Python implementation of the cnf format

Packages

• cnfembed - Text-preserving cnf to json, a single file for embedding.
• cnftest - Harness to run the conformance tests.

Specification

Consult the full specification for examples and details of the format.

Running tests

The cnftest harness runs the full conformance corpus, from a local copy of the spec kept for the tests. To run the tests:

python3 -m unittest discover

Performance

The following table offers a vague data point on the performance of the implementation. The benchmark was run using the data of a real yaml file with ~67k nodes in a diversified distribution totaling ~800kb. The same file was converted to cnf in the same structure, and also compact json.

A conformant YAML 1.2 pure Python implementation was selected, not named here as this is just supposed to show that the performance is not so bad, even being a pure Python implementation, and even if we opt to translate first into json rather than doing a direct map decode.

Example

This simple example shows the conversion of cnf to json:

key: "value"
nested.key: 0xff
string:
    """
    Hello
    world
    """

One call decodes it to JSON:

from cnfembed import to_json

json = to_json(doc)

This results in:

{"key":"value","nested":{"key":255},"string":"Hello\nworld\n"}

For the time being this port converts one direction only: cnf to json.

A string that fails to parse raises Error with the message including the line and column of the problem:

from cnfembed import Error, to_json

try:
    to_json("a: bare\n")
except Error as err:
    print(err)  # 1:4: cannot parse unquoted value `bare`

For actual embedding into your project, you may opt to copy the cnfembed/cnf.py file alone.