Coverage for python/lsst/daf/butler/core/storageClassDelegate.py: 18%
123 statements
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1# This file is part of daf_butler.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (http://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <http://www.gnu.org/licenses/>.
22"""Support for reading and writing composite objects."""
24from __future__ import annotations
26__all__ = ("DatasetComponent", "StorageClassDelegate")
28import collections.abc
29import copy
30import logging
31from dataclasses import dataclass
32from typing import TYPE_CHECKING, Any, Dict, Iterable, Mapping, Optional, Set, Tuple, Type
34from lsst.utils.introspection import get_full_type_name
36if TYPE_CHECKING:
37 from .storageClass import StorageClass
39log = logging.getLogger(__name__)
42@dataclass
43class DatasetComponent:
44 """Component of a dataset and associated information."""
46 name: str
47 """Name of the component.
48 """
50 storageClass: StorageClass
51 """StorageClass to be used when reading or writing this component.
52 """
54 component: Any
55 """Component extracted from the composite object.
56 """
59class StorageClassDelegate:
60 """Delegate class for StorageClass components and parameters.
62 This class delegates the handling of components and parameters for the
63 python type associated with a particular `StorageClass`.
65 A delegate is required for any storage class that defines components
66 (derived or otherwise) or support read parameters. It is used for
67 composite disassembly and assembly.
69 Attributes
70 ----------
71 storageClass : `StorageClass`
73 Parameters
74 ----------
75 storageClass : `StorageClass`
76 `StorageClass` to be used with this delegate.
77 """
79 def __init__(self, storageClass: StorageClass):
80 assert storageClass is not None
81 self.storageClass = storageClass
83 @staticmethod
84 def _attrNames(componentName: str, getter: bool = True) -> Tuple[str, ...]:
85 """Return list of suitable attribute names to attempt to use.
87 Parameters
88 ----------
89 componentName : `str`
90 Name of component/attribute to look for.
91 getter : `bool`
92 If true, return getters, else return setters.
94 Returns
95 -------
96 attrs : `tuple(str)`
97 Tuple of strings to attempt.
98 """
99 root = "get" if getter else "set"
101 # Capitalized name for getXxx must only capitalize first letter and not
102 # downcase the rest. getVisitInfo and not getVisitinfo
103 first = componentName[0].upper()
104 if len(componentName) > 1:
105 tail = componentName[1:]
106 else:
107 tail = ""
108 capitalized = f"{root}{first}{tail}"
109 return (componentName, f"{root}_{componentName}", capitalized)
111 def assemble(self, components: Dict[str, Any], pytype: Optional[Type] = None) -> Any:
112 """Construct an object from components based on storageClass.
114 This generic implementation assumes that instances of objects
115 can be created either by passing all the components to a constructor
116 or by calling setter methods with the name.
118 Parameters
119 ----------
120 components : `dict`
121 Collection of components from which to assemble a new composite
122 object. Keys correspond to composite names in the `StorageClass`.
123 pytype : `type`, optional
124 Override the type from the
125 :attr:`StorageClassDelegate.storageClass`
126 to use when assembling the final object.
128 Returns
129 -------
130 composite : `object`
131 New composite object assembled from components.
133 Raises
134 ------
135 ValueError
136 Some components could not be used to create the object or,
137 alternatively, some components were not defined in the associated
138 StorageClass.
139 """
140 if pytype is not None:
141 cls = pytype
142 else:
143 cls = self.storageClass.pytype
145 # Check that the storage class components are consistent
146 understood = set(self.storageClass.components)
147 requested = set(components.keys())
148 unknown = requested - understood
149 if unknown:
150 raise ValueError(f"Requested component(s) not known to StorageClass: {unknown}")
152 # First try to create an instance directly using keyword args
153 try:
154 obj = cls(**components)
155 except TypeError:
156 obj = None
158 # Now try to use setters if direct instantiation didn't work
159 if not obj:
160 obj = cls()
162 failed = []
163 for name, component in components.items():
164 if component is None:
165 continue
166 for attr in self._attrNames(name, getter=False):
167 if hasattr(obj, attr):
168 if attr == name: # Real attribute
169 setattr(obj, attr, component)
170 else:
171 setter = getattr(obj, attr)
172 setter(component)
173 break
174 else:
175 failed.append(name)
177 if failed:
178 raise ValueError(f"Unhandled components during assembly ({failed})")
180 return obj
182 def getValidComponents(self, composite: Any) -> Dict[str, Any]:
183 """Extract all non-None components from a composite.
185 Parameters
186 ----------
187 composite : `object`
188 Composite from which to extract components.
190 Returns
191 -------
192 comps : `dict`
193 Non-None components extracted from the composite, indexed by the
194 component name as derived from the
195 `StorageClassDelegate.storageClass`.
196 """
197 components = {}
198 if self.storageClass.isComposite():
199 for c in self.storageClass.components:
200 if isinstance(composite, collections.abc.Mapping):
201 comp = composite[c]
202 else:
203 try:
204 comp = self.getComponent(composite, c)
205 except AttributeError:
206 pass
207 else:
208 if comp is not None:
209 components[c] = comp
210 return components
212 def getComponent(self, composite: Any, componentName: str) -> Any:
213 """Attempt to retrieve component from composite object by heuristic.
215 Will attempt a direct attribute retrieval, or else getter methods of
216 the form "get_componentName" and "getComponentName".
218 Parameters
219 ----------
220 composite : `object`
221 Item to query for the component.
222 componentName : `str`
223 Name of component to retrieve.
225 Returns
226 -------
227 component : `object`
228 Component extracted from composite.
230 Raises
231 ------
232 AttributeError
233 The attribute could not be read from the composite.
234 """
235 component = None
237 if hasattr(composite, "__contains__") and componentName in composite:
238 component = composite[componentName]
239 return component
241 for attr in self._attrNames(componentName, getter=True):
242 if hasattr(composite, attr):
243 component = getattr(composite, attr)
244 if attr != componentName: # We have a method
245 component = component()
246 break
247 else:
248 raise AttributeError(f"Unable to get component {componentName}")
249 return component
251 def disassemble(
252 self, composite: Any, subset: Optional[Iterable] = None, override: Optional[Any] = None
253 ) -> Dict[str, DatasetComponent]:
254 """Disassembler a composite.
256 This is a generic implementation of a disassembler.
257 This implementation attempts to extract components from the parent
258 by looking for attributes of the same name or getter methods derived
259 from the component name.
261 Parameters
262 ----------
263 composite : `object`
264 Parent composite object consisting of components to be extracted.
265 subset : iterable, optional
266 Iterable containing subset of components to extract from composite.
267 Must be a subset of those defined in
268 `StorageClassDelegate.storageClass`.
269 override : `object`, optional
270 Object to use for disassembly instead of parent. This can be useful
271 when called from subclasses that have composites in a hierarchy.
273 Returns
274 -------
275 components : `dict`
276 `dict` with keys matching the components defined in
277 `StorageClassDelegate.storageClass`
278 and values being `DatasetComponent` instances describing the
279 component.
281 Raises
282 ------
283 ValueError
284 A requested component can not be found in the parent using generic
285 lookups.
286 TypeError
287 The parent object does not match the supplied
288 `StorageClassDelegate.storageClass`.
289 """
290 if not self.storageClass.isComposite():
291 raise TypeError(
292 f"Can not disassemble something that is not a composite (storage class={self.storageClass})"
293 )
295 if not self.storageClass.validateInstance(composite):
296 raise TypeError(
297 "Unexpected type mismatch between parent and StorageClass "
298 f"({type(composite)} != {self.storageClass.pytype})"
299 )
301 requested = set(self.storageClass.components)
303 if subset is not None:
304 subset = set(subset)
305 diff = subset - requested
306 if diff:
307 raise ValueError(f"Requested subset is not a subset of supported components: {diff}")
308 requested = subset
310 if override is not None:
311 composite = override
313 components = {}
314 for c in list(requested):
315 # Try three different ways to get a value associated with the
316 # component name.
317 try:
318 component = self.getComponent(composite, c)
319 except AttributeError:
320 # Defer complaining so we get an idea of how many problems
321 # we have
322 pass
323 else:
324 # If we found a match store it in the results dict and remove
325 # it from the list of components we are still looking for.
326 if component is not None:
327 components[c] = DatasetComponent(c, self.storageClass.components[c], component)
328 requested.remove(c)
330 if requested:
331 raise ValueError(f"Unhandled components during disassembly ({requested})")
333 return components
335 def handleParameters(self, inMemoryDataset: Any, parameters: Optional[Mapping[str, Any]] = None) -> Any:
336 """Modify the in-memory dataset using the supplied parameters.
338 Can return a possibly new object.
340 For safety, if any parameters are given to this method an
341 exception will be raised. This is to protect the user from
342 thinking that parameters have been applied when they have not been
343 applied.
345 Parameters
346 ----------
347 inMemoryDataset : `object`
348 Object to modify based on the parameters.
349 parameters : `dict`
350 Parameters to apply. Values are specific to the parameter.
351 Supported parameters are defined in the associated
352 `StorageClass`. If no relevant parameters are specified the
353 inMemoryDataset will be return unchanged.
355 Returns
356 -------
357 inMemoryDataset : `object`
358 Updated form of supplied in-memory dataset, after parameters
359 have been used.
361 Raises
362 ------
363 ValueError
364 Parameters have been provided to this default implementation.
365 """
366 if parameters:
367 raise ValueError(f"Parameters ({parameters}) provided to default implementation.")
369 return inMemoryDataset
371 @classmethod
372 def selectResponsibleComponent(cls, derivedComponent: str, fromComponents: Set[Optional[str]]) -> str:
373 """Select the best component for calculating a derived component.
375 Given a possible set of components to choose from, return the
376 component that should be used to calculate the requested derived
377 component.
379 Parameters
380 ----------
381 derivedComponent : `str`
382 The derived component that is being requested.
383 fromComponents : `set` of `str`
384 The available set of component options from which that derived
385 component can be computed. `None` can be included but should
386 be ignored.
388 Returns
389 -------
390 required : `str`
391 The component that should be used.
393 Raises
394 ------
395 NotImplementedError
396 Raised if this delegate refuses to answer the question.
397 ValueError
398 Raised if this delegate can not determine a relevant component
399 from the supplied options.
400 """
401 raise NotImplementedError("This delegate does not support derived components")
403 def copy(self, inMemoryDataset: Any) -> Any:
404 """Copy the supplied python type and return the copy.
406 Parameters
407 ----------
408 inMemoryDataset : `object`
409 Object to copy.
411 Returns
412 -------
413 copied : `object`
414 A copy of the supplied object. Can be the same object if the
415 object is known to be read-only.
417 Raises
418 ------
419 NotImplementedError
420 Raised if none of the default methods for copying work.
422 Notes
423 -----
424 The default implementation uses `copy.deepcopy()`.
425 It is generally expected that this method is the equivalent of a deep
426 copy. Subclasses can override this method if they already know the
427 optimal approach for deep copying.
428 """
430 try:
431 return copy.deepcopy(inMemoryDataset)
432 except Exception as e:
433 raise NotImplementedError(
434 f"Unable to deep copy the supplied python type ({get_full_type_name(inMemoryDataset)}) "
435 f"using default methods ({e})"
436 )