ElementCallable.validate() - Code Metrics - Inspection of "Elem none" - sprout42/StarStruct - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Pull Request — master (#42)

by TJ

created 2016-12-20 21:08 UTC

ElementCallable.validate() C

↳ Parent: ElementCallable

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	9
CRAP Score	8

Importance

Changes	2
Bugs	0	Features	0

Metric	Value
cc	8
c	2
b	0
f	0
dl	0
loc	20
ccs	9
cts	9
cp	1
crap	8
rs	6.6666

"""
Element callable.

Call a function to validate data.

TODO: Update the format here

.. code-block:: python

    from binascii import crc32

    ExampleMessage = Message('VarTest', [('x', 'B'), ('y', 'B')])

    CRCedMessage = Message('CRCedMessage', [
       ('data', ExampleMessage),                    # A data field that has the example message in it
       ('crc', 'I', crc32, ['data']),               # Crc the data, and give an error if we have something unexpected
       ('crc', 'I', crc32, ['data'], False),        # Crc the data, but don't give an error
   ])

Following creating this message, you have two options:

1. Specify a value. The function will be used to validate the value.

.. code-block:: python

    def adder(x, y):
        return x + y

    AdderMessage = Message('AdderMessage', [
        ('item_a', 'H'),
        ('item_b', 'B'),
        ('function_data', 'I', adder, ['item_a', 'item_b']),
    ])

    test_data = {
        'item_a': 2,
        'item_b': 5,
        'function_data': 7,
    }

    made = AdderMessage.make(test_data)
    assert made.item_a == 2
    assert made.item_b == 5
    assert made.function_data == 7

    # If you specify the wrong value, you'll get a ValueError
    test_data = {
        'item_a': 2,
        'item_b': 5,
        'function_data': 33,
    }

    try:
        made = AdderMessage.make(test_data)
    except ValueError:
        print('Told you so')

    # Unless you specify `False` in your original item, then
    # nobody will care.

2. Use the function to generate a value.

.. code-block:: python

    def adder(x, y):
        return x + y

    AdderMessage = Message('AdderMessage', [
        ('item_a', 'H'),
        ('item_b', 'B'),
        ('function_data', 'I', adder, ['item_a', 'item_b']),
    ])

    test_data = {
        'item_a': 2,
        'item_b': 5,
    }

    made = AdderMessage.make(test_data)
    assert made.item_a == 2
    assert made.item_b == 5
    assert made.function_data == 7

"""

import copy
import struct

from typing import Optional
# .scrutinizer.yml
before_commands:
    - sudo pip install abc # Python2
    - sudo pip3 install abc # Python3

from starstruct.element import register, Element
from starstruct.modes import Mode


@register

class ElementCallable(Element):
    """
    Initialize a StarStruct element object.

    :param field: The fields passed into the constructor of the element
    :param mode: The mode in which to pack the bytes
    :param alignment: Number of bytes to align to
    """
    accepted_mesages = (True, False)

    # pylint: disable=too-many-instance-attributes
    def __init__(self, field: list, mode: Optional[Mode]=Mode.Native, alignment: Optional[int]=1):
        # All of the type checks have already been performed by the class
        # factory
        self.name = field[0]

        # Callable elements use the normal struct packing method
        self.format = field[1]

        if isinstance(field[2], dict):
            self.ref = field[2]

            default_list = [None, None]
            self._make_func = self.ref.get('make', default_list)[0]
            self._make_args = self.ref.get('make', default_list)[1:]

            self._pack_func = self.ref.get('pack', default_list)[0]
            self._pack_args = self.ref.get('pack', default_list)[1:]

            self._unpack_func = self.ref.get('unpack', default_list)[0]
            self._unpack_args = self.ref.get('unpack', default_list)[1:]
        elif isinstance(field[2], set):
            instruction = field[2].copy().pop()
            self.ref = {'all': instruction}

            self._make_func = self._pack_func = self._unpack_func = instruction[0]
            self._make_args = self._pack_args = self._unpack_args = instruction[1:]

        if len(field) == 4:
            self._error_on_bad_result = field[3]
        else:
            self._error_on_bad_result = True

        self._elements = []

        self.update(mode, alignment)

    @property
    def _struct(self):
        return struct.Struct(self._mode.value + self.format)

    @staticmethod
    def valid(field: tuple) -> bool:
        """
        See :py:func:`starstruct.element.Element.valid`

        :param field: The items to determine the structure of the element
        """
        required_keys = {'pack', 'unpack', 'make'}

        if len(field) >= 3 and isinstance(field[0], str) and isinstance(field[1], str):
            if isinstance(field[2], dict):
                if set(field[2].keys()) <= required_keys and \
                        all(isinstance(val, tuple) for val in field[2].values()):
                    return True
            elif isinstance(field[2], set):
                return len(field[2]) == 1 and \
                    all(isinstance(val, tuple) for val in field[2])

        return False


    def validate(self, msg):
        """
        Ensure that the supplied message contains the required information for
        this element object to operate.

        All elements that are Variable must reference valid Length elements.
        """
        for action in self.ref.values():
            for arg in action[1:]:
                if arg in ElementCallable.accepted_mesages:
                    continue
                elif isinstance(arg, str):
                    pass
                elif hasattr(arg, 'decode'):
                    arg = arg.decode('utf-8')
                elif hasattr(arg, 'to_bytes'):
                    arg = arg.to_bytes((arg.bit_length() + 7) // 8, self._mode.to_byteorder()).decode('utf-8')

                if arg not in msg:
                    raise ValueError('Need all keys to be in the message, {0} was not found\nAction: {1} -> {2}'.format(arg, action, action[1:]))

    def update(self, mode=None, alignment=None):
        """change the mode of the struct format"""
        if mode:
            self._mode = mode

        if alignment:
            self._alignment = alignment

    def pack(self, msg):
        """Pack the provided values into the supplied buffer."""
        pack_values = self.call_func(msg, self._pack_func, self._pack_args)

        # Test if the object is iterable
        # If it isn't, then turn it into a list
        try:
            _ = (p for p in pack_values)
        except TypeError:
            pack_values = [pack_values]

        # Unpack the items for struct to allow for mutli-value
        # items to be passed in.
        return self._struct.pack(*pack_values)


    def unpack(self, msg, buf):
        """Unpack data from the supplied buffer using the initialized format."""
        ret = self._struct.unpack_from(buf)
        if isinstance(ret, (list, tuple)) and len(ret) == 1:
            # We only change it not to a list if we expected one value.
            # Otherwise, we keep it as a list, because that's what we would
            # expect (like for a 16I type of struct
            ret = ret[0]

        # Only check for errors if they haven't told us not to
        if self._error_on_bad_result:
            # Pretend we're getting a dictionary to make our item,
            # but it has no reference to `self`. This is so we check
            # for errors correctly.
            temp_dict = copy.deepcopy(msg._asdict())
            temp_dict.pop(self.name)
            expected_value = self.call_func(msg, self._unpack_func, self._unpack_args)

            # Check for an error
            if expected_value != ret:
                raise ValueError('Expected value was: {0}, but got: {1}'.format(
                    expected_value,
                    ret,
                ))

        if self.name in self._unpack_args:
            msg = msg._replace(**{self.name: ret})


        ret = self.call_func(msg, self._unpack_func, self._unpack_args, original=ret)

        return (ret, buf[self._struct.size:])

    def make(self, msg):
        """Return the expected "made" value"""
        # If we aren't going to error on a bad result
        # and our name is in the message, just send the value
        # No need to do extra work.
        if not self._error_on_bad_result \
                and self.name in msg \
                and msg[self.name] is not None:
            return msg[self.name]

        ret = self.call_func(msg, self._make_func, self._make_args)

        if self.name in msg:
            if ret != msg[self.name]:
                raise ValueError('Excepted value: {0}, but got: {1}'.format(ret, msg[self.name]))

        return ret

    def call_func(self, msg, func, args, original=None):
        if func is None:
            return original

        items = self.prepare_args(msg, args)
        return func(*items)


    def prepare_args(self, msg, args):
        items = []

        if hasattr(msg, '_asdict'):
            msg = msg._asdict()

        for reference in args:
            if isinstance(reference, str):
                index = reference
                attr = 'make'
            elif isinstance(reference, bytes):
                index = reference.decode('utf-8')
                attr = 'pack'
            else:
                raise ValueError('Needed str or bytes for the reference')

            items.append(
                getattr(self._elements[index], attr)(msg)
            )

        return items


Pull Request — master (#42)

ElementCallable.validate() C

Complexity

Size

Duplication

Code Coverage

Importance

1. Missing Dependencies

2. Missing init.py files

1		"""
2		Element callable.
3
4		Call a function to validate data.
5
6		TODO: Update the format here
7
8		.. code-block:: python
9
10		from binascii import crc32
11
12		ExampleMessage = Message('VarTest', [('x', 'B'), ('y', 'B')])
13
14		CRCedMessage = Message('CRCedMessage', [
15		('data', ExampleMessage), # A data field that has the example message in it
16		('crc', 'I', crc32, ['data']), # Crc the data, and give an error if we have something unexpected
17		('crc', 'I', crc32, ['data'], False), # Crc the data, but don't give an error
18		])
19
20		Following creating this message, you have two options:
21
22		1. Specify a value. The function will be used to validate the value.
23
24		.. code-block:: python
25
26		def adder(x, y):
27		return x + y
28
29		AdderMessage = Message('AdderMessage', [
30		('item_a', 'H'),
31		('item_b', 'B'),
32		('function_data', 'I', adder, ['item_a', 'item_b']),
33		])
34
35		test_data = {
36		'item_a': 2,
37		'item_b': 5,
38		'function_data': 7,
39		}
40
41		made = AdderMessage.make(test_data)
42		assert made.item_a == 2
43		assert made.item_b == 5
44		assert made.function_data == 7
45
46		# If you specify the wrong value, you'll get a ValueError
47		test_data = {
48		'item_a': 2,
49		'item_b': 5,
50		'function_data': 33,
51		}
52
53		try:
54		made = AdderMessage.make(test_data)
55		except ValueError:
56		print('Told you so')
57
58		# Unless you specify `False` in your original item, then
59		# nobody will care.
60
61		2. Use the function to generate a value.
62
63		.. code-block:: python
64
65		def adder(x, y):
66		return x + y
67
68		AdderMessage = Message('AdderMessage', [
69		('item_a', 'H'),
70		('item_b', 'B'),
71		('function_data', 'I', adder, ['item_a', 'item_b']),
72		])
73
74		test_data = {
75		'item_a': 2,
76		'item_b': 5,
77		}
78
79		made = AdderMessage.make(test_data)
80		assert made.item_a == 2
81		assert made.item_b == 5
82		assert made.function_data == 7
83
84	1	"""
85	1
86		import copy
87	1	import struct
88
89	1	from typing import Optional
		0 ignored issues – show Configuration introduced 2016-11-30 19:25 UTC by Report Bug Copy Issue Report The import `typing` could not be resolved. This can be caused by one of the following: 1. Missing Dependencies This error could indicate a configuration issue of Pylint. Make sure that your libraries are available by adding the necessary commands. # .scrutinizer.yml before_commands: - sudo pip install abc # Python2 - sudo pip3 install abc # Python3 Tip: We are currently not using virtualenv to run pylint, when installing your modules make sure to use the command for the correct version. 2. Missing __init__.py files This error could also result from missing `__init__.py` files in your module folders. Make sure that you place one file in each sub-folder. Loading history...
90	1
91		from starstruct.element import register, Element
92		from starstruct.modes import Mode
93	1
94	1
95		@register
		0 ignored issues – show best-practice introduced 2016-12-20 21:16 UTC by Report Bug Copy Issue Report Too many instance attributes (13/7) Loading history...
96		class ElementCallable(Element):
97		"""
98		Initialize a StarStruct element object.
99
100		:param field: The fields passed into the constructor of the element
101		:param mode: The mode in which to pack the bytes
102		:param alignment: Number of bytes to align to
103		"""
104	1	accepted_mesages = (True, False)
105
106		# pylint: disable=too-many-instance-attributes
107	1	def __init__(self, field: list, mode: Optional[Mode]=Mode.Native, alignment: Optional[int]=1):
108		# All of the type checks have already been performed by the class
109		# factory
110	1	self.name = field[0]
111	1
112	1	# Callable elements use the normal struct packing method
113		self.format = field[1]
114	1
115	1	if isinstance(field[2], dict):
116		self.ref = field[2]
117	1
118		default_list = [None, None]
119	1	self._make_func = self.ref.get('make', default_list)[0]
120		self._make_args = self.ref.get('make', default_list)[1:]
121	1
122		self._pack_func = self.ref.get('pack', default_list)[0]
123	1	self._pack_args = self.ref.get('pack', default_list)[1:]
124
125	1	self._unpack_func = self.ref.get('unpack', default_list)[0]
126		self._unpack_args = self.ref.get('unpack', default_list)[1:]
127	1	elif isinstance(field[2], set):
128		instruction = field[2].copy().pop()
129	1	self.ref = {'all': instruction}
130	1
131		self._make_func = self._pack_func = self._unpack_func = instruction[0]
132		self._make_args = self._pack_args = self._unpack_args = instruction[1:]
133
134		if len(field) == 4:
135		self._error_on_bad_result = field[3]
136	1	else:
137		self._error_on_bad_result = True
138
139		self._elements = []
140
141		self.update(mode, alignment)
142	1
143		@property
144		def _struct(self):
145		return struct.Struct(self._mode.value + self.format)
146
147		@staticmethod
148		def valid(field: tuple) -> bool:
149	1	"""
150		See :py:func:`starstruct.element.Element.valid`
151
152		:param field: The items to determine the structure of the element
153		"""
154	1	required_keys = {'pack', 'unpack', 'make'}
155
156	1	if len(field) >= 3 and isinstance(field[0], str) and isinstance(field[1], str):
157	1	if isinstance(field[2], dict):
158		if set(field[2].keys()) <= required_keys and \
159	1	all(isinstance(val, tuple) for val in field[2].values()):
160	1	return True
161		elif isinstance(field[2], set):
162	1	return len(field[2]) == 1 and \
163		all(isinstance(val, tuple) for val in field[2])
164	1
165		return False
166	1
167
168	1	def validate(self, msg):
169	1	"""
170		Ensure that the supplied message contains the required information for
171		this element object to operate.
172	1
173		All elements that are Variable must reference valid Length elements.
174		"""
175	1	for action in self.ref.values():
176		for arg in action[1:]:
177		if arg in ElementCallable.accepted_mesages:
178		continue
179	1	elif isinstance(arg, str):
180	1	pass
181	1	elif hasattr(arg, 'decode'):
182		arg = arg.decode('utf-8')
183		elif hasattr(arg, 'to_bytes'):
184	1	arg = arg.to_bytes((arg.bit_length() + 7) // 8, self._mode.to_byteorder()).decode('utf-8')
185	1
186		if arg not in msg:
187		raise ValueError('Need all keys to be in the message, {0} was not found\nAction: {1} -> {2}'.format(arg, action, action[1:]))
188
189		def update(self, mode=None, alignment=None):
190	1	"""change the mode of the struct format"""
191		if mode:
192	1	self._mode = mode
193
194		if alignment:
195		self._alignment = alignment
196
197	1	def pack(self, msg):
198		"""Pack the provided values into the supplied buffer."""
199		pack_values = self.call_func(msg, self._pack_func, self._pack_args)
200	1
201		# Test if the object is iterable
202	1	# If it isn't, then turn it into a list
203		try:
204	1	_ = (p for p in pack_values)
205	1	except TypeError:
206	1	pack_values = [pack_values]
207	1
208	1	# Unpack the items for struct to allow for mutli-value
209	1	# items to be passed in.
210	1	return self._struct.pack(*pack_values)
		0 ignored issues – show Coding Style introduced 2016-12-19 19:55 UTC by Report Bug Copy Issue Report Usage of `` or `` arguments should usually be done with care. Generally, there is nothing wrong with usage of `` or `**` arguments. For readability of the code base, we suggest to not over-use these language constructs though. For more information, we can recommend this blog post from Ned Batchelder including its comments which also touches this aspect. Loading history...
211
212		def unpack(self, msg, buf):
213		"""Unpack data from the supplied buffer using the initialized format."""
214	1	ret = self._struct.unpack_from(buf)
215		if isinstance(ret, (list, tuple)) and len(ret) == 1:
216		# We only change it not to a list if we expected one value.
217		# Otherwise, we keep it as a list, because that's what we would
218	1	# expect (like for a 16I type of struct
219		ret = ret[0]
220	1
221	1	# Only check for errors if they haven't told us not to
222	1	if self._error_on_bad_result:
223		# Pretend we're getting a dictionary to make our item,
224	1	# but it has no reference to `self`. This is so we check
225		# for errors correctly.
226		temp_dict = copy.deepcopy(msg._asdict())
227		temp_dict.pop(self.name)
228		expected_value = self.call_func(msg, self._unpack_func, self._unpack_args)
229
230		# Check for an error
231		if expected_value != ret:
232		raise ValueError('Expected value was: {0}, but got: {1}'.format(
233		expected_value,
234		ret,
235		))
236
237		if self.name in self._unpack_args:
238		msg = msg._replace(**{self.name: ret})
		0 ignored issues – show Coding Style introduced 2016-12-20 21:16 UTC by Report Bug Copy Issue Report Usage of `` or `` arguments should usually be done with care. Generally, there is nothing wrong with usage of `` or `**` arguments. For readability of the code base, we suggest to not over-use these language constructs though. For more information, we can recommend this blog post from Ned Batchelder including its comments which also touches this aspect. Loading history...
239
240		ret = self.call_func(msg, self._unpack_func, self._unpack_args, original=ret)
241
242		return (ret, buf[self._struct.size:])
243
244		def make(self, msg):
245		"""Return the expected "made" value"""
246		# If we aren't going to error on a bad result
247		# and our name is in the message, just send the value
248		# No need to do extra work.
249		if not self._error_on_bad_result \
250		and self.name in msg \
251		and msg[self.name] is not None:
252		return msg[self.name]
253
254		ret = self.call_func(msg, self._make_func, self._make_args)
255
256		if self.name in msg:
257		if ret != msg[self.name]:
258		raise ValueError('Excepted value: {0}, but got: {1}'.format(ret, msg[self.name]))
259
260		return ret
261
262		def call_func(self, msg, func, args, original=None):
263		if func is None:
264		return original
265
266		items = self.prepare_args(msg, args)
267		return func(*items)
		0 ignored issues – show Coding Style introduced 2016-12-20 18:46 UTC by Report Bug Copy Issue Report Usage of `` or `` arguments should usually be done with care. Generally, there is nothing wrong with usage of `` or `**` arguments. For readability of the code base, we suggest to not over-use these language constructs though. For more information, we can recommend this blog post from Ned Batchelder including its comments which also touches this aspect. Loading history...
268
269		def prepare_args(self, msg, args):
270		items = []
271
272		if hasattr(msg, '_asdict'):
273		msg = msg._asdict()
274
275		for reference in args:
276		if isinstance(reference, str):
277		index = reference
278		attr = 'make'
279		elif isinstance(reference, bytes):
280		index = reference.decode('utf-8')
281		attr = 'pack'
282		else:
283		raise ValueError('Needed str or bytes for the reference')
284
285		items.append(
286		getattr(self._elements[index], attr)(msg)
287		)
288
289		return items
290

sprout42 / StarStruct

Pull Request — master (#42)

ElementCallable.validate() C

Complexity

Size

Duplication

Code Coverage

Importance

1. Missing Dependencies

2. Missing __init__.py files

Duplication Side-by-Side

Filter issues like

2. Missing init.py files