Avoiding UnsupportedOperationException by unwrapping externalPtr?

[Per Nyfelt]

Hi,

I am trying to use more complex java java libraries directly in Renjin but are running into issues with UnsupportedOperationExceptions.

The following example results in a java.lang.UnsupportedOperationException. It looks like this is because the comment object that was created looks like an externalPtr to the rootElement$addContent() method and hence it is not recognized:

import(org.jdom2.Document)
import(org.jdom2.Element)
import(org.jdom2.Comment)

doc <- Document$new()
rootElement <- Element$new("Root");
doc$setRootElement(rootElement);

comment <- Comment$new("This is a comment");
rootElement$addContent(comment);

Is is possible to explicitly unwrap the comment object so that the java method can be called directly?

I looked in the code and found org.renjin.invoke.reflection.converters.ObjectConverter.

This makes it work more often:

rootElement$addContent(ObjectConverter$INSTANCE$convertToJava(comment))

What is even more wonderful (but strange) is that the mere presence of 

import(org.renjin.invoke.reflection.converters.ObjectConverter)

...magically makes the code work!

import(org.jdom2.Document)
import(org.jdom2.Element)
import(org.jdom2.Comment)
import(org.jdom2.Attribute)

import(org.renjin.invoke.reflection.converters.ObjectConverter)

doc <- Document$new()
print("#Create root element")
rootElement <- Element$new("Root");
doc$setRootElement(rootElement);

print("#add a comment")
comment <- Comment$new("This is a comment");
# No need for this as the import is enough
#rootElement$addContent(ObjectConverter$INSTANCE$convertToJava(comment))
rootElement$addContent(comment);

print("# add child")
child1 <- Element$new("child");
child1$addContent("This is child 1");

print("# add attribute")
attr1 <- Attribute$new("key1", "value1");
child1$setAttribute(attr1);
rootElement$addContent(child1);

I verified it on both 0.9.2726 and 3.5-beta76 and the behavior seems to be identical.

However the behavior is intermittent in the sense that "sometimes" I see get the UnsupportedOperationException but if I just do "mvn clean install" a few times the problem goes away. It looks like some kind of timing issue since the UnsupportedOperationException occurs on different places from one time to another and sometimes not at all. 

When adding more code the chance of getting an UnsupportedOperationException increases.

Using the renjin-maven-plugin and executing this code as a test almost always works fine (not sure why). The issue is much more frequent when directly invoking the RenjinScriptEngine with this type of code directly.

Is the magic import effect intended functionality? 

Any ideas about why the UnsupportedOperationException would show up some times?

The full code is available here: https://github.com/Alipsa/rjdom

Best regards,

Per

[Bertram, Alexander]

Do you get a stack trace?

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Alexander Bertram

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Tel. Nederlands: +31(0)647205388
Skype: akbertram

[Per Nyfelt]

org.renjin.eval.EvalException: java.lang.UnsupportedOperationException

at org.renjin.sexp.FunctionCall.eval(FunctionCall.java:89)

at org.renjin.primitives.special.AssignLeftFunction.assignLeft(AssignLeftFunction.java:58)

at org.renjin.primitives.special.AssignLeftFunction.apply(AssignLeftFunction.java:42)

at org.renjin.sexp.FunctionCall.eval(FunctionCall.java:80)

at org.renjin.sexp.ExpressionVector.eval(ExpressionVector.java:85)

at org.renjin.eval.Context.evaluate(Context.java:280)

at org.renjin.script.RenjinScriptEngine.eval(RenjinScriptEngine.java:174)

at org.renjin.script.RenjinScriptEngine.eval(RenjinScriptEngine.java:133)

at test.alipsa.rjdom.CreateXmlTest.testJdomCreation(CreateXmlTest.java:60)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.base/java.lang.reflect.Method.invoke(Method.java:566)

at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)

at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)

at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)

at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)

at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)

at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)

at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)

at org.junit.runners.ParentRunner.run(ParentRunner.java:413)

at org.junit.runner.JUnitCore.run(JUnitCore.java:137)

at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)

at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)

at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)

Caused by: java.lang.UnsupportedOperationException

at org.renjin.invoke.reflection.converters.CollectionConverter.acceptsSEXP(CollectionConverter.java:60)

at org.renjin.invoke.reflection.AbstractOverload.accept(AbstractOverload.java:132)

at org.renjin.invoke.reflection.FunctionBinding.invoke(FunctionBinding.java:171)

at org.renjin.invoke.reflection.FunctionBinding.evaluateArgsAndInvoke(FunctionBinding.java:154)

at org.renjin.invoke.reflection.MethodFunction.apply(MethodFunction.java:58)

at org.renjin.sexp.FunctionCall.eval(FunctionCall.java:80)

... 33 more

On Monday, March 9, 2020 at 9:29:57 PM UTC+1, Alexander Bertram wrote:

Do you get a stack trace?

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[Per Nyfelt]

Another attempt on the same code which blew up a bit earlier (when adding a comment). Stack trace is similar:

org.renjin.eval.EvalException: java.lang.UnsupportedOperationException

at org.renjin.sexp.FunctionCall.eval(FunctionCall.java:89)

... 30 more

[Per Nyfelt]

I ran the R script in the simplest way possible i.e:

RenjinScriptEngine engine = new RenjinScriptEngineFactory().getScriptEngine();
engine.eval(script);

see here: https://github.com/Alipsa/rjdom/blob/master/src/test/java/test/alipsa/rjdom/CreateXmlTest.java for details