Refactor client capabilities into its own class (#2805)

### Motivation

As pointed out by @andyw8, our implementation of the global state was growing a little too much and so was the body of `apply_options`. This PR extracts a new object to store client capabilities, so that we can organize concerns a bit better.

### Implementation

Extracted the client capabilities into an object and adapted the code that was using them for the new structure.

### Automated Tests

Updated existing tests.

lib/ruby_lsp/base_server.rb

@@ -66,7 +66,9 @@ def start
                 # If the client supports request delegation and we're working with an ERB document and there was
                 # something to parse, then we have to maintain the client updated about the virtual state of the host
                 # language source
-                if document.parse! && @global_state.supports_request_delegation && document.is_a?(ERBDocument)
+                if document.parse! && @global_state.client_capabilities.supports_request_delegation &&
+                    document.is_a?(ERBDocument)
+
                   send_message(
                     Notification.new(
                       method: "delegate/textDocument/virtualState",

lib/ruby_lsp/client_capabilities.rb

@@ -0,0 +1,60 @@
+# typed: strict
+# frozen_string_literal: true
+
+module RubyLsp
+  # This class stores all client capabilities that the Ruby LSP and its add-ons depend on to ensure that we're
+  # not enabling functionality unsupported by the editor connecting to the server
+  class ClientCapabilities
+    extend T::Sig
+
+    sig { returns(T::Boolean) }
+    attr_reader :supports_watching_files,
+      :supports_request_delegation,
+      :window_show_message_supports_extra_properties
+
+    sig { void }
+    def initialize
+      # The editor supports watching files. This requires two capabilities: dynamic registration and relative pattern
+      # support
+      @supports_watching_files = T.let(false, T::Boolean)
+
+      # The editor supports request delegation. This is an experimental capability since request delegation has not been
+      # standardized into the LSP spec yet
+      @supports_request_delegation = T.let(false, T::Boolean)
+
+      # The editor supports extra arbitrary properties for `window/showMessageRequest`. Necessary for add-ons to show
+      # dialogs with user interactions
+      @window_show_message_supports_extra_properties = T.let(false, T::Boolean)
+
+      # Which resource operations the editor supports, like renaming files
+      @supported_resource_operations = T.let([], T::Array[String])
+    end
+
+    sig { params(capabilities: T::Hash[Symbol, T.untyped]).void }
+    def apply_client_capabilities(capabilities)
+      workspace_capabilities = capabilities[:workspace] || {}
+
+      file_watching_caps = workspace_capabilities[:didChangeWatchedFiles]
+      if file_watching_caps&.dig(:dynamicRegistration) && file_watching_caps&.dig(:relativePatternSupport)
+        @supports_watching_files = true
+      end
+
+      @supports_request_delegation = capabilities.dig(:experimental, :requestDelegation) || false
+      supported_resource_operations = workspace_capabilities.dig(:workspaceEdit, :resourceOperations)
+      @supported_resource_operations = supported_resource_operations if supported_resource_operations
+
+      supports_additional_properties = capabilities.dig(
+        :window,
+        :showMessage,
+        :messageActionItem,
+        :additionalPropertiesSupport,
+      )
+      @window_show_message_supports_extra_properties = supports_additional_properties || false
+    end
+
+    sig { returns(T::Boolean) }
+    def supports_rename?
+      @supported_resource_operations.include?("rename")
+    end
+  end
+end

lib/ruby_lsp/global_state.rb

@@ -21,18 +21,14 @@ class GlobalState
     attr_reader :encoding
 
     sig { returns(T::Boolean) }
-    attr_reader :supports_watching_files,
-      :experimental_features,
-      :supports_request_delegation,
-      :top_level_bundle,
-      :window_show_message_supports_extra_properties
-
-    sig { returns(T::Array[String]) }
-    attr_reader :supported_resource_operations
+    attr_reader :experimental_features, :top_level_bundle
 
     sig { returns(TypeInferrer) }
     attr_reader :type_inferrer
 
+    sig { returns(ClientCapabilities) }
+    attr_reader :client_capabilities
+
     sig { void }
     def initialize
       @workspace_uri = T.let(URI::Generic.from_path(path: Dir.pwd), URI::Generic)
@@ -44,12 +40,9 @@ def initialize
       @has_type_checker = T.let(true, T::Boolean)
       @index = T.let(RubyIndexer::Index.new, RubyIndexer::Index)
       @supported_formatters = T.let({}, T::Hash[String, Requests::Support::Formatter])
-      @supports_watching_files = T.let(false, T::Boolean)
       @experimental_features = T.let(false, T::Boolean)
       @type_inferrer = T.let(TypeInferrer.new(@index), TypeInferrer)
       @addon_settings = T.let({}, T::Hash[String, T.untyped])
-      @supports_request_delegation = T.let(false, T::Boolean)
-      @supported_resource_operations = T.let([], T::Array[String])
       @top_level_bundle = T.let(
         begin
           Bundler.with_original_env { Bundler.default_gemfile }
@@ -59,7 +52,7 @@ def initialize
         end,
         T::Boolean,
       )
-      @window_show_message_supports_extra_properties = T.let(false, T::Boolean)
+      @client_capabilities = T.let(ClientCapabilities.new, ClientCapabilities)
     end
 
     sig { params(addon_name: String).returns(T.nilable(T::Hash[Symbol, T.untyped])) }
@@ -137,32 +130,15 @@ def apply_options(options)
       end
       @index.configuration.encoding = @encoding
 
-      file_watching_caps = options.dig(:capabilities, :workspace, :didChangeWatchedFiles)
-      if file_watching_caps&.dig(:dynamicRegistration) && file_watching_caps&.dig(:relativePatternSupport)
-        @supports_watching_files = true
-      end
-
       @experimental_features = options.dig(:initializationOptions, :experimentalFeaturesEnabled) || false
+      @client_capabilities.apply_client_capabilities(options[:capabilities]) if options[:capabilities]
 
       addon_settings = options.dig(:initializationOptions, :addonSettings)
       if addon_settings
         addon_settings.transform_keys!(&:to_s)
         @addon_settings.merge!(addon_settings)
       end
 
-      @supports_request_delegation = options.dig(:capabilities, :experimental, :requestDelegation) || false
-      supported_resource_operations = options.dig(:capabilities, :workspace, :workspaceEdit, :resourceOperations)
-      @supported_resource_operations = supported_resource_operations if supported_resource_operations
-
-      supports_additional_properties = options.dig(
-        :capabilities,
-        :window,
-        :showMessage,
-        :messageActionItem,
-        :additionalPropertiesSupport,
-      )
-      @window_show_message_supports_extra_properties = supports_additional_properties || false
-
       notifications
     end
 

lib/ruby_lsp/internal.rb

@@ -29,6 +29,7 @@
 require "ruby_lsp/utils"
 require "ruby_lsp/static_docs"
 require "ruby_lsp/scope"
+require "ruby_lsp/client_capabilities"
 require "ruby_lsp/global_state"
 require "ruby_lsp/server"
 require "ruby_lsp/type_inferrer"

lib/ruby_lsp/requests/rename.rb

@@ -72,7 +72,7 @@ def perform
 
         # If the client doesn't support resource operations, such as renaming files, then we can only return the basic
         # text changes
-        unless @global_state.supported_resource_operations.include?("rename")
+        unless @global_state.client_capabilities.supports_rename?
           return Interface::WorkspaceEdit.new(changes: changes)
         end
 

lib/ruby_lsp/requests/request.rb

@@ -26,7 +26,7 @@ def perform; end
         ).void
       end
       def delegate_request_if_needed!(global_state, document, char_position)
-        if global_state.supports_request_delegation &&
+        if global_state.client_capabilities.supports_request_delegation &&
             document.is_a?(ERBDocument) &&
             document.inside_host_language?(char_position)
           raise DelegateRequestError

lib/ruby_lsp/server.rb

@@ -267,7 +267,7 @@ def run_initialize(message)
       send_message(Result.new(id: message[:id], response: response))
 
       # Not every client supports dynamic registration or file watching
-      if global_state.supports_watching_files
+      if @global_state.client_capabilities.supports_watching_files
         send_message(
           Request.new(
             id: @current_request_id,

test/global_state_test.rb

@@ -121,7 +121,7 @@ def test_watching_files_if_supported
           },
         },
       })
-      assert(state.supports_watching_files)
+      assert(state.client_capabilities.supports_watching_files)
     end
 
     def test_watching_files_if_not_supported
@@ -136,7 +136,7 @@ def test_watching_files_if_not_supported
           },
         },
       })
-      refute(state.supports_watching_files)
+      refute(state.client_capabilities.supports_watching_files)
     end
 
     def test_watching_files_if_not_reported
@@ -146,7 +146,7 @@ def test_watching_files_if_not_reported
           workspace: {},
         },
       })
-      refute(state.supports_watching_files)
+      refute(state.client_capabilities.supports_watching_files)
     end
 
     def test_linter_specification