Use RBS for indexing Core classes

Gemfile.lock

@@ -12,6 +12,7 @@ PATH
     ruby-lsp (0.17.2)
       language_server-protocol (~> 3.17.0)
       prism (>= 0.29.0, < 0.30)
+      rbs (>= 3, < 4)
       sorbet-runtime (>= 0.5.10782)
 
 GEM
@@ -31,6 +32,7 @@ GEM
       reline (>= 0.4.2)
     json (2.7.2)
     language_server-protocol (3.17.0.3)
+    logger (1.6.0)
     minitest (5.23.1)
     minitest-reporters (1.6.1)
       ansi
@@ -54,6 +56,8 @@ GEM
     rbi (0.1.13)
       prism (>= 0.18.0, < 1.0.0)
       sorbet-runtime (>= 0.5.9204)
+    rbs (3.5.1)
+      logger
     regexp_parser (2.9.2)
     reline (0.5.0)
       io-console (~> 0.5)

lib/ruby_indexer/lib/ruby_indexer/rbs_indexer.rb

@@ -0,0 +1,63 @@
+# typed: strict
+# frozen_string_literal: true
+
+module RubyIndexer
+  class RBSIndexer
+    extend T::Sig
+
+    sig { params(index: Index).void }
+    def initialize(index)
+      @index = index
+    end
+
+    sig { void }
+    def index_core_classes
+      loader = RBS::EnvironmentLoader.new
+      RBS::Environment.from_loader(loader).resolve_type_names
+
+      loader.each_signature do |source, pathname, _buffer, declarations, _directives|
+        process_signature(source, pathname, declarations)
+      end
+    end
+
+    private
+
+    sig { params(source: T.untyped, pathname: Pathname, declarations: T::Array[RBS::AST::Declarations::Base]).void }
+    def process_signature(source, pathname, declarations)
+      declarations.each do |declaration|
+        process_declaration(declaration, pathname)
+      end
+    end
+
+    sig { params(declaration: RBS::AST::Declarations::Base, pathname: Pathname).void }
+    def process_declaration(declaration, pathname)
+      case declaration
+      when RBS::AST::Declarations::Class
+        handle_class_declaration(declaration, pathname)
+      else # rubocop:disable Style/EmptyElse
+        # Other kinds not yet handled
+      end
+    end
+
+    sig { params(declaration: RBS::AST::Declarations::Class, pathname: Pathname).void }
+    def handle_class_declaration(declaration, pathname)
+      nesting = [declaration.name.name.to_s]
+      file_path = pathname.to_s
+      location = to_ruby_indexer_location(declaration.location)
+      comments = Array(declaration.comment&.string)
+      parent_class = declaration.super_class&.name&.name&.to_s
+      class_entry = Entry::Class.new(nesting, file_path, location, comments, parent_class)
+      @index << class_entry
+    end
+
+    sig { params(rbs_location: RBS::Location).returns(RubyIndexer::Location) }
+    def to_ruby_indexer_location(rbs_location)
+      RubyIndexer::Location.new(
+        rbs_location.start_line,
+        rbs_location.end_line,
+        rbs_location.start_column,
+        rbs_location.end_column,
+      )
+    end
+  end
+end

lib/ruby_indexer/ruby_indexer.rb

@@ -11,6 +11,7 @@
 require "ruby_indexer/lib/ruby_indexer/configuration"
 require "ruby_indexer/lib/ruby_indexer/prefix_tree"
 require "ruby_indexer/lib/ruby_indexer/location"
+require "ruby_indexer/lib/ruby_indexer/rbs_indexer"
 
 module RubyIndexer
   @configuration = T.let(Configuration.new, Configuration)

lib/ruby_indexer/test/configuration_test.rb

@@ -54,7 +54,7 @@ def test_indexables_includes_default_gems
 
       assert_includes(indexables, "#{RbConfig::CONFIG["rubylibdir"]}/pathname.rb")
       assert_includes(indexables, "#{RbConfig::CONFIG["rubylibdir"]}/ipaddr.rb")
-      assert_includes(indexables, "#{RbConfig::CONFIG["rubylibdir"]}/abbrev.rb")
+      assert_includes(indexables, "#{RbConfig::CONFIG["rubylibdir"]}/erb.rb")
     end
 
     def test_indexables_includes_project_files

lib/ruby_indexer/test/rbs_indexer_test.rb

@@ -0,0 +1,29 @@
+# typed: true
+# frozen_string_literal: true
+
+require_relative "test_case"
+
+module RubyIndexer
+  class RBSIndexerTest < TestCase
+    def setup
+      @index = RubyIndexer::Index.new
+      RBSIndexer.new(@index).index_core_classes
+    end
+
+    def test_index_core_classes
+      entries = @index["Array"]
+      refute_nil(entries)
+      assert_equal(1, entries.length)
+      entry = entries.first
+      assert_match(%r{/gems/rbs-.*/core/array.rbs}, entry.file_path)
+      assert_equal("array.rbs", entry.file_name)
+      assert_equal("Object", entry.parent_class)
+
+      # Using fixed positions would be fragile, so let's just check some basics.
+      assert_operator(entry.location.start_line, :>, 0)
+      assert_operator(entry.location.end_line, :>, entry.location.start_line)
+      assert_equal(0, entry.location.start_column)
+      assert_operator(entry.location.end_column, :>, 0)
+    end
+  end
+end

lib/ruby_lsp/internal.rb

@@ -18,6 +18,7 @@
 require "prism"
 require "prism/visitor"
 require "language_server-protocol"
+require "rbs"
 
 require "ruby-lsp"
 require "ruby_lsp/base_server"

lib/ruby_lsp/server.rb

@@ -690,6 +690,17 @@ def shutdown
 
     sig { params(config_hash: T::Hash[String, T.untyped]).void }
     def perform_initial_indexing(config_hash)
+      index_core_classes
+      index_ruby_code(config_hash)
+    end
+
+    sig { void }
+    def index_core_classes
+      RubyIndexer::RBSIndexer.new(@global_state.index).index_core_classes
+    end
+
+    sig { params(config_hash: T::Hash[String, T.untyped]).void }
+    def index_ruby_code(config_hash)
       # The begin progress invocation happens during `initialize`, so that the notification is sent before we are
       # stuck indexing files
       RubyIndexer.configuration.apply_config(config_hash)

ruby-lsp.gemspec

@@ -20,6 +20,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency("language_server-protocol", "~> 3.17.0")
   s.add_dependency("prism", ">= 0.29.0", "< 0.30")
+  s.add_dependency("rbs", ">= 3", "< 4")
   s.add_dependency("sorbet-runtime", ">= 0.5.10782")
 
   s.required_ruby_version = ">= 3.0"