comparison src/app/Session.ts @ 467:b963af7e6eaf

Clear undo history ahead of read pointer when updating the history.

     return item;
   }
 
   shift(): T {
     const item = this.shiftMutating();
-    this.history.push([...this.stack]);
+    this.updateHistory();
     return item;
   }
 
   unshiftMutating(item: T): number {
     this.stack = [item, ...this.stack];
     return this.stack.length;
   }
 
   unshift(item: T): number {
     const newLength = this.unshift(item);
-    this.history.push([...this.stack]);
+    this.updateHistory();
     return newLength;
   }
 
   findIndex(predicate: (value: T,
                         index: number,

     return this.stack[index];
   }
 
   set(index: number, value: T) {
     this.setMutating(index, value);
-    this.history.push([...this.stack]);
+    this.updateHistory();
   }
 
   setMutating(index: number, value: T) {
     this.stack = [
       ...this.stack.slice(0, index),

       if (!indices.includes(i)) {
         acc.push(item);
       }
       return acc;
     }, [] as T[]);
-    this.history.push([...this.stack]);
+    this.updateHistory();
   }
 
   stepBack(): void {
     const latest = this.history.length - 1;
     if (++this.historyOffset <= latest) {

     } else {
       this.historyOffset = 0;
     }
   }
 
+  updateHistory(): void {
+    if (this.historyOffset !== 0) {
+      this.history = this.history.slice(
+        0,
+        this.history.length - this.historyOffset
+      );
+      this.historyOffset = 0;
+    }
+    this.history.push([...this.stack]);
+  }
+
   toIterable(): Iterable<T> {
     return this.stack;
   }
 }