Give Task an RPC-style interaction with its Worker

This commit makes all interactions between Task and Worker look
like method calls. The worker now has a global `callTaskMethod`
function that it can use to call methods on the Task object. And the
Task can use `callWorkerMethod` to call methods on a global `handler`
object in the worker. The worker's initial `handler` actually contains
the `start` method, which the Task initially calls to kick things off.
Then the global `handler` gets replaced with whatever `handlerPath`
is specified by the Task. The worker then calls `workerStarted` on its
parent Task object.

This commit also gets rid of the `onProgress` method with the reply
semantics, favoring a more explicit interaction. When `snippetsLoaded`
finishes adding the snippet data, we call `loadNextPackageSnippets`
explicitly rather than returning a reply message.

src/packages/snippets/index.coffee

@@ -4,7 +4,7 @@ PEG = require 'pegjs'
 _ = require 'underscore'
 SnippetExpansion = require './src/snippet-expansion'
 Snippet = require './src/snippet'
-SnippetsTask = require './src/snippets-task'
+SnippetsTask = require './src/load-snippets-task'
 
 module.exports =
 class Snippets extends AtomPackage

src/packages/snippets/spec/snippets-spec.coffee

@@ -1,6 +1,6 @@
 Snippets = require 'snippets'
 Snippet = require 'snippets/src/snippet'
-SnippetsTask = require 'snippets/src/snippets-task'
+LoadSnippetsTask = require 'snippets/src/load-snippets-task'
 RootView = require 'root-view'
 Buffer = require 'buffer'
 Editor = require 'editor'
@@ -11,7 +11,7 @@ describe "Snippets extension", ->
   [buffer, editor] = []
   beforeEach ->
     rootView = new RootView(require.resolve('fixtures/sample.js'))
-    spyOn(SnippetsTask.prototype, 'start')
+    spyOn(LoadSnippetsTask.prototype, 'start')
     atom.loadPackage("snippets")
     editor = rootView.getActiveEditor()
     buffer = editor.getBuffer()
@@ -214,7 +214,7 @@ describe "Snippets extension", ->
   describe "snippet loading", ->
     it "loads non-hidden snippet files from all atom packages with snippets directories, logging a warning if a file can't be parsed", ->
       spyOn(console, 'warn').andCallThrough()
-      jasmine.unspy(SnippetsTask.prototype, 'start')
+      jasmine.unspy(LoadSnippetsTask.prototype, 'start')
       snippets.loaded = false
       snippets.loadAll()
 
@@ -228,7 +228,7 @@ describe "Snippets extension", ->
         expect(console.warn.calls.length).toBeGreaterThan 0
 
     it "loads snippets from all TextMate packages with snippets", ->
-      jasmine.unspy(SnippetsTask.prototype, 'start')
+      jasmine.unspy(LoadSnippetsTask.prototype, 'start')
       snippets.loaded = false
       snippets.loadAll()
 

src/packages/snippets/src/load-snippets-handler.coffee

@@ -1,15 +1,13 @@
+fs = require 'fs'
+
 module.exports =
-  loadTextmateSnippets: ({path}) ->
-    fs = require 'fs'
+  loadTextmateSnippets: (path) ->
     snippetsDirPath = fs.join(path, 'Snippets')
     snippets = fs.list(snippetsDirPath).map (snippetPath) ->
       fs.readPlist(snippetPath)
-    self.postMessage
-      type: 'loadSnippets'
-      snippets: snippets
+    @snippetsLoaded(snippets)
 
-  loadAtomSnippets: ({path}) ->
-    fs = require 'fs'
+  loadAtomSnippets: (path) ->
     snippetsDirPath = fs.join(path, 'snippets')
     snippets = []
     for snippetsPath in fs.list(snippetsDirPath)
@@ -18,6 +16,6 @@ module.exports =
         snippets.push(fs.readObject(snippetsPath))
       catch e
         console.warn "Error reading snippets file '#{snippetsPath}'"
-    self.postMessage
-      type: 'loadSnippets'
-      snippets: snippets
+    @snippetsLoaded(snippets)
+
+  snippetsLoaded: (snippets) -> callTaskMethod('snippetsLoaded', snippets)

src/packages/snippets/src/load-snippets-task.coffee

@@ -0,0 +1,42 @@
+Task = require 'Task'
+TextMatePackage = require 'text-mate-package'
+
+module.exports =
+class LoadSnippetsTask extends Task
+  constructor: (@snippets) ->
+    super('snippets/src/load-snippets-handler')
+    @packages = atom.getPackages()
+    @packages.push(path: config.configDirPath)
+
+  started: ->
+    @loadNextPackageSnippets()
+
+  loadNextPackageSnippets: ->
+    unless @packages.length
+      @snippets.loaded = true
+      return
+
+    @packageBeingLoaded = @packages.shift()
+    if @packageBeingLoaded instanceof TextMatePackage
+      method = 'loadTextmateSnippets'
+    else
+      method = 'loadAtomSnippets'
+    @callWorkerMethod(method, @packageBeingLoaded.path)
+
+  snippetsLoaded: (snippets) ->
+    if @packageBeingLoaded instanceof TextMatePackage
+      snippets = @translateTextmateSnippets(snippets)
+    @snippets.add(snippet) for snippet in snippets
+    @loadNextPackageSnippets()
+
+  translateTextmateSnippets: (tmSnippets) ->
+    atomSnippets = {}
+    for { scope, name, content, tabTrigger } in tmSnippets
+      if scope
+        scope = TextMatePackage.cssSelectorFromScopeSelector(scope)
+      else
+        scope = '*'
+
+      snippetsForScope = (atomSnippets[scope] ?= {})
+      snippetsForScope[name] = { prefix: tabTrigger, body: content }
+    [atomSnippets]

src/packages/snippets/src/snippets-task.coffee

@@ -1,42 +0,0 @@
-Task = require 'task'
-TextMatePackage = require 'text-mate-package'
-
-module.exports =
-class SnippetsTask extends Task
-
-  constructor: (@snippets) ->
-    super('snippets/src/snippets-reader')
-
-    @packages = atom.getPackages()
-    @packages.push(path: config.configDirPath)
-
-  onProgress: (event) =>
-    if event.data.type is 'loadSnippets'
-      rawSnippets = event.data.snippets
-      if @package instanceof TextMatePackage
-        @snippets.add(@translateTextmateSnippets(rawSnippets))
-      else
-        @snippets.add(snippet) for snippet in rawSnippets
-
-    @package = @packages.shift()
-    if not @package?
-      @snippets.loaded = true
-      return
-
-    if @package instanceof TextMatePackage
-      eventType = 'loadTextmateSnippets'
-    else
-      eventType = 'loadAtomSnippets'
-    { type: eventType, path: @package.path }
-
-  translateTextmateSnippets: (tmSnippets) ->
-    atomSnippets = {}
-    for { scope, name, content, tabTrigger } in tmSnippets
-      if scope
-        scope = TextMatePackage.cssSelectorFromScopeSelector(scope)
-      else
-        scope = '*'
-
-      snippetsForScope = (atomSnippets[scope] ?= {})
-      snippetsForScope[name] = { prefix: tabTrigger, body: content }
-    atomSnippets

src/stdlib/task-shell.coffee

@@ -1,21 +1,29 @@
+# This file is loaded within Task's worker thread. It will attempt to invoke
+# any message with a 'method' and 'args' key on the global `handler` object. The
+# initial `handler` object contains the `start` method, which is called by the
+# task itself to relay information from the window thread and bootstrap the
+# worker's environment. The `start` method then replaces the handler with an
+# object required from the given `handlerPath`.
+
 self.window = {}
 self.attachEvent = ->
 self.console =
-  warn: ->
-    self.postMessage
-      type: 'warn'
-      details: arguments
-  log: ->
-    self.postMessage
-      type: 'log'
-      details: arguments
+  warn: -> callTaskMethod 'warn', arguments...
+  log: -> callTaskMethod 'log', arguments...
+  error: -> callTaskMethod 'error', arguments...
 
-self.addEventListener 'message', (event) ->
-  switch event.data.type
-    when 'start'
-      window.resourcePath = event.data.resourcePath
-      importScripts(event.data.requirePath)
-      self.task = require(event.data.taskPath)
-      self.postMessage(type:'started')
-    else
-      self.task[event.data.type](event.data)
+# `callTaskMethod` can be used to invoke method's on the parent `Task` object
+# back in the window thread.
+self.callTaskMethod = (method, args...) ->
+  postMessage(method: method, args: args)
+
+# The worker's initial handler replaces itself when `start` is invoked
+self.handler =
+  start: ({resourcePath, requirePath, handlerPath}) ->
+    window.resourcePath = resourcePath
+    importScripts(requirePath)
+    self.handler = require(handlerPath)
+    callTaskMethod 'started'
+
+self.addEventListener 'message', ({data}) ->
+  handler[data.method]?(data.args...) if data.method

src/stdlib/task.coffee

@@ -1,26 +1,32 @@
 module.exports =
 class Task
-
   constructor: (@path) ->
 
-  onProgress: (event) ->
-
   start: ->
-    worker = new Worker(require.getPath('task-shell'))
-    worker.onmessage = (event) =>
-      switch event.data.type
-        when 'warn'
-          console.warn(event.data.details...)
-          return
-        when 'log'
-          console.log(event.data.details...)
-          return
+    @worker = new Worker(require.getPath('task-shell'))
+    @worker.onmessage = ({data}) =>
+      if data.method and this[data.method]
+        this[data.method](data.args...)
+      else
+        @onMessage(data)
+    @startWorker()
 
-      reply = @onProgress(event)
-      worker.postMessage(reply) if reply
+  log: -> console.log(arguments...)
+  warn: -> console.warn(arguments...)
+  error: -> console.error(arguments...)
 
-    worker.postMessage
-      type: 'start'
+  startWorker: ->
+    @callWorkerMethod 'start'
       resourcePath: window.resourcePath
       requirePath: require.getPath('require')
-      taskPath: @path
+      handlerPath: @path
+
+  started: ->
+
+  onMessage: (message) ->
+
+  callWorkerMethod: (method, args...) ->
+    @postMessage({method, args})
+
+  postMessage: (data) ->
+    @worker.postMessage(data)