oniguruma VS vscode-oniguruma

As a ruby developer, I was happy to find that VS Code / TextMate grammar files use the same regular expression engine called Oniguruma as ruby itself. Thus, I could be sure that when trying my regular expressions in my favorite online regex tool, rubular.com, there would be no inconsistencies due to the engine inner workings.

However, parsing these files requires a C library called Oniguruma to parse and execute these files. Because this library does not run in a pure JavaScript environment – which was a requirement for Monaco historically due to browser support – Monaco ships out-of-the-box with a different grammar language.

Luckily, there is a project that has fitted my needs perfectly: vscode-grammar-test. It’s a command line tool that builds on the VS Code regex engine and grammar file parser and allows to run unit tests directly against a given grammar file.

Shiki does this because the underlying library vscode-textmate or vscode-oniguruma returns black if the value is not a valid color. This explains why Code Hike uses blackish color codes instead of variables. But what if we write a variable directly into the theme instead of the color code.

More specifically, we’re using [vscode-oniguruma](https://github.com/microsoft/vscode-oniguruma), which is made by Microsoft. But this introduced yet another problem: Integrating TextMate into Monaco typically requires hacks of some kind, and introduces some flaws into the experience.