ISPN-3917 Implement projections for unindexed filters

[anistor]

Also refactor the Matcher interface and the interface for single filters (no callback)

Jira: https://issues.jboss.org/browse/ISPN-3917

[Sanne]

I've started to look but couldn't finish.

@gustavonalle could you review this too? Good to familiarize with this functionality.

[anistor]

rebased.

[anistor]

@wburns Please have a look too, since you'll be the first user of the Matcher/ObjectFilter api :)

[anistor]

Updated tests.

[wburns]

First pass seems fine to me. Seems like the API is a bit nicer now thanks 👍

[gustavocoding]

Looks nice!

I found issues with a couple of expressions:

from Person p where p.age > 10 and p.age < 30  => matches even if p is 40 years old
from Person p where p.license is null => throws NPE (same for p.license = null)

[anistor]

Thanks @wburns and @gustavonalle! I noticed the comment only now. Will try to fix asap.

[anistor]

Thanks for spotting those issues. I fixed them.

@gustavonalle I think you added comments directly on the commit rather that in the 'conversation' or 'changed files' tab. github has the nasty habit of occasionally removing such comments when the commit in question is updated, which just happened. So I'll answer here:

1. re FilterResult, unless @wburns needs it I would avoid adding an extra object to represent the result for now. The whole object-filter module is internal, so we can easily change the API whenever we feel the need.

2. re FilterQuery and Matcher, yes, we plan to have a single Query interface for both indexed and non-indexed search. But the factory is different, and the returned instances are not useable interchangeably. FilterQuery is an implementation detail that the user should not see.

[gustavocoding]

Makes sense!

Re the issues, sorry for not being specific, but the second use case

from Person p where p.license is null

is for an existing property, and I'm afraid it is still throwing NPE

[anistor]

@gustavonalle I've just found a problem with != operator and fixed it and added test for it. Also added tests for 'is null' for both existing and missing property but could not find the NPE you mention. I'm surely not doing it right. Could you please try again on the new version and post a stacktrace or the test code that fails? Thanks!

[gustavocoding]

The NPE happens when an existing property of the instance obj has null value:

java.lang.NullPointerException
    at org.infinispan.objectfilter.impl.predicateindex.ReflectionMatcherEvalContext.processAttributes(ReflectionMatcherEvalContext.java:20)
    at org.infinispan.objectfilter.impl.predicateindex.ReflectionMatcherEvalContext.processAttribute(ReflectionMatcherEvalContext.java:40)
    at org.infinispan.objectfilter.impl.predicateindex.ReflectionMatcherEvalContext.processAttributes(ReflectionMatcherEvalContext.java:33)

[anistor]

Got it now! That was easily fixed for the reflection based cased. But running the same test for a protobuf encoded entity leads to another issue, https://issues.jboss.org/browse/ISPN-4319. I'll solve that separately.

[gustavocoding]

Integrated!