Python RSON

RSON is a superset of the JSON format. It extends JSON with the primary goal of allowing references in the JSON itself.

In addition to that, RSON also allows:

• Line comments
• Block comments
• Trailing commas

These are just some niceties are not the primary goal of the RSON format.

Usage

The RSON format allows references by adding 2 types of tokens:

1. DEF node - defines a ref-name for the value
2. REF node - references the given ref-name

The DEF node can be used on any JSON value. This node defines a name for the value which can then used to refer to the same value. The REF node can only appear as an object value or an array member, and is used to refer to a defined name.

Here is an example of how this would work:

// team.rson

[
    {
        "members": [
            {
                "name": "Alice",
                "role": $ROLE_DEVELOPER
            },
            {
                "name": "Bob",
                "role": $ROLE_MANAGER
            },
            {
                "name": "Charlie",
                "role": $ROLE_DESIGNER
            },
            {
                "name": "David",
                "role": $ROLE_DEVELOPER
            }
        ],
        "roles": [
            {
                "name": "Developer"
            }(ROLE_DEVELOPER),
            {
                "name": "Designer"
            }(ROLE_DESIGNER),
            {
                "name": "Manager"
            }(ROLE_MANAGER)
        ]
    }
]

We can load the teams.rson file with the following code:

from rson import load

with open("teams.rson") as f:
    team = load(f)[0]

    target_role_name = input("Which role to look for? ")

    for role in team["roles"]:
        if role["name"].lower() == target_role_name.lower():
            target_role = role
            break
    else:
        print("Could not find role " + target_role_name)
        exit()

    members_with_role = [
        member for member in team["members"]
        if member["role"] is target_role # <- note the identity check here
    ]

    print(f"Found {len(members_with_role)} members with role {role['name']}:")
    for i, member in enumerate(members_with_role):
        print(f"\t{i}. {member['name']}")

and a sample execution:

Which role to look for? developer
Found 2 members with role Developer:
        0. Alice
        1. David

Specification

The ref-name must conform to the following regex:

[A-Za-z_][A-Za-z_0-9]*

Or, in plain english:

The first character must be a valid english letter or an underscore, and the following letters must be either an english letter, an underscore or a digit. A ref-name must have at least 1 character (the first character).

A DEF node can be used for every JSON value, so this makes the following valid as well:

{
    "organization": {
        "name": "Xpo Development"(ORG_NAME)
    },
    "title": $ORG_NAME
}

Contributing

Feel free to open an issue or a PR.

ToDo

• Implement the load function
• Implement the loads function
• Implement the dump function
• Implement the dumps function