revert to precheck pushWouldTrim

src/common/CircularList.test.ts

@@ -257,20 +257,4 @@ describe('CircularList', () => {
       assert.equal(list.get(3), 4);
     });
   });
-  describe('trimAndRecycle', function(): void {
-    it('should return correct element', function(): void {
-      const list = new CircularList<number[]>(5);
-      list.push([0]);
-      list.push([1]);
-      list.push([2]);
-      list.push([3]);
-      list.push([4]);
-      assert.equal(list.trimAndRecycle()[0], 0);
-      assert.equal(list.trimAndRecycle()[0], 1);
-      assert.equal(list.trimAndRecycle()[0], 2);
-      assert.equal(list.trimAndRecycle()[0], 3);
-      assert.equal(list.trimAndRecycle()[0], 4);
-      assert.equal(list.trimAndRecycle()[0], 0);
-    });
-  });
 });

src/common/CircularList.ts

@@ -90,10 +90,7 @@ export class CircularList<T> extends EventEmitter implements ICircularList<T> {
   public push(value: T): void {
     this._array[this._getCyclicIndex(this._length)] = value;
     if (this._length === this._maxLength) {
-      this._startIndex++;
-      if (this._startIndex === this._maxLength) {
-        this._startIndex = 0;
-      }
+      this._startIndex = ++this._startIndex % this._maxLength;
       this.emit('trim', 1);
     } else {
       this._length++;
@@ -101,18 +98,11 @@ export class CircularList<T> extends EventEmitter implements ICircularList<T> {
   }
 
   /**
-   * Recycling trim.
-   * This is used to recycle buffer lines in Terminal.scroll when
-   * the list is at maxLength as a push replacement.
-   * Returns the old line as new one to be recycled.
-   * Note: There are no bound checks for performance reasons,
-   * the method is a special optimization for Terminal.scroll,
-   * do not use it anywhere else.
+   * Whether a push would trim.
+   * True when the ringbuffer is full.
    */
-  public trimAndRecycle(): T | undefined {
-    this._startIndex = ++this._startIndex % this._maxLength;
-    this.emit('trim', 1);
-    return this._array[this._getCyclicIndex(this._length - 1)];
+  public pushWouldTrim(): boolean {
+    return this._length === this._maxLength;
   }
 
   /**

src/common/Types.ts

@@ -28,7 +28,7 @@ export interface ICircularList<T> extends IEventEmitter {
   get(index: number): T | undefined;
   set(index: number, value: T): void;
   push(value: T): void;
-  trimAndRecycle(): T | undefined;
+  pushWouldTrim(): boolean;
   pop(): T | undefined;
   splice(start: number, deleteCount: number, ...items: T[]): void;
   trimStart(count: number): void;