(GH-#187) Add a stdio mode to the language server

Author: ananace

server/README.md

@@ -111,6 +111,7 @@ Usage: puppet-languageserver.rb [options]
     -d, --no-preload                 Do not preload Puppet information when the language server starts.  Default is to preload
         --debug=DEBUG                Output debug information.  Either specify a filename or 'STDOUT'.  Default is no debug output
     -s, --slow-start                 Delay starting the TCP Server until Puppet initialisation has completed.  Default is to start fast
+        --stdio                      Runs the server in stdio mode, without a TCP listener
     -h, --help                       Prints this help
     -v, --version                    Prints the Langauge Server version
 ```

server/lib/puppet-languageserver.rb

@@ -19,6 +19,7 @@ class CommandLineParser
     def self.parse(options)
       # Set defaults here
       args = {
+        stdio: false,
         port: 8081,
         ipaddress: '127.0.0.1',
         stop_on_client_exit: true,
@@ -60,6 +61,10 @@ def self.parse(options)
           args[:fast_start_tcpserver] = false
         end
 
+        opts.on('--stdio', "Runs the server in stdio mode, without a TCP listener") do |_misc|
+          args[:stdio] = true
+        end
+
         opts.on('--local-workspace=PATH', 'The workspace or file path that will be used to provide module-specific functionality. Default is no workspace path.') do |path|
           args[:workspace] = path
         end
@@ -122,13 +127,29 @@ def self.init_puppet_worker(options)
   def self.rpc_server(options)
     log_message(:info, 'Starting RPC Server...')
 
-    server = PuppetVSCode::SimpleTCPServer.new
+    if options[:stdio]
+      $stdin.sync = true
+      $stdout.sync = true
+
+      handler = PuppetLanguageServer::MessageRouter.new
+      handler.socket = $stdout
+      handler.post_init
+
+      loop do
+        data = $stdin.readpartial(1048576)
+        raise 'Receieved an empty input string' if data.length.zero?
 
-    options[:servicename] = 'LANGUAGE SERVER'
+        handler.receive_data(data)
+      end
+    else
+      server = PuppetVSCode::SimpleTCPServer.new
 
-    server.add_service(options[:ipaddress], options[:port])
-    trap('INT') { server.stop_services(true) }
-    server.start(PuppetLanguageServer::MessageRouter, options, 2)
+      options[:servicename] = 'LANGUAGE SERVER'
+
+      server.add_service(options[:ipaddress], options[:port])
+      trap('INT') { server.stop_services(true) }
+      server.start(PuppetLanguageServer::MessageRouter, options, 2)
+    end
 
     log_message(:info, 'Language Server exited.')
   end

server/lib/puppet-languageserver/json_rpc_handler.rb

@@ -37,7 +37,7 @@ module PuppetLanguageServer
   KEY_CODE      = 'code'.freeze
   KEY_MESSAGE   = 'message'.freeze
 
-  class JSONRPCHandler < PuppetVSCode::SimpleTCPServerConnection
+  class JSONRPCHandler < PuppetVSCode::SocketConnection
     def initialize(*_options)
       @key_jsonrpc = KEY_JSONRPC
       @key_id = KEY_ID

server/lib/puppet-vscode/simple_tcp_server.rb

@@ -4,9 +4,8 @@
 # http://stackoverflow.com/questions/29858113/unable-to-make-socket-accept-non-blocking-ruby-2-2
 
 module PuppetVSCode
-  class SimpleTCPServerConnection
+  class SocketConnection
     attr_accessor :socket
-    attr_accessor :simple_tcp_server
 
     # Methods to override
     def post_init
@@ -35,6 +34,21 @@ def send_data(data)
       true
     end
 
+    # @api public
+    def close_connection_after_writing
+      true
+    end
+
+    # @api public
+    def close_connection
+      true
+    end
+  end
+
+  class SimpleTCPServerConnection < SocketConnection
+    attr_accessor :socket
+    attr_accessor :simple_tcp_server
+
     # @api public
     def close_connection_after_writing
       socket.flush