How to build an AST for Solidity?

Question

I'm trying to build a parser for Solidity, and it would help if I could build a working version off of the existing parser. I've tried looking at the source code on the official git, but I haven't worked on a project of this magnitude before and it's confusing. Could some one tell me how I could isolate the parsing and AST modules so I can read a script and build an AST from it?

(I understand the scope might be a little too broad for this question, but I'd really appreciate any pointers)

Answer 1

If you use solc --ast, the compiler will output a json-representation of the AST (this is also included in the npm version of the compiler). Is that enough for your purposes? If not, please come to gitter to discuss.

Answer 2

In addition to chriseth's answer, there's also the solidity-parser project which is useful if you A) are developing in a Javascript context, or B) don't want the parser to error if there are unresolved imports (unfortunately solc --ast will error if there are imports it cannot find).

Answer 3

In addition to Tim's answer there's also a python-solidity-parser based on the ANTLR syntax and AST format used in solidity-parser-antlr that you can use if you want to avoid depending on the compiler. Note: compiler AST is the truth.

Answer 4

I have used 3 tools, maybe you can try:

1. https://github.com/iamdefinitelyahuman/py-solc-ast
2. https://github.com/ConsenSys/solc-typed-ast
3. https://github.com/ethereum/solidity/tree/develop/docs/grammar

Answer 5

Use flag --ast-compact-json, which gives the "AST of all source files in a compact JSON format."

solc --ast-compact-json contract.sol