Make sure the Server CLI Runner can pick up changes in sources

* We change the API here, now the provided builder is a proc that
  returns a new Builder instance which will always correspond to an
  up-to-date code.
* As a result - now the server runner will supply an up-to-date code
  each refresh.
* Also refactors the Server CLI Runner to use Opal::SimpleServer.
* Ensure files are rewinded as they need to be re-read at each refresh

lib/opal/cli.rb

@@ -48,14 +48,12 @@ def initialize(options = nil)
 
       @requires.unshift('opal') unless options.delete(:skip_opal_require)
 
-      @compiler_options = Hash[
-        *compiler_option_names.map do |option|
-          key = option.to_sym
-          next unless options.key? key
-          value = options.delete(key)
-          [key, value]
-        end.compact.flatten
-      ]
+      @compiler_options = compiler_option_names.map do |option|
+        key = option.to_sym
+        next unless options.key? key
+        value = options.delete(key)
+        [key, value]
+      end.compact.to_h
 
       raise ArgumentError, 'no libraries to compile' if @lib_only && @requires.empty?
       raise ArgumentError, 'no runnable code provided (evals or file)' if @evals.empty? && @file.nil? && !@lib_only
@@ -68,6 +66,16 @@ def run
       return debug_source_map if @debug_source_map
       return run_repl if @repl
 
+      rbrequires.each { |file| require file }
+
+      runner = self.runner
+
+      # Some runners may need to use a dynamic builder, that is,
+      # a builder that will try to build the entire package every time
+      # a page is loaded - for example a Server runner that needs to
+      # rerun if files are changed.
+      builder = proc { create_builder }
+
       @exit_status = runner.call(
         options: runner_options,
         output: output,
@@ -90,13 +98,7 @@ def run_repl
 
     attr_reader :exit_status
 
-    def builder
-      @builder ||= create_builder
-    end
-
     def create_builder
-      rbrequires.each(&Kernel.method(:require))
-
       builder = Opal::Builder.new(
         stubs: stubs,
         compiler_options: compiler_options,
@@ -181,6 +183,7 @@ def evals_or_file
       if evals.any?
         yield evals.join("\n"), '-e'
       elsif file && (filename != '-' || evals.empty?)
+        file.rewind
         yield file.read, filename
       end
     end

lib/opal/cli_runners.rb

@@ -10,7 +10,8 @@ module Opal
   # - `output`: an IO-like object responding to `#write` and `#puts`
   # - `argv`: is the arguments vector coming from the CLI that is being
   #     forwarded to the program
-  # - `builder`: the current instance of Opal::Builder
+  # - `builder`: a proc returning a new instance of Opal::Builder so it
+  #     can be re-created and pick up the most up-to-date sources
   #
   # Runners can be registered using `#register_runner(name, runner)`.
   #
@@ -21,7 +22,7 @@ class RunnerError < StandardError
     @register = {}
 
     def self.[](name)
-      @register[name.to_sym]
+      @register[name.to_sym]&.call
     end
 
     # @private
@@ -44,18 +45,18 @@ def self.to_h
     def self.register_runner(name, runner, path = nil)
       autoload runner, path if path
 
-      if runner.respond_to?(:call)
-        self[name] = runner
+      if runner.respond_to? :call
+        self[name] = -> { runner }
       else
-        self[name] = ->(data) { const_get(runner).call(data) }
+        self[name] = -> { const_get(runner) }
       end
 
       nil
     end
 
     # Alias a runner name
     def self.alias_runner(new_name, old_name)
-      self[new_name.to_sym] = self[old_name.to_sym]
+      self[new_name.to_sym] = -> { self[old_name.to_sym] }
 
       nil
     end

lib/opal/cli_runners/chrome.rb

@@ -20,7 +20,7 @@ def self.call(data)
       end
 
       def initialize(data)
-        builder = data[:builder]
+        builder = data[:builder].call
         options = data[:options]
         argv    = data[:argv]
 

lib/opal/cli_runners/compiler.rb

@@ -5,7 +5,7 @@
 # The compiler runner will just output the compiled JavaScript
 Opal::CliRunners::Compiler = ->(data) {
   options  = data[:options] || {}
-  builder  = data.fetch(:builder)
+  builder  = data.fetch(:builder).call
   map_file = options[:map_file]
   output   = data.fetch(:output)
 

lib/opal/cli_runners/gjs.rb

@@ -10,11 +10,12 @@ module CliRunners
     class Gjs
       def self.call(data)
         exe = ENV['GJS_PATH'] || 'gjs'
+        builder = data[:builder].call
 
         opts = Shellwords.shellwords(ENV['GJS_OPTS'] || '')
-        opts.unshift('-m') if data[:builder].esm?
+        opts.unshift('-m') if builder.esm?
 
-        SystemRunner.call(data) do |tempfile|
+        SystemRunner.call(data.merge(builder: -> { builder })) do |tempfile|
           [exe, *opts, tempfile.path, *data[:argv]]
         end
       rescue Errno::ENOENT

lib/opal/cli_runners/mini_racer.rb

@@ -9,7 +9,7 @@ class MiniRacer
       def self.call(data)
         ::MiniRacer::Platform.set_flags! :harmony
 
-        builder = data.fetch(:builder)
+        builder = data.fetch(:builder).call
         output = data.fetch(:output)
         # TODO: pass it
         argv = data.fetch(:argv)

lib/opal/cli_runners/server.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'opal/simple_server'
+
 module Opal
   module CliRunners
     class Server
@@ -11,9 +13,8 @@ def self.call(data)
 
       def initialize(data)
         options = data[:options] || {}
-        builder = data[:builder]
+        @builder = data[:builder]
 
-        @code = builder.to_s + "\n" + builder.source_map.to_data_uri_comment
         @argv = data[:argv] || []
 
         @output = data[:output] || $stdout
@@ -25,7 +26,7 @@ def initialize(data)
         @static_folder = File.expand_path(@static_folder) if @static_folder
       end
 
-      attr_reader :output, :port, :server, :static_folder, :code, :argv
+      attr_reader :output, :port, :server, :static_folder, :builder, :argv
 
       def run
         unless argv.empty?
@@ -35,7 +36,7 @@ def run
         require 'rack'
         require 'logger'
 
-        app = build_app(code)
+        app = build_app(builder)
 
         @server = Rack::Server.start(
           app:       app,
@@ -49,8 +50,8 @@ def exit_status
         nil
       end
 
-      def build_app(source)
-        app = App.new(source)
+      def build_app(builder)
+        app = App.new(builder: builder, main: 'cli-runner')
 
         if static_folder
           not_found = [404, {}, []]
@@ -65,30 +66,14 @@ def build_app(source)
         app
       end
 
-      class App
-        def initialize(source)
-          @source = source
+      class App < SimpleServer
+        def initialize(options = {})
+          @builder = options.fetch(:builder)
+          super
         end
 
-        BODY = <<-HTML
-          <!doctype html>
-          <html>
-            <head>
-              <meta charset="utf-8"/>
-              <script src="/cli_runner.js"></script>
-            </head>
-          </html>
-        HTML
-
-        def call(env)
-          case env['PATH_INFO']
-          when '/'
-            [200, { 'Content-Type' => 'text/html' }, [BODY]]
-          when '/cli_runner.js'
-            [200, { 'Content-Type' => 'text/javascript' }, [@source]]
-          else
-            [404, {}, ['not found']]
-          end
+        def builder(_)
+          @builder.call
         end
       end
     end

lib/opal/cli_runners/system_runner.rb

@@ -13,7 +13,7 @@
 # @yieldreturn command [Array<String>] the command to be used in the system call
 SystemRunner = ->(data, &block) {
   options  = data[:options] || {}
-  builder  = data.fetch(:builder)
+  builder  = data.fetch(:builder).call
   output   = data.fetch(:output)
 
   env      = options.fetch(:env, {})

lib/opal/simple_server.rb

@@ -11,6 +11,8 @@
 #
 # @example (CLI)
 #   rackup -ropal -ropal/simple_server -b 'Opal.append_path("app"); run Opal::SimpleServer.new'
+#   ... or use the Server runner ...
+#   opal -Rserver app.rb
 class Opal::SimpleServer
   require 'set'
   require 'erb'
@@ -54,13 +56,16 @@ def call_js(path)
     ]
   end
 
-  def fetch_asset(path)
+  def builder(path)
     builder = Opal::Builder.new
     builder.build(path.gsub(/(\.(?:rb|js|opal))*\z/, ''))
+  end
+
+  def fetch_asset(path)
+    builder = self.builder(path)
     {
       data: builder.to_s,
-      map: builder.source_map,
-      source: builder.source_for(path),
+      map: builder.source_map
     }
   end
 

spec/lib/cli_runners/server_spec.rb

@@ -15,11 +15,10 @@ def app
       expect(options[:Port]).to eq(1234)
     end
 
-    builder = Opal::Builder.new
-    builder.build_str("puts 123", "app.rb")
+    builder = -> { Opal::Builder.new.build_str("puts 123", "app.rb") }
     described_class.call(builder: builder, options: {port: 1234})
 
-    get '/cli_runner.js'
+    get '/assets/cli_runner.js'
     expect(last_response.body).to include(".$puts(123)")
   end
 end

spec/lib/cli_spec.rb

@@ -138,7 +138,7 @@
       let(:options)  { {:gems => [gem_name], :evals => ['']} }
 
       it "adds the gem's lib paths to Opal.path" do
-        builder = cli.builder
+        builder = cli.create_builder
 
         spec = Gem::Specification.find_by_name(gem_name)
         spec.require_paths.each do |require_path|