yorm.get_mapper() - Code Metrics - Inspection of "Remove unused argument" - jacebrowning/yorm - Measure and Improve Code Quality continuously with Scrutinizer

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Push — develop ( 6ce2f8...c255a9 )

by Jace

created 2016-02-11 04:23 UTC

yorm.get_mapper() A

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Complexity

Conditions

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Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	2
CRAP Score	1

Metric	Value
cc	1
dl	0
loc	3
ccs	2
cts	2
cp	1
crap	1
rs	10

"""Core YAML mapping functionality."""

import os
import abc
import functools
from pprint import pformat

from . import common, exceptions, settings
from .bases import Container

MAPPER = '__mapper__'

log = common.logger(__name__)


def get_mapper(obj):
    """Get `Mapper` instance attached to an object."""
    return getattr(obj, MAPPER, None)


def set_mapper(obj, path, attrs, auto=True, root=None):
    """Create and attach a `Mapper` instance to an object."""
    mapper = Mapper(obj, path, attrs, auto=auto, root=root)
    setattr(obj, MAPPER, mapper)
    return mapper


def file_required(create=False):
    """Decorator for methods that require the file to exist.

    :param create: boolean or the method to decorate

    """
    def decorator(method):

        @functools.wraps(method)
        def wrapped(self, *args, **kwargs):  # pylint: disable=W0621
            if not self.path:
                return None
            if not self.exists and self.auto:
                if create is True and not self.deleted:
                    self.create()
                else:
                    msg = "cannot access deleted: {}".format(self.path)
                    raise exceptions.FileDeletedError(msg)
            return method(self, *args, **kwargs)

        return wrapped

    if callable(create):
        return decorator(create)
    else:
        return decorator


def prevent_recursion(method):
    """Decorator to prevent indirect recursive calls."""

    @functools.wraps(method)
    def wrapped(self, *args, **kwargs):
        # pylint: disable=W0212
        if self._activity:
            return
        self._activity = True
        result = method(self, *args, **kwargs)
        self._activity = False
        return result

    return wrapped


def prefix(obj):
    """Prefix a string with a fake designator if enabled."""
    fake = "(fake) " if settings.fake else ""
    name = obj if isinstance(obj, str) else "'{}'".format(obj)
    return fake + name


class BaseHelper(metaclass=abc.ABCMeta):
    """Utility class to map attributes to text files.

    To start mapping attributes to a file:

        create -> [empty] -> FILE

    When getting an attribute:

        FILE -> read -> [text] -> load -> [dict] -> fetch -> ATTRIBUTES

    When setting an attribute:

        ATTRIBUTES -> store -> [dict] -> dump -> [text] -> write -> FILE

    After the mapped file is no longer needed:

        delete -> [null] -> FILE

    """

    def __init__(self, path, auto=True):
        self.path = path
        self.auto = auto
        self.auto_store = False
        self.exists = self.path and os.path.isfile(self.path)
        self.deleted = False
        self._activity = False
        self._timestamp = 0
        self._fake = ""

    def __str__(self):
        return str(self.path)

    @property
    def text(self):
        """Get file contents."""
        log.info("Getting contents of %s...", prefix(self))
        if settings.fake:
            text = self._fake
        else:
            text = self._read()
        log.trace("Text read: \n%s", text[:-1])
        return text

    @text.setter
    def text(self, text):
        """Set file contents."""
        log.info("Setting contents of %s...", prefix(self))
        if settings.fake:
            self._fake = text
        else:
            self._write(text)
        log.trace("Text wrote: \n%s", text[:-1])
        self.modified = True

    @property
    def modified(self):
        """Determine if the file has been modified."""
        if settings.fake:
            changes = self._timestamp is not None
            return changes
        elif not self.exists:
            return True
        else:
            was = self._timestamp
            now = common.stamp(self.path)
            return was != now

    @modified.setter
    def modified(self, changes):
        """Mark the file as modified if there are changes."""
        if changes:
            log.debug("Marked %s as modified", prefix(self))
            self._timestamp = 0
        else:
            if settings.fake or self.path is None:
                self._timestamp = None
            else:
                self._timestamp = common.stamp(self.path)
            log.debug("Marked %s as unmodified", prefix(self))

    @property
    def ext(self):
        if '.' in self.path:
            return self.path.split('.')[-1]
        else:
            return 'yml'

    def create(self, obj):
        """Create a new file for the object."""
        log.info("Creating %s for %r...", prefix(self), obj)
        if self.exists:
            log.warning("Already created: %s", self)
            return
        if not settings.fake:
            common.create_dirname(self.path)
            common.touch(self.path)
        self.exists = True
        self.deleted = False

    @file_required
    @prevent_recursion
    def fetch(self, obj, attrs):
        """Update the object's mapped attributes from its file."""
        log.info("Fetching %r from %s...", obj, prefix(self))

        # Parse data from file
        text = self._read()
        data = self._load(text=text, path=self.path, ext=self.ext)
        log.trace("Loaded data: \n%s", pformat(data))

        # Update all attributes
        attrs2 = attrs.copy()
        for name, data in data.items():
            attrs2.pop(name, None)

            # Find a matching converter
            try:
                converter = attrs[name]
            except KeyError:
                # TODO: determine if runtime import is the best way to avoid
                # cyclic import
                from .converters import match
                converter = match(name, data)
                attrs[name] = converter

            # Convert the loaded attribute
            attr = getattr(obj, name, None)
            if all((isinstance(attr, converter),
                    issubclass(converter, Container))):
                attr.update_value(data)
            else:
                attr = converter.to_value(data)
                setattr(obj, name, attr)
            self._remap(attr)
            log.trace("Value fetched: %s = %r", name, attr)

        # Add missing attributes
        for name, converter in attrs2.items():
            if not hasattr(obj, name):
                value = converter.to_value(None)
                msg = "Fetched default value for missing attribute: %s = %r"
                log.warning(msg, name, value)
                setattr(obj, name, value)

        # Set meta attributes
        self.modified = False

    @file_required(create=True)
    @prevent_recursion
    def store(self, obj, attrs):
        """Format and save the object's mapped attributes to its file."""
        log.info("Storing %r to %s...", obj, prefix(self))

        # Format the data items
        data = {}
        for name, converter in attrs.items():
            try:
                value = getattr(obj, name)
            except AttributeError:
                value = None
                msg = "Storing default data for missing attribute '%s'..."
                log.warning(msg, name)

            data2 = converter.to_data(value)

            log.trace("Data to store: %s = %r", name, data2)
            data[name] = data2

        # Dump data to file
        text = self._dump(data=data, ext=self.ext)
        self._write(text)

        # Set meta attributes
        self.modified = True
        self.auto_store = self.auto

    def delete(self):
        """Delete the object's file from the file system."""
        if self.exists:
            log.info("Deleting %s...", prefix(self))
            if not settings.fake:
                common.delete(self.path)
        else:
            log.warning("Already deleted: %s", self)
        self.exists = False
        self.deleted = True

    @file_required
    def _read(self):
        """Read text from the object's file.

        :param path: path to a text file

        :return: contexts of text file

        """
        if settings.fake:
            return self._fake
        elif not self.exists:
            return ""
        else:
            return common.read_text(self.path)

    @file_required
    def _write(self, text):
        """Write text to the object's file.

        :param text: text to write to a file
        :param path: path to the file

        """
        if settings.fake:
            self._fake = text
        else:
            common.write_text(text, self.path)

    @abc.abstractstaticmethod
    def _load(text, path, ext):  # pragma: no cover (abstract method)
        """Parsed data from text.

        :param text: text read from a file
        :param path: path to the file (for displaying errors)

        :return: dictionary of parsed data

        """
        raise NotImplementedError

    @abc.abstractstaticmethod
    def _dump(data, ext):  # pragma: no cover (abstract method)
        """Dump data to text.

        :param data: dictionary of data

        :return: text to write to a file

        """
        raise NotImplementedError

    def _remap(self, obj):
        """Restore mapping on nested attributes."""
        if isinstance(obj, Container):
            set_mapper(obj, None, common.attrs[obj.__class__], root=self)
            if isinstance(obj, dict):
                for obj2 in obj.values():
                    self._remap(obj2)
            else:
                assert isinstance(obj, list)
                for obj2 in obj:
                    self._remap(obj2)


class Helper(BaseHelper):
    """Utility class to map attributes to YAML files."""

    @staticmethod
    def _load(text, path, ext):
        """Load YAML data from text.

        :param text: text read from a file
        :param path: path to the file (for displaying errors)

        :return: dictionary of YAML data

        """
        return common.load_file(text, path, ext)

    @staticmethod
    def _dump(data, ext):
        """Dump YAML data to text.

        :param data: dictionary of YAML data

        :return: text to write to a file

        """
        return common.dump_file(data, ext)


class Mapper(Helper):
    """Maps an object's attribute to YAML files."""

    def __init__(self, obj, path, attrs, auto=True, root=None):
        super().__init__(path, auto=auto)
        self.obj = obj
        self.attrs = attrs
        self.root = root

    def create(self):  # pylint: disable=W0221
        super().create(self.obj)

    def fetch(self):  # pylint: disable=W0221
        if self.root and self.root.auto and not self._activity:
            self._activity = True
            self.root.fetch()
            self._activity = False
        super().fetch(self.obj, self.attrs)

    def store(self):  # pylint: disable=W0221
        if self.root and self.root.auto and not self._activity:
            self._activity = True
            self.root.store()
            self._activity = False
        super().store(self.obj, self.attrs)


1		"""Core YAML mapping functionality."""
2
3	1	import os
4	1	import abc
5	1	import functools
6	1	from pprint import pformat
7
8	1	from . import common, exceptions, settings
9	1	from .bases import Container
10
11	1	MAPPER = '__mapper__'
12
13	1	log = common.logger(__name__)
14
15
16	1	def get_mapper(obj):
17		"""Get `Mapper` instance attached to an object."""
18	1	return getattr(obj, MAPPER, None)
19
20
21	1	def set_mapper(obj, path, attrs, auto=True, root=None):
22		"""Create and attach a `Mapper` instance to an object."""
23	1	mapper = Mapper(obj, path, attrs, auto=auto, root=root)
24	1	setattr(obj, MAPPER, mapper)
25	1	return mapper
26
27
28	1	def file_required(create=False):
29		"""Decorator for methods that require the file to exist.
30
31		:param create: boolean or the method to decorate
32
33		"""
34	1	def decorator(method):
35
36	1	@functools.wraps(method)
37		def wrapped(self, args, *kwargs): # pylint: disable=W0621
38	1	if not self.path:
39	1	return None
40	1	if not self.exists and self.auto:
41	1	if create is True and not self.deleted:
42	1	self.create()
43		else:
44	1	msg = "cannot access deleted: {}".format(self.path)
45	1	raise exceptions.FileDeletedError(msg)
46	1	return method(self, args, *kwargs)
47
48	1	return wrapped
49
50	1	if callable(create):
51	1	return decorator(create)
52		else:
53	1	return decorator
54
55
56	1	def prevent_recursion(method):
57		"""Decorator to prevent indirect recursive calls."""
58
59	1	@functools.wraps(method)
60		def wrapped(self, args, *kwargs):
61		# pylint: disable=W0212
62	1	if self._activity:
63	1	return
64	1	self._activity = True
65	1	result = method(self, args, *kwargs)
66	1	self._activity = False
67	1	return result
68
69	1	return wrapped
70
71
72	1	def prefix(obj):
73		"""Prefix a string with a fake designator if enabled."""
74	1	fake = "(fake) " if settings.fake else ""
75	1	name = obj if isinstance(obj, str) else "'{}'".format(obj)
76	1	return fake + name
77
78
79	1	class BaseHelper(metaclass=abc.ABCMeta):
80		"""Utility class to map attributes to text files.
81
82		To start mapping attributes to a file:
83
84		create -> [empty] -> FILE
85
86		When getting an attribute:
87
88		FILE -> read -> [text] -> load -> [dict] -> fetch -> ATTRIBUTES
89
90		When setting an attribute:
91
92		ATTRIBUTES -> store -> [dict] -> dump -> [text] -> write -> FILE
93
94		After the mapped file is no longer needed:
95
96		delete -> [null] -> FILE
97
98		"""
99
100	1	def __init__(self, path, auto=True):
101	1	self.path = path
102	1	self.auto = auto
103	1	self.auto_store = False
104	1	self.exists = self.path and os.path.isfile(self.path)
105	1	self.deleted = False
106	1	self._activity = False
107	1	self._timestamp = 0
108	1	self._fake = ""
109
110	1	def __str__(self):
111	1	return str(self.path)
112
113	1	@property
114		def text(self):
115		"""Get file contents."""
116	1	log.info("Getting contents of %s...", prefix(self))
117	1	if settings.fake:
118	1	text = self._fake
119		else:
120	1	text = self._read()
121	1	log.trace("Text read: \n%s", text[:-1])
122	1	return text
123
124	1	@text.setter
125		def text(self, text):
126		"""Set file contents."""
127	1	log.info("Setting contents of %s...", prefix(self))
128	1	if settings.fake:
129	1	self._fake = text
130		else:
131	1	self._write(text)
132	1	log.trace("Text wrote: \n%s", text[:-1])
133	1	self.modified = True
134
135	1	@property
136		def modified(self):
137		"""Determine if the file has been modified."""
138	1	if settings.fake:
139	1	changes = self._timestamp is not None
140	1	return changes
141	1	elif not self.exists:
142	1	return True
143		else:
144	1	was = self._timestamp
145	1	now = common.stamp(self.path)
146	1	return was != now
147
148	1	@modified.setter
149		def modified(self, changes):
150		"""Mark the file as modified if there are changes."""
151	1	if changes:
152	1	log.debug("Marked %s as modified", prefix(self))
153	1	self._timestamp = 0
154		else:
155	1	if settings.fake or self.path is None:
156	1	self._timestamp = None
157		else:
158	1	self._timestamp = common.stamp(self.path)
159	1	log.debug("Marked %s as unmodified", prefix(self))
160
161	1	@property
162		def ext(self):
163	1	if '.' in self.path:
164	1	return self.path.split('.')[-1]
165		else:
166	1	return 'yml'
167
168	1	def create(self, obj):
169		"""Create a new file for the object."""
170	1	log.info("Creating %s for %r...", prefix(self), obj)
171	1	if self.exists:
172	1	log.warning("Already created: %s", self)
173	1	return
174	1	if not settings.fake:
175	1	common.create_dirname(self.path)
176	1	common.touch(self.path)
177	1	self.exists = True
178	1	self.deleted = False
179
180	1	@file_required
181	1	@prevent_recursion
182		def fetch(self, obj, attrs):
183		"""Update the object's mapped attributes from its file."""
184	1	log.info("Fetching %r from %s...", obj, prefix(self))
185
186		# Parse data from file
187	1	text = self._read()
188	1	data = self._load(text=text, path=self.path, ext=self.ext)
189	1	log.trace("Loaded data: \n%s", pformat(data))
190
191		# Update all attributes
192	1	attrs2 = attrs.copy()
193	1	for name, data in data.items():
194	1	attrs2.pop(name, None)
195
196		# Find a matching converter
197	1	try:
198	1	converter = attrs[name]
199	1	except KeyError:
200		# TODO: determine if runtime import is the best way to avoid
201		# cyclic import
202	1	from .converters import match
203	1	converter = match(name, data)
204	1	attrs[name] = converter
205
206		# Convert the loaded attribute
207	1	attr = getattr(obj, name, None)
208	1	if all((isinstance(attr, converter),
209		issubclass(converter, Container))):
210	1	attr.update_value(data)
211		else:
212	1	attr = converter.to_value(data)
213	1	setattr(obj, name, attr)
214	1	self._remap(attr)
215	1	log.trace("Value fetched: %s = %r", name, attr)
216
217		# Add missing attributes
218	1	for name, converter in attrs2.items():
219	1	if not hasattr(obj, name):
220	1	value = converter.to_value(None)
221	1	msg = "Fetched default value for missing attribute: %s = %r"
222	1	log.warning(msg, name, value)
223	1	setattr(obj, name, value)
224
225		# Set meta attributes
226	1	self.modified = False
227
228	1	@file_required(create=True)
229	1	@prevent_recursion
230		def store(self, obj, attrs):
231		"""Format and save the object's mapped attributes to its file."""
232	1	log.info("Storing %r to %s...", obj, prefix(self))
233
234		# Format the data items
235	1	data = {}
236	1	for name, converter in attrs.items():
237	1	try:
238	1	value = getattr(obj, name)
239	1	except AttributeError:
240	1	value = None
241	1	msg = "Storing default data for missing attribute '%s'..."
242	1	log.warning(msg, name)
243
244	1	data2 = converter.to_data(value)
245
246	1	log.trace("Data to store: %s = %r", name, data2)
247	1	data[name] = data2
248
249		# Dump data to file
250	1	text = self._dump(data=data, ext=self.ext)
251	1	self._write(text)
252
253		# Set meta attributes
254	1	self.modified = True
255	1	self.auto_store = self.auto
256
257	1	def delete(self):
258		"""Delete the object's file from the file system."""
259	1	if self.exists:
260	1	log.info("Deleting %s...", prefix(self))
261	1	if not settings.fake:
262	1	common.delete(self.path)
263		else:
264	1	log.warning("Already deleted: %s", self)
265	1	self.exists = False
266	1	self.deleted = True
267
268	1	@file_required
269		def _read(self):
270		"""Read text from the object's file.
271
272		:param path: path to a text file
273
274		:return: contexts of text file
275
276		"""
277	1	if settings.fake:
278	1	return self._fake
279	1	elif not self.exists:
280	1	return ""
281		else:
282	1	return common.read_text(self.path)
283
284	1	@file_required
285		def _write(self, text):
286		"""Write text to the object's file.
287
288		:param text: text to write to a file
289		:param path: path to the file
290
291		"""
292	1	if settings.fake:
293	1	self._fake = text
294		else:
295	1	common.write_text(text, self.path)
296
297	1	@abc.abstractstaticmethod
298		def _load(text, path, ext): # pragma: no cover (abstract method)
299		"""Parsed data from text.
300
301		:param text: text read from a file
302		:param path: path to the file (for displaying errors)
303
304		:return: dictionary of parsed data
305
306		"""
307		raise NotImplementedError
308
309	1	@abc.abstractstaticmethod
310		def _dump(data, ext): # pragma: no cover (abstract method)
311		"""Dump data to text.
312
313		:param data: dictionary of data
314
315		:return: text to write to a file
316
317		"""
318		raise NotImplementedError
319
320	1	def _remap(self, obj):
321		"""Restore mapping on nested attributes."""
322	1	if isinstance(obj, Container):
323	1	set_mapper(obj, None, common.attrs[obj.__class__], root=self)
324	1	if isinstance(obj, dict):
325	1	for obj2 in obj.values():
326	1	self._remap(obj2)
327		else:
328	1	assert isinstance(obj, list)
329	1	for obj2 in obj:
330	1	self._remap(obj2)
331
332
333	1	class Helper(BaseHelper):
334		"""Utility class to map attributes to YAML files."""
335
336	1	@staticmethod
337		def _load(text, path, ext):
338		"""Load YAML data from text.
339
340		:param text: text read from a file
341		:param path: path to the file (for displaying errors)
342
343		:return: dictionary of YAML data
344
345		"""
346	1	return common.load_file(text, path, ext)
347
348	1	@staticmethod
349		def _dump(data, ext):
350		"""Dump YAML data to text.
351
352		:param data: dictionary of YAML data
353
354		:return: text to write to a file
355
356		"""
357	1	return common.dump_file(data, ext)
358
359
360	1	class Mapper(Helper):
361		"""Maps an object's attribute to YAML files."""
362
363	1	def __init__(self, obj, path, attrs, auto=True, root=None):
364	1	super().__init__(path, auto=auto)
365	1	self.obj = obj
366	1	self.attrs = attrs
367	1	self.root = root
368
369	1	def create(self): # pylint: disable=W0221
370	1	super().create(self.obj)
371
372	1	def fetch(self): # pylint: disable=W0221
373	1	if self.root and self.root.auto and not self._activity:
374	1	self._activity = True
375	1	self.root.fetch()
376	1	self._activity = False
377	1	super().fetch(self.obj, self.attrs)
378
379	1	def store(self): # pylint: disable=W0221
380	1	if self.root and self.root.auto and not self._activity:
381	1	self._activity = True
382	1	self.root.store()
383	1	self._activity = False
384		super().store(self.obj, self.attrs)
385

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