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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/>. 

 

from abc import ABCMeta, abstractmethod 

 

from .mappingFactory import MappingFactory 

from .utils import getFullTypeName 

 

__all__ = ("Formatter", "FormatterFactory") 

 

 

class Formatter(metaclass=ABCMeta): 

"""Interface for reading and writing Datasets with a particular 

`StorageClass`. 

""" 

 

@classmethod 

def name(cls): 

"""Returns the fully qualified name of the formatter. 

""" 

return getFullTypeName(cls) 

 

@abstractmethod 

def read(self, fileDescriptor, component=None): 

"""Read a Dataset. 

 

Parameters 

---------- 

fileDescriptor : `FileDescriptor` 

Identifies the file to read, type to read it into and parameters 

to be used for reading. 

component : `str`, optional 

Component to read from the file. Only used if the `StorageClass` 

for reading differed from the `StorageClass` used to write the 

file. 

 

Returns 

------- 

inMemoryDataset : `InMemoryDataset` 

The requested Dataset. 

""" 

raise NotImplementedError("Type does not support reading") 

 

@abstractmethod 

def write(self, inMemoryDataset, fileDescriptor): 

"""Write a Dataset. 

 

Parameters 

---------- 

inMemoryDataset : `InMemoryDataset` 

The Dataset to store. 

fileDescriptor : `FileDescriptor` 

Identifies the file to write. 

 

Returns 

------- 

path : `str` 

The path to where the Dataset was stored. 

""" 

raise NotImplementedError("Type does not support writing") 

 

@abstractmethod 

def predictPath(self, location): 

"""Return the path that would be returned by write, without actually 

writing. 

 

location : `Location` 

The location to simulate writing to. 

""" 

raise NotImplementedError("Type does not support writing") 

 

 

class FormatterFactory: 

"""Factory for `Formatter` instances. 

""" 

 

def __init__(self): 

self._mappingFactory = MappingFactory(Formatter) 

 

def getFormatter(self, entity): 

"""Get a new formatter instance. 

 

Parameters 

---------- 

entity : `DatasetRef`, `DatasetType` or `StorageClass`, or `str` 

Entity to use to determine the formatter to return. 

`StorageClass` will be used as a last resort if `DatasetRef` 

or `DatasetType` instance is provided. 

""" 

if isinstance(entity, str): 

names = (entity,) 

else: 

names = entity._lookupNames() 

return self._mappingFactory.getFromRegistry(*names) 

 

def registerFormatter(self, type_, formatter): 

"""Register a `Formatter`. 

 

Parameters 

---------- 

type_ : `str` or `StorageClass` or `DatasetType` 

Type for which this formatter is to be used. 

formatter : `str` 

Identifies a `Formatter` subclass to use for reading and writing 

Datasets of this type. 

 

Raises 

------ 

ValueError 

If formatter does not name a valid formatter type. 

""" 

self._mappingFactory.placeInRegistry(type_, formatter)