make jison compiles go faster

[cosmicexplorer]

Problem

Jison compiles parser.js very slowly:

> time cake build:parser
cake build:parser  11.65s user 0.24s system 107% cpu 11.044 total

Since the parser is also compiled whenever we run cake build, this means any change to the compiler takes ~12 seconds to reload (or almost 30 seconds if you run cake build twice!).

Solution

• I optimized one method in Jison: rewrite followSets() to drastically improve compile performance zaach/jison#408.

Result

The generated parser seems to be byte-for-byte the same, while being generated much faster:

> time cake build:parser
cake build:parser  4.63s user 0.49s system 123% cpu 4.147 total

We can go even faster (https://github.com/cosmicexplorer/jison/tree/performance-work-for-coffeescript), but the additional changes in that branch are quite extensive, and don't produce a significant performance improvement. This change is easy to audit and does most of the work.

TODO

• The package.json entry points to my own github user repository. It's pinned to a commit, so it can't change, but if we're going to use a git reference, it should probably be owned by a maintainer of the repo.
  • We could also vendor Jison (since it doesn't seem to be actively maintained).

[shreeve]

Take a look at the solar.coffee parser generator in #5495

I originally was based on Jison, but totally rewrote it from scratch.

I now generate the parser.js file for CoffeeScript in less than 100ms, down from 12.5 seconds.

[cosmicexplorer]

The reason I spent the time to fix jison instead of rewriting it was the hope that it would be easier for maintainers to review a change. Rewriting it is the easy part.