yorm.wrapped() - Code Metrics - Inspection of "Sort JSON keys on dump" - jacebrowning/yorm - Measure and Improve Code Quality continuously with Scrutinizer

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Push — develop ( 43cfbd...dbd5e6 )

by Jace

created 2016-01-02 02:54 UTC

yorm.wrapped() A

↳ Parent: yorm.prevent_recursion()

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	7
CRAP Score	2

Metric	Value
cc	2
dl	0
loc	9
ccs	7
cts	7
cp	1
crap	2
rs	9.6667

"""Core YAML mapping functionality."""

import os
import abc
import functools

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."""
    try:
        mapper = getattr(obj, MAPPER)
    except AttributeError:
        if isinstance(obj, (dict, list)):
            return None
        else:
            msg = "mapped {!r} missing {!r} attribute".format(obj, MAPPER)
            raise AttributeError(msg) from None
    else:
        return mapper


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: %r", text)
        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: %r", text)
        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: {}".format(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
7	1	from . import common, exceptions, settings
8	1	from .bases import Container
9
10	1	MAPPER = '__mapper__'
11
12	1	log = common.logger(__name__)
13
14
15	1	def get_mapper(obj):
16		"""Get `Mapper` instance attached to an object."""
17	1	try:
18	1	mapper = getattr(obj, MAPPER)
19	1	except AttributeError:
20	1	if isinstance(obj, (dict, list)):
21	1	return None
22		else:
23	1	msg = "mapped {!r} missing {!r} attribute".format(obj, MAPPER)
24	1	raise AttributeError(msg) from None
25		else:
26	1	return mapper
27
28
29	1	def set_mapper(obj, path, attrs, auto=True, root=None):
30		"""Create and attach a `Mapper` instance to an object."""
31	1	mapper = Mapper(obj, path, attrs, auto=auto, root=root)
32	1	setattr(obj, MAPPER, mapper)
33	1	return mapper
34
35
36	1	def file_required(create=False):
37		"""Decorator for methods that require the file to exist.
38
39		:param create: boolean or the method to decorate
40
41		"""
42	1	def decorator(method):
43
44	1	@functools.wraps(method)
45		def wrapped(self, args, *kwargs): # pylint: disable=W0621
46	1	if not self.path:
47	1	return None
48	1	if not self.exists and self.auto:
49	1	if create is True and not self.deleted:
50	1	self.create()
51		else:
52	1	msg = "cannot access deleted: {}".format(self.path)
53	1	raise exceptions.FileDeletedError(msg)
54	1	return method(self, args, *kwargs)
55
56	1	return wrapped
57
58	1	if callable(create):
59	1	return decorator(create)
60		else:
61	1	return decorator
62
63
64	1	def prevent_recursion(method):
65		"""Decorator to prevent indirect recursive calls."""
66
67	1	@functools.wraps(method)
68		def wrapped(self, args, *kwargs):
69		# pylint: disable=W0212
70	1	if self._activity:
71	1	return
72	1	self._activity = True
73	1	result = method(self, args, *kwargs)
74	1	self._activity = False
75	1	return result
76
77	1	return wrapped
78
79
80	1	def prefix(obj):
81		"""Prefix a string with a fake designator if enabled."""
82	1	fake = "(fake) " if settings.fake else ""
83	1	name = obj if isinstance(obj, str) else "'{}'".format(obj)
84	1	return fake + name
85
86
87	1	class BaseHelper(metaclass=abc.ABCMeta):
88		"""Utility class to map attributes to text files.
89
90		To start mapping attributes to a file:
91
92		create -> [empty] -> FILE
93
94		When getting an attribute:
95
96		FILE -> read -> [text] -> load -> [dict] -> fetch -> ATTRIBUTES
97
98		When setting an attribute:
99
100		ATTRIBUTES -> store -> [dict] -> dump -> [text] -> write -> FILE
101
102		After the mapped file is no longer needed:
103
104		delete -> [null] -> FILE
105
106		"""
107
108	1	def __init__(self, path, auto=True):
109	1	self.path = path
110	1	self.auto = auto
111	1	self.auto_store = False
112	1	self.exists = self.path and os.path.isfile(self.path)
113	1	self.deleted = False
114	1	self._activity = False
115	1	self._timestamp = 0
116	1	self._fake = ""
117
118	1	def __str__(self):
119	1	return str(self.path)
120
121	1	@property
122		def text(self):
123		"""Get file contents."""
124	1	log.info("getting contents of %s...", prefix(self))
125	1	if settings.fake:
126	1	text = self._fake
127		else:
128	1	text = self._read()
129	1	log.trace("text read: %r", text)
130	1	return text
131
132	1	@text.setter
133		def text(self, text):
134		"""Set file contents."""
135	1	log.info("setting contents of %s...", prefix(self))
136	1	if settings.fake:
137	1	self._fake = text
138		else:
139	1	self._write(text)
140	1	log.trace("text wrote: %r", text)
141	1	self.modified = True
142
143	1	@property
144		def modified(self):
145		"""Determine if the file has been modified."""
146	1	if settings.fake:
147	1	changes = self._timestamp is not None
148	1	return changes
149	1	elif not self.exists:
150	1	return True
151		else:
152	1	was = self._timestamp
153	1	now = common.stamp(self.path)
154	1	return was != now
155
156	1	@modified.setter
157		def modified(self, changes):
158		"""Mark the file as modified if there are changes."""
159	1	if changes:
160	1	log.debug("marked %s as modified", prefix(self))
161	1	self._timestamp = 0
162		else:
163	1	if settings.fake or self.path is None:
164	1	self._timestamp = None
165		else:
166	1	self._timestamp = common.stamp(self.path)
167	1	log.debug("marked %s as unmodified", prefix(self))
168
169	1	@property
170		def ext(self):
171	1	if '.' in self.path:
172	1	return self.path.split('.')[-1]
173		else:
174	1	return 'yml'
175
176	1	def create(self, obj):
177		"""Create a new file for the object."""
178	1	log.info("creating %s for %r...", prefix(self), obj)
179	1	if self.exists:
180	1	log.warning("already created: %s", self)
181	1	return
182	1	if not settings.fake:
183	1	common.create_dirname(self.path)
184	1	common.touch(self.path)
185	1	self.exists = True
186	1	self.deleted = False
187
188	1	@file_required
189	1	@prevent_recursion
190		def fetch(self, obj, attrs):
191		"""Update the object's mapped attributes from its file."""
192	1	log.info("fetching %r from %s...", obj, prefix(self))
193
194		# Parse data from file
195	1	text = self._read()
196	1	data = self._load(text=text, path=self.path, ext=self.ext)
197	1	log.trace("loaded: {}".format(data))
198
199		# Update all attributes
200	1	attrs2 = attrs.copy()
201	1	for name, data in data.items():
202	1	attrs2.pop(name, None)
203
204		# Find a matching converter
205	1	try:
206	1	converter = attrs[name]
207	1	except KeyError:
208		# TODO: determine if runtime import is the best way to avoid
209		# cyclic import
210	1	from .converters import match
211	1	converter = match(name, data)
212	1	attrs[name] = converter
213
214		# Convert the loaded attribute
215	1	attr = getattr(obj, name, None)
216	1	if all((isinstance(attr, converter),
217		issubclass(converter, Container))):
218	1	attr.update_value(data)
219		else:
220	1	attr = converter.to_value(data)
221	1	setattr(obj, name, attr)
222	1	self._remap(attr)
223	1	log.trace("value fetched: %s = %r", name, attr)
224
225		# Add missing attributes
226	1	for name, converter in attrs2.items():
227	1	if not hasattr(obj, name):
228	1	value = converter.to_value(None)
229	1	msg = "fetched default value for missing attribute: %s = %r"
230	1	log.warning(msg, name, value)
231	1	setattr(obj, name, value)
232
233		# Set meta attributes
234	1	self.modified = False
235
236	1	@file_required(create=True)
237	1	@prevent_recursion
238		def store(self, obj, attrs):
239		"""Format and save the object's mapped attributes to its file."""
240	1	log.info("storing %r to %s...", obj, prefix(self))
241
242		# Format the data items
243	1	data = {}
244	1	for name, converter in attrs.items():
245	1	try:
246	1	value = getattr(obj, name)
247	1	except AttributeError:
248	1	value = None
249	1	msg = "storing default data for missing attribute '%s'..."
250	1	log.warning(msg, name)
251
252	1	data2 = converter.to_data(value)
253
254	1	log.trace("data to store: %s = %r", name, data2)
255	1	data[name] = data2
256
257		# Dump data to file
258	1	text = self._dump(data=data, ext=self.ext)
259	1	self._write(text)
260
261		# Set meta attributes
262	1	self.modified = True
263	1	self.auto_store = self.auto
264
265	1	def delete(self):
266		"""Delete the object's file from the file system."""
267	1	if self.exists:
268	1	log.info("deleting %s...", prefix(self))
269	1	if not settings.fake:
270	1	common.delete(self.path)
271		else:
272	1	log.warning("already deleted: %s", self)
273	1	self.exists = False
274	1	self.deleted = True
275
276	1	@file_required
277		def _read(self):
278		"""Read text from the object's file.
279
280		:param path: path to a text file
281
282		:return: contexts of text file
283
284		"""
285	1	if settings.fake:
286	1	return self._fake
287	1	elif not self.exists:
288	1	return ""
289		else:
290	1	return common.read_text(self.path)
291
292	1	@file_required
293		def _write(self, text):
294		"""Write text to the object's file.
295
296		:param text: text to write to a file
297		:param path: path to the file
298
299		"""
300	1	if settings.fake:
301	1	self._fake = text
302		else:
303	1	common.write_text(text, self.path)
304
305	1	@abc.abstractstaticmethod
306		def _load(text, path, ext): # pragma: no cover (abstract method)
307		"""Parsed data from text.
308
309		:param text: text read from a file
310		:param path: path to the file (for displaying errors)
311
312		:return: dictionary of parsed data
313
314		"""
315		raise NotImplementedError
316
317	1	@abc.abstractstaticmethod
318		def _dump(data, ext): # pragma: no cover (abstract method)
319		"""Dump data to text.
320
321		:param data: dictionary of data
322
323		:return: text to write to a file
324
325		"""
326		raise NotImplementedError
327
328	1	def _remap(self, obj):
329		"""Restore mapping on nested attributes."""
330	1	if isinstance(obj, Container):
331	1	set_mapper(obj, None, common.attrs[obj.__class__], root=self)
332	1	if isinstance(obj, dict):
333	1	for obj2 in obj.values():
334	1	self._remap(obj2)
335		else:
336	1	assert isinstance(obj, list)
337	1	for obj2 in obj:
338	1	self._remap(obj2)
339
340
341	1	class Helper(BaseHelper):
342		"""Utility class to map attributes to YAML files."""
343
344	1	@staticmethod
345		def _load(text, path, ext):
346		"""Load YAML data from text.
347
348		:param text: text read from a file
349		:param path: path to the file (for displaying errors)
350
351		:return: dictionary of YAML data
352
353		"""
354	1	return common.load_file(text, path, ext)
355
356	1	@staticmethod
357		def _dump(data, ext):
358		"""Dump YAML data to text.
359
360		:param data: dictionary of YAML data
361
362		:return: text to write to a file
363
364		"""
365	1	return common.dump_file(data, ext)
366
367
368	1	class Mapper(Helper):
369		"""Maps an object's attribute to YAML files."""
370
371	1	def __init__(self, obj, path, attrs, auto=True, root=None):
372	1	super().__init__(path, auto=auto)
373	1	self.obj = obj
374	1	self.attrs = attrs
375	1	self.root = root
376
377	1	def create(self): # pylint: disable=W0221
378	1	super().create(self.obj)
379
380	1	def fetch(self): # pylint: disable=W0221
381	1	if self.root and self.root.auto and not self._activity:
382	1	self._activity = True
383	1	self.root.fetch()
384	1	self._activity = False
385	1	super().fetch(self.obj, self.attrs)
386
387	1	def store(self): # pylint: disable=W0221
388	1	if self.root and self.root.auto and not self._activity:
389	1	self._activity = True
390	1	self.root.store()
391	1	self._activity = False
392		super().store(self.obj, self.attrs)
393

jacebrowning / yorm

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yorm.wrapped() A

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