Map Python object to ECMA-JSON compliant objects

json_ecma_compliance.py

import math


class JSONECMACompliance(object):
    @classmethod
    def make_standards_compliant(cls, json_serializable_obj, inf_value='Infinity',
                                 negative_inf_value='-Infinity', nan_value='NaN'):
        """
        Python decided it wouldn't conform to ECMA JSON standard.
        This converts illegal values (Infinity, -Infinity, NaN) to strings with the same values.

        JSON spec: http://www.json.org/

        :param json_serializable_obj: object which will be json serialized
        :param inf_value: value to replace infinite values with. Must be an ECMA compliant value
        :param negative_inf_value: value to replace negative infinite values with.
            Must be an ECMA compliant value
        :param nan_value: value to replace NaN values with. Must be an ECMA compliant value
        :return: json serializable object which will serialize in a standards compliant manner
        """
        mapper = cls._get_json_value_mapper(inf_value, negative_inf_value, nan_value)
        return cls._deep_map_values(json_serializable_obj, mapper)

    @classmethod
    def _deep_map_values(cls, obj, callback):
        if isinstance(obj, dict):
            return {v_name: cls._deep_map_values(v, callback) for v_name, v in obj.iteritems()}
        elif isinstance(obj, list):
            return [cls._deep_map_values(v, callback) for i, v in enumerate(obj)]
        else:
            return callback(obj)

    @classmethod
    def _get_json_value_mapper(cls, inf_value, negative_inf_value, nan_value):
        def _map_json_serializable_values(v):
            if isinstance(v, float):
                if math.isinf(v):
                    return inf_value if v > 0 else negative_inf_value
                elif math.isnan(v):
                    return nan_value
                else:
                    return v
            else:
                return v
        return _map_json_serializable_values