Merge pull request #805 from Shopify/vs/add_show_syntax_tree

Add show syntax tree request

Author: vinistock

lib/ruby_lsp/executor.rb

@@ -169,6 +169,8 @@ def run(request)
         completion(uri, request.dig(:params, :position))
       when "textDocument/definition"
         definition(uri, request.dig(:params, :position))
+      when "rubyLsp/textDocument/showSyntaxTree"
+        { ast: Requests::ShowSyntaxTree.new(@store.get(uri)).run }
       end
     end
 

lib/ruby_lsp/requests.rb

@@ -20,6 +20,7 @@ module RubyLsp
   # - [PathCompletion](rdoc-ref:RubyLsp::Requests::PathCompletion)
   # - [CodeLens](rdoc-ref:RubyLsp::Requests::CodeLens)
   # - [Definition](rdoc-ref:RubyLsp::Requests::Definition)
+  # - [ShowSyntaxTree](rdoc-ref:RubyLsp::Requests::ShowSyntaxTree)
 
   module Requests
     autoload :BaseRequest, "ruby_lsp/requests/base_request"
@@ -39,6 +40,7 @@ module Requests
     autoload :PathCompletion, "ruby_lsp/requests/path_completion"
     autoload :CodeLens, "ruby_lsp/requests/code_lens"
     autoload :Definition, "ruby_lsp/requests/definition"
+    autoload :ShowSyntaxTree, "ruby_lsp/requests/show_syntax_tree"
 
     # :nodoc:
     module Support

lib/ruby_lsp/requests/show_syntax_tree.rb

@@ -0,0 +1,33 @@
+# typed: strict
+# frozen_string_literal: true
+
+module RubyLsp
+  module Requests
+    # ![Show syntax tree demo](../../show_syntax_tree.gif)
+    #
+    # Show syntax tree is a custom [LSP
+    # request](https://microsoft.github.io/language-server-protocol/specification#requestMessage) that displays the AST
+    # for the current document in a new tab.
+    #
+    # # Example
+    #
+    # ```ruby
+    # # Executing the Ruby LSP: Show syntax tree command will display the AST for the document
+    # 1 + 1
+    # # (program (statements ((binary (int "1") + (int "1")))))
+    # ```
+    #
+    class ShowSyntaxTree < BaseRequest
+      extend T::Sig
+
+      sig { override.returns(String) }
+      def run
+        return "Document contains syntax error" if @document.syntax_error?
+
+        output_string = +""
+        PP.pp(@document.tree, output_string)
+        output_string
+      end
+    end
+  end
+end

misc/show_syntax_tree.gif

@@ -0,0 +1,41 @@
+# typed: true
+# frozen_string_literal: true
+
+require "test_helper"
+
+class ShowSyntaxTreeTest < Minitest::Test
+  def setup
+    @message_queue = Thread::Queue.new
+  end
+
+  def teardown
+    @message_queue.close
+  end
+
+  def test_returns_nil_if_document_has_syntax_error
+    store = RubyLsp::Store.new
+    store.set(uri: "file:///fake.rb", source: "foo do", version: 1)
+    response = RubyLsp::Executor.new(store, @message_queue).execute({
+      method: "rubyLsp/textDocument/showSyntaxTree",
+      params: { textDocument: { uri: "file:///fake.rb" } },
+    }).response
+
+    assert_equal("Document contains syntax error", response[:ast])
+  end
+
+  def test_returns_ast_if_document_is_parsed
+    store = RubyLsp::Store.new
+    store.set(uri: "file:///fake.rb", source: "foo = 123", version: 1)
+    document = store.get("file:///fake.rb")
+    document.parse
+
+    response = RubyLsp::Executor.new(store, @message_queue).execute({
+      method: "rubyLsp/textDocument/showSyntaxTree",
+      params: { textDocument: { uri: "file:///fake.rb" } },
+    }).response
+
+    assert_equal(<<~AST, response[:ast])
+      (program (statements ((assign (var_field (ident "foo")) (int "123")))))
+    AST
+  end
+end