BitsetsNET.RLEBitset.AndWith C# (CSharp) Method

        public void AndWith(IBitset otherSet)
        {
            RLEBitset otherRLESet = (RLEBitset)otherSet; // cast to an RLEBitset

            List<Run> runsA = this.runArray;
            List<Run> runsB = otherRLESet.runArray;

            int i = 0;
            int j = 0;

            while (i < runsA.Count && j < runsB.Count)
            {
                int x = runsA[i].StartIndex;
                int y = runsA[i].EndIndex;
                int w = runsB[j].StartIndex;
                int z = runsB[j].EndIndex;

                if (x < w)
                {
                    if (y < w)
                    {
                        runsA.RemoveAt(i);
                    }
                    else // (y >= w)
                    {
                        // crops the current run in runsA from the left to align with
                        // the start of the current run in runsB
                        Run ithRun = runsA[i];
                        ithRun.StartIndex = w;
                        runsA[i] = ithRun;
                        var what = this.runArray[i];
                        if (y <= z)
                        {
                            i++;
                        }
                        else // (y > z )
                        {
                            // splits the run from runsA into two runs
                            Run newRun =  new Run(z + 1, y);
                            Run newRun2 = runsA[i];
                            newRun2.EndIndex = z;
                            runsA[i] = newRun2;
                            runsA.Insert(i + 1, newRun);
                            i++;
                            j++;
                        }
                    }
                }
                else // (x >= w)
                {
                    if (y <= z)
                    {
                        i++;
                    }
                    else // (y > z)
                    {
                        if (x <= z)
                        {
                            // splits the run from runsA into two runs
                            Run newRun = new Run(z + 1, y);
                            Run newRun2 = runsA[i];
                            newRun2.EndIndex = z;
                            runsA[i] = newRun2;
                            runsA.Insert(i + 1, newRun);
                            i++;
                            j++;
                        }
                        else
                        {
                            j++;
                        }
                    }
                }
            }
            //this truncates runsA if we've considered all of the runs in runsB
            this.runArray = this.runArray.Take(i).ToList();
        }