Ejemplo n.º 1
0
def SipStrategy(query,
                sipCollection,
                factGraph,
                derivedPreds,
                bindings={},
                processedRules=None,
                network=None,
                debug=False,
                buildProof=False,
                memoizeMemory=None,
                proofLevel=1):
    """
    Accordingly, we define a sip-strategy for computing the answers to a query
    expressed using a set of Datalog rules, and a set of sips, one for each
    adornment of a rule head, as follows...

    Each evaluation uses memoization (via Python decorators) but also relies on well-formed
    rewrites for using semi-naive bottom up method over large SPARQL data.

    """
    memoizeMemory = memoizeMemory and memoizeMemory or {}
    queryLiteral = BuildUnitermFromTuple(query)
    processedRules = processedRules and processedRules or set()
    if bindings:
        # There are bindings.  Apply them to the terms in the query
        queryLiteral.ground(bindings)

    if debug:
        print("%sSolving" % ('\t' * proofLevel), queryLiteral, bindings)
    # Only consider ground triple pattern isomorphism with matching bindings
    goalRDFStatement = queryLiteral.toRDFTuple()

    if queryLiteral in memoizeMemory:
        if debug:
            print("%sReturning previously calculated results for " %
                  ('\t' * proofLevel), queryLiteral)
        for answers in memoizeMemory[queryLiteral]:
            yield answers
    elif AlphaNode(goalRDFStatement).alphaNetworkHash(
        True,
        skolemTerms=list(bindings.values())) in \
        [AlphaNode(r.toRDFTuple()).alphaNetworkHash(True,
                                                    skolemTerms=list(bindings.values()))
            for r in processedRules
         if AdornLiteral(goalRDFStatement).adornment ==
         r.adornment]:
        if debug:
            print("%s Goal already processed..." %
                  ('\t' * proofLevel))
    else:
        isGround = literalIsGround(queryLiteral)
        if buildProof:
            ns = NodeSet(goalRDFStatement,
                         network=network, identifier=BNode())
        else:
            ns = None
        # adornedProgram = factGraph.adornedProgram
        queryPred = GetOp(queryLiteral)
        if sipCollection is None:
            rules = []
        else:
            # For every rule head matching the query, we invoke the rule,
            # thus determining an adornment, and selecting a sip to follow
            rules = sipCollection.headToRule.get(queryPred, set())
            if None in sipCollection.headToRule:
                # If there are second order rules, we add them
                # since they are a 'wildcard'
                rules.update(sipCollection.headToRule[None])

        # maintained list of rules that haven't been processed before and
        # match the query
        validRules = []

        # each subquery contains values for the bound arguments that are passed
        # through the sip arcs entering the node corresponding to that literal. For
        # each subquery generated, there is a set of answers.
        answers = []

        # variableMapping = {}

        # Some TBox queries can be 'joined' together into SPARQL queries against
        # 'base' predicates via an RDF dataset
        # These atomic concept inclusion axioms can be evaluated together
        # using a disjunctive operator at the body of a horn clause
        # where each item is a query of the form uniPredicate(?X):
        # Or( uniPredicate1(?X1), uniPredicate2(?X), uniPredicate3(?X), ..)
        # In this way massive, conjunctive joins can be 'mediated'
        # between the stated facts and the top-down solver
        @parameterizedPredicate([i for i in derivedPreds])
        def IsAtomicInclusionAxiomRHS(rule, dPreds):
            """
            This is an atomic inclusion axiom with
            a variable (or bound) RHS:  uniPred(?ENTITY)
            """
            bodyList = list(iterCondition(rule.formula.body))
            body = first(bodyList)
            return GetOp(body) not in dPreds and \
                len(bodyList) == 1 and \
                body.op == RDF.type

        atomicInclusionAxioms = list(filter(
            IsAtomicInclusionAxiomRHS, rules))
        if atomicInclusionAxioms and len(atomicInclusionAxioms) > 1:
            if debug:
                print("\tCombining atomic inclusion axioms: ")
                pprint(atomicInclusionAxioms, sys.stderr)
            if buildProof:
                factStep = InferenceStep(ns, source='some RDF graph')
                ns.steps.append(factStep)

            axioms = [rule.formula.body
                      for rule in atomicInclusionAxioms]

            # attempt to exaustively apply any available substitutions
            # and determine if query if fully ground
            vars = [v for v in GetArgs(queryLiteral,
                                       secondOrder=True)
                    if isinstance(v, Variable)]
            openVars, axioms, _bindings = \
                normalizeBindingsAndQuery(vars,
                                          bindings,
                                          axioms)
            if openVars:
                # mappings = {}
                # See if we need to do any variable mappings from the query literals
                # to the literals in the applicable rules
                query, rt = EDBQuery(axioms,
                                     factGraph,
                                     openVars,
                                     _bindings).evaluate(debug,
                                                         symmAtomicInclusion=True)
                if buildProof:
                    # FIXME: subquery undefined
                    factStep.groundQuery = subquery
                for ans in rt:
                    if buildProof:
                        factStep.bindings.update(ans)
                    memoizeMemory.setdefault(queryLiteral, set()).add(
                        (prepMemiozedAns(ans), ns))
                    yield ans, ns
            else:
                # All the relevant derivations have been explored and the result
                # is a ground query we can directly execute against the facts
                if buildProof:
                    factStep.bindings.update(bindings)
                query, rt = EDBQuery(axioms,
                                     factGraph,
                                     _bindings).evaluate(debug,
                                                         symmAtomicInclusion=True)
                if buildProof:
                    # FIXME: subquery undefined
                    factStep.groundQuery = subquery
                memoizeMemory.setdefault(queryLiteral, set()).add(
                    (prepMemiozedAns(rt), ns))
                yield rt, ns
            rules = filter(
                lambda i: not IsAtomicInclusionAxiomRHS(i), rules)
        for rule in rules:
            # An exception is the special predicate ph; it is treated as a base
            # predicate and the tuples in it are those supplied for qb by
            # unification.
            headBindings = getBindingsFromLiteral(
                goalRDFStatement, rule.formula.head)
            # comboBindings = dict([(k, v) for k, v in itertools.chain(
            #                                           bindings.items(),
            #                                           headBindings.items())])
            varMap = rule.formula.head.getVarMapping(queryLiteral)
            if headBindings and\
                [term for term in rule.formula.head.getDistinguishedVariables(True)
                 if varMap.get(term, term) not in headBindings]:
                continue
            # subQueryAnswers = []
            # dontStop = True
            # projectedBindings = comboBindings.copy()
            if debug:
                print("%sProcessing rule" %
                      ('\t' * proofLevel), rule.formula)
                if debug and sipCollection:
                    print(
                        "Sideways Information Passing (sip) graph for %s: " % queryLiteral)
                    print(sipCollection.serialize(format='n3'))
                    for sip in SIPRepresentation(sipCollection):
                        print(sip)
            try:
                # Invoke the rule
                if buildProof:
                    step = InferenceStep(ns, rule.formula)
                else:
                    step = None
                for rt, step in\
                    invokeRule([headBindings],
                               iter(iterCondition(rule.formula.body)),
                               rule.sip,
                               (proofLevel + 1,
                                memoizeMemory,
                                sipCollection,
                                factGraph,
                                derivedPreds,
                                processedRules.union([
                                    AdornLiteral(query)])),
                               step=step,
                               debug=debug):
                    if rt:
                        if isinstance(rt, dict):
                            # We received a mapping and must rewrite it via
                            # correlation between the variables in the rule head
                            # and the variables in the original query (after applying
                            # bindings)
                            varMap = rule.formula.head.getVarMapping(
                                queryLiteral)
                            if varMap:
                                rt = MakeImmutableDict(
                                    refactorMapping(varMap, rt))
                            if buildProof:
                                step.bindings = rt
                        else:
                            if buildProof:
                                step.bindings = headBindings
                        validRules.append(rule)
                        if buildProof:
                            ns.steps.append(step)
                        if isGround:
                            yield True, ns
                        else:
                            memoizeMemory.setdefault(queryLiteral, set()).add(
                                (prepMemiozedAns(rt),
                                 ns))
                            yield rt, ns

            except RuleFailure:
                # Clean up failed antecedents
                if buildProof:
                    if ns in step.antecedents:
                        step.antecedents.remove(ns)
        if not validRules:
            # No rules matching, query factGraph for answers
            successful = False
            if buildProof:
                factStep = InferenceStep(ns, source='some RDF graph')
                ns.steps.append(factStep)
            if not isGround:
                subquery, rt = EDBQuery([queryLiteral],
                                        factGraph,
                                        [v for v in GetArgs(queryLiteral,
                                                            secondOrder=True)
                                         if isinstance(v, Variable)],

                                        bindings).evaluate(debug)
                if buildProof:
                    factStep.groundQuery = subquery
                for ans in rt:
                    successful = True
                    if buildProof:
                        factStep.bindings.update(ans)
                    memoizeMemory.setdefault(queryLiteral, set()).add(
                        (prepMemiozedAns(ans),
                         ns))
                    yield ans, ns
                if not successful and queryPred not in derivedPreds:
                    # Open query didn't return any results and the predicate
                    # is ostensibly marked as derived predicate, so we have
                    # failed
                    memoizeMemory.setdefault(
                        queryLiteral, set()).add((False, ns))
                    yield False, ns
            else:
                # All the relevant derivations have been explored and the result
                # is a ground query we can directly execute against the facts
                if buildProof:
                    factStep.bindings.update(bindings)

                subquery, rt = EDBQuery([queryLiteral],
                                        factGraph,
                                        bindings).evaluate(debug)
                if buildProof:
                    factStep.groundQuery = subquery
                memoizeMemory.setdefault(queryLiteral, set()).add(
                    (prepMemiozedAns(rt),
                     ns))
                yield rt, ns
Ejemplo n.º 2
0
def SipStrategy(query,
                sipCollection,
                factGraph,
                derivedPreds,
                bindings={},
                processedRules=None,
                network=None,
                debug=False,
                buildProof=False,
                memoizeMemory=None,
                proofLevel=1):
    """
    Accordingly, we define a sip-strategy for computing the answers to a query
    expressed using a set of Datalog rules, and a set of sips, one for each
    adornment of a rule head, as follows...

    Each evaluation uses memoization (via Python decorators) but also relies on well-formed
    rewrites for using semi-naive bottom up method over large SPARQL data.

    """
    memoizeMemory = memoizeMemory and memoizeMemory or {}
    queryLiteral = BuildUnitermFromTuple(query)
    processedRules = processedRules and processedRules or set()
    if bindings:
        #There are bindings.  Apply them to the terms in the query
        queryLiteral.ground(bindings)

    if debug:
        print("%sSolving" % ('\t' * proofLevel), queryLiteral, bindings)
    # Only consider ground triple pattern isomorphism with matching bindings
    goalRDFStatement = queryLiteral.toRDFTuple()

    if queryLiteral in memoizeMemory:
        if debug:
            print("%sReturning previously calculated results for " % \
                        ('\t' * proofLevel), queryLiteral)
        for answers in memoizeMemory[queryLiteral]:
            yield answers
    elif AlphaNode(goalRDFStatement).alphaNetworkHash(
                                      True,
                                      skolemTerms=list(bindings.values())) in \
        [AlphaNode(r.toRDFTuple()).alphaNetworkHash(True,
                                                    skolemTerms=list(bindings.values()))
            for r in processedRules
                if AdornLiteral(goalRDFStatement).adornment == \
                   r.adornment]:
        if debug:
            print("%s Goal already processed..." % \
                ('\t' * proofLevel))
    else:
        isGround = literalIsGround(queryLiteral)
        if buildProof:
            ns = NodeSet(goalRDFStatement, network=network, identifier=BNode())
        else:
            ns = None
        # adornedProgram = factGraph.adornedProgram
        queryPred = GetOp(queryLiteral)
        if sipCollection is None:
            rules = []
        else:
            #For every rule head matching the query, we invoke the rule,
            #thus determining an adornment, and selecting a sip to follow
            rules = sipCollection.headToRule.get(queryPred, set())
            if None in sipCollection.headToRule:
                #If there are second order rules, we add them
                #since they are a 'wildcard'
                rules.update(sipCollection.headToRule[None])

        #maintained list of rules that haven't been processed before and
        #match the query
        validRules = []

        #each subquery contains values for the bound arguments that are passed
        #through the sip arcs entering the node corresponding to that literal. For
        #each subquery generated, there is a set of answers.
        answers = []

        # variableMapping = {}

        #Some TBox queries can be 'joined' together into SPARQL queries against
        #'base' predicates via an RDF dataset
        #These atomic concept inclusion axioms can be evaluated together
        #using a disjunctive operator at the body of a horn clause
        #where each item is a query of the form uniPredicate(?X):
        #Or( uniPredicate1(?X1), uniPredicate2(?X), uniPredicate3(?X), ..)
        #In this way massive, conjunctive joins can be 'mediated'
        #between the stated facts and the top-down solver
        @parameterizedPredicate([i for i in derivedPreds])
        def IsAtomicInclusionAxiomRHS(rule, dPreds):
            """
            This is an atomic inclusion axiom with
            a variable (or bound) RHS:  uniPred(?ENTITY)
            """
            bodyList = list(iterCondition(rule.formula.body))
            body = first(bodyList)
            return GetOp(body) not in dPreds and \
                   len(bodyList) == 1 and \
                   body.op == RDF.type

        atomicInclusionAxioms = list(filter(IsAtomicInclusionAxiomRHS, rules))
        if atomicInclusionAxioms and len(atomicInclusionAxioms) > 1:
            if debug:
                print("\tCombining atomic inclusion axioms: ")
                pprint(atomicInclusionAxioms, sys.stderr)
            if buildProof:
                factStep = InferenceStep(ns, source='some RDF graph')
                ns.steps.append(factStep)

            axioms = [rule.formula.body for rule in atomicInclusionAxioms]

            #attempt to exaustively apply any available substitutions
            #and determine if query if fully ground
            vars = [
                v for v in GetArgs(queryLiteral, secondOrder=True)
                if isinstance(v, Variable)
            ]
            openVars, axioms, _bindings = \
                    normalizeBindingsAndQuery(vars,
                                              bindings,
                                              axioms)
            if openVars:
                # mappings = {}
                #See if we need to do any variable mappings from the query literals
                #to the literals in the applicable rules
                query, rt = EDBQuery(axioms, factGraph, openVars,
                                     _bindings).evaluate(
                                         debug, symmAtomicInclusion=True)
                if buildProof:
                    factStep.groundQuery = subquery
                for ans in rt:
                    if buildProof:
                        factStep.bindings.update(ans)
                    memoizeMemory.setdefault(queryLiteral, set()).add(
                        (prepMemiozedAns(ans), ns))
                    yield ans, ns
            else:
                #All the relevant derivations have been explored and the result
                #is a ground query we can directly execute against the facts
                if buildProof:
                    factStep.bindings.update(bindings)
                query, rt = EDBQuery(axioms, factGraph, _bindings).evaluate(
                    debug, symmAtomicInclusion=True)
                if buildProof:
                    factStep.groundQuery = subquery
                memoizeMemory.setdefault(queryLiteral, set()).add(
                    (prepMemiozedAns(rt), ns))
                yield rt, ns
            rules = filter(lambda i: not IsAtomicInclusionAxiomRHS(i), rules)
        for rule in rules:
            #An exception is the special predicate ph; it is treated as a base
            #predicate and the tuples in it are those supplied for qb by unification.
            headBindings = getBindingsFromLiteral(goalRDFStatement,
                                                  rule.formula.head)
            # comboBindings = dict([(k, v) for k, v in itertools.chain(
            #                                           bindings.items(),
            #                                           headBindings.items())])
            varMap = rule.formula.head.getVarMapping(queryLiteral)
            if headBindings and\
                [term for term in rule.formula.head.getDistinguishedVariables(True)
                        if varMap.get(term, term) not in headBindings]:
                continue
            # subQueryAnswers = []
            # dontStop = True
            # projectedBindings = comboBindings.copy()
            if debug:
                print("%sProcessing rule" % \
                            ('\t' * proofLevel), rule.formula)
                if debug and sipCollection:
                    print("Sideways Information Passing (sip) graph for %s: " %
                          queryLiteral)
                    print(sipCollection.serialize(format='n3'))
                    for sip in SIPRepresentation(sipCollection):
                        print(sip)
            try:
                # Invoke the rule
                if buildProof:
                    step = InferenceStep(ns, rule.formula)
                else:
                    step = None
                for rt, step in\
                  invokeRule([headBindings],
                              iter(iterCondition(rule.formula.body)),
                              rule.sip,
                              (proofLevel + 1,
                               memoizeMemory,
                               sipCollection,
                               factGraph,
                               derivedPreds,
                               processedRules.union([
                                 AdornLiteral(query)])),
                              step=step,
                              debug=debug):
                    if rt:
                        if isinstance(rt, dict):
                            #We received a mapping and must rewrite it via
                            #correlation between the variables in the rule head
                            #and the variables in the original query (after applying
                            #bindings)
                            varMap = rule.formula.head.getVarMapping(
                                queryLiteral)
                            if varMap:
                                rt = MakeImmutableDict(
                                    refactorMapping(varMap, rt))
                            if buildProof:
                                step.bindings = rt
                        else:
                            if buildProof:
                                step.bindings = headBindings
                        validRules.append(rule)
                        if buildProof:
                            ns.steps.append(step)
                        if isGround:
                            yield True, ns
                        else:
                            memoizeMemory.setdefault(queryLiteral, set()).add(
                                (prepMemiozedAns(rt), ns))
                            yield rt, ns

            except RuleFailure:
                # Clean up failed antecedents
                if buildProof:
                    if ns in step.antecedents:
                        step.antecedents.remove(ns)
        if not validRules:
            #No rules matching, query factGraph for answers
            successful = False
            if buildProof:
                factStep = InferenceStep(ns, source='some RDF graph')
                ns.steps.append(factStep)
            if not isGround:
                subquery, rt = EDBQuery([queryLiteral], factGraph, [
                    v for v in GetArgs(queryLiteral, secondOrder=True)
                    if isinstance(v, Variable)
                ], bindings).evaluate(debug)
                if buildProof:
                    factStep.groundQuery = subquery
                for ans in rt:
                    successful = True
                    if buildProof:
                        factStep.bindings.update(ans)
                    memoizeMemory.setdefault(queryLiteral, set()).add(
                        (prepMemiozedAns(ans), ns))
                    yield ans, ns
                if not successful and queryPred not in derivedPreds:
                    #Open query didn't return any results and the predicate
                    #is ostensibly marked as derived predicate, so we have failed
                    memoizeMemory.setdefault(queryLiteral, set()).add(
                        (False, ns))
                    yield False, ns
            else:
                #All the relevant derivations have been explored and the result
                #is a ground query we can directly execute against the facts
                if buildProof:
                    factStep.bindings.update(bindings)

                subquery, rt = EDBQuery([queryLiteral], factGraph,
                                        bindings).evaluate(debug)
                if buildProof:
                    factStep.groundQuery = subquery
                memoizeMemory.setdefault(queryLiteral, set()).add(
                    (prepMemiozedAns(rt), ns))
                yield rt, ns
Ejemplo n.º 3
0
def invokeRule(priorAnswers,
               bodyLiteralIterator,
               sip,
               otherargs,
               priorBooleanGoalSuccess=False,
               step=None,
               debug=False,
               buildProof=False):
    """
    Continue invokation of rule using (given) prior answers and list of
    remaining body literals (& rule sip).  If prior answers is a list,
    computation is split disjunctively

    [..] By combining the answers to all these subqueries, we generate
    answers for the original query involving the rule head

    Can also takes a PML step and updates it as it navigates the
    top-down proof tree (passing it on and updating it where necessary)

    """
    assert not buildProof or step is not None

    proofLevel, memoizeMemory, sipCollection, \
        factGraph, derivedPreds, processedRules = otherargs

    remainingBodyList = [i for i in bodyLiteralIterator]
    lazyGenerator = lazyGeneratorPeek(priorAnswers, 2)
    if lazyGenerator.successful:
        # There are multiple answers in this step, we need to call invokeRule
        # recursively for each answer, returning the first positive attempt
        success = False
        rt = None
        _step = None
        ansNo = 0
        for priorAns in lazyGenerator:
            ansNo += 1
            try:
                if buildProof:
                    newStep = InferenceStep(step.parent,
                                            step.rule,
                                            source=step.source)
                    newStep.antecedents = [ant for ant in step.antecedents]
                else:
                    newStep = None
                for rt, _step in\
                    invokeRule([priorAns],
                               iter([i for i in remainingBodyList]),
                               sip,
                               otherargs,
                               priorBooleanGoalSuccess,
                               newStep,
                               debug=debug,
                               buildProof=buildProof):
                    if rt:
                        yield rt, _step
            except RuleFailure:
                pass
        if not success:
            # None of prior answers were successful
            # indicate termination of rule processing
            raise RuleFailure(
                "Unable to solve either of %s against remainder of rule: %s" % (
                    ansNo, remainingBodyList))
            # yield False, _InferenceStep(step.parent, step.rule,
            # source=step.source)
    else:
        lazyGenerator = lazyGeneratorPeek(lazyGenerator)
        projectedBindings = lazyGenerator.successful and first(
            lazyGenerator) or {}

        # First we check if we can combine a large group of subsequent body literals
        # into a single query
        # if we have a template map then we use it to further
        # distinguish which builtins can be solved via
        # cumulative SPARQl query - else we solve
        # builtins one at a time
        def sparqlResolvable(literal):
            if isinstance(literal, Uniterm):
                return not literal.naf and GetOp(literal) not in derivedPreds
            else:
                return isinstance(literal, N3Builtin) and \
                    literal.uri in factGraph.templateMap

        def sparqlResolvableNoTemplates(literal):

            if isinstance(literal, Uniterm):
                return not literal.naf and GetOp(literal) not in derivedPreds
            else:
                return False

        conjGroundLiterals = list(
            itertools.takewhile(
                hasattr(factGraph, 'templateMap') and sparqlResolvable or
                sparqlResolvableNoTemplates,
                remainingBodyList))

        bodyLiteralIterator = iter(remainingBodyList)

        if len(conjGroundLiterals) > 1:
            # If there are literals to combine *and* a mapping from rule
            # builtins to SPARQL FILTER templates ..
            basePredicateVars = set(
                reduce(lambda x, y: x + y,
                       [list(GetVariables(arg, secondOrder=True)) for arg in conjGroundLiterals]))
            if projectedBindings:
                openVars = basePredicateVars.intersection(projectedBindings)
            else:
                # We don't have any given bindings, so we need to treat
                # the body as an open query
                openVars = basePredicateVars

            queryConj = EDBQuery([copy.deepcopy(lit) for lit in conjGroundLiterals],
                                 factGraph,
                                 openVars,
                                 projectedBindings)

            query, answers = queryConj.evaluate(debug)

            if isinstance(answers, bool):
                combinedAnswers = {}
                rtCheck = answers
            else:
                if projectedBindings:
                    combinedAnswers = (mergeMappings1To2(ans,
                                                         projectedBindings,
                                                         makeImmutable=True) for ans in answers)
                else:
                    combinedAnswers = (MakeImmutableDict(ans)
                                       for ans in answers)
                combinedAnsLazyGenerator = lazyGeneratorPeek(combinedAnswers)
                rtCheck = combinedAnsLazyGenerator.successful

            if not rtCheck:
                raise RuleFailure(
                    "No answers for combined SPARQL query: %s" % query)
            else:
                # We have solved the previous N body literals with a single
                # conjunctive query, now we need to make each of the literals
                # an antecedent to a 'query' step.
                if buildProof:
                    queryStep = InferenceStep(None, source='some RDF graph')
                    # FIXME: subquery undefined
                    queryStep.groundQuery = subquery
                    queryStep.bindings = {}  # combinedAnswers[-1]
                    # FIXME: subquery undefined
                    queryHash = URIRef(
                        "tag:[email protected]:Queries#" +
                        makeMD5Digest(subquery))
                    queryStep.identifier = queryHash
                    for subGoal in conjGroundLiterals:
                        subNs = NodeSet(subGoal.toRDFTuple(),
                                        identifier=BNode())
                        subNs.steps.append(queryStep)
                        step.antecedents.append(subNs)
                        queryStep.parent = subNs
                for rt, _step in invokeRule(
                        isinstance(answers, bool) and [
                            projectedBindings] or combinedAnsLazyGenerator,
                        iter(remainingBodyList[len(conjGroundLiterals):]),
                        sip,
                        otherargs,
                        isinstance(answers, bool),
                        step,
                        debug=debug,
                        buildProof=buildProof):
                    yield rt, _step

        else:
            # Continue processing rule body condition
            # one literal at a time
            try:
                bodyLiteral = next(
                    bodyLiteralIterator) if py3compat.PY3 else bodyLiteralIterator.next()
                # if a N3 builtin, execute it using given bindings for boolean answer
                # builtins are moved to end of rule when evaluating rules via
                # sip
                if isinstance(bodyLiteral, N3Builtin):
                    lhs = bodyLiteral.argument
                    rhs = bodyLiteral.result
                    lhs = isinstance(
                        lhs, Variable) and projectedBindings[lhs] or lhs
                    rhs = isinstance(
                        rhs, Variable) and projectedBindings[rhs] or rhs
                    assert lhs is not None and rhs is not None
                    if bodyLiteral.func(lhs, rhs):
                        if debug:
                            print("Invoked %s(%s, %s) -> True" % (
                                bodyLiteral.uri, lhs, rhs))
                        # positive answer means we can continue processing the
                        # rule body
                        if buildProof:
                            ns = NodeSet(bodyLiteral.toRDFTuple(),
                                         identifier=BNode())
                            step.antecedents.append(ns)
                        for rt, _step in invokeRule(
                                [projectedBindings],
                                bodyLiteralIterator,
                                sip,
                                otherargs,
                                step,
                                priorBooleanGoalSuccess,
                                debug=debug,
                                buildProof=buildProof):
                            yield rt, _step
                    else:
                        if debug:
                            print("Successfully invoked %s(%s, %s) -> False" % (
                                bodyLiteral.uri, lhs, rhs))
                        raise RuleFailure("Failed builtin invokation %s(%s, %s)" %
                                          (bodyLiteral.uri, lhs, rhs))
                else:
                    # For every body literal, subqueries are generated according
                    # to the sip
                    sipArcPred = URIRef(GetOp(bodyLiteral) +
                                        '_' + '_'.join(GetArgs(bodyLiteral)))
                    assert len(list(IncomingSIPArcs(sip, sipArcPred))) < 2
                    subquery = copy.deepcopy(bodyLiteral)
                    subquery.ground(projectedBindings)

                    for N, x in IncomingSIPArcs(sip, sipArcPred):
                        # That is, each subquery contains values for the bound arguments
                        # that are passed through the sip arcs entering the node
                        # corresponding to that literal

                        # Create query out of body literal and apply
                        # sip-provided bindings
                        subquery = copy.deepcopy(bodyLiteral)
                        subquery.ground(projectedBindings)
                    if literalIsGround(subquery):
                        # subquery is ground, so there will only be boolean answers
                        # we return the conjunction of the answers for the current
                        # subquery

                        answer = False
                        ns = None

                        answers = first(
                            itertools.dropwhile(
                                lambda item: not item[0],
                                SipStrategy(
                                    subquery.toRDFTuple(),
                                    sipCollection,
                                    factGraph,
                                    derivedPreds,
                                    MakeImmutableDict(projectedBindings),
                                    processedRules,
                                    network=step is not None and
                                    step.parent.network or None,
                                    debug=debug,
                                    buildProof=buildProof,
                                    memoizeMemory=memoizeMemory,
                                    proofLevel=proofLevel)))
                        if answers:
                            answer, ns = answers
                        if not answer and not bodyLiteral.naf or \
                                (answer and bodyLiteral.naf):
                            # negative answer means the invokation of the rule fails
                            # either because we have a positive literal and there
                            # is no answer for the subgoal or the literal is
                            # negative and there is an answer for the subgoal
                            raise RuleFailure(
                                "No solutions solving ground query %s" % subquery)
                        else:
                            if buildProof:
                                if not answer and bodyLiteral.naf:
                                    ns.naf = True
                                step.antecedents.append(ns)
                            # positive answer means we can continue processing the rule body
                            # either because we have a positive literal and answers
                            # for subgoal or a negative literal and no answers for the
                            # the goal
                            for rt, _step in invokeRule(
                                    [projectedBindings],
                                    bodyLiteralIterator,
                                    sip,
                                    otherargs,
                                    True,
                                    step,
                                    debug=debug):
                                yield rt, _step
                    else:
                        _answers = \
                            SipStrategy(
                                subquery.toRDFTuple(),
                                sipCollection,
                                factGraph,
                                derivedPreds,
                                MakeImmutableDict(
                                    projectedBindings),
                                processedRules,
                                network=step is not None and
                                step.parent.network or None,
                                debug=debug,
                                buildProof=buildProof,
                                memoizeMemory=memoizeMemory,
                                proofLevel=proofLevel)

                        # solve (non-ground) subgoal
                        def collectAnswers(_ans):
                            for ans, ns in _ans:
                                if isinstance(ans, dict):
                                    try:
                                        map = mergeMappings1To2(
                                            ans, projectedBindings,
                                            makeImmutable=True)
                                        yield map
                                    except:
                                        pass
                        combinedAnswers = collectAnswers(_answers)
                        answers = lazyGeneratorPeek(combinedAnswers)
                        if not answers.successful \
                                and not bodyLiteral.naf \
                                or (bodyLiteral.naf and answers.successful):
                            raise RuleFailure(
                                "No solutions solving ground query %s" % subquery)
                        else:
                            # Either we have a positive subgoal and answers
                            # or a negative subgoal and no answers
                            if buildProof:
                                if answers.successful:
                                    goals = set([g for a, g in answers])
                                    assert len(goals) == 1
                                    step.antecedents.append(goals.pop())
                                else:
                                    newNs = NodeSet(
                                        bodyLiteral.toRDFTuple(),
                                        network=step.parent.network,
                                        identifier=BNode(),
                                        naf=True)
                                    step.antecedents.append(newNs)
                            for rt, _step in invokeRule(
                                    answers,
                                    bodyLiteralIterator,
                                    sip,
                                    otherargs,
                                    priorBooleanGoalSuccess,
                                    step,
                                    debug=debug,
                                    buildProof=buildProof):
                                yield rt, _step
            except StopIteration:
                # Finished processing rule
                if priorBooleanGoalSuccess:
                    yield projectedBindings and projectedBindings or True, step
                elif projectedBindings:
                    # Return the most recent (cumulative) answers and the given
                    # step
                    yield projectedBindings, step
                else:
                    raise RuleFailure(
                        "Finished processing rule unsuccessfully")
Ejemplo n.º 4
0
def invokeRule(priorAnswers,
               bodyLiteralIterator,
               sip,
               otherargs,
               priorBooleanGoalSuccess=False,
               step=None,
               debug=False,
               buildProof=False):
    """
    Continue invokation of rule using (given) prior answers and list of
    remaining body literals (& rule sip).  If prior answers is a list,
    computation is split disjunctively

    [..] By combining the answers to all these subqueries, we generate
    answers for the original query involving the rule head

    Can also takes a PML step and updates it as it navigates the
    top-down proof tree (passing it on and updating it where necessary)

    """
    assert not buildProof or step is not None

    proofLevel, memoizeMemory, sipCollection, \
        factGraph, derivedPreds, processedRules = otherargs

    remainingBodyList = [i for i in bodyLiteralIterator]
    lazyGenerator = lazyGeneratorPeek(priorAnswers, 2)
    if lazyGenerator.successful:
        # There are multiple answers in this step, we need to call invokeRule
        # recursively for each answer, returning the first positive attempt
        success = False
        rt = None
        _step = None
        ansNo = 0
        for priorAns in lazyGenerator:
            ansNo += 1
            try:
                if buildProof:
                    newStep = InferenceStep(step.parent,
                                            step.rule,
                                            source=step.source)
                    newStep.antecedents = [ant for ant in step.antecedents]
                else:
                    newStep = None
                for rt, _step in\
                   invokeRule([priorAns],
                              iter([i for i in remainingBodyList]),
                              sip,
                              otherargs,
                              priorBooleanGoalSuccess,
                              newStep,
                              debug=debug,
                              buildProof=buildProof):
                    if rt:
                        yield rt, _step
            except RuleFailure:
                pass
        if not success:
            # None of prior answers were successful
            # indicate termination of rule processing
            raise RuleFailure(
                "Unable to solve either of %s against remainder of rule: %s" %
                (ansNo, remainingBodyList))
            # yield False, _InferenceStep(step.parent, step.rule, source=step.source)
    else:
        lazyGenerator = lazyGeneratorPeek(lazyGenerator)
        projectedBindings = lazyGenerator.successful and first(
            lazyGenerator) or {}

        # First we check if we can combine a large group of subsequent body literals
        # into a single query
        # if we have a template map then we use it to further
        # distinguish which builtins can be solved via
        # cumulative SPARQl query - else we solve
        # builtins one at a time
        def sparqlResolvable(literal):
            if isinstance(literal, Uniterm):
                return not literal.naf and GetOp(literal) not in derivedPreds
            else:
                return isinstance(literal, N3Builtin) and \
                       literal.uri in factGraph.templateMap

        def sparqlResolvableNoTemplates(literal):

            if isinstance(literal, Uniterm):
                return not literal.naf and GetOp(literal) not in derivedPreds
            else:
                return False

        conjGroundLiterals = list(
                        itertools.takewhile(
                          hasattr(factGraph, 'templateMap') and sparqlResolvable or \
                          sparqlResolvableNoTemplates,
                          remainingBodyList))

        bodyLiteralIterator = iter(remainingBodyList)

        if len(conjGroundLiterals) > 1:
            # If there are literals to combine *and* a mapping from rule
            # builtins to SPARQL FILTER templates ..
            basePredicateVars = set(
                reduce(lambda x, y: x + y, [
                    list(GetVariables(arg, secondOrder=True))
                    for arg in conjGroundLiterals
                ]))
            if projectedBindings:
                openVars = basePredicateVars.intersection(projectedBindings)
            else:
                # We don't have any given bindings, so we need to treat
                # the body as an open query
                openVars = basePredicateVars

            queryConj = EDBQuery(
                [copy.deepcopy(lit) for lit in conjGroundLiterals], factGraph,
                openVars, projectedBindings)

            query, answers = queryConj.evaluate(debug)

            if isinstance(answers, bool):
                combinedAnswers = {}
                rtCheck = answers
            else:
                if projectedBindings:
                    combinedAnswers = (mergeMappings1To2(ans,
                                                         projectedBindings,
                                                         makeImmutable=True)
                                       for ans in answers)
                else:
                    combinedAnswers = (MakeImmutableDict(ans)
                                       for ans in answers)
                combinedAnsLazyGenerator = lazyGeneratorPeek(combinedAnswers)
                rtCheck = combinedAnsLazyGenerator.successful

            if not rtCheck:
                raise RuleFailure("No answers for combined SPARQL query: %s" %
                                  query)
            else:
                # We have solved the previous N body literals with a single
                # conjunctive query, now we need to make each of the literals
                # an antecedent to a 'query' step.
                if buildProof:
                    queryStep = InferenceStep(None, source='some RDF graph')
                    queryStep.groundQuery = subquery
                    queryStep.bindings = {}  # combinedAnswers[-1]
                    queryHash = URIRef(
                            "tag:[email protected]:Queries#" + \
                                                    makeMD5Digest(subquery))
                    queryStep.identifier = queryHash
                    for subGoal in conjGroundLiterals:
                        subNs = NodeSet(subGoal.toRDFTuple(),
                                        identifier=BNode())
                        subNs.steps.append(queryStep)
                        step.antecedents.append(subNs)
                        queryStep.parent = subNs
                for rt, _step in invokeRule(
                        isinstance(answers, bool) and [projectedBindings]
                        or combinedAnsLazyGenerator,
                        iter(remainingBodyList[len(conjGroundLiterals):]),
                        sip,
                        otherargs,
                        isinstance(answers, bool),
                        step,
                        debug=debug,
                        buildProof=buildProof):
                    yield rt, _step

        else:
            # Continue processing rule body condition
            # one literal at a time
            try:
                bodyLiteral = next(
                    bodyLiteralIterator
                ) if py3compat.PY3 else bodyLiteralIterator.next()
                # if a N3 builtin, execute it using given bindings for boolean answer
                # builtins are moved to end of rule when evaluating rules via sip
                if isinstance(bodyLiteral, N3Builtin):
                    lhs = bodyLiteral.argument
                    rhs = bodyLiteral.result
                    lhs = isinstance(
                        lhs, Variable) and projectedBindings[lhs] or lhs
                    rhs = isinstance(
                        rhs, Variable) and projectedBindings[rhs] or rhs
                    assert lhs is not None and rhs is not None
                    if bodyLiteral.func(lhs, rhs):
                        if debug:
                            print("Invoked %s(%s, %s) -> True" %
                                  (bodyLiteral.uri, lhs, rhs))
                        # positive answer means we can continue processing the rule body
                        if buildProof:
                            ns = NodeSet(bodyLiteral.toRDFTuple(),
                                         identifier=BNode())
                            step.antecedents.append(ns)
                        for rt, _step in invokeRule([projectedBindings],
                                                    bodyLiteralIterator,
                                                    sip,
                                                    otherargs,
                                                    step,
                                                    priorBooleanGoalSuccess,
                                                    debug=debug,
                                                    buildProof=buildProof):
                            yield rt, _step
                    else:
                        if debug:
                            print("Successfully invoked %s(%s, %s) -> False" %
                                  (bodyLiteral.uri, lhs, rhs))
                        raise RuleFailure(
                            "Failed builtin invokation %s(%s, %s)" %
                            (bodyLiteral.uri, lhs, rhs))
                else:
                    # For every body literal, subqueries are generated according
                    # to the sip
                    sipArcPred = URIRef(GetOp(bodyLiteral) + \
                                '_' + '_'.join(GetArgs(bodyLiteral)))
                    assert len(list(IncomingSIPArcs(sip, sipArcPred))) < 2
                    subquery = copy.deepcopy(bodyLiteral)
                    subquery.ground(projectedBindings)

                    for N, x in IncomingSIPArcs(sip, sipArcPred):
                        #That is, each subquery contains values for the bound arguments
                        #that are passed through the sip arcs entering the node
                        #corresponding to that literal

                        #Create query out of body literal and apply sip-provided bindings
                        subquery = copy.deepcopy(bodyLiteral)
                        subquery.ground(projectedBindings)
                    if literalIsGround(subquery):
                        #subquery is ground, so there will only be boolean answers
                        #we return the conjunction of the answers for the current
                        #subquery

                        answer = False
                        ns = None

                        answers = first(
                                    itertools.dropwhile(
                                            lambda item: not item[0],
                                            SipStrategy(
                                                    subquery.toRDFTuple(),
                                                    sipCollection,
                                                    factGraph,
                                                    derivedPreds,
                                                    MakeImmutableDict(projectedBindings),
                                                    processedRules,
                                                    network=step is not None and \
                                                            step.parent.network or None,
                                                    debug=debug,
                                                    buildProof=buildProof,
                                                    memoizeMemory=memoizeMemory,
                                                    proofLevel=proofLevel)))
                        if answers:
                            answer, ns = answers
                        if not answer and not bodyLiteral.naf or \
                            (answer and bodyLiteral.naf):
                            #negative answer means the invokation of the rule fails
                            #either because we have a positive literal and there
                            #is no answer for the subgoal or the literal is
                            #negative and there is an answer for the subgoal
                            raise RuleFailure(
                                "No solutions solving ground query %s" %
                                subquery)
                        else:
                            if buildProof:
                                if not answer and bodyLiteral.naf:
                                    ns.naf = True
                                step.antecedents.append(ns)
                            #positive answer means we can continue processing the rule body
                            #either because we have a positive literal and answers
                            #for subgoal or a negative literal and no answers for the
                            #the goal
                            for rt, _step in invokeRule([projectedBindings],
                                                        bodyLiteralIterator,
                                                        sip,
                                                        otherargs,
                                                        True,
                                                        step,
                                                        debug=debug):
                                yield rt, _step
                    else:
                        _answers = \
                                SipStrategy(subquery.toRDFTuple(),
                                            sipCollection,
                                            factGraph,
                                            derivedPreds,
                                            MakeImmutableDict(projectedBindings),
                                            processedRules,
                                            network=step is not None and \
                                                    step.parent.network or None,
                                            debug=debug,
                                            buildProof=buildProof,
                                            memoizeMemory=memoizeMemory,
                                            proofLevel=proofLevel)

                        # solve (non-ground) subgoal
                        def collectAnswers(_ans):
                            for ans, ns in _ans:
                                if isinstance(ans, dict):
                                    try:
                                        map = mergeMappings1To2(
                                            ans,
                                            projectedBindings,
                                            makeImmutable=True)
                                        yield map
                                    except:
                                        pass

                        combinedAnswers = collectAnswers(_answers)
                        answers = lazyGeneratorPeek(combinedAnswers)
                        if not answers.successful \
                            and not bodyLiteral.naf \
                            or (bodyLiteral.naf and answers.successful):
                            raise RuleFailure(
                                "No solutions solving ground query %s" %
                                subquery)
                        else:
                            # Either we have a positive subgoal and answers
                            # or a negative subgoal and no answers
                            if buildProof:
                                if answers.successful:
                                    goals = set([g for a, g in answers])
                                    assert len(goals) == 1
                                    step.antecedents.append(goals.pop())
                                else:
                                    newNs = NodeSet(
                                        bodyLiteral.toRDFTuple(),
                                        network=step.parent.network,
                                        identifier=BNode(),
                                        naf=True)
                                    step.antecedents.append(newNs)
                            for rt, _step in invokeRule(
                                    answers,
                                    bodyLiteralIterator,
                                    sip,
                                    otherargs,
                                    priorBooleanGoalSuccess,
                                    step,
                                    debug=debug,
                                    buildProof=buildProof):
                                yield rt, _step
            except StopIteration:
                #Finished processing rule
                if priorBooleanGoalSuccess:
                    yield projectedBindings and projectedBindings or True, step
                elif projectedBindings:
                    #Return the most recent (cumulative) answers and the given step
                    yield projectedBindings, step
                else:
                    raise RuleFailure(
                        "Finished processing rule unsuccessfully")