RBS parser

rbs_parser provides an API and a command line tool to parse Ruby RBS signatures and translate them to Sorbet's RBI format.

See the comparison of supported features by both specifications and what rbs2rbi is able to translate.

Compilation

Compile the rbs2rbi translator:

$ make

Requirements:

bison 3.4
ragel 6.10
clang 11.0

Usage

Given the following RBS file:

# calculator.rbs

class Calculator
  def sum: (Integer, Integer) -> Integer
end

Translate it to RBI with rbs2rbi:

$ rbs2rbi calculator.rbs

RBI is output to stdout, parsing errors and RBI translation errors to stderr:

# typed: true

class Calculator
  extend T::Sig

  sig { params(arg0: Integer, arg1: Integer).returns(Integer) }
  def sum(arg0, arg1); end
end

What's supported?

Take a look at our comparison of RBS and RBI.

Declarations	RBS	RBI
class	✅	✅
class parent	✅	✅
class abstract	❌	✅
class final	❌	✅
class sealed	❌	✅
module	✅	✅
module final	❌	✅
module self type	✅	❌
interface	✅	🔶
extension	✅	❌
struct	❌	✅
type alias	✅	✅
constant	✅	✅
global	✅	❌

Members	RBS	RBI
ivar	✅	❌
method	✅	✅
method multiple signatures	✅	🔶
method self	✅	✅
method self?	✅	🔶
method super	✅	❌
method final	❌	✅
method override	❌	✅
attr reader	✅	✅
attr writer	✅	✅
attr accessor	✅	✅
attr instance variable	✅	❌
mixin	✅	✅
mixin interface	✅	❌
alias	✅	🔶
visibility	✅	❌

Types	RBS	RBI
class instance	✅	✅
class singleton	✅	✅
interface	✅	🔶
alias	✅	🔶
literal	✅	🔶
union	✅	✅
intersection	✅	✅
optional	✅	✅
record	✅	✅
tuple	✅	✅
enum	❌	✅
type parameters	✅	✅
type parameters bound	❌	✅
type parameters variance	✅	✅
type parameters unchecked	✅	❌
method type parameters	✅	✅
proc	✅	✅
instance type	✅	✅
base types	✅	🔶

Writing your own translator

Create a subclass of Visitor or PrintVisitor:

#include "File.hh"
#include "PrintVisitor.hh"

class PrintMyFormat : public PrintVisitor {
public:
    PrintMyFormat(std::ostream &output) : PrintVisitor(output){};

    virtual void visit(File *file) {
        for (auto *decl : file->decls) {
            enterVisit(decl);
        }
    }

    virtual void visit(TypeBool *type) { print("Bool"); }

    virtual void visit(TypeNil *type) { print("Nil"); }

	// ...
}

Running the tests

$ make check

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/Shopify/rbs_parser. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

akimd/rbs_parser