Highlighting In Vim

Syntax hilighting for vim

from [this email thread]

Installation

1. make yourself a ~/.vim/ directory
2. make a syntax directory in there
3. save upload:ngc.vim into ~/.vim/syntax/
4. save upload:filetype.vim into ~/.vim/ (or merge with your existing one, if any):
5. open, or restart vim
6. open any files with *.ngc extensions, and it should auto-highlight them

You can also force highlighting with:

  :set syntax=ngc

There are ways to have Vim check a few lines in the file to determine type, but that's more involved, and an exercise for a later date. You can duplicate the au! line in filetype.vim to add your own extension(s), or just modify the one that's already there (*.ngc).

The syntax file I made is understandably remedial, given the single night of R&D, but it already properly highlights a rather extensive set of the files I tested. I endeavored to break up each highlighting type in sensible, pre-defined ways, such that the power user with lots of the standard sub-types defined for their Vim sessions could benefit from something passably familiar. In fact, there are no custom highlight types - all are linked to types that already exist in Vim. I happen to have a lot of my subtypes as the same core type colors, so there's actually more separation of highlight types than you're seeing, but already I think it's a bit easier to visually parse.

Feature Summary

Here's what I got to highlight before giving up:

• conditionals (if, else, endif)
• repeats (do, while, endwhile, break, continue)
• functions (sub, endsub, call, return)
• comments
• special comments (log stuff, print, msg, debug)
• identifiers (e.g. vars: #1, #<foo>, #<also_works>)
• operators (+, -, *, /, %, and all the EQ, and ACOS things)
• constants (ints, and floats)
• all g-codes
• all m-codes
• any o-code style number
• old-fashioned n# line numbers
• TODO, FIXME, XXX
• axes (x, y, z, a, b, c, u, v, w)
• feed rates
• "special" characters (i, j, k, e, d, l, p, r, s)
• tool selects, w/ h offset tool indices

Cool extras:

• everything is case-insensitive, as w/ NGC/LinuxCNC (g1, and G1 are the same)
• line breaks in comments break their highlighting to indicate the error
• special comments allow whitespace around keyword (e.g. ( MSG , etc...)
• identifiers inside special comments have their own highlight type
• n# labels, and o-codes only match if first non whitespace block on line
• TODO stuff all works from within comments, of course (where else?)
• axes highlight only if preceded by whitespace, and followed by digit, or [
• feed rates follow axes' rules, but can also be first characters on line
• special chars follow the rules of axes

Caveats:

• "-" is a tough one, in that it means 'minus,' and also 'negative'
  • it currently never highlights with the constant (always an operator)
  • I've at various points had it working in various ways
  • this has much to do with the order in which highlights are defined
  • it would appear to have a non-trivial, multi-workaround solution
  • any change to order, or method breaks other highlighting - sigh...
• I got a bit lazy by the time I got to special chars/tool select stuff
  • there are likely some oddities in this stuff
  • I rarely/never use any of that stuff; it was low-priority for me
• probably plenty more :)

There could be all manner of fancy extras, like catching lots of other errors, and flagging them as such, but it gets rather complicated rather quickly. I wanted to post this ASAP in case it helps any Vim users, and in case anyone wanted to enhance it with things like more robust error-checking, tighter adherence to the spec, or new ways to break up the concepts (e.g. highlighting an entire X[#<something>] block as a single type (not my preference, but perhaps someone would prefer that), or properly checking item locations in lines, or getting negative constants working, without breaking all else. There are a lot of parts of the g-code spec that I've never touched (e.g. I've never used an M-code), so I've probably missed whole swaths of highlightables.

Anyway, feedback/corrections much appreciated, and if anyone gets it working, or makes some nice modifications, I'd love to hear about it. I don't think I have wiki powers, but if someone would like to add it, that would also be nice. Thanks! you're welcome. btw, how to edit wiki pages.

-Gary Fixler