SOLR-16646: New function query operator isnan to verify if value is NaN

[gabrielmagno]

https://issues.apache.org/jira/browse/SOLR-16646

Description

We created a new function query operator called isnan, that checks rather a value is a float NaN (not a number).

Solution

A new Value Source parser called isnan was added. It will get the input value, treat it as a float and use the Java builtin function Float.isNaN to verify if the value is NaN.

Tests

We added a new assert in the testBooleanFunctions test that verifies four cases of NaN values:
 - isnan(12.3456) should be false;
 - isnan(0) should be false;
 - isnan(div(0,0)) should be true;
 - isnan(sqrt(-1)) should be true.

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide

[gabrielmagno]

I tried running ./gradlew check, but I got an error that I'm not sure if it is related to my changes or is a bug from upstream master:

* What went wrong:
Execution failed for task ':solr:core:validateSourcePatterns'.
> Found source pattern violations (skip with -Pvalidation.sourcePatterns.failOnError=false):
  UTF-8 byte order mark
  tabs instead spaces\

[risdenk]

@gabrielmagno looks like its related to your change. ./gradlew tidy may fix it. I see in [solr/core/src/java/org/apache/solr/search/ValueSourceParser.java](https://github.com/apache/solr/pull/1331/files#diff-d13890bf504c239f648ea33d439b4e5d489594683190fd5ab2fc6ce68313dd0c) that indentation is off compared to the other examples above and below. I'm guessing your editor has tabs instead of spaces.

[gabrielmagno]

@gabrielmagno looks like its related to your change. ./gradlew tidy may fix it. I see in [solr/core/src/java/org/apache/solr/search/ValueSourceParser.java](https://github.com/apache/solr/pull/1331/files#diff-d13890bf504c239f648ea33d439b4e5d489594683190fd5ab2fc6ce68313dd0c) that indentation is off compared to the other examples above and below. I'm guessing your editor has tabs instead of spaces.

Thank you @risdenk , I ran ./gradlew tidy and it is fixed.

There is now a problem on QueryEqualityTest. I will work on that.

[gabrielmagno]

Fixed. gradlew check seems to be running fine now!

[risdenk]

Looks good - only thing needed is solr/CHANGES.txt entry

[risdenk]

Thanks @gabrielmagno