xquery:eval yields NullPointerException

On Thu, Mar 14, 2013 at 3:35 PM, Marco Lettere <marco.lettere at dedalus.eu> wrote: > Hi all, > on the way to writing a small DSL I stumbled upon the following BaseX 7.6 > issue. > I'm not able to explain to myself why the first two expressions of the > following xquery module return correctly whereas the last yields > NullPointerException (as shown in the appended stacktrace). > What I'm mtrying to do is to wrap up some modification code into > userfriendly function calls that can be used in mini xquery scripts to > formalize xml workflow. > Thank you for any help, > Marco. > > declare variable $globals := map { > 'change' := local:change#1, > 'generate' := local:gen#0 > }; > > declare function local:gen(){ > <b/> > }; > > declare function local:change($doc){ > copy $newdoc := $doc > modify( > insert node <a/> as last into $newdoc > ) > return $newdoc > }; > > ( > xquery:eval("copy $newdoc := <b/> > modify( > insert node <a/> as last into $newdoc > ) > return $newdoc",$globals), > > xquery:eval("$generate()", $globals), > xquery:eval("$change($doc)", map:new( ($globals, map { "doc" := <b/>}))) > ) > > The stacktrace and query plan: > > Error: > Improper use? Potential bug? Your feedback is welcome: > Contact: basex-talk at mailman.uni-konstanz.de > Version: BaseX 7.6 > Java: Oracle Corporation, 1.7.0_15 > OS: Linux, i386 > Stack Trace: > java.lang.NullPointerException > org.basex.query.up.expr.Transform.value(Transform.java:68) > org.basex.query.QueryContext.value(QueryContext.java:296) > org.basex.query.func.UserFunc.value(UserFunc.java:175) > org.basex.query.QueryContext.value(QueryContext.java:296) > org.basex.query.func.BaseFuncCall.value(BaseFuncCall.java:68) > org.basex.query.QueryContext.value(QueryContext.java:296) > org.basex.query.value.item.FuncItem.invValue(FuncItem.java:104) > org.basex.query.func.DynamicFunc.value(DynamicFunc.java:56) > org.basex.query.QueryContext.value(QueryContext.java:296) > org.basex.query.QueryContext.value(QueryContext.java:254) > org.basex.query.func.FNXQuery.eval(FNXQuery.java:95) > org.basex.query.func.FNXQuery.eval(FNXQuery.java:71) > org.basex.query.func.FNXQuery.iter(FNXQuery.java:37) > org.basex.query.QueryContext.iter(QueryContext.java:285) > org.basex.query.expr.List$1.next(List.java:100) > org.basex.query.QueryContext.execute(QueryContext.java:524) > org.basex.query.QueryProcessor.execute(QueryProcessor.java:96) > org.basex.core.cmd.AQuery.query(AQuery.java:77) > org.basex.core.cmd.XQuery.run(XQuery.java:22) > org.basex.core.Command.run(Command.java:342) > org.basex.core.Command.exec(Command.java:321) > org.basex.core.Command.execute(Command.java:78) > org.basex.gui.GUI.exec(GUI.java:397) > org.basex.gui.GUI$7.run(GUI.java:349) > Compiling: > - pre-evaluating map { "change":=function($1) as item()* { > local:change(($1)) }, "generate":=function() as item()* { local:gen(()) } } > Optimized Query: > declare function local:change($doc) { copy $newdoc as node() := $doc modify > insert node element a { () } into $newdoc return $newdoc }; > declare function local:gen() { element b { () } }; > (xquery:eval("copy $newdoc := $generate() > modify( > insert node <a/> as last into $newdoc > ) > return $newdoc", map{ "change":=function($1) as item()* { > local:change(($1)) }, "generate":=function() as item()* { local:gen(()) } > }), xquery:eval("$generate()", map{ "change":=function($1) as item()* { > local:change(($1)) }, "generate":=function() as item()* { local:gen(()) } > }), xquery:eval("$change($doc)", map:new((map{ "change":=function($1) as > item()* { local:change(($1)) }, "generate":=function() as item()* { > local:gen(()) } }, map { "doc":=element b { () } })))) > Query plan: > <QueryPlan> > <UserFuncs> > <UserFunc name="local:change" arg0="doc"> > <Transform> > <Let var="$newdoc as node()"> > <VarRef> > <Var name="$doc" id="2"/> > </VarRef> > </Let> > <Insert> > <VarRef> > <Var name="$newdoc as node()" id="3"/> > </VarRef> > <CElem> > <QNm value="a" type="xs:QName"/> > </CElem> > </Insert> > <VarRef> > <Var name="$newdoc as node()" id="3"/> > </VarRef> > </Transform> > </UserFunc> > <UserFunc name="local:gen"> > <CElem> > <QNm value="b" type="xs:QName"/> > </CElem> > </UserFunc> > </UserFuncs> > <VarStack> > <Var name="$globals" id="0"/> > </VarStack> > <List> > <FNXQuery name="eval(string[,bindings])"> > <Str value="copy $newdoc := $generate()&#x0A; modify(&#x0A; > insert node &lt;a/&gt; as last into $newdoc &#x0A; )&#x0A; > return $newdoc" type="xs:string"/> > <Map size="2"> > <Str value="change" type="xs:string"/> > <FuncItem type="function(item()*) as item()*"> > <Var name="$1" id="1"/> > <BaseFuncCall name="local:change(($1))"> > <VarRef> > <Var name="$1" id="1"/> > </VarRef> > </BaseFuncCall> > </FuncItem> > <Str value="generate" type="xs:string"/> > <FuncItem type="function() as item()*"> > <BaseFuncCall name="local:gen(())"/> > </FuncItem> > </Map> > </FNXQuery> > <FNXQuery name="eval(string[,bindings])"> > <Str value="$generate()" type="xs:string"/> > <Map size="2"> > <Str value="change" type="xs:string"/> > <FuncItem type="function(item()*) as item()*"> > <Var name="$1" id="1"/> > <BaseFuncCall name="local:change(($1))"> > <VarRef> > <Var name="$1" id="1"/> > </VarRef> > </BaseFuncCall> > </FuncItem> > <Str value="generate" type="xs:string"/> > <FuncItem type="function() as item()*"> > <BaseFuncCall name="local:gen(())"/> > </FuncItem> > </Map> > </FNXQuery> > <FNXQuery name="eval(string[,bindings])"> > <Str value="$change($doc)" type="xs:string"/> > <FNMap name="new([maps[,coll]])"> > <List> > <Map size="2"> > <Str value="change" type="xs:string"/> > <FuncItem type="function(item()*) as item()*"> > <Var name="$1" id="1"/> > <BaseFuncCall name="local:change(($1))"> > <VarRef> > <Var name="$1" id="1"/> > </VarRef> > </BaseFuncCall> > </FuncItem> > <Str value="generate" type="xs:string"/> > <FuncItem type="function() as item()*"> > <BaseFuncCall name="local:gen(())"/> > </FuncItem> > </Map> > <LitMap> > <Str value="doc" type="xs:string"/> > <CElem> > <QNm value="b" type="xs:QName"/> > </CElem> > </LitMap> > </List> > </FNMap> > </FNXQuery> > </List> > </QueryPlan> > > _______________________________________________ > BaseX-Talk mailing list > BaseX-Talk at mailman.uni-konstanz.de > https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk

On Mon, Mar 18, 2013 at 3:59 PM, Christian Grün <christian.gruen at gmail.com> wrote: > Surely looks like a bug [1]. I’d be interested if you have tried to > build your query without xquery:eval. It may be worth noting that all > queries using eval() calls are hardly optimizable, because a > dynamically built query can do lots of unexpected things (excluding, > thankfully, updates). > > [1] https://github.com/BaseXdb/basex/issues/662 > ___________________________ > > On Thu, Mar 14, 2013 at 3:35 PM, Marco Lettere <marco.lettere at dedalus.eu> wrote: >> Hi all, >> on the way to writing a small DSL I stumbled upon the following BaseX 7.6 >> issue. >> I'm not able to explain to myself why the first two expressions of the >> following xquery module return correctly whereas the last yields >> NullPointerException (as shown in the appended stacktrace). >> What I'm mtrying to do is to wrap up some modification code into >> userfriendly function calls that can be used in mini xquery scripts to >> formalize xml workflow. >> Thank you for any help, >> Marco. >> >> declare variable $globals := map { >> 'change' := local:change#1, >> 'generate' := local:gen#0 >> }; >> >> declare function local:gen(){ >> <b/> >> }; >> >> declare function local:change($doc){ >> copy $newdoc := $doc >> modify( >> insert node <a/> as last into $newdoc >> ) >> return $newdoc >> }; >> >> ( >> xquery:eval("copy $newdoc := <b/> >> modify( >> insert node <a/> as last into $newdoc >> ) >> return $newdoc",$globals), >> >> xquery:eval("$generate()", $globals), >> xquery:eval("$change($doc)", map:new( ($globals, map { "doc" := <b/>}))) >> ) >> >> The stacktrace and query plan: >> >> Error: >> Improper use? Potential bug? Your feedback is welcome: >> Contact: basex-talk at mailman.uni-konstanz.de >> Version: BaseX 7.6 >> Java: Oracle Corporation, 1.7.0_15 >> OS: Linux, i386 >> Stack Trace: >> java.lang.NullPointerException >> org.basex.query.up.expr.Transform.value(Transform.java:68) >> org.basex.query.QueryContext.value(QueryContext.java:296) >> org.basex.query.func.UserFunc.value(UserFunc.java:175) >> org.basex.query.QueryContext.value(QueryContext.java:296) >> org.basex.query.func.BaseFuncCall.value(BaseFuncCall.java:68) >> org.basex.query.QueryContext.value(QueryContext.java:296) >> org.basex.query.value.item.FuncItem.invValue(FuncItem.java:104) >> org.basex.query.func.DynamicFunc.value(DynamicFunc.java:56) >> org.basex.query.QueryContext.value(QueryContext.java:296) >> org.basex.query.QueryContext.value(QueryContext.java:254) >> org.basex.query.func.FNXQuery.eval(FNXQuery.java:95) >> org.basex.query.func.FNXQuery.eval(FNXQuery.java:71) >> org.basex.query.func.FNXQuery.iter(FNXQuery.java:37) >> org.basex.query.QueryContext.iter(QueryContext.java:285) >> org.basex.query.expr.List$1.next(List.java:100) >> org.basex.query.QueryContext.execute(QueryContext.java:524) >> org.basex.query.QueryProcessor.execute(QueryProcessor.java:96) >> org.basex.core.cmd.AQuery.query(AQuery.java:77) >> org.basex.core.cmd.XQuery.run(XQuery.java:22) >> org.basex.core.Command.run(Command.java:342) >> org.basex.core.Command.exec(Command.java:321) >> org.basex.core.Command.execute(Command.java:78) >> org.basex.gui.GUI.exec(GUI.java:397) >> org.basex.gui.GUI$7.run(GUI.java:349) >> Compiling: >> - pre-evaluating map { "change":=function($1) as item()* { >> local:change(($1)) }, "generate":=function() as item()* { local:gen(()) } } >> Optimized Query: >> declare function local:change($doc) { copy $newdoc as node() := $doc modify >> insert node element a { () } into $newdoc return $newdoc }; >> declare function local:gen() { element b { () } }; >> (xquery:eval("copy $newdoc := $generate() >> modify( >> insert node <a/> as last into $newdoc >> ) >> return $newdoc", map{ "change":=function($1) as item()* { >> local:change(($1)) }, "generate":=function() as item()* { local:gen(()) } >> }), xquery:eval("$generate()", map{ "change":=function($1) as item()* { >> local:change(($1)) }, "generate":=function() as item()* { local:gen(()) } >> }), xquery:eval("$change($doc)", map:new((map{ "change":=function($1) as >> item()* { local:change(($1)) }, "generate":=function() as item()* { >> local:gen(()) } }, map { "doc":=element b { () } })))) >> Query plan: >> <QueryPlan> >> <UserFuncs> >> <UserFunc name="local:change" arg0="doc"> >> <Transform> >> <Let var="$newdoc as node()"> >> <VarRef> >> <Var name="$doc" id="2"/> >> </VarRef> >> </Let> >> <Insert> >> <VarRef> >> <Var name="$newdoc as node()" id="3"/> >> </VarRef> >> <CElem> >> <QNm value="a" type="xs:QName"/> >> </CElem> >> </Insert> >> <VarRef> >> <Var name="$newdoc as node()" id="3"/> >> </VarRef> >> </Transform> >> </UserFunc> >> <UserFunc name="local:gen"> >> <CElem> >> <QNm value="b" type="xs:QName"/> >> </CElem> >> </UserFunc> >> </UserFuncs> >> <VarStack> >> <Var name="$globals" id="0"/> >> </VarStack> >> <List> >> <FNXQuery name="eval(string[,bindings])"> >> <Str value="copy $newdoc := $generate()&#x0A; modify(&#x0A; >> insert node &lt;a/&gt; as last into $newdoc &#x0A; )&#x0A; >> return $newdoc" type="xs:string"/> >> <Map size="2"> >> <Str value="change" type="xs:string"/> >> <FuncItem type="function(item()*) as item()*"> >> <Var name="$1" id="1"/> >> <BaseFuncCall name="local:change(($1))"> >> <VarRef> >> <Var name="$1" id="1"/> >> </VarRef> >> </BaseFuncCall> >> </FuncItem> >> <Str value="generate" type="xs:string"/> >> <FuncItem type="function() as item()*"> >> <BaseFuncCall name="local:gen(())"/> >> </FuncItem> >> </Map> >> </FNXQuery> >> <FNXQuery name="eval(string[,bindings])"> >> <Str value="$generate()" type="xs:string"/> >> <Map size="2"> >> <Str value="change" type="xs:string"/> >> <FuncItem type="function(item()*) as item()*"> >> <Var name="$1" id="1"/> >> <BaseFuncCall name="local:change(($1))"> >> <VarRef> >> <Var name="$1" id="1"/> >> </VarRef> >> </BaseFuncCall> >> </FuncItem> >> <Str value="generate" type="xs:string"/> >> <FuncItem type="function() as item()*"> >> <BaseFuncCall name="local:gen(())"/> >> </FuncItem> >> </Map> >> </FNXQuery> >> <FNXQuery name="eval(string[,bindings])"> >> <Str value="$change($doc)" type="xs:string"/> >> <FNMap name="new([maps[,coll]])"> >> <List> >> <Map size="2"> >> <Str value="change" type="xs:string"/> >> <FuncItem type="function(item()*) as item()*"> >> <Var name="$1" id="1"/> >> <BaseFuncCall name="local:change(($1))"> >> <VarRef> >> <Var name="$1" id="1"/> >> </VarRef> >> </BaseFuncCall> >> </FuncItem> >> <Str value="generate" type="xs:string"/> >> <FuncItem type="function() as item()*"> >> <BaseFuncCall name="local:gen(())"/> >> </FuncItem> >> </Map> >> <LitMap> >> <Str value="doc" type="xs:string"/> >> <CElem> >> <QNm value="b" type="xs:QName"/> >> </CElem> >> </LitMap> >> </List> >> </FNMap> >> </FNXQuery> >> </List> >> </QueryPlan> >> >> _______________________________________________ >> BaseX-Talk mailing list >> BaseX-Talk at mailman.uni-konstanz.de >> https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk