Introduce TextEditorRegistry::build

This way, we can construct text editors with the right parameters from the start

spec/text-editor-registry-spec.js

@@ -2,6 +2,7 @@
 
 import TextEditorRegistry from '../src/text-editor-registry'
 import TextEditor from '../src/text-editor'
+import TextBuffer from 'text-buffer'
 import {it, fit, ffit, fffit} from './async-spec-helpers'
 import dedent from 'dedent'
 
@@ -10,7 +11,9 @@ describe('TextEditorRegistry', function () {
 
   beforeEach(function () {
     registry = new TextEditorRegistry({
+      assert: atom.assert,
       config: atom.config,
+      clipboard: atom.clipboard,
       grammarRegistry: atom.grammars
     })
 
@@ -61,6 +64,19 @@ describe('TextEditorRegistry', function () {
     })
   })
 
+  describe('.build', function () {
+    it('constructs a TextEditor with the right parameters based on its path and text', async function () {
+      await atom.packages.activatePackage('language-javascript')
+      await atom.packages.activatePackage('language-c')
+
+      atom.config.set('editor.tabLength', 8, {scope: '.source.js'})
+
+      const editor = registry.build({buffer: new TextBuffer({filePath: 'test.js'})})
+      expect(editor.getGrammar().name).toBe("JavaScript")
+      expect(editor.getTabLength()).toBe(8)
+    })
+  })
+
   describe('.maintainGrammar', function () {
     it('assigns a grammar to the editor based on its path', async function () {
       await atom.packages.activatePackage('language-javascript')
@@ -573,7 +589,9 @@ describe('TextEditorRegistry', function () {
       const editor2Copy = TextEditor.deserialize(editor2.serialize(), atom)
 
       const registryCopy = new TextEditorRegistry({
+        assert: atom.assert,
         config: atom.config,
+        clipboard: atom.clipboard,
         grammarRegistry: atom.grammars
       })
       registryCopy.deserialize(JSON.parse(JSON.stringify(registry.serialize())))

src/atom-environment.coffee

@@ -190,7 +190,9 @@ class AtomEnvironment extends Model
 
     @commandInstaller = new CommandInstaller(@getVersion(), @applicationDelegate)
 
-    @textEditors = new TextEditorRegistry({@config, grammarRegistry: @grammars})
+    @textEditors = new TextEditorRegistry({
+      @config, grammarRegistry: @grammars, assert: @assert.bind(this), @clipboard
+    })
 
     @workspace = new Workspace({
       @config, @project, packageManager: @packages, grammarRegistry: @grammars, deserializerManager: @deserializers,

src/text-editor-registry.js

@@ -2,7 +2,8 @@
 
 import {Emitter, Disposable, CompositeDisposable} from 'event-kit'
 import {Point, Range} from 'atom'
-import NullGrammar from './null-grammar'
+import TextEditor from './text-editor'
+import ScopeDescriptor from './scope-descriptor'
 
 const EDITOR_PARAMS_BY_SETTING_KEY = [
   ['core.fileEncoding', 'encoding'],
@@ -38,7 +39,9 @@ const GRAMMAR_SELECTION_RANGE = Range(Point.ZERO, Point(10, 0)).freeze()
 // done using your editor, be sure to call `dispose` on the returned disposable
 // to avoid leaking editors.
 export default class TextEditorRegistry {
-  constructor ({config, grammarRegistry}) {
+  constructor ({config, grammarRegistry, clipboard, assert}) {
+    this.assert = assert
+    this.clipboard = clipboard
     this.config = config
     this.grammarRegistry = grammarRegistry
     this.scopedSettingsDelegate = new ScopedSettingsDelegate(config)
@@ -95,6 +98,25 @@ export default class TextEditorRegistry {
     return new Disposable(() => this.remove(editor))
   }
 
+  build (params) {
+    params = Object.assign({
+      clipboard: this.clipboard,
+      assert: this.assert
+    }, params)
+
+    let scope = null
+    if (params.buffer) {
+      const filePath = params.buffer.getPath()
+      const headContent = params.buffer.getTextInRange(GRAMMAR_SELECTION_RANGE)
+      params.grammar = this.grammarRegistry.selectGrammar(filePath, headContent)
+      scope = new ScopeDescriptor({scopes: [params.grammar.scopeName]})
+    }
+
+    Object.assign(params, this.textEditorParamsForScope(scope))
+
+    return new TextEditor(params)
+  }
+
   // Remove a `TextEditor`.
   //
   // * `editor` The editor to remove.
@@ -174,8 +196,16 @@ export default class TextEditorRegistry {
     }
 
     this.editorsWithMaintainedGrammar.add(editor)
-    if (editor.getGrammar() !== NullGrammar) {
-      this.editorGrammarOverrides[editor.id] = editor.getGrammar().scopeName
+
+    const buffer = editor.getBuffer()
+    for (let existingEditor of this.editorsWithMaintainedGrammar) {
+      if (existingEditor.getBuffer() === buffer) {
+        const existingOverride = this.editorGrammarOverrides[existingEditor.id]
+        if (existingOverride) {
+          this.editorGrammarOverrides[editor.id] = existingOverride
+        }
+        break
+      }
     }
 
     this.selectGrammarForEditor(editor)
@@ -285,17 +315,12 @@ export default class TextEditorRegistry {
   subscribeToSettingsForEditorScope (editor) {
     const scopeDescriptor = editor.getRootScopeDescriptor()
     const scopeChain = scopeDescriptor.getScopeChain()
-    const configOptions = {scope: scopeDescriptor}
 
-    const params = {}
-    for (const [settingKey, paramName] of EDITOR_PARAMS_BY_SETTING_KEY) {
-      params[paramName] = this.config.get(settingKey, configOptions)
-    }
-
-    editor.update(params)
+    editor.update(this.textEditorParamsForScope(scopeDescriptor))
 
     if (!this.scopesWithConfigSubscriptions.has(scopeChain)) {
       this.scopesWithConfigSubscriptions.add(scopeChain)
+      const configOptions = {scope: scopeDescriptor}
 
       for (const [settingKey, paramName] of EDITOR_PARAMS_BY_SETTING_KEY) {
         this.subscriptions.add(
@@ -325,6 +350,15 @@ export default class TextEditorRegistry {
       )
     }
   }
+
+  textEditorParamsForScope (scopeDescriptor) {
+    const result = {}
+    const configOptions = {scope: scopeDescriptor}
+    for (const [settingKey, paramName] of EDITOR_PARAMS_BY_SETTING_KEY) {
+      result[paramName] = this.config.get(settingKey, configOptions)
+    }
+    return result
+  }
 }
 
 function shouldEditorUseSoftTabs (editor, tabType, softTabs) {

src/workspace.coffee

@@ -561,10 +561,7 @@ class Workspace extends Model
         throw error
 
     @project.bufferForPath(filePath, options).then (buffer) =>
-      new TextEditor(Object.assign(
-        {@clipboard, @assert, buffer, largeFileMode},
-        options
-      ))
+      @textEditorRegistry.build(Object.assign({buffer, largeFileMode}, options))
 
   handleGrammarUsed: (grammar) ->
     return unless grammar?
@@ -581,7 +578,7 @@ class Workspace extends Model
   #
   # Returns a {TextEditor}.
   buildTextEditor: (params) ->
-    editor = new TextEditor(Object.assign({@clipboard, @assert}, params))
+    editor = @textEditorRegistry.build(params)
     subscriptions = new CompositeDisposable(
       @textEditorRegistry.maintainGrammar(editor)
       @textEditorRegistry.maintainConfig(editor),