Viewing file:  QuadSlot.py (2.88 KB) -rw-r--r--
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"""
Utility functions associated with RDF terms:
- normalizing (to 64 bit integers via half-md5-hashes)
- escaping literal's for SQL persistence
"""
from rdflib.BNode import BNode
from rdflib import RDF
from rdflib.Literal import Literal
from rdflib.URIRef import URIRef
import md5
from rdflib.term_utils import *
from rdflib.Graph import QuotedGraph
from rdflib.store.REGEXMatching import REGEXTerm
Any = None
SUBJECT = 0
PREDICATE = 1
OBJECT = 2
CONTEXT = 3
DATATYPE_INDEX = CONTEXT + 1
LANGUAGE_INDEX = CONTEXT + 2
SlotPrefixes = {
SUBJECT : 'subject',
PREDICATE : 'predicate',
OBJECT : 'object',
CONTEXT : 'context',
DATATYPE_INDEX : 'dataType',
LANGUAGE_INDEX : 'language'
}
POSITION_LIST = [SUBJECT,PREDICATE,OBJECT,CONTEXT]
def EscapeQuotes(qstr):
"""
Ported from Ft.Lib.DbUtil
"""
if qstr is None:
return ''
tmp = qstr.replace("\\","\\\\")
tmp = tmp.replace("'", "\\'")
return tmp
def dereferenceQuad(index,quad):
assert index <= LANGUAGE_INDEX, "Invalid Quad Index"
if index == DATATYPE_INDEX:
return isinstance(quad[OBJECT],Literal) and quad[OBJECT].datatype or None
elif index == LANGUAGE_INDEX:
return isinstance(quad[OBJECT],Literal) and quad[OBJECT].language or None
else:
return quad[index]
def genQuadSlots(quads):
return [QuadSlot(index,quads[index])for index in POSITION_LIST]
def normalizeValue(value,termType):
if value is None:
value = u'http://www.w3.org/2002/07/owl#NothingU'
else:
value = (isinstance(value,Graph) and value.identifier or str(value)) + termType
return int(md5.new(isinstance(value,unicode) and value.encode('utf-8') or value).hexdigest()[:16],16)
def normalizeNode(node):
return normalizeValue(node, term2Letter(node))
class QuadSlot:
def __repr__(self):
#NOTE: http://docs.python.org/ref/customization.html
return "QuadSlot(%s,%s,%s)"%(SlotPrefixes[self.position],self.term,self.md5Int)
def __init__(self,position,term):
assert position in POSITION_LIST, "Unknown quad position: %s"%position
self.position = position
self.term = term
self.md5Int = normalizeValue(term,term2Letter(term))
self.termType = term2Letter(term)
def EscapeQuotes(self,qstr):
"""
Ported from Ft.Lib.DbUtil
"""
if qstr is None:
return ''
tmp = qstr.replace("\\","\\\\")
tmp = tmp.replace("'", "\\'")
return tmp
def normalizeTerm(self):
if isinstance(self.term,(QuotedGraph,Graph)):
return self.term.identifier.encode('utf-8')
elif isinstance(self.term,Literal):
return self.EscapeQuotes(self.term).encode('utf-8')
elif self.term is None or isinstance(self.term,(list,REGEXTerm)):
return self.term
else:
return self.term.encode('utf-8')
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