Pretty damn impressive.
Though I must wonder: how complete is it? What does it and does it not support? It's at least complete enough to be self-hosting, but beyond that? The code doesn't use that much of C.
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Though I must wonder: how complete is it? What does it and does it not support? It's at least complete enough to be self-hosting, but beyond that? The code doesn't use that much of C.
Granted, while building a parser that can parse (let alone compiling) the full C language is nontrivial, any undergrad should be able to build a parser and compiler for a sufficiently simple subset of it. (In my undergrad, we used this subset to build a "compiler" in second year: https://www.student.cs.uwaterloo.ca/~cs241/wlp4/WLP4.html)
[1] http://www.cs.berkeley.edu/~necula/cil/cil016.html [2] https://github.com/rui314/8cc
As for your example, I'll be solomonic and say that you and Joe are right, of sorts (though I do think it'd be more than an afternoon).
It's certainly far more than a days work if you handwrite a lexer and parser that does the amount of additional work that yours do (AST construction; a lot of error reporting and sanity checking). But you can get very far with C very quickly if you use parser generation tools and have prior experience writing compilers and your goal is "just" to get something to parse it as quickly as possible - it's a tiny language.
Of course, in practice most real compilers don't use these parser-generation tools exactly because things like proper error reporting etc. is far harder, and a simple recursive descent parser is so much easier to work with.