https://github.com/raphexion/gustav

Small helper library for and in Erlang
https://github.com/raphexion/gustav

binary-data erlang erlang-library helpers serialization

Last synced: 23 days ago
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Small helper library for and in Erlang

• Host: GitHub
• URL: https://github.com/raphexion/gustav
• Owner: Raphexion
• License: apache-2.0
• Created: 2018-06-14T17:41:21.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2019-04-23T17:40:03.000Z (over 5 years ago)
• Last Synced: 2024-12-09T03:39:54.259Z (about 1 month ago)
• Topics: binary-data, erlang, erlang-library, helpers, serialization
• Language: Erlang
• Homepage:
• Size: 36.1 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
gustav

=====

[![Build Status](https://travis-ci.org/Raphexion/gustav.svg?branch=master)](https://travis-ci.org/Raphexion/gustav)

[![codecov.io](https://codecov.io/gh/Raphexion/gustav/coverage.svg?branch=master)](https://codecov.io/gh/Raphexion/gustav?branch=master)

A helper library for two use-cases:

1. To help pack-up and un-pack data

2. To help with writing a udp-server

Examples

--------

Imagine that you have a state `#{a => 1, b => 2, c => 3, d => 4}`.

You need to pack-up this data (serialize) and send it over the wire.

Your protocol specifies that:

| Variable | Bits in payload |

|----------|-----------------|

| a        | 8               |

| b        | 16              |

| c        | 32              |

| d        | 8               |

Which can be described compactly as `[{a, 8}, {b, 16}, {c, 32}, {d, 8}]`.

When using *Gustav*, packing up the dictionary into a binary payload:

```

Dictionary = #{a => 1, b => 2, c => 3, d => 4},

Packer = packer(Dictionary),

Payload = Packer([{a, 8}, {b, 16}, {c, 32}, {d, 8}]),

Payload.

<<1:8, 2:16, 3:32, 4:8>>

```

To unpack the binary payload is similar.

We describe the binary protocol `[{a, 8}, {b, 16}, {c, 32}, {d, 8}]`

and use a unpacker function.

Normally we only want to unpack the data into an empty map `#{}`.

However, in some cases it is convenient to allow some "other" data

in the map (state).

Using *Gustav*, to unpacking a binary payload into a dictionary:

```

Payload = <<1:8, 2:16, 3:32, 4:8>>,

UnPacker = unpacker(#{}, Payload),

NewDictionary = UnPacker([{a, 8}, {b, 16}, {c, 32}, {d, 8}]),

NewDictionary.

#{a => 1, b => 2, c => 3, d => 4}

```

Or if you already have some data you want to preserve `#{q => 42}`:

```

OrgDictionary = #{q => 42}  %% q => 42 is mapping we want to

Payload = <<1:8, 2:16, 3:32, 4:8>>,

UnPacker = unpacker(OrgDictionary, Payload),

NewDictionary = UnPacker([{a, 8}, {b, 16}, {c, 32}, {d, 8}]),

NewDictionary.

#{a => 1, b => 2, c => 3, d => 4, q => 42}

```

Build

-----

    $ rebar3 compile