Source code for dictdumper.json

# -*- coding: utf-8 -*-
"""dumper a JSON file

:mod:`dictdumper.json` contains :class:`~dictdumper.json.JSON`
only, which dumpers a JavaScript object notation (JSON) file.
Usage sample is described as below.

.. code:: python

    >>> dumper = JSON(file_name)
    >>> dumper(content_dict_1, name=content_name_1)
    >>> dumper(content_dict_2, name=content_name_2)
    ............

"""
# Writer for JSON files
# Dump a JSON file for PCAP analyser

from __future__ import unicode_literals

import collections
import datetime
import math
import os
import string

from dictdumper._dateutil import isoformat
from dictdumper._hexlify import hexlify
from dictdumper._types import bytes_type, str_type
from dictdumper.dumper import Dumper

__all__ = ['JSON']

#: JSON head string.
_HEADER_START = '{\n'

#: JSON tail string.
_HEADER_END = '\n}'

#: Mapping for escaping special characters (c.f. :data:`json.encoder.ESCAPE_DCT`).
ESCAPE_DCT = {
    '\\': '\\\\',
    '"': '\\"',
    '\b': '\\b',
    '\f': '\\f',
    '\n': '\\n',
    '\r': '\\r',
    '\t': '\\t',
    '\x0b': '\\u000b',
}


[docs]class JSON(Dumper): """Dump JavaScript object notation (JSON) format file. .. code:: python >>> dumper = JSON(file_name) >>> dumper(content_dict_1, name=content_name_1) >>> dumper(content_dict_2, name=content_name_2) ............ Attributes: _file (str): output file name _sptr (int): indicates start of appending point (file pointer) _tctr (int): tab level counter _hsrt (str): :data:`~dictdumper.json._HEADER_START` _hend (str): :data:`~dictdumper.json._HEADER_END` _vctr (DefaultDict[int, int]): value counter dict .. note:: Terminology: .. code:: object ::= "{}" | ("{" members "}") members ::= pair | (pair "," members) pair ::= string ":" value array ::= "[]" | ("[" elements "]") elements ::= value | (value "," elements) value ::= string | number | object | array | true | false | null """ ########################################################################## # Properties. ########################################################################## @property def kind(self): """File format of current dumper. :rtype: Literal['json'] """ return 'json' ########################################################################## # Type codes. ########################################################################## #: Tuple[Tuple[type, str]]: Type codes. __type__ = ( # string (str_type, 'string'), # date (datetime.date, 'date'), (datetime.datetime, 'date'), (datetime.time, 'date'), # bool (bool, 'bool'), # number (int, 'number'), (float, 'number'), # object (dict, 'object'), # array (list, 'array'), # null (type(None), 'null'), ) ########################################################################## # Attributes. ########################################################################## #: JSON head string. _hsrt = _HEADER_START #: JSON tail string. _hend = _HEADER_END ########################################################################## # Data models. ##########################################################################
[docs] def __init__(self, fname, **kwargs): """Initialise dumper. Args: fname (str): output file name **kwargs: addition keyword arguments for initialisation """ super(JSON, self).__init__(fname, **kwargs) #: DefaultDict[int, int]: Value counter dict. self._vctr = collections.defaultdict(int) # value counter dict
########################################################################## # Utilities. ##########################################################################
[docs] def _encode_value(self, o): # pylint: disable=unused-argument """Check content type for function call. Args: o (Any): object to convert Returns: Any: the converted object See Also: The function is a direct wrapper for :meth:`~dictdumper.dumper.Dumper.object_hook`. Notes: The function will by default converts :obj:`bytearray`, :obj:`memoryview`, :obj:`tuple`, :obj:`set`, :obj:`frozenset` to JSON serialisable data. """ if isinstance(o, (bytes_type, bytearray)): return self.make_object(o, o.decode(errors='replace'), hex=hexlify(o)) if isinstance(o, memoryview): tobytes = o.tobytes() return self.make_object(o, tobytes.decode(errors='replace'), hex=hexlify(tobytes)) if isinstance(o, (tuple, set, frozenset)): return self.make_object(o, list(o)) return self.object_hook(o)
[docs] def _append_value(self, value, file, name): """Call this function to write contents. Args: value (Dict[str, Any]): content to be dumped file (io.TextIOWrapper): output file name (str): name of current content block """ tabs = '\t' * self._tctr cmma = ',\n' if self._vctr[self._tctr] else '' keys = '{cmma}{tabs}"{name}": '.format(cmma=cmma, tabs=tabs, name=name) file.seek(self._sptr, os.SEEK_SET) file.write(keys) self._vctr[self._tctr] += 1 self._append_object(value, file)
########################################################################## # Functions. ##########################################################################
[docs] def _append_object(self, value, file): """Call this function to write object contents. Args: value (Dict[str, Any]): content to be dumped file (io.TextIOWrapper): output file """ labs = '{' file.write(labs) self._tctr += 1 for (item, text) in value.items(): tabs = '\t' * self._tctr cmma = ',' if self._vctr[self._tctr] else '' keys = '{cmma}\n{tabs}"{item}": '.format(cmma=cmma, tabs=tabs, item=item) file.write(keys) self._vctr[self._tctr] += 1 enc_text = self._encode_value(text) func = self._encode_func(enc_text) func(enc_text, file) self._vctr[self._tctr] = 0 self._tctr -= 1 tabs = '\t' * self._tctr labs = '\n{tabs}{}'.format('}', tabs=tabs) file.write(labs)
[docs] def _append_array(self, value, file): """Call this function to write array contents. Args: value (List[Any]): content to be dumped file (io.TextIOWrapper): output file """ val_list = [self._encode_value(item) for item in value] mul_line = False for item in val_list: if isinstance(item, dict): mul_line = True break labs = '[\n' if mul_line else '[ ' file.write(labs) self._tctr += 1 tabs = '\t' * self._tctr for item in val_list: if self._vctr[self._tctr]: file.write(',\n' if mul_line else ', ') if mul_line: file.write(tabs) self._vctr[self._tctr] += 1 func = self._encode_func(item) func(item, file) self._vctr[self._tctr] = 0 self._tctr -= 1 if mul_line: tabs = '\t' * self._tctr labs = '\n{tabs}]'.format(tabs=tabs) else: labs = ' ]' file.write(labs)
[docs] def _append_string(self, value, file): # pylint: disable=no-self-use """Call this function to write string contents. Args: value (str): content to be dumped file (io.TextIOWrapper): output file """ text = '' for char in str_type(value): if char in string.printable: temp = ESCAPE_DCT.get(char, char) else: temp = '\\u{0:04x}'.format(ord(char)) text += temp labs = '"{text}"'.format(text=text) file.write(labs)
[docs] def _append_date(self, value, file): # pylint: disable=no-self-use """Call this function to write date contents. Args: value (Union[datetime.date, datetime.datetime, datetime.time]): content to be dumped file (io.TextIOWrapper): output file """ text = isoformat(value) labs = '"{text}"'.format(text=text) file.write(labs)
[docs] def _append_number(self, value, file): """Call this function to write number contents. Args: value (Union[int, float]): content to be dumped file (io.TextIOWrapper): output file """ if math.isnan(value): text = self.make_object(value, None, number=str_type(value).replace(u'nan', u'NaN')) self._append_object(text, file) elif math.isinf(value): text = self.make_object(value, None, number=str_type(value).replace(u'inf', u'Infinity')) self._append_object(text, file) else: labs = str_type(value) file.write(labs)
[docs] def _append_bool(self, value, file): # pylint: disable=no-self-use """Call this function to write bool contents. Args: value (bool): content to be dumped file (io.TextIOWrapper): output file """ labs = 'true' if value else 'false' file.write(labs)
[docs] def _append_null(self, value, file): # pylint: disable=unused-argument,no-self-use """Call this function to write null contents. Args: value (None): content to be dumped file (io.TextIOWrapper): output file """ labs = 'null' file.write(labs)