remarkov.persistance

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from json import JSONDecoder, JSONEncoder

ORDER, TRANSITIONS, START_STATES = "order", "transitions", "start_states"
DEFAULT_JSON_INDENT = 4


class V1Decoder(JSONDecoder):
    def __init__(self):
        super().__init__(object_hook=self.__object_hook)

    def __object_hook(self, obj):
        if ORDER in obj and TRANSITIONS in obj and START_STATES in obj:
            from remarkov.model import Model

            remarkov = Model()
            remarkov.order = obj[ORDER]

            for transition in obj[TRANSITIONS]:
                state = tuple(transition["state"])
                for token in transition["tokens"]:
                    remarkov.transitions.declare(state, token)

            for start_state in obj[START_STATES]:
                remarkov.transitions.declare_start(tuple(start_state))

            return remarkov

        return obj


class V1Encoder(JSONEncoder):
    def __init__(self, compress: bool):
        super().__init__(indent=None if compress else DEFAULT_JSON_INDENT)

    def default(self, obj):
        return {
            ORDER: obj.order,
            # save each transition as an object
            TRANSITIONS: [
                {"state": list(state), "tokens": tokens}
                for state, tokens in obj.transitions.items()
            ],
            START_STATES: [list(state) for state in obj.transitions.start_states],
        }

# class V1Decoder(json.decoder.JSONDecoder):

View Source

class V1Decoder(JSONDecoder):
    def __init__(self):
        super().__init__(object_hook=self.__object_hook)

    def __object_hook(self, obj):
        if ORDER in obj and TRANSITIONS in obj and START_STATES in obj:
            from remarkov.model import Model

            remarkov = Model()
            remarkov.order = obj[ORDER]

            for transition in obj[TRANSITIONS]:
                state = tuple(transition["state"])
                for token in transition["tokens"]:
                    remarkov.transitions.declare(state, token)

            for start_state in obj[START_STATES]:
                remarkov.transitions.declare_start(tuple(start_state))

            return remarkov

        return obj

Simple JSON http://json.org decoder

Performs the following translations in decoding by default:

+---------------+-------------------+ | JSON | Python | +===============+===================+ | object | dict | +---------------+-------------------+ | array | list | +---------------+-------------------+ | string | str | +---------------+-------------------+ | number (int) | int | +---------------+-------------------+ | number (real) | float | +---------------+-------------------+ | true | True | +---------------+-------------------+ | false | False | +---------------+-------------------+ | null | None | +---------------+-------------------+

It also understands NaN, Infinity, and -Infinity as their corresponding float values, which is outside the JSON spec.

# V1Decoder()

View Source

    def __init__(self):
        super().__init__(object_hook=self.__object_hook)

object_hook, if specified, will be called with the result of every JSON object decoded and its return value will be used in place of the given dict. This can be used to provide custom deserializations (e.g. to support JSON-RPC class hinting).

object_pairs_hook, if specified will be called with the result of every JSON object decoded with an ordered list of pairs. The return value of object_pairs_hook will be used instead of the dict. This feature can be used to implement custom decoders. If object_hook is also defined, the object_pairs_hook takes priority.

parse_float, if specified, will be called with the string of every JSON float to be decoded. By default this is equivalent to float(num_str). This can be used to use another datatype or parser for JSON floats (e.g. decimal.Decimal).

parse_int, if specified, will be called with the string of every JSON int to be decoded. By default this is equivalent to int(num_str). This can be used to use another datatype or parser for JSON integers (e.g. float).

parse_constant, if specified, will be called with one of the following strings: -Infinity, Infinity, NaN. This can be used to raise an exception if invalid JSON numbers are encountered.

If strict is false (true is the default), then control characters will be allowed inside strings. Control characters in this context are those with character codes in the 0-31 range, including '\t' (tab), '\n', '\r' and '\0'.

Inherited Members

json.decoder.JSONDecoder: decode; raw_decode

# class V1Encoder(json.encoder.JSONEncoder):

View Source

class V1Encoder(JSONEncoder):
    def __init__(self, compress: bool):
        super().__init__(indent=None if compress else DEFAULT_JSON_INDENT)

    def default(self, obj):
        return {
            ORDER: obj.order,
            # save each transition as an object
            TRANSITIONS: [
                {"state": list(state), "tokens": tokens}
                for state, tokens in obj.transitions.items()
            ],
            START_STATES: [list(state) for state in obj.transitions.start_states],
        }

Extensible JSON http://json.org encoder for Python data structures.

Supports the following objects and types by default:

To extend this to recognize other objects, subclass and implement a .default() method with another method that returns a serializable object for o if possible, otherwise it should call the superclass implementation (to raise TypeError).

# V1Encoder(compress: bool)

View Source

    def __init__(self, compress: bool):
        super().__init__(indent=None if compress else DEFAULT_JSON_INDENT)

Constructor for JSONEncoder, with sensible defaults.

If skipkeys is false, then it is a TypeError to attempt encoding of keys that are not str, int, float or None. If skipkeys is True, such items are simply skipped.

If ensure_ascii is true, the output is guaranteed to be str objects with all incoming non-ASCII characters escaped. If ensure_ascii is false, the output can contain non-ASCII characters.

If check_circular is true, then lists, dicts, and custom encoded objects will be checked for circular references during encoding to prevent an infinite recursion (which would cause an OverflowError). Otherwise, no such check takes place.

If allow_nan is true, then NaN, Infinity, and -Infinity will be encoded as such. This behavior is not JSON specification compliant, but is consistent with most JavaScript based encoders and decoders. Otherwise, it will be a ValueError to encode such floats.

If sort_keys is true, then the output of dictionaries will be sorted by key; this is useful for regression tests to ensure that JSON serializations can be compared on a day-to-day basis.

If indent is a non-negative integer, then JSON array elements and object members will be pretty-printed with that indent level. An indent level of 0 will only insert newlines. None is the most compact representation.

If specified, separators should be an (item_separator, key_separator) tuple. The default is (', ', ': ') if indent is None and (',', ': ') otherwise. To get the most compact JSON representation, you should specify (',', ':') to eliminate whitespace.

If specified, default is a function that gets called for objects that can't otherwise be serialized. It should return a JSON encodable version of the object or raise a TypeError.

# def default(self, obj):

View Source

    def default(self, obj):
        return {
            ORDER: obj.order,
            # save each transition as an object
            TRANSITIONS: [
                {"state": list(state), "tokens": tokens}
                for state, tokens in obj.transitions.items()
            ],
            START_STATES: [list(state) for state in obj.transitions.start_states],
        }

Implement this method in a subclass such that it returns a serializable object for o, or calls the base implementation (to raise a TypeError).

For example, to support arbitrary iterators, you could implement default like this::

def default(self, o):
    try:
        iterable = iter(o)
    except TypeError:
        pass
    else:
        return list(iterable)
    # Let the base class default method raise the TypeError
    return JSONEncoder.default(self, o)

Inherited Members

json.encoder.JSONEncoder: item_separator; key_separator; encode; iterencode