Replace Antlr4 with Langium

[MrCoder]

[Draft] Langium is a new DSL parser.

Benifits:

It offers two main benifits - a. it can generate a default LSP implemenation and b. it is performant.

Built-in LSP implementation

Even though this renderer (@zenuml/core) does not include an Editor. It is almost impossible to build a good editor without involving the DSL parser which is part of the core renderer package.

Attempts of LSP implementation on Antlr4

1. (NOT) AntlrVSIX

You may come across AntlrVSIX (https://github.com/kaby76/AntlrVSIX) if search keywords like "Antlr4 LSP". It is a LSP that supplort Antlr as a lanaguge NOT languages developed using Antlr. Also it is mainly designed as a Visual Studio Extension.

Performance

According to the offical document, "Langium is based off of Chevrontain".

Chevrontain is about 5 times performant than Antlr4. It is even slightly faster than HandBuilt.

Challenges / Questions

Does Langium expose positions of characters parsed?

It has a built-in implementation of LSP (Language Server Protocol) which can be used to configure Monaco editor.