Add validation of custom grok patterns file

[Marusyk]

Context

The support of custom grok patterns was added in #15

Just add the directory with name Patterns and a file (the file name doesn't matter) with your own patterns.

Like Patterns\grok-custom-patterns:

ZIPCODE [1-9]{1}[0-9]{2}\s{0,1}[0-9]{3}

and use:

Grok grok = new Grok("%{ZIPCODE:zipcode}:%{EMAILADDRESS:email}");
var grokResult = grok.Parse($"122001:[email protected]");

IndexOutOfRangeException

There is an issue when that custom file has the wrong content.

How to reproduce

Add to the Patterns\grok-custom-patterns the following data:

pattern

How to fix

Add some validation on load of custom grok file content. It should be pattern name, space, then the regexp for that pattern

[ManasviGoyal]

@Marusyk please elaborate so that i can get started

[Marusyk]

@ManasviGoyal thanks for your interest. You can start whenever you want

[ManasviGoyal]

@Marusyk how is this different from #19 ?
most of things are already added

[Marusyk]

@ManasviGoyal this is about bug IndexOutOfRangeException and about adding some validation
#19 was about adding documentation to the README
Please see description of the issue carefully

[Marusyk]

Hi @ManasviGoyal, are you still working on that?

[ManasviGoyal]

Hi @ManasviGoyal, are you still working on that?

I am busy with some work this month. You can can assign it someone else. No issue with me.

[MazixM]

Hi, i would like to try to fix it. Can i?

[GioMaz]

Hello, I would like to contribute to this issue as well

[Marusyk]

Hi @MazixM and @GioMaz,
Thanks for your interest.
You need to create a Pull Request with changes. Then we can choose the best one