[jboss-jira] [JBoss JIRA] Commented: (JBRULES-1460) MVEL parser uses wrong precedence for []

[Michael Neale (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBRULES-1460?page=comments#action_12402335 ] 
            
Michael Neale commented on JBRULES-1460:
----------------------------------------

But, its an MVEL iss..... sorry ;) couldn't resist  /joke ;)

Mike is going to take a look into this. 

Oh, and beanshell had far more issues (the most mature would be javascript/rhino - but that has other quirks - but its worth considering a dialect of it). 

> MVEL parser uses wrong precedence for []
> ----------------------------------------
>
>                 Key: JBRULES-1460
>                 URL: http://jira.jboss.com/jira/browse/JBRULES-1460
>             Project: JBoss Drools
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>    Affects Versions: 4.0.4
>            Reporter: Godmar Back
>
> Consider this .drl file:
> --
> package test;
> import java.util.ArrayList;
> import java.util.HashMap;
> dialect "mvel"
> rule "Rule #1"
> when
> then
>     m = new HashMap();
>     l = new ArrayList();
>     l.add("first");
>     m.put("content", l);
>     System.out.println(m["content"][0]);
> end
> ---
> which produces:
> org.mvel.PropertyAccessException: unable to resolve property: out.println(m["content"][0])
>         at org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:285)
>         at org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:107)
>         at org.mvel.ast.LiteralDeepPropertyNode.getReducedValueAccelerated(LiteralDeepPropertyNode.java:26)
>         at org.mvel.MVELRuntime.execute(MVELRuntime.java:88)
>         at org.mvel.CompiledExpression.getValue(CompiledExpression.java:107)
>         at org.mvel.MVEL.executeExpression(MVEL.java:223)
>         at org.drools.base.mvel.MVELConsequence.evaluate(MVELConsequence.java:47)
>         at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:550)
>         at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:514)
>         at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:471)
>         at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:433)
>         at org.libx.autodetect.DroolsDriver$Host.fireAllRules(DroolsDriver.java:63)
>         at org.libx.autodetect.DroolsDriver.main(DroolsDriver.java:135)
> Caused by: org.mvel.PropertyAccessException: unable to resolve property: unable to resolve method: java.io.PrintStream.println(java.util.ArrayList, org.mvel.util.FastList) [arglength=2]
>         at org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:558)
>         at org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:257)
>         ... 12 more
> Exception in thread "main" org.drools.spi.ConsequenceException: org.mvel.PropertyAccessException: unable to resolve property: out.println(m["content"][0])
>         at org.drools.base.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:14)
>         at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:554)
>         at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:514)
>         at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:471)
>         at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:433)
>         at org.libx.autodetect.DroolsDriver$Host.fireAllRules(DroolsDriver.java:63)
>         at org.libx.autodetect.DroolsDriver.main(DroolsDriver.java:135)
> Caused by: org.mvel.PropertyAccessException: unable to resolve property: out.println(m["content"][0])
>         at org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:285)
>         at org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:107)
>         at org.mvel.ast.LiteralDeepPropertyNode.getReducedValueAccelerated(LiteralDeepPropertyNode.java:26)
>         at org.mvel.MVELRuntime.execute(MVELRuntime.java:88)
>         at org.mvel.CompiledExpression.getValue(CompiledExpression.java:107)
>         at org.mvel.MVEL.executeExpression(MVEL.java:223)
>         at org.drools.base.mvel.MVELConsequence.evaluate(MVELConsequence.java:47)
>         at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:550)
>         ... 5 more
> Caused by: org.mvel.PropertyAccessException: unable to resolve property: unable to resolve method: java.io.PrintStream.println(java.util.ArrayList, org.mvel.util.FastList) [arglength=2]
>         at org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:558)
>         at org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:257)
>         ... 12 more
> but changing:
>     System.out.println(m["content"][0]);
> to
>     System.out.println((m["content"])[0]);
> works. (So does assigning m["content"] to a temporary variable.)
> BTW: if you say that's a MVEL issue, not a Drools issue, consider that I have no other reason to use MVEL than to be able to use Drools. That's why I filed this bug here. I don't know how to run MVEL in any other environment, nor am I interested in it - I'd rather use a mature scripting language (beanshell comes to mind) that doesn't exhibit such basic bugs. Why don't you?

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