Solidity compiler's innards

acrosacros Member Posts: 63 ✭✭

Could anyone give a brief description of how the solc compiler works? I can't find much documentation on the subject... describes the language more than the compiler.

As far as parsers/compilers are concerned, I'm mostly familiar with how ANTRL processes DSLs. I was curious to know how similar (or not) this compiler was. Does it use c++ libraries (for tokenizing for instance), or is it an entirely custom effort? And if so, what was the motivation? Why not have used something like ANTLR, or even a c++ equivalent?

If someone could point me to the most relevant files in the solidity repo, that would be awesome!



  • chrisethchriseth Member Posts: 170 ✭✭✭
    So you are asking specifically about the parsing part of the compiler, and not the type-checking and code-generation part?

    It is a simple recursive descent parser which originated from V8's JavaScript parser. The reason not to use a parser generator was that it is much easier to modify the parser and debug the parsing process. I think parser generators are great, but they do not work well with an evolving grammar. Also JavaScript's / Solidity's grammar is really well suited for recursive descent as there are almost no ambiguities and or left-recursions.
  • acrosacros Member Posts: 63 ✭✭
    Thanks, this is very helpful! Any place in the code you recommend I take a look at for the parser?

    I guess the parsing is a good place for me to start (I want to get a high-level understanding of the compiler in general).

    I agree with your statement about evolving grammar, so this makes sense at this point.

    I don't really see that big a resemblance between Solidity and JS though, starting with the type system... If anything it gives more a feel of c++ meets java, but maybe it's just me!
  • chrisethchriseth Member Posts: 170 ✭✭✭
    The Scanner is in Scanner.h/Scanner.cpp, the Parser in Parser.h/Parser.cpp and the output data structure of the parser is in AST.h / AST.cpp.
  • acrosacros Member Posts: 63 ✭✭
    awesome, thanks :)
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