Add diagram generation feature and integrate Railroad Diagrams

[ydah]

Overview

Lrama provides an API for generating HTML syntax diagrams. These visual diagrams are highly useful as grammar development tools and can also serve as a form of automatic self-documentation.

This feature was inspired by the functionality of Chevrotain, a parser construction toolkit for JavaScript.

Motivation

The main motivation for adding this feature was to make the structure of parse.y, and thus the structure of Ruby's grammar, easier to understand. I thought that generating syntax diagrams in a more human-readable format would be beneficial.

These diagrams are highly useful as grammar development tools and can also serve as automatic self-documentation, which I believe is a significant advancement.

Library for Rendering Railroad Diagrams

Chevrotain used tabatkins/railroad-diagrams, but this library only supported JavaScript and Python.

To address this, I created a Ruby library and integrated it into Lrama: https://github.com/ydah/railroad_diagrams

This makes collaboration with Lrama easier and allows improvements to the library based on Lrama's needs. For these reasons, I decided to release it as a Ruby gem.

[ydah]

memo) If this cache is present, the following will fail at v2.5 If I could delete the cache, that might solve the problem, but I don't have the authority to delete that cache.

see: https://github.com/ruby/lrama/actions/runs/13088401502/job/36522284488

[yui-knk]

Could comment out the line instead of deletion and add the link to failed CI job as comments?

[ydah]

I add comment: ffd3115

[ydah]

memo) If we're using it in ruby/ruby, the library may not be installed by default. In such cases, you need to handle it like this:

This ensures that the script doesn't break if the gem isn't available, while also notifying the user about the missing dependency.

But if there is a better way, I would like to know.

[yui-knk]

Yes, we should not enforce any installation of gems for ruby/ruby build.
However current implementation causes warnings on ruby/ruby build (see: https://github.com/ruby/lrama/actions/runs/13088787136/job/36523059170?pr=523#step:14:76), we also need to avoid such situation.
When I implemented stackprof integration, I postponed require until entry point method is called.

Then my suggestions are:

1. extract require logic (L. 4 - 8) to an instance method
2. call the instance method when it's necessary, it might be needed when Diagram#initialize is called

By the way, we can assume "erb" is bundled to ruby then please keep require "erb" as is.

[yui-knk]

lrama/lib/lrama/report/profile/call_stack.rb

Line 24 in 1df1c1b

def self.require_stackprof

is an example.

[ydah]

Thank you! I updated 9113e0b

[yui-knk]

It might be good to add how to specify the option.

[ydah]

Indeed it is. I updated: 4280ca2