Method trackRange

src/shared/vscode/trackers.ts:263–308

(document: vs.TextDocument, range: Range, callback: (newRange: Range | undefined) => void)

	}

	public trackRange(document: vs.TextDocument, range: Range, callback: (newRange: Range | undefined) => void): IAmDisposable {
		let start: Position | undefined = range.start;
		let end: Position | undefined = range.end;

		// TODO(dantup): If start/end are the same, just short-cut this with one position tracker.
		// TODO(dantup): Because both the start/end positions move when content is modified before
		//  this range and we track both start/end, we end up firing once after the start moves, then
		//  the end. It would be better if we just atomically update the range once (which might
		//  mean just not using position tracker as-is?)

		const startDisposable = this.positionTracker.trackPosition(document, range.start, (newPos) => {
			start = newPos;
			updateRange();
		});

		const endDisposable = this.positionTracker.trackPosition(document, range.end, (newPos) => {
			end = newPos;
			updateRange();
		});

		const updateRange = () => {
			const newRange = (start && end) ? { start, end } : undefined;
			callback(newRange);

			// If we don't have a range because one position went away, be sure to dispose the other tracker.
			if (!newRange) {
				startDisposable.dispose();
				endDisposable.dispose();
			}
		};

		const entry: RangeTrackerEntry = {
			dispose: () => {
				startDisposable.dispose();
				endDisposable.dispose();
				const index = this.rangeTrackers.indexOf(entry);
				if (index !== -1) {
					this.rangeTrackers.splice(index, 1);
				}
			}
		};

		this.rangeTrackers.push(entry);

		return entry;
	}

	public dispose() {
		this.positionTracker.dispose();