Create Pipeline Rules syntax highlighting mode for Ace

[kyleknighted]

Description

Created custom Mode for Ace Editor to introduce syntax highlighting for Pipeline Rules

Motivation and Context

• User request
• Improve code readability

How Has This Been Tested?

Screenshots (if appropriate):

Before:

After:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[kyleknighted]

Errors currently in master

client.js:772 POST http://localhost:9000/api/system/pipelines/rule/parse 400 (Bad Request)

FetchProvider.js:19 There was an error fetching a resource: cannot POST http://localhost:9000/api/system/pipelines/rule/parse (400). Additional information: Not available

After adding in the syntax highlighting, an additional error is added to the mix, even though the mode actually loads fine and renders appropriately

index.js:3802 GET http://127.0.0.1:8080/system/pipelines/rules/mode-pipeline.js net::ERR_ABORTED 404 (Not Found)

I could use an additional set of eyes to help me figure out what's causing this 404 even though it actually works.

[dennisoelkers]

I have played with the PR today and it is a good improvement!

Some suggestions:

• The mode should be named pipeline/pipeline_rule, not graylog to make it more specific.

• The mode file can be reduced in size dramatically. While playing with it, I removed the JavaScript mode and let the graylog mode inherit from TextMode. Also, the folding is not required.

• The mode contains a number of keywords (match|pipeline|all|either) which are not used in the rule language. I think you got them from the internal representation of pipelines, which is different from pipeline rules. While we might support editing them at some point, it would be a different mode than the pipeline rules.

• rule|when|then|end should be keywords, not constants. This way the highlighting lets you differentiate visually between the outer framing of the rule and the used functions:
  

• Instead of maintaining a huge list of functions, we should try to fetch them again from the backend. (Maybe by using an instance of the mode again, which is passed to react-ace, so it is not evaluated in its scope, but ours)

• If that is not possible, we should replace the static list with a regex. IMO it is confusing if a function that is in the list has a different color than a function that is supplied by a plugin (but is still correct). Validating that a function is defined is done by the editor anyway.