Replace TokenizedBuffer.setVisible with simpler .startTokenizing

We will still wait to tokenize a buffer until it is visible in *some*
tab, but we no longer enable and disable tokenization as different
editors become visible.

spec/tokenized-buffer-spec.js

@@ -23,12 +23,8 @@ describe('TokenizedBuffer', () => {
     tokenizedBuffer && tokenizedBuffer.destroy()
   })
 
-  function startTokenizing (tokenizedBuffer) {
-    tokenizedBuffer.setVisible(true)
-  }
-
   function fullyTokenize (tokenizedBuffer) {
-    tokenizedBuffer.setVisible(true)
+    tokenizedBuffer.startTokenizing()
     while (tokenizedBuffer.firstInvalidRow() != null) {
       advanceClock()
     }
@@ -67,7 +63,7 @@ describe('TokenizedBuffer', () => {
       beforeEach(() => {
         buffer = atom.project.bufferForPathSync('sample.js')
         tokenizedBuffer = new TokenizedBuffer({buffer, config, config, grammar: atom.grammars.grammarForScopeName('source.js')})
-        startTokenizing(tokenizedBuffer)
+        tokenizedBuffer.startTokenizing()
       })
 
       it('stops tokenization', () => {
@@ -83,7 +79,7 @@ describe('TokenizedBuffer', () => {
         buffer = atom.project.bufferForPathSync('sample.js')
         tokenizedBuffer = new TokenizedBuffer({buffer, config, grammar: atom.grammars.grammarForScopeName('source.js')})
         buffer.setLanguageMode(tokenizedBuffer)
-        startTokenizing(tokenizedBuffer)
+        tokenizedBuffer.startTokenizing()
       })
 
       afterEach(() => {
@@ -298,7 +294,7 @@ describe('TokenizedBuffer', () => {
 
         buffer = atom.project.bufferForPathSync('sample-with-tabs.coffee')
         tokenizedBuffer = new TokenizedBuffer({buffer, config, grammar: atom.grammars.grammarForScopeName('source.coffee')})
-        startTokenizing(tokenizedBuffer)
+        tokenizedBuffer.startTokenizing()
       })
 
       afterEach(() => {
@@ -445,7 +441,7 @@ describe('TokenizedBuffer', () => {
 
       const jsScopeStartId = grammar.startIdForScope(grammar.scopeName)
       const jsScopeEndId = grammar.endIdForScope(grammar.scopeName)
-      startTokenizing(tokenizedBuffer)
+      tokenizedBuffer.startTokenizing()
       expect(tokenizedBuffer.tokenizedLines[0]).toBeUndefined()
       expect(tokenizedBuffer.tokenizedLineForRow(0).text).toBe(line0)
       expect(tokenizedBuffer.tokenizedLineForRow(0).tags).toEqual([jsScopeStartId, line0.length, jsScopeEndId])

src/text-editor.js

@@ -953,8 +953,10 @@ class TextEditor {
 
   // Controls visibility based on the given {Boolean}.
   setVisible (visible) {
-    const languageMode = this.buffer.getLanguageMode()
-    languageMode.setVisible && languageMode.setVisible(visible)
+    if (visible) {
+      const languageMode = this.buffer.getLanguageMode()
+      if (languageMode.startTokenizing) languageMode.startTokenizing()
+    }
   }
 
   setMini (mini) {
@@ -4130,7 +4132,9 @@ class TextEditor {
     }
     const languageMode = this.buffer.getLanguageMode()
 
-    if (languageMode.setVisible) languageMode.setVisible(this.component && this.component.visible)
+    if (this.component && this.component.visible && languageMode.startTokenizing) {
+      languageMode.startTokenizing()
+    }
     this.languageModeSubscription = languageMode.onDidTokenize && languageMode.onDidTokenize(() => {
       this.emitter.emit('did-tokenize')
     })

src/tokenized-buffer.js

@@ -23,7 +23,7 @@ class TokenizedBuffer {
     this.regexesByPattern = {}
 
     this.alive = true
-    this.visible = false
+    this.tokenizationStarted = false
     this.id = params.id != null ? params.id : nextId++
     this.buffer = params.buffer
     this.largeFileMode = params.largeFileMode
@@ -255,15 +255,15 @@ class TokenizedBuffer {
     }
   }
 
-  setVisible (visible) {
-    this.visible = visible
-    if (this.visible && this.grammar.name !== 'Null Grammar' && !this.largeFileMode) {
+  startTokenizing () {
+    this.tokenizationStarted = true
+    if (this.grammar.name !== 'Null Grammar' && !this.largeFileMode) {
       this.tokenizeInBackground()
     }
   }
 
   tokenizeInBackground () {
-    if (!this.visible || this.pendingChunk || !this.alive) return
+    if (!this.tokenizationStarted || this.pendingChunk || !this.alive) return
 
     this.pendingChunk = true
     _.defer(() => {