Various fixes

- Add buffers being retained on full reset (CIS)
- Remove setup event, simplify
- Only have one trim listener active at once
- Disallow activate events if nothing changed (just in case)

src/BufferSet.ts

@@ -61,24 +61,35 @@ export class BufferSet extends EventEmitter implements IBufferSet {
    * Sets the normal Buffer of the BufferSet as its currently active Buffer
    */
   public activateNormalBuffer(): void {
+    if (this._activeBuffer === this._normal) {
+      return;
+    }
     // The alt buffer should always be cleared when we switch to the normal
     // buffer. This frees up memory since the alt buffer should always be new
     // when activated.
     this._alt.clear();
-
     this._activeBuffer = this._normal;
-    this.emit('activate', this._normal);
+    this.emit('activate', {
+      activeBuffer: this._normal,
+      inactiveBuffer: this._alt
+    });
   }
 
   /**
    * Sets the alt Buffer of the BufferSet as its currently active Buffer
    */
   public activateAltBuffer(): void {
+    if (this._activeBuffer === this._alt) {
+      return;
+    }
     // Since the alt buffer is always cleared when the normal buffer is
     // activated, we want to fill it when switching to it.
     this._alt.fillViewportRows();
     this._activeBuffer = this._alt;
-    this.emit('activate', this._alt);
+    this.emit('activate', {
+      activeBuffer: this._alt,
+      inactiveBuffer: this._normal
+    });
   }
 
   /**

src/SelectionManager.ts

@@ -8,7 +8,7 @@ import * as Browser from './utils/Browser';
 import { CharMeasure } from './utils/CharMeasure';
 import { CircularList } from './utils/CircularList';
 import { EventEmitter } from './EventEmitter';
-import { ITerminal, ICircularList, ISelectionManager, IBuffer } from './Interfaces';
+import { ITerminal, ICircularList, ISelectionManager, IBuffer, IListenerType } from './Interfaces';
 import { SelectionModel } from './SelectionModel';
 import { LineData, CharData } from './Types';
 import { CHAR_DATA_WIDTH_INDEX, CHAR_DATA_CHAR_INDEX } from './Buffer';
@@ -95,6 +95,7 @@ export class SelectionManager extends EventEmitter implements ISelectionManager
 
   private _mouseMoveListener: EventListener;
   private _mouseUpListener: EventListener;
+  private _trimListener: IListenerType;
 
   constructor(
     private _terminal: ITerminal,
@@ -118,28 +119,10 @@ export class SelectionManager extends EventEmitter implements ISelectionManager
   private _initListeners(): void {
     this._mouseMoveListener = event => this._onMouseMove(<MouseEvent>event);
     this._mouseUpListener = event => this._onMouseUp(<MouseEvent>event);
+    this._trimListener = (amount: number) => this._onTrim(amount);
 
-    this._updateBufferSetHandlers();
-    this._terminal.on('setup', () => {
-        this._onSetupHandler();
-    });
-  }
-
-  private _onSetupHandler(): void {
-      this.clearSelection();
-      this._updateBufferSetHandlers();
-  }
-
-  private _updateBufferSetHandlers(): void {
-      this._terminal.buffers.on('activate', (buffer: IBuffer) => {
-          this.clearSelection();
-      });
-      // Only adjust the selection on trim, shiftElements is rarely used (only in
-      // reverseIndex) and delete in a splice is only ever used when the same
-      // number of elements was just added. Given this is could actually be
-      // beneficial to leave the selection as is for these cases.
-      this._terminal.buffers.normal.lines.on('trim', (amount: number) => this._onTrim(amount));
-      this._terminal.buffers.alt.lines.on('trim', (amount: number) => this._onTrim(amount));
+    this._terminal.buffer.lines.on('trim', this._trimListener);
+    this._terminal.buffers.on('activate', e => this._onBufferActivate(e));
   }
 
   /**
@@ -556,6 +539,16 @@ export class SelectionManager extends EventEmitter implements ISelectionManager
       this._terminal.emit('selection');
   }
 
+  private _onBufferActivate(e: {activeBuffer: IBuffer, inactiveBuffer: IBuffer}): void {
+    this.clearSelection();
+    // Only adjust the selection on trim, shiftElements is rarely used (only in
+    // reverseIndex) and delete in a splice is only ever used when the same
+    // number of elements was just added. Given this is could actually be
+    // beneficial to leave the selection as is for these cases.
+    e.inactiveBuffer.lines.off('trim', this._trimListener);
+    e.activeBuffer.lines.on('trim', this._trimListener);
+  }
+
   /**
    * Converts a viewport column to the character index on the buffer line, the
    * latter takes into account wide characters.

src/Terminal.ts

@@ -292,7 +292,6 @@ export class Terminal extends EventEmitter implements ITerminal, IInputHandlingT
 
     // Create the terminal's buffers and set the current buffer
     this.buffers = new BufferSet(this);
-    this.emit('setup');
   }
 
   /**
@@ -2077,9 +2076,11 @@ export class Terminal extends EventEmitter implements ITerminal, IInputHandlingT
     this.options.cols = this.cols;
     const customKeyEventHandler = this.customKeyEventHandler;
     const inputHandler = this.inputHandler;
+    const buffers = this.buffers;
     this.setup();
     this.customKeyEventHandler = customKeyEventHandler;
     this.inputHandler = inputHandler;
+    this.buffers = buffers;
     this.refresh(0, this.rows - 1);
     this.viewport.syncScrollArea();
   }

src/utils/TestUtils.test.ts

@@ -37,7 +37,7 @@ export class MockTerminal implements ITerminal {
     throw new Error('Method not implemented.');
   }
   on(event: string, callback: () => void): void {
-    /* Simply do nothing */
+    throw new Error('Method not implemented.');
   }
   off(type: string, listener: IListenerType): void {
     throw new Error('Method not implemented.');