src/python/m5/ext/pystats/jsonserializable.py

# Copyright (c) 2021 The Regents of The University of California
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from datetime import datetime
import json
from typing import Dict, List, Union, Any, IO

from .storagetype import StorageType

class JsonSerializable:
    """
    Classes which inherit from JsonSerializable can be translated into JSON
    using Python's json package.

    Usage
    -----
    ```
    import m5.pystats.gem5stats as gem5stats

    simstat = gem5stats.get_simstat(root)
    print(simstat.dumps())
    ```
    """

    def to_json(self) -> Dict:
        """
        Translates the current object into a JSON dictionary.

        Returns
        -------
        Dict
            The JSON dictionary.
        """

        model_dct = {}
        for key, value in self.__dict__.items():
            new_value = self.__process_json_value(value)
            model_dct[key] = new_value
        return model_dct

    def __process_json_value(self,
                            value: Any) -> Union[str,int,float,Dict,List,None]:
        """
        Translate values into a value which can be handled by the Python stdlib
        JSON package.

        Parameters
        ----------
        value: Any
            The value to be translated.

        Returns
        -------
        Union[str,int,float,Dict,List]
            A value which can be handled by the Python stdlib JSON package.
        """

        if isinstance(value, JsonSerializable):
            return value.to_json()
        elif isinstance(value, (str, int, float)):
            return value
        elif isinstance(value, datetime):
            return value.replace(microsecond=0).isoformat()
        elif isinstance(value, list):
            return [self.__process_json_value(v) for v in value]
        elif isinstance(value, StorageType):
            return str(value.name)

        return None


    def dumps(self, **kwargs) -> str:
        """
        This function mirrors the Python stdlib JSON module method
        `json.dumps`. It is used to obtain the gem5 statistics output to a
        JSON string.

        Parameters
        ----------
        root: Root
            The root of the simulation.

        kwargs: Dict[str, Any]
            Additional parameters to be passed to the `json.dumps` method.

        Returns
        -------
        str
            A string of the gem5 Statistics in a JSON format.


        Usage Example
        -------------
        ```
        import m5.pystats.gem5stats as gem5stats

        simstat = gem5stats.get_simstat(root)
        print(simstat.dumps(indent=6))
        ```

        The above will print the simulation statistic JSON string. The
        indentation will be 6 (by default the indentation is 4).
        """

        # Setting the default indentation to something readable.
        if 'indent' not in kwargs:
            kwargs['indent'] = 4

        return json.dumps(obj=self.to_json(), **kwargs)

    def dump(self, fp: IO[str], **kwargs) -> None:
        """
        This function mirrors the Python stdlib JSON module method
        `json.dump`. The root of the simulation is passed, and the JSON is
        output to the specified.


        Parameters
        ----------
        fp: IO[str]
            The Text IO stream to output the JSON to.

        **kwargs:
            Additional parameters to be passed to the ``json.dump`` method.

        Usage
        -----
        ```
        import m5.pystats.gem5stats as gem5stats

        simstat = gem5stats.get_simstat(root)
        with open("test.json") as f:
            simstat.dump(fp=f, indent=6)
        ```

        The above will dump the json output to the 'test.json' file. The
        indentation will be of 6 (by default the indentation is 4).
        """

        # Setting the default indentation to something readable.
        if 'indent' not in kwargs:
            kwargs['indent'] = 4

        json.dump(obj=self.to_json(), fp=fp, **kwargs)