Discard cut off combined data when resizing BufferLines

src/BufferLine.test.ts

@@ -9,6 +9,10 @@ import { NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE, DEFAULT_ATTR } from '.
 
 
 class TestBufferLine extends BufferLine {
+  public get combined(): {[index: number]: string} {
+    return this._combined;
+  }
+
   public toArray(): CharData[] {
     const result = [];
     for (let i = 0; i < this.length; ++i) {
@@ -154,6 +158,15 @@ describe('BufferLine', function(): void {
       line.resize(0, [1, 'a', 0, 'a'.charCodeAt(0)]);
       chai.expect(line.toArray()).eql(Array(0).fill([1, 'a', 0, 'a'.charCodeAt(0)]));
     });
+    it('should remove combining data', () => {
+      const line = new TestBufferLine(10, [1, 'a', 0, 'a'.charCodeAt(0)], false);
+      line.set(9, [ null, '😁', 1, '😁'.charCodeAt(0) ]);
+      chai.expect(line.translateToString()).eql('aaaaaaaaa😁');
+      chai.expect(Object.keys(line.combined).length).eql(1);
+      line.resize(5, [1, 'a', 0, 'a'.charCodeAt(0)]);
+      chai.expect(line.translateToString()).eql('aaaaa');
+      chai.expect(Object.keys(line.combined).length).eql(0);
+    });
   });
   describe('getTrimLength', function(): void {
     it('empty line', function(): void {

src/BufferLine.ts

@@ -250,8 +250,17 @@ export class BufferLine implements IBufferLine {
         const data = new Uint32Array(cols * CELL_SIZE);
         data.set(this._data.subarray(0, cols * CELL_SIZE));
         this._data = data;
+        // Remove any cut off combined data
+        const keys = Object.keys(this._combined);
+        for (let i = 0; i < keys.length; i++) {
+          const key = parseInt(keys[i], 10);
+          if (key >= cols) {
+            delete this._combined[key];
+          }
+        }
       } else {
         this._data = null;
+        this._combined = {};
       }
     }
     this.length = cols;