:
- Readme: README.md
- License: COPYING
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README
# Erlpack
Erlpack is a fast encoder and decoder for the Erlang Term Format (version 131) for Python and JavaScript.
# JavaScript
## Things that can be packed:
- [X] Null
- [X] Booleans
- [X] Strings
- [ ] Atoms
- [X] Unicode Strings
- [X] Floats
- [X] Integers
- [ ] Longs
- [ ] Longs over 64 bits
- [X] Objects
- [X] Arrays
- [ ] Tuples
- [ ] PIDs
- [ ] Ports
- [ ] Exports
- [ ] References
## How to pack:
```js
let erlpack = require("erlpack");
packed = erlpack.pack({'a': true, 'list': ['of', 3, 'things', 'to', 'pack']});
```
## How to unpack:
Note: Unpacking requires the binary data be a Uint8Array or Buffer. For those using electron/libchromium see the gotcha below.
```js
let erlpack = require("erlpack");
let unpacked = null;
let packed = new Buffer('', 'binary');
try {
unpacked = erlpack.unpack(packed);
}
catch (e) {
// got an exception parsing
}
```
## Libchromium / Electron Gotcha
Some versions of libchromium replace the native data type backing TypedArrays with a custom data type called
blink::WebArrayBuffer. To keep erlpack' dependencies simple this data type is not supported directly. If you're using
Electron / Libchromium you need to convert the blink::WebArrayBuffer into a node::Buffer before passing to erlpack. You will
need to add this code into your native package somewhere:
```cpp
v8::Local ConvertToNodeBuffer(const v8::Local& blinkArray)
{
if (node::Buffer::HasInstance(blinkArray)) {
return blinkArray;
}
else if (blinkArray->IsArrayBufferView()) {
auto byteArray = v8::ArrayBufferView::Cast(*blinkArray);
return node::Buffer::Copy(v8::Isolate::GetCurrent(), (const char*)byteArray->Buffer()->GetContents().Data(), byteArray->ByteLength()).ToLocalChecked();
}
return v8::Local(v8::Null(v8::Isolate::GetCurrent()));
}
```
Then in JavaScript something like:
```js
let packed = NativeUtils.convertToNodeBuffer(new Uint8Array(binaryPayload));
// unpack now using erlpack.unpack(packed)
```
# Python
## Things that can be packed:
- [X] None
- [X] Booleans
- [X] Strings
- [X] Atoms
- [X] Unicode Strings
- [X] Floats
- [X] Integers
- [X] Longs
- [ ] Longs over 64 bits
- [X] Dictionaries
- [X] Lists
- [X] Tuples
- [X] User Types (via an encode hook)
- [ ] PIDs
- [ ] Ports
- [ ] Exports
- [ ] References
## How to pack:
```py
from erlpack import pack
packed = pack(["thing", "to", "pack"])
```
## How to unpack:
```py
from erlpack import unpack
unpacked = unpack(packed)
```
## How to pack an atom:
```py
from erlpack import Atom, pack
packed = pack(Atom('hello'))
```
## How to use an encode hook.
```py
from erlpack import ErlangTermEncoder
def encode_hook(obj):
if isinstance(obj, datetime.datetime):
return obj.isoformat()
encoder = ErlangTermEncoder(encode_hook=encode_hook)
packed = encoder.pack(datetime.datetime(2015, 12, 25, 12, 23, 55))
```
## How to make custom types packable.
```py
from erlpack import pack, Atom
class User(object):
def __init__(self, name, age):
self.name = name
self.age = age
def __erlpack__(self):
return {
Atom('name'): self.name,
Atom('age'): self.age
}
u = User(name='Jake', age=23)
packed = pack(u)
```
# Go (golang)
Discord has moved away from Go internally and so we do not maintain a version of erlpack in Go ourselves. However, all is
not lost!, please check out: https://github.com/JakeMakesStuff/go-erlpack
# Building
## Python
Generating the new `.cpp` files can be accomplished by running `python setup.py --use-cython build_ext --inplace`.
`cython` must be installed for this to work.
### Testing
1. Install the development version of erlpack with `python setup.py develop`.
2. Install `pytest`.
3. Execute `pytest py/tests`.