John Doty
de0a76818e
Precedence now works for, like, resolving expressions in a single big table but uh... it takes the time from 700ms to like 7s so I've reverted it for now. |
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| grammar.py | ||
| LICENSE.md | ||
| parser.py | ||
| parser_faster.py | ||
| README.md | ||
A collection of LR parser generators, from LR0 through LALR.
One day I read a tweet, asking for a tool which accepted a grammar and an input file and which then produced simple parsed output, without any kind of in-between. (There was other ranty stuff about how none of the existing tools really worked, but that was beside the point.)
Upon reading the tweet, it occured to me that I didn't know how LR parsers worked and how they were generated, except in the broadest of terms. Thus, I set about writing this, learning as I went.
This code is not written to be fast, or even efficient, although it runs its test cases fast enough. It was instead written to be easy to follow along with, so that when I forget how all this works I can come back to the code and read along and learn all over again.
(BTW, the notes I read to learn how all this works are at http://dragonbook.stanford.edu/lecture-notes/Stanford-CS143/. Specifically, I started with handout 8, 'Bottom-up-parsing', and went from there. (I did eventually have to backtrack a little into handout 7, since that's where First() and Follow() are covered.)
Enjoy!
doty 2016-12-09