private static _commonPrefix(a: ITextModel, aLen: number, aDelta: number, b: ITextBuffer, bLen: number, bDelta: number): number {
let result = 0;
for (let i = 0; i < maxResult && a.getLineContent(aDelta + i) === b.getLineContent(bDelta + i); i++) {
result++;
}
}
private static _commonSuffix(a: ITextModel, aLen: number, aDelta: number, b: ITextBuffer, bLen: number, bDelta: number): number {