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

[Godmar Back (JIRA)]

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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