Let's stop parser Hell

[Jacob Carlborg]

On 2012-07-07 03:12, Jonathan M Davis wrote:

> Now, the issue of a "strong, dependable formalization of D's syntax" is
> another thing entirely. Porting dmd's lexer and parser to Phobos would keep
> the Phobos implementation in line with dmd much more easily and avoid
> inconsistencies in the language definition and the like. However, if we write a
> new lexer and parser specifically for Phobos which _doesn't_ port the lexer or
> parser from dmd, then that _would_ help drive making the spec match the
> compiler (or vice versa). So, I agree that could be a definite argument for
> writing a lexer and parser from scratch rather than porting the one from dmd,
> but I don't buy the bit about it smothering parser generators at all. I think
> that the use cases are completely different.

I think the whole point of having a compiler as a library is that the 
compiler should use the library as well. Otherwise the two will get out 
of sync.

Just look at Clang, LLVM, LLDB and Xcode, they took the correct 
approach. Clang and LLVM (and I think LLDB) are available as libraries. 
Then the compiler, debugger (lldb) and IDE uses these libraries as part 
of their implementation. They don't have their own implementation that 
is similar to the libraries, making it "easy" to stay in sync. They 
_use_ the libraries as libraries.

This is what DMD and Phobos should do as well. If it's too complicated 
to port the lexer/parser to D then it would be better, at least as a 
first step, to modify DMD as needed. Create a C API for DMD and then 
create D bindings to be put into Phobos.

-- 
/Jacob Carlborg