Support ILink.dispose

When displaying hovers/overlays using the link provider API currently
it's not possible to know when unused links are no longer cached in
xterm.js which can result in leaked event listeners.

src/browser/Linkifier2.ts

@@ -125,6 +125,13 @@ export class Linkifier2 extends Disposable implements ILinkifier2 {
 
   private _askForLink(position: IBufferCellPosition, useLineCache: boolean): void {
     if (!this._activeProviderReplies || !useLineCache) {
+      this._activeProviderReplies?.forEach(reply => {
+        reply?.forEach(linkWithState => {
+          if (linkWithState.link.dispose) {
+            linkWithState.link.dispose();
+          }
+        });
+      });
       this._activeProviderReplies = new Map();
       this._activeLine = position.y;
     }

src/browser/Types.d.ts

@@ -275,6 +275,7 @@ interface ILink {
   activate(event: MouseEvent, text: string): void;
   hover?(event: MouseEvent, text: string): void;
   leave?(event: MouseEvent, text: string): void;
+  dispose?(): void;
 }
 
 interface ILinkDecorations {

test/api/Terminal.api.ts

@@ -755,6 +755,55 @@ describe('API Integration Tests', function(): void {
       await pollFor(page, `window.calls`, ['provide 1', 'hover 1-3', 'leave 1-3', 'hover 5-7', 'leave 5-7', 'provide 2', 'provide 1', 'hover 9-11']);
       await page.evaluate(`window.disposable.dispose()`);
     });
+
+    it('should dispose links when hovering away', async () => {
+      await openTerminal(page, { rendererType: 'dom' });
+      await writeSync(page, 'foo bar baz');
+      // Wait for renderer to catch up as links are cleared on render
+      await pollFor(page, `document.querySelector('.xterm-rows').textContent`, 'foo bar baz ');
+      await page.evaluate(`
+        window.calls = [];
+        window.disposable = window.term.registerLinkProvider({
+          provideLinks: (position, cb) => {
+            window.calls.push('provide ' + position);
+            if (position === 1) {
+              cb([{
+                range: { start: { x: 1, y: 1 }, end: { x: 3, y: 1 } },
+                text: '',
+                activate: () => window.calls.push('activate'),
+                dispose: () => window.calls.push('dispose 1-3'),
+                hover: () => window.calls.push('hover 1-3'),
+                leave: () => window.calls.push('leave 1-3')
+              }, {
+                range: { start: { x: 5, y: 1 }, end: { x: 7, y: 1 } },
+                text: '',
+                activate: () => window.calls.push('activate'),
+                dispose: () => window.calls.push('dispose 5-7'),
+                hover: () => window.calls.push('hover 5-7'),
+                leave: () => window.calls.push('leave 5-7')
+              }, {
+                range: { start: { x: 9, y: 1 }, end: { x: 11, y: 1 } },
+                text: '',
+                activate: () => window.calls.push('activate'),
+                dispose: () => window.calls.push('dispose 9-11'),
+                hover: () => window.calls.push('hover 9-11'),
+                leave: () => window.calls.push('leave 9-11')
+              }]);
+            }
+          }
+        });
+      `);
+      const dims = await getDimensions();
+      await moveMouseCell(page, dims, 2, 1);
+      await pollFor(page, `window.calls`, ['provide 1', 'hover 1-3']);
+      await moveMouseCell(page, dims, 6, 1);
+      await pollFor(page, `window.calls`, ['provide 1', 'hover 1-3', 'leave 1-3', 'hover 5-7']);
+      await moveMouseCell(page, dims, 6, 2);
+      await pollFor(page, `window.calls`, ['provide 1', 'hover 1-3', 'leave 1-3', 'hover 5-7', 'leave 5-7', 'dispose 1-3', 'dispose 5-7', 'dispose 9-11', 'provide 2']);
+      await moveMouseCell(page, dims, 10, 1);
+      await pollFor(page, `window.calls`, ['provide 1', 'hover 1-3', 'leave 1-3', 'hover 5-7', 'leave 5-7', 'dispose 1-3', 'dispose 5-7', 'dispose 9-11', 'provide 2', 'provide 1', 'hover 9-11']);
+      await page.evaluate(`window.disposable.dispose()`);
+    });
   });
 });
 

typings/xterm.d.ts

@@ -1158,6 +1158,11 @@ declare module 'xterm' {
      * @param text The text of the link.
      */
     leave?(event: MouseEvent, text: string): void;
+
+    /**
+     * Called when the link is released and no longer used by xterm.js.
+     */
+    dispose?(): void;
   }
 
   /**