Re: getting the query from an SXP expression

I followed your sugestion, but I had the same issue.  To make the issue
reproducible, I published the code in:

https://github.com/danielhz/test-OpAsQuery

Daniel


Andy Seaborne <andy@seaborne.org> writes:

> Works for me in a single file but it looks like missed initialization
> or in the wrong order and Java is complicated in the os static class
> initialization.
>
> Could you try with
>
> public static void main( String[] args ) {
>     JenaSystem.init();
> ....
>     }
>
> please
>
>     Andy
>
> On 05/12/2021 19:39, Daniel Hernandez wrote:
>> Hi Andy,
>> Andy Seaborne <andy@seaborne.org> writes:
>>> Jena tries to - it's quite pragmatic:
>>>
>>> https://github.com/apache/jena/blob/main/jena-arq/src/main/java/org/apache/jena/sparql/algebra/OpAsQuery.java
>>>
>>>      Andy
>> When I was reviewing the OpAsQuery implementaion in Jena, and I had
>> a
>> problem: It works with some S-expressions, but fails with others.  My
>> testing code includes the following files:
>> File 1:
>> package cl.degu.sparql;
>> import org.apache.jena.query.Query;
>> import org.apache.jena.sparql.algebra.OpAsQuery;
>> import org.apache.jena.sparql.algebra.Algebra;
>> public class SSEtoSPARQL {
>>      public static Query translate(String sse) {
>>          return OpAsQuery.asQuery(Algebra.parse(sse));
>>      }
>> }
>> FILE 2:
>> package cl.degu.sparql;
>> public class App
>> {
>>      public static void main( String[] args )
>>      {
>>          String sse;
>>          // First example
>>          sse = "(project ?s (bgp (triple ?s ?p ?c)))";
>>          System.out.println(SSEtoSPARQL.translate(sse));
>>          // Second example
>>          sse = "(project ?s (bgp (triple ?s <http://example.org> ?c)))";
>>          System.out.println(SSEtoSPARQL.translate(sse));
>>      }
>> }
>> The first example works, but the second example produces an
>> error. The
>> output of the main function is the following:
>> SELECT  ?s
>> WHERE
>>    { ?s  ?p  ?c }
>> Exception in thread "main" java.lang.ExceptionInInitializerError
>> 	at org.apache.jena.sparql.sse.lang.ParseHandlerPlain.emitIRI(ParseHandlerPlain.java:165)
>> 	at org.apache.jena.sparql.sse.lang.ParseHandlerResolver.emitIRI(ParseHandlerResolver.java:150)
>> 	at org.apache.jena.sparql.sse.lang.ParserSSEBase.emitIRI(ParserSSEBase.java:46)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.IRIref(SSE_ParserCore.java:277)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.RDFTerm(SSE_ParserCore.java:230)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.Term(SSE_ParserCore.java:217)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.TermOrList(SSE_ParserCore.java:62)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.BareList(SSE_ParserCore.java:194)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.List(SSE_ParserCore.java:108)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.TermOrList(SSE_ParserCore.java:80)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.BareList(SSE_ParserCore.java:194)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.List(SSE_ParserCore.java:108)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.TermOrList(SSE_ParserCore.java:80)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.BareList(SSE_ParserCore.java:194)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.List(SSE_ParserCore.java:108)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.TermOrList(SSE_ParserCore.java:80)
>> 	at org.apache.jena.sparql.sse.lang.parser.SSE_ParserCore.parse(SSE_ParserCore.java:34)
>> 	at org.apache.jena.sparql.sse.lang.SSE_Parser.parse$(SSE_Parser.java:47)
>> 	at org.apache.jena.sparql.sse.lang.SSE_Parser.parse(SSE_Parser.java:40)
>> 	at org.apache.jena.sparql.sse.SSE.parse(SSE.java:452)
>> 	at org.apache.jena.sparql.sse.SSE.parse(SSE.java:373)
>> 	at org.apache.jena.sparql.sse.SSE.parse(SSE.java:368)
>> 	at org.apache.jena.sparql.algebra.Algebra.parse(Algebra.java:107)
>> 	at cl.degu.sparql.SSEtoSPARQL.translate(SSEtoSPARQL.java:9)
>> 	at cl.degu.sparql.App.main(App.java:16)
>> Caused by: java.lang.NullPointerException
>> 	at org.apache.jena.query.ARQ.isTrueOrUndef(ARQ.java:654)
>> 	at org.apache.jena.riot.system.RiotLib.<clinit>(RiotLib.java:59)
>> 	... 25 more
>> I included Jena into the project with the following dependency:
>>      <dependency>
>>        <groupId>org.apache.jena</groupId>
>>        <artifactId>apache-jena-libs</artifactId>
>>        <version>4.2.0</version>
>>        <type>pom</type>
>>      </dependency>
>>
>> Daniel
>>

Received on Monday, 6 December 2021 06:23:05 UTC