# Etiquette
<a href="https://hex.pm/packages/etiquette"><img alt="Hex Version" src="https://img.shields.io/hexpm/v/etiquette"></a>
<a href="https://hexdocs.pm/etiquette"><img alt="Hex Docs" src="http://img.shields.io/badge/hex.pm-docs-green.svg?style=flat"></a>
<br>
A new way of creating and following a protocol
## Summary
Following an example Header Packet
<table aria-label="Header Packet">
<tr>
<th colspan="8">Byte 0</th>
</tr>
<tr>
<td colspan="1">Header Fixed</td>
<td colspan="2">Packet Type</td>
<td colspan="5">Type-Specific fields</td>
</tr>
</table>
We can turn it into
```elixir
defmodule Example.Spec do
use Etiquette.Spec
packet "Header Packet", id: :header_packet do
field "Header Fixed", 1, fixed: 1, doc: "Whether the packet is a header."
field "Packet Type", 2, doc: "The type of the payload. Can be any 0-3 integer."
field "Type-Specific fields", (..), id: :type_specific_fields, doc: "The packet payload."
end
packet "Hello Packet", of: :header_packet do
field "Packet Type", 2, fixed: 0b00
field "Hello-specific payload", 8, part_of: :type_specific_fields
end
packet "Conversation Packet", of: :header_packet do
field "Packet Type", 2, fixed: 0b01
field "Conversation-specific payload", 8, part_of: :type_specific_fields
end
packet "Bye Packet", of: :header_packet do
field "Packet Type", 2, fixed: 0b11
field "Bye-specific payload", 8, part_of: :type_specific_fields
end
end
```
Such that we now have a specification
```elixir
iex> Example.Spec.is_header_packet?(<<1::1, "A random string inside 30 bytes"::30>>)
true
iex> Example.Spec.is_hello_packet?(<<1::1, 0b00::2, "rest">>)
true
iex> Example.Spec.is_hello_packet?(<<1::1, 0b10::2, "rest">>)
false
iex> Example.Spec.is_bye_packet?(<<1::1, 0b11::2, 0xFF, 0xAA>>)
true
iex> Example.Spec.parse_bye_packet(<<1::1, 0b11::2, 0xFF, 0xAA>>)
{
%{
header_fixed: 1,
packet_type: 3,
bye_specific_payload: 255
},
<<170>>
}
iex> # Notice how only the fields that are not fixed need to be provided
iex> Example.Spec.build_bye_packet(0xFF) |> Example.Spec.parse_bye_packet()
{
%{
header_fixed: 1,
packet_type: 3,
bye_specific_payload: 0xFF
},
""
}
iex> Example.Spec.build_bye_packet(0xFF) |> Example.Spec.is_bye_packet?()
true
```
Not only are the functions available and functional, but the provided
documentation and other arguments are also analyzed to provide in-depth
documentation of each generated function:
