Joshua Taylor created JENA-489:
----------------------------------
Summary: error message for builtin with wrong number of args is
wrong
Key: JENA-489
URL: https://issues.apache.org/jira/browse/JENA-489
Project: Apache Jena
Issue Type: Bug
Components: Jena
Affects Versions: Jena 2.10.0
Reporter: Joshua Taylor
Priority: Trivial
Fix For: Jena 2.10.2
The message for a syntax error in the rule parser when a builtin is used in a
backwards rule with the wrong number of arguments is wrong. The message is
generated in emitBody(Functor functor) in RuleClauseCode by these lines:
{noformat}
throw new LPRuleSyntaxException("Wrong number of arguments to
functor " + functor.getName()
+ " expected " +
functor.getArgLength(), rule);
{noformat}
Instead of functor.getArgLength() should be builtin.getArgLength(). In context
these are:
{noformat}
void emitBody(Functor functor) {
Node[] fargs = functor.getArgs();
Builtin builtin = functor.getImplementor();
if (builtin == null) {
throw new LPRuleSyntaxException("Unknown builtin operation " +
functor.getName(), rule);
}
if (builtin.getArgLength() != 0 && builtin.getArgLength() !=
fargs.length) {
throw new LPRuleSyntaxException("Wrong number of arguments to
functor " + functor.getName()
+ " expected " +
functor.getArgLength(), rule);
}
for (int i = 0; i < fargs.length; i++) {
Node node = fargs[i];
// We optionally force an eager dereference of variables here.
// We used to force this but the current builtin implementations
// now robust against it (the do a deref themselves anyway).
emitBodyPut(node, i, true);
}
code[p++] = CALL_BUILTIN;
code[p++] = (byte)fargs.length;
args.add(builtin);
}
{noformat}
Code that demonstates the misleading message follows:
{noformat}
import com.hp.hpl.jena.rdf.model.InfModel;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.reasoner.rulesys.GenericRuleReasoner;
import com.hp.hpl.jena.reasoner.rulesys.Rule;
import com.hp.hpl.jena.reasoner.rulesys.builtins.Sum;
import com.hp.hpl.jena.vocabulary.RDF;
public class JenaBuiltinErrorMessageExample {
static String rules = "" +
"[(?x thriceValue ?vvv) <-\n" +
" (?x rdf:value ?v)\n" +
" sum(?v,?v,?v,?vvv)]\n" +
"";
Sum sum;
public static void main( String[] args ) {
GenericRuleReasoner reasoner = new GenericRuleReasoner(
Rule.parseRules( rules ));
Model base = ModelFactory.createDefaultModel();
base.createResource().addLiteral( RDF.value, 10 );
InfModel inf = ModelFactory.createInfModel( reasoner, base );
inf.write( System.out, "N3" );
}
}
{noformat}
This throws an exception with a misleading message:
{noformat}
Exception in thread "main"
com.hp.hpl.jena.reasoner.rulesys.impl.LPRuleSyntaxException: Syntax error in
backward rule: [ (?x thriceValue ?vvv) <- (?x rdf:value ?v) sum(?v ?v ?v ?vvv) ]
Wrong number of arguments to functor sum expected 4
at
com.hp.hpl.jena.reasoner.rulesys.impl.RuleClauseCode$CompileState.emitBody(RuleClauseCode.java:607)
at
com.hp.hpl.jena.reasoner.rulesys.impl.RuleClauseCode.compile(RuleClauseCode.java:213)
at
com.hp.hpl.jena.reasoner.rulesys.impl.LPRuleStore.compileAll(LPRuleStore.java:249)
at
com.hp.hpl.jena.reasoner.rulesys.impl.LPRuleStore.codeFor(LPRuleStore.java:99)
at
com.hp.hpl.jena.reasoner.rulesys.impl.LPRuleStore.codeFor(LPRuleStore.java:119)
at
com.hp.hpl.jena.reasoner.rulesys.impl.LPInterpreter.<init>(LPInterpreter.java:91)
at
com.hp.hpl.jena.reasoner.rulesys.impl.LPBRuleEngine.find(LPBRuleEngine.java:109)
at
com.hp.hpl.jena.reasoner.rulesys.FBRuleInfGraph.findWithContinuation(FBRuleInfGraph.java:575)
at
com.hp.hpl.jena.reasoner.rulesys.FBRuleInfGraph.graphBaseFind(FBRuleInfGraph.java:606)
at
com.hp.hpl.jena.reasoner.BaseInfGraph.graphBaseFind(BaseInfGraph.java:370)
at com.hp.hpl.jena.graph.impl.GraphBase.find(GraphBase.java:266)
at
com.hp.hpl.jena.graph.compose.DisjointUnion.graphBaseFind(DisjointUnion.java:39)
at com.hp.hpl.jena.graph.impl.GraphBase.find(GraphBase.java:266)
at
com.hp.hpl.jena.graph.impl.GraphBase.graphBaseFind(GraphBase.java:287)
at com.hp.hpl.jena.graph.impl.GraphBase.find(GraphBase.java:284)
at
com.hp.hpl.jena.rdf.model.impl.ModelCom.listStatements(ModelCom.java:449)
at
com.hp.hpl.jena.rdf.model.impl.ModelCom.listStatements(ModelCom.java:455)
at
com.hp.hpl.jena.n3.N3JenaWriterPP.prepareLists(N3JenaWriterPP.java:81)
at com.hp.hpl.jena.n3.N3JenaWriterPP.prepare(N3JenaWriterPP.java:67)
at
com.hp.hpl.jena.n3.N3JenaWriterCommon.processModel(N3JenaWriterCommon.java:275)
at
com.hp.hpl.jena.n3.N3JenaWriterCommon.write(N3JenaWriterCommon.java:197)
at
com.hp.hpl.jena.n3.N3JenaWriterCommon.write(N3JenaWriterCommon.java:209)
at com.hp.hpl.jena.n3.N3JenaWriter.write(N3JenaWriter.java:171)
at com.hp.hpl.jena.rdf.model.impl.ModelCom.write(ModelCom.java:327)
at
JenaBuiltinErrorMessageExample.main(JenaBuiltinErrorMessageExample.java:20)
{noformat}
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