Changes and fixes to grammar: Number literals, preprocessor, string

[akberg]

I've been searching hopelessly for a remotely useful GLSL language support for VSCode for a while, and this one immediately seems to provide a mostly decent highlighting. I did however notice a few misses, that need fixing -- and added an extra which is open for discussion:

• Fixed the regex for fixed point numeric literals (which was failing on hex numbers due to precedence issues), leaving it more comprehensive.
• Fixed regex and naming of preprocessor directives to highlight only valid directives, to work with a larger set of themes, and to allow advanced themes to highlight preprocessor directives differently from other keywords.
• For discussion: Some GL extensions (e.g. GL_GOOGLE_include_directive) provide the include directive for including files and reusing code. For this, I've added the include keyword to the preprocessor list, and a rule for double-quoted strings. I'm not using GLES though, just GL, so I don't know how available those extensions are for ES. In any case, supporting the highlighting would make the extension more accessible, given that this is pretty much the only useful syntax highlighter on the marketplace.

[racz16]

Hi, thanks for contributing.

Fixed point numbers

You're right, it was a mistake, thanks for fixing it. My only nitpick is that in all other places, I use \\d, instead of 0-9, so please, change that back.

Preprocessor directives

Preprocessor directives are a bit more complicated. While it's not a bad idea to color preprocessor directives basically as keywords and the content as regular GLSL code, your implementation has a couple of problems.

• It's a bit strange and misleading that if I start to write a directive, at first, it'll be colored as a directive (because # alone is a valid directive), then the coloring breaks, because #def is not a valid directive, and when I finish #define, it colors the code correctly again. When I type, I feel like I made a mistake, because coloring changes.
  

• If a new language version or extension adds a new preprocessor directive to GLSL, the coloring won't be right.
  

• Your implementation accepts ## as a valid directive.
  

• It can't handle comments before directives. It can't handle comments between the # and the directive's name, but the current implementation can't handle it either.
  

• It can't handle the error directive's message.
  

• It colors defines in 3 different ways.
  

• Maybe it would be a good idea to color special items as constant.language.glsl, like es, on, off, all, required, warn, disable, all, STDGL, optimize, debug, maybe there are some others.
  

Includes and string

My extension only supports WebGL-related GLSL versions: GLSL ES 1, and GLSL ES 3. Since these versions don't support the include directive neither as a core feature, nor as an extension, I don't really want to support it. First of all, in WebGL, you have to use the browser's built-in shader compiler, which means, includes won't work. You can't use some other compiler, or generate SPIR-V. So while this might work in VS Code, it wouldn't work in the browser. But even if the syntax highlight works with includes, all other features wouldn't. The compiler would mark it as an error, you wouldn't get any items in code completion from the included files, etc. Also, I don't support other, features that are not available in WebGL, like compute shaders, SSBOs, etc.

On the other hand, I started to work on a new extension, which uses the Language Server Protocol, and it'll support all 17 GLSL versions, it'll properly handle preprocessor directives for example the include, and it'll work in Visual Studio as well. Sadly, at the moment I don't really have the time to work on it, but eventually, it'll be the successor of this extension, and hopefully, it'll solve all problems.

[racz16]

@akberg, will you continue to work on this Pull request?