Add Workspace::observeActiveTextEditor()

src/workspace.js

@@ -216,6 +216,7 @@ module.exports = class Workspace extends Model {
       bottom: this.createDock('bottom')
     }
     this.activePaneContainer = this.paneContainers.center
+    this.activeTextEditor = null
 
     this.panelContainers = {
       top: new PanelContainer({viewRegistry: this.viewRegistry, location: 'top'}),
@@ -422,6 +423,17 @@ module.exports = class Workspace extends Model {
       this.didChangeActivePaneItem(item)
       this.emitter.emit('did-change-active-pane-item', item)
     }
+
+    if (paneContainer === this.getCenter()) {
+      const activeTextEditorChanged =
+        (item instanceof TextEditor) || (this.activeTextEditor instanceof TextEditor)
+
+      if (activeTextEditorChanged) {
+        this.activeTextEditor = (item instanceof TextEditor) ? item : null
+        const itemValue = (item instanceof TextEditor) ? item : undefined
+        this.emitter.emit('did-change-active-text-editor', itemValue)
+      }
+    }
   }
 
   didChangeActivePaneItem (item) {
@@ -648,6 +660,10 @@ module.exports = class Workspace extends Model {
     return this.emitter.on('did-stop-changing-active-pane-item', callback)
   }
 
+  onDidChangeActiveTextEditor (callback) {
+    return this.emitter.on('did-change-active-text-editor', callback)
+  }
+
   // Essential: Invoke the given callback with the current active pane item and
   // with all future active pane items in the workspace.
   //
@@ -660,6 +676,13 @@ module.exports = class Workspace extends Model {
     return this.onDidChangeActivePaneItem(callback)
   }
 
+  observeActiveTextEditor (callback) {
+    const activeTextEditor = this.getActiveTextEditor()
+    if (activeTextEditor != null) { callback(activeTextEditor) }
+
+    return this.onDidChangeActiveTextEditor(callback)
+  }
+
   // Essential: Invoke the given callback whenever an item is opened. Unlike
   // {::onDidAddPaneItem}, observers will be notified for items that are already
   // present in the workspace when they are reopened.