Haelwenn (lanodan) Monnier via public-inbox
#bare-py 
Python implementation of BARE. It should be a complete implementation. Unions might still cause weird behavior.
BARE is a binary encoding for datastructure that produces small messages, but is still 8-bit aligned. The usual workflow is writing a schema file and using the bare command to generate a python module representing your data structure.
#Example
The schema:
type PublicKey data<128>
type Time string # ISO 8601
enum Department {
ACCOUNTING
ADMINISTRATION
CUSTOMER_SERVICE
DEVELOPMENT
# Reserved for the CEO
JSMITH = 99
}
type Customer {
name: string
email: string
address: Address
orders: []{
orderId: i64
quantity: i32
}
metadata: map[string]data
}
type Employee {
name: string
email: string
address: Address
department: Department
hireDate: Time
publicKey: optional<PublicKey>
metadata: map[string]data
}
type Person (Customer | Employee)
type Address {
address: [4]string
city: string
state: string
country: string
}
Generate schema.py with the bare command
$ bare schema.bare schema.py
#Packing data
from schema import Customer, Address, Person
address = Address()
address.address = ["Address line 1", "", "", ""]
address.city = "The big city"
address.state = "Drenthe"
address.country = "The Netherlands"
customer = Customer()
customer.name = "Martijn Braam"
customer.email = "spam@example.org"
customer.address = address
customer.orders = [
{'orderId': 5, 'quantity': 1},
{'orderId': 6, 'quantity': 2}
]
customer.metadata = {
'ssh': b'jafsl8dfaf2',
'gpg': b'jofa8f2jdlasfj8'
}
# Write a Customer as a BARE encoded file
with open('example.bin', 'wb') as handle:
handle.write(customer.pack())
# Write it as a Person instead, only works with tagged unions
with open('person.bin', 'wb') as handle:
handle.write(Person.pack(customer))
$ xxd example.bin
00000000: 0d4d 6172 7469 6a6e 2042 7261 616d 1073 .Martijn Braam.s
00000010: 7061 6d40 6578 616d 706c 652e 6f72 670e pam@example.org.
00000020: 4164 6472 6573 7320 6c69 6e65 2031 0000 Address line 1..
00000030: 000c 5468 6520 6269 6720 6369 7479 0744 ..The big city.D
00000040: 7265 6e74 6865 0f54 6865 204e 6574 6865 renthe.The Nethe
00000050: 726c 616e 6473 0205 0000 0000 0000 0001 rlands..........
00000060: 0000 0006 0000 0000 0000 0002 0000 0002 ................
00000070: 0373 7368 0b6a 6166 736c 3864 6661 6632 .ssh.jafsl8dfaf2
00000080: 0367 7067 0f6a 6f66 6138 6632 6a64 6c61 .gpg.jofa8f2jdla
00000090: 7366 6a38 sfj8
#Unpacking data
from schema import Address
with open('address.bin', 'rb') as handle:
raw = handle.read()
address = Address.unpack(raw)
print(address.city)
#Debugging messages
The bare-dump command can be used to decode the binary messages with a supplied schema. It will output the bytes annotated with the information from the schema and the decoded data.
$ bare-dump cursor.bare Cursor --base64 MgGolKbTCwA=
struct Cursor
|count 32 INT = 25
|next 01 union, tag = 1 (INT)
||INT A8 94 A6 D3 0B INT = 1563739412
|search 00 String =