276 lines
11 KiB
Python
276 lines
11 KiB
Python
import copy
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import logging
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import os
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import re
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##
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import requests
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from lxml import etree, objectify
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_logger = logging.getLogger('config:{0}'.format(__name__))
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class Config(object):
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def __init__(self, xsd_path = None, *args, **kwargs):
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self.xsd_path = None
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self.tree = None
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self.namespaced_tree = None
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self.xml = None
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self.namespaced_xml = None
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self.raw = None
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self.xsd = None
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self.defaultsParser = None
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self.obj = None
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_logger.info('Instantiated {0}.'.format(type(self).__name__))
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def main(self, validate = True, populate_defaults = True):
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self.fetch()
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self.parseRaw()
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if populate_defaults:
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self.populateDefaults()
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if validate:
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self.validate()
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self.pythonize()
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return(None)
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def fetch(self): # Just a fail-safe; this is overridden by specific subclasses.
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pass
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return(None)
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def getXSD(self, xsdpath = None):
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if not xsdpath:
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xsdpath = self.xsd_path
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raw_xsd = None
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base_url = None
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if xsdpath:
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_logger.debug('XSD path specified.')
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orig_xsdpath = xsdpath
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xsdpath = os.path.abspath(os.path.expanduser(xsdpath))
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_logger.debug('Transformed XSD path: {0} => {1}'.format(orig_xsdpath, xsdpath))
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if not os.path.isfile(xsdpath):
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_logger.error('The specified XSD path {0} does not exist on the local filesystem.'.format(xsdpath))
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raise ValueError('Specified XSD path does not exist')
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with open(xsdpath, 'rb') as fh:
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raw_xsd = fh.read()
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base_url = os.path.split(xsdpath)[0]
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else:
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_logger.debug('No XSD path specified; getting it from the configuration file.')
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xsi = self.xml.nsmap.get('xsi', 'http://www.w3.org/2001/XMLSchema-instance')
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_logger.debug('xsi: {0}'.format(xsi))
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schemaLocation = '{{{0}}}schemaLocation'.format(xsi)
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schemaURL = self.xml.attrib.get(schemaLocation,
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'https://schema.xml.r00t2.io/projects/aif.xsd')
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_logger.debug('Detected schema map: {0}'.format(schemaURL))
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split_url = schemaURL.split()
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if len(split_url) == 2: # a properly defined schemaLocation
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schemaURL = split_url[1]
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else:
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schemaURL = split_url[0] # a LAZY schemaLocation
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_logger.info('Detected schema location: {0}'.format(schemaURL))
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if schemaURL.startswith('file://'):
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schemaURL = re.sub(r'^file://', r'', schemaURL)
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_logger.debug('Fetching local file {0}'.format(schemaURL))
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with open(schemaURL, 'rb') as fh:
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raw_xsd = fh.read()
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base_url = os.path.dirname(schemaURL)
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else:
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_logger.debug('Fetching remote file: {0}'.format(schemaURL))
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req = requests.get(schemaURL)
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if not req.ok:
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_logger.error('Unable to fetch XSD.')
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raise RuntimeError('Could not download XSD')
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raw_xsd = req.content
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base_url = os.path.split(req.url)[0] # This makes me feel dirty.
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_logger.debug('Loaded XSD at {0} ({1} bytes).'.format(xsdpath, len(raw_xsd)))
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_logger.debug('Parsed XML base URL: {0}'.format(base_url))
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self.xsd = etree.XMLSchema(etree.XML(raw_xsd, base_url = base_url))
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_logger.info('Rendered XSD.')
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return(None)
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def parseRaw(self, parser = None):
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self.xml = etree.fromstring(self.raw, parser = parser)
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_logger.debug('Generated xml.')
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self.namespaced_xml = etree.fromstring(self.raw, parser = parser)
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_logger.debug('Generated namespaced xml.')
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self.tree = self.xml.getroottree()
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_logger.debug('Generated tree.')
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self.namespaced_tree = self.namespaced_xml.getroottree()
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_logger.debug('Generated namespaced tree.')
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self.tree.xinclude()
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_logger.debug('Parsed XInclude for tree.')
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self.namespaced_tree.xinclude()
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_logger.debug('Parsed XInclude for namespaced tree.')
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self.stripNS()
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return(None)
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def populateDefaults(self):
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_logger.info('Populating missing values with defaults from XSD.')
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if not self.xsd:
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self.getXSD()
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if not self.defaultsParser:
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self.defaultsParser = etree.XMLParser(schema = self.xsd, attribute_defaults = True)
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self.parseRaw(parser = self.defaultsParser)
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return(None)
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def pythonize(self, stripped = True, obj = 'tree'):
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# https://bugs.launchpad.net/lxml/+bug/1850221
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_logger.debug('Pythonizing to native objects')
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strobj = self.toString(stripped = stripped, obj = obj)
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self.obj = objectify.fromstring(strobj)
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objectify.annotate(self.obj)
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objectify.xsiannotate(self.obj)
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return(None)
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def removeDefaults(self):
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_logger.info('Removing default values from missing values.')
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self.parseRaw()
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return(None)
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def stripNS(self, obj = None):
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_logger.debug('Stripping namespace.')
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# https://stackoverflow.com/questions/30232031/how-can-i-strip-namespaces-out-of-an-lxml-tree/30233635#30233635
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xpathq = "descendant-or-self::*[namespace-uri()!='']"
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if not obj:
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_logger.debug('No XML object selected; using instance\'s xml and tree.')
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for x in (self.tree, self.xml):
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for e in x.xpath(xpathq):
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e.tag = etree.QName(e).localname
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elif isinstance(obj, (etree._Element, etree._ElementTree)):
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_logger.debug('XML object provided: {0}'.format(etree.tostring(obj, with_tail = False).decode('utf-8')))
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obj = copy.deepcopy(obj)
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for e in obj.xpath(xpathq):
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e.tag = etree.QName(e).localname
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return(obj)
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else:
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_logger.error('A non-XML object was provided.')
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raise ValueError('Did not know how to parse obj parameter')
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return(None)
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def toString(self, stripped = False, obj = None):
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if isinstance(obj, (etree._Element, etree._ElementTree)):
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_logger.debug('Converting an XML object to a string')
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if stripped:
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_logger.debug('Stripping before stringifying.')
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obj = self.stripNS(obj)
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elif obj in ('tree', None):
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if not stripped:
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_logger.debug('Converting the instance\'s namespaced tree to a string.')
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obj = self.namespaced_tree
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else:
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_logger.debug('Converting the instance\'s stripped tree to a string.')
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obj = self.tree
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elif obj == 'xml':
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if not stripped:
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_logger.debug('Converting instance\'s namespaced XML to a string')
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obj = self.namespaced_xml
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else:
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_logger.debug('Converting instance\'s stripped XML to a string')
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obj = self.xml
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else:
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_logger.error(('obj parameter must be "tree", "xml", or of type '
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'lxml.etree._Element or lxml.etree._ElementTree'))
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raise TypeError('Invalid obj type')
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obj = copy.deepcopy(obj)
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strxml = etree.tostring(obj,
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encoding = 'utf-8',
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xml_declaration = True,
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pretty_print = True,
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with_tail = True,
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inclusive_ns_prefixes = True)
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_logger.debug('Rendered string output successfully.')
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return(strxml)
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def validate(self):
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if not self.xsd:
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self.getXSD()
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_logger.debug('Checking validation against namespaced tree.')
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self.xsd.assertValid(self.namespaced_tree)
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return(None)
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class LocalFile(Config):
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def __init__(self, path, xsd_path = None, *args, **kwargs):
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super().__init__(xsd_path = xsd_path, *args, **kwargs)
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self.type = 'local'
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self.source = path
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def fetch(self):
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orig_src = self.source
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self.source = os.path.abspath(os.path.expanduser(self.source))
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_logger.debug('Canonized path: {0} => {1}'.format(orig_src, self.source))
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if not os.path.isfile(self.source):
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_logger.error('Config at {0} not found.'.format(self.source))
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raise ValueError('Config file does not exist'.format(self.source))
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with open(self.source, 'rb') as fh:
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self.raw = fh.read()
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_logger.debug('Fetched configuration ({0} bytes).'.format(len(self.raw)))
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return(None)
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class RemoteFile(Config):
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def __init__(self, uri, xsd_path = None, *args, **kwargs):
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super().__init__(*args, **kwargs)
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self.type = 'remote'
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self.source = uri
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def fetch(self):
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r = requests.get(self.source)
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if not r.ok():
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_logger.error('Could not fetch {0}'.format(self.source))
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raise RuntimeError('Could not download XML')
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self.raw = r.content
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_logger.debug('Fetched configuration ({0} bytes).'.format(len(self.raw)))
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return(None)
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class ConfigStr(Config):
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def __init__(self, rawxml, xsd_path = None, *args, **kwargs):
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super().__init__(*args, **kwargs)
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self.type = 'raw_str'
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self.source = rawxml
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def fetch(self):
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self.raw = self.source.encode('utf-8')
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_logger.debug('Raw configuration (str) passed in ({0} bytes); converted to bytes.'.format(len(self.raw)))
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return(None)
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class ConfigBin(Config):
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def __init__(self, rawbinaryxml, xsd_path = None, *args, **kwargs):
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super().__init__(*args, **kwargs)
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self.type = 'raw_bin'
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self.source = rawbinaryxml
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def fetch(self):
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self.raw = self.source
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_logger.debug('Raw configuration (binary) passed in ({0} bytes); converted to bytes.'.format(len(self.raw)))
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return(None)
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detector = {'raw': (re.compile(r'^\s*(?P<xml><(\?xml|aif)\s+.*)\s*$', re.DOTALL | re.MULTILINE), ConfigStr),
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'remote': (re.compile(r'^(?P<uri>(?P<scheme>(https?|ftps?)://)(?P<path>.*))\s*$'), RemoteFile),
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'local': (re.compile(r'^(file://)?(?P<path>(/?[^/]+)+/?)$'), LocalFile)}
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def getConfig(cfg_ref, validate = True, populate_defaults = True, xsd_path = None):
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cfgobj = None
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# This is kind of gross.
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for configtype, (pattern, configClass) in detector.items():
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try:
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if pattern.search(cfg_ref):
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cfgobj = configClass(cfg_ref, xsd_path = xsd_path)
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_logger.info('Config detected as {0}.'.format(configtype))
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break
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except TypeError:
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ptrn = re.compile(detector['raw'][0].pattern.encode('utf-8'))
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if not ptrn.search(cfg_ref):
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_logger.error('Could not detect which configuration type was passed.')
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raise ValueError('Unexpected/unparseable cfg_ref.')
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else:
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_logger.info('Config detected as ConfigBin.')
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cfgobj = ConfigBin(cfg_ref, xsd_path = xsd_path)
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break
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if cfgobj:
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_logger.info('Parsing configuration.')
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cfgobj.main(validate = validate, populate_defaults = populate_defaults)
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return(cfgobj)
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