src/vs/editor/common/cursor/cursor.ts/CompositionState/deduceOutcome
class CompositionState:	deduceOutcome(textModel: ITextModel, selections: Selection[]): CompositionOutcome[] | null {
		if (!this._original) {
			return null;
		}
		const current = CompositionState._capture(textModel, selections);
		if (!current) {
			return null;
		}
		if (this._original.length !== current.length) {
			return null;
		}
		const result: CompositionOutcome[] = [];
		for (let i = 0, len = this._original.length; i < len; i++) {
			result.push(CompositionState._deduceOutcome(this._original[i], current[i]));
		}
		return result;
	}