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# This file is part of daf_butler. 

# 

# Developed for the LSST Data Management System. 

# This product includes software developed by the LSST Project 

# (http://www.lsst.org). 

# See the COPYRIGHT file at the top-level directory of this distribution 

# for details of code ownership. 

# 

# This program is free software: you can redistribute it and/or modify 

# it under the terms of the GNU General Public License as published by 

# the Free Software Foundation, either version 3 of the License, or 

# (at your option) any later version. 

# 

# This program is distributed in the hope that it will be useful, 

# but WITHOUT ANY WARRANTY; without even the implied warranty of 

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

# GNU General Public License for more details. 

# 

# You should have received a copy of the GNU General Public License 

# along with this program. If not, see <http://www.gnu.org/licenses/>. 

 

"""Support for Storage Classes.""" 

 

import builtins 

import logging 

 

from .utils import doImport, Singleton, getFullTypeName 

from .assembler import CompositeAssembler 

from .config import ConfigSubset 

 

log = logging.getLogger(__name__) 

 

__all__ = ("StorageClass", "StorageClassFactory", "StorageClassConfig") 

 

 

class StorageClassConfig(ConfigSubset): 

component = "storageClasses" 

defaultConfigFile = "storageClasses.yaml" 

 

 

class StorageClass: 

"""Class describing how a label maps to a particular Python type. 

 

Parameters 

---------- 

name : `str` 

Name to use for this class. 

pytype : `type` 

Python type (or name of type) to associate with the `StorageClass` 

components : `dict`, optional 

`dict` mapping name of a component to another `StorageClass`. 

assembler : `str`, optional 

Fully qualified name of class supporting assembly and disassembly 

of a `pytype` instance. 

""" 

_cls_name = "BaseStorageClass" 

_cls_components = None 

_cls_assembler = None 

_cls_pytype = None 

defaultAssembler = CompositeAssembler 

defaultAssemblerName = getFullTypeName(defaultAssembler) 

 

def __init__(self, name=None, pytype=None, components=None, assembler=None): 

if name is None: 

name = self._cls_name 

if pytype is None: 

pytype = self._cls_pytype 

if components is None: 

components = self._cls_components 

if assembler is None: 

assembler = self._cls_assembler 

self.name = name 

self._pytypeName = pytype 

if pytype is None: 

self._pytypeName = "object" 

self._pytype = object 

self._components = components if components is not None else {} 

# if the assembler is not None also set it and clear the default 

# assembler 

if assembler is not None: 

self._assemblerClassName = assembler 

self._assembler = None 

elif components is not None: 

# We set a default assembler for composites so that a class is 

# guaranteed to support something if it is a composite. 

log.debug("Setting default assembler for %s", self.name) 

self._assembler = self.defaultAssembler 

self._assemblerClassName = self.defaultAssemblerName 

else: 

self._assembler = None 

self._assemblerClassName = None 

# The types are created on demand and cached 

self._pytype = None 

 

@property 

def components(self): 

"""Component names mapped to associated `StorageClass` 

""" 

return self._components 

 

@property 

def pytype(self): 

"""Python type associated with this `StorageClass`.""" 

if self._pytype is not None: 

return self._pytype 

# Handle case where we did get a python type not string 

if not isinstance(self._pytypeName, str): 

pytype = self._pytypeName 

self._pytypeName = self._pytypeName.__name__ 

elif hasattr(builtins, self._pytypeName): 

pytype = getattr(builtins, self._pytypeName) 

else: 

pytype = doImport(self._pytypeName) 

self._pytype = pytype 

return self._pytype 

 

@property 

def assemblerClass(self): 

"""Class to use to (dis)assemble an object from components.""" 

if self._assembler is not None: 

return self._assembler 

if self._assemblerClassName is None: 

return None 

self._assembler = doImport(self._assemblerClassName) 

return self._assembler 

 

def assembler(self): 

"""Return an instance of an assembler. 

 

Returns 

------- 

assembler : `CompositeAssembler` 

Instance of the assembler associated with this `StorageClass`. 

Assembler is constructed with this `StorageClass`. 

 

Raises 

------ 

TypeError 

This StorageClass has no associated assembler. 

""" 

cls = self.assemblerClass 

if cls is None: 

raise TypeError(f"No assembler class is associated with StorageClass {self.name}") 

return cls(storageClass=self) 

 

def isComposite(self): 

"""Boolean indicating whether this `StorageClass` is a composite 

or not. 

 

Returns 

------- 

isComposite : `bool` 

`True` if this `StorageClass` is a composite, `False` 

otherwise. 

""" 

if self.components: 

return True 

return False 

 

def _lookupNames(self): 

"""Names to use when looking up this DatasetRef in a configuration. 

 

The names are returned in order of priority. 

 

Returns 

------- 

names : `tuple` of `str` 

Tuple of solely the `StorageClass` name. 

""" 

return (self.name, ) 

 

def validateInstance(self, instance): 

"""Check that the supplied Python object has the expected Python type 

 

Parameters 

---------- 

instance : `object` 

Object to check. 

 

Returns 

------- 

isOk : `bool` 

True if the supplied instance object can be handled by this 

`StorageClass`, False otherwise. 

""" 

return isinstance(instance, self.pytype) 

 

def __eq__(self, other): 

"""Equality checks name, pytype name, assembler name, and components""" 

if self.name != other.name: 

return False 

 

193 ↛ 194line 193 didn't jump to line 194, because the condition on line 193 was never true if not isinstance(other, StorageClass): 

return False 

 

# We must compare pytype and assembler by name since we do not want 

# to trigger an import of external module code here 

if self._assemblerClassName != other._assemblerClassName: 

return False 

if self._pytypeName != other._pytypeName: 

return False 

 

# Ensure we have the same component keys in each 

if set(self.components.keys()) != set(other.components.keys()): 

return False 

 

# Ensure that all the components have the same type 

for k in self.components: 

if self.components[k] != other.components[k]: 

return False 

 

# If we got to this point everything checks out 

return True 

 

def __hash__(self): 

return hash(self.name) 

 

def __repr__(self): 

return "{}({}, pytype={}, assembler={}, components={})".format(type(self).__qualname__, 

self.name, 

self._pytypeName, 

self._assemblerClassName, 

list(self.components.keys())) 

 

 

class StorageClassFactory(metaclass=Singleton): 

"""Factory for `StorageClass` instances. 

 

This class is a singleton, with each instance sharing the pool of 

StorageClasses. Since code can not know whether it is the first 

time the instance has been created, the constructor takes no arguments. 

To populate the factory with storage classes, a call to 

`~StorageClassFactory.addFromConfig()` should be made. 

 

Parameters 

---------- 

config : `StorageClassConfig` or `str`, optional 

Load configuration. In a ButlerConfig` the relevant configuration 

is located in the ``storageClasses`` section. 

""" 

 

def __init__(self, config=None): 

self._storageClasses = {} 

self._configs = [] 

 

246 ↛ 247line 246 didn't jump to line 247, because the condition on line 246 was never true if config is not None: 

self.addFromConfig(config) 

 

def __contains__(self, storageClassOrName): 

"""Indicates whether the storage class exists in the factory. 

 

Parameters 

---------- 

storageClassOrName : `str` or `StorageClass` 

If `str` is given existence of the named StorageClass 

in the factory is checked. If `StorageClass` is given 

existence and equality are checked. 

 

Returns 

------- 

in : `bool` 

True if the supplied string is present, or if the supplied 

`StorageClass` is present and identical. 

 

Notes 

----- 

The two different checks (one for "key" and one for "value") based on 

the type of the given argument mean that it is possible for 

StorageClass.name to be in the factory but StorageClass to not be 

in the factory. 

""" 

if isinstance(storageClassOrName, str): 

return storageClassOrName in self._storageClasses 

elif isinstance(storageClassOrName, StorageClass): 

if storageClassOrName.name in self._storageClasses: 

return storageClassOrName == self._storageClasses[storageClassOrName.name] 

return False 

 

def addFromConfig(self, config): 

"""Add more `StorageClass` definitions from a config file. 

 

Parameters 

---------- 

config : `StorageClassConfig`, `Config` or `str` 

Storage class configuration. Can contain a ``storageClasses`` 

key if part of a global configuration. 

""" 

sconfig = StorageClassConfig(config) 

self._configs.append(sconfig) 

 

# Since we can not assume that we will get definitions of 

# components or parents before their classes are defined 

# we have a helper function that we can call recursively 

# to extract definitions from the configuration. 

def processStorageClass(name, sconfig): 

# Maybe we've already processed this through recursion 

297 ↛ 298line 297 didn't jump to line 298, because the condition on line 297 was never true if name not in sconfig: 

return 

info = sconfig.pop(name) 

 

# Always create the storage class so we can ensure that 

# we are not trying to overwrite with a different definition 

components = None 

if "components" in info: 

components = {} 

for cname, ctype in info["components"].items(): 

307 ↛ 308line 307 didn't jump to line 308, because the condition on line 307 was never true if ctype not in self: 

processStorageClass(ctype, sconfig) 

components[cname] = self.getStorageClass(ctype) 

 

# Extract scalar items from dict that are needed for StorageClass Constructor 

storageClassKwargs = {k: info[k] for k in ("pytype", "assembler") if k in info} 

 

# Fill in other items 

storageClassKwargs["components"] = components 

 

# Create the new storage class and register it 

baseClass = None 

if "inheritsFrom" in info: 

baseName = info["inheritsFrom"] 

321 ↛ 322line 321 didn't jump to line 322, because the condition on line 321 was never true if baseName not in self: 

processStorageClass(baseName, sconfig) 

baseClass = type(self.getStorageClass(baseName)) 

 

newStorageClassType = self.makeNewStorageClass(name, baseClass, **storageClassKwargs) 

newStorageClass = newStorageClassType() 

self.registerStorageClass(newStorageClass) 

 

for name in list(sconfig.keys()): 

processStorageClass(name, sconfig) 

 

@staticmethod 

def makeNewStorageClass(name, baseClass=StorageClass, **kwargs): 

"""Create a new Python class as a subclass of `StorageClass`. 

 

Parameters 

---------- 

name : `str` 

Name to use for this class. 

baseClass : `type`, optional 

Base class for this `StorageClass`. Must be either `StorageClass` 

or a subclass of `StorageClass`. If `None`, `StorageClass` will 

be used. 

 

Returns 

------- 

newtype : `type` subclass of `StorageClass` 

Newly created Python type. 

""" 

 

if baseClass is None: 

baseClass = StorageClass 

if not issubclass(baseClass, StorageClass): 

raise ValueError(f"Base class must be a StorageClass not {baseClass}") 

 

# convert the arguments to use different internal names 

clsargs = {f"_cls_{k}": v for k, v in kwargs.items() if v is not None} 

clsargs["_cls_name"] = name 

 

# Components are a special case because we want to be able to 

# combine components here with components in the parent 

# so the parent can define a component of class Image but the child 

# can override with ImageF. 

compKey = "_cls_components" 

if compKey in clsargs: 

components = getattr(baseClass, compKey, None) 

if components is not None: 

components = components.copy() 

# Merge with the supplied values 

components.update(clsargs[compKey]) 

clsargs[compKey] = components 

 

return type(f"StorageClass{name}", (baseClass,), clsargs) 

 

def getStorageClass(self, storageClassName): 

"""Get a StorageClass instance associated with the supplied name. 

 

Parameters 

---------- 

storageClassName : `str` 

Name of the storage class to retrieve. 

 

Returns 

------- 

instance : `StorageClass` 

Instance of the correct `StorageClass`. 

 

Raises 

------ 

KeyError 

The requested storage class name is not registered. 

""" 

return self._storageClasses[storageClassName] 

 

def registerStorageClass(self, storageClass): 

"""Store the `StorageClass` in the factory. 

 

Will be indexed by `StorageClass.name` and will return instances 

of the supplied `StorageClass`. 

 

Parameters 

---------- 

storageClass : `StorageClass` 

Type of the Python `StorageClass` to register. 

 

Raises 

------ 

ValueError 

If a storage class has already been registered with 

storageClassName and the previous definition differs. 

""" 

if storageClass.name in self._storageClasses: 

existing = self.getStorageClass(storageClass.name) 

if existing != storageClass: 

raise ValueError(f"New definition for StorageClass {storageClass.name} ({storageClass}) " 

f"differs from current definition ({existing})") 

else: 

self._storageClasses[storageClass.name] = storageClass 

 

def _unregisterStorageClass(self, storageClassName): 

"""Remove the named StorageClass from the factory. 

 

Parameters 

---------- 

storageClassName : `str` 

Name of storage class to remove. 

 

Raises 

------ 

KeyError 

The named storage class is not registered. 

 

Notes 

----- 

This method is intended to simplify testing of StorageClassFactory 

functionality and it is not expected to be required for normal usage. 

""" 

del self._storageClasses[storageClassName]