difftools.cs

YetAnotherForum.Net+ScrewTurnWiki中文完美汉化增强版

			int Delta = (UpperA - LowerA) - (UpperB - LowerB);
			bool oddDelta = (Delta & 1) != 0;

			/// vector for the (0,0) to (x,y) search
			int[] DownVector = new int[2 * MAX + 2];

			/// vector for the (u,v) to (N,M) search
			int[] UpVector = new int[2 * MAX + 2];

			// The vectors in the publication accepts negative indexes. the vectors implemented here are 0-based
			// and are access using a specific offset: UpOffset UpVector and DownOffset for DownVektor
			int DownOffset = MAX - DownK;
			int UpOffset = MAX - UpK;

			int MaxD = ((UpperA - LowerA + UpperB - LowerB) / 2) + 1;

			// Debug.Write(2, "SMS", String.Format("Search the box: A[{0}-{1}] to B[{2}-{3}]", LowerA, UpperA, LowerB, UpperB));

			// init vectors
			DownVector[DownOffset + DownK + 1] = LowerA;
			UpVector[UpOffset + UpK - 1] = UpperA;

			for(int D = 0; D <= MaxD; D++) {

				// Extend the forward path.
				for(int k = DownK - D; k <= DownK + D; k += 2) {
					// Debug.Write(0, "SMS", "extend forward path " + k.ToString());

					// find the only or better starting point
					int x, y;
					if(k == DownK - D) {
						x = DownVector[DownOffset + k + 1]; // down
					}
					else {
						x = DownVector[DownOffset + k - 1] + 1; // a step to the right
						if((k < DownK + D) && (DownVector[DownOffset + k + 1] >= x))
							x = DownVector[DownOffset + k + 1]; // down
					}
					y = x - k;

					// find the end of the furthest reaching forward D-path in diagonal k.
					while((x < UpperA) && (y < UpperB) && (DataA.data[x] == DataB.data[y])) {
						x++; y++;
					}
					DownVector[DownOffset + k] = x;

					// overlap ?
					if(oddDelta && (UpK - D < k) && (k < UpK + D)) {
						if(UpVector[UpOffset + k] <= DownVector[DownOffset + k]) {
							ret.x = DownVector[DownOffset + k];
							ret.y = DownVector[DownOffset + k] - k;
							// ret.u = UpVector[UpOffset + k];      // 2002.09.20: no need for 2 points 
							// ret.v = UpVector[UpOffset + k] - k;
							return (ret);
						} // if
					} // if

				} // for k

				// Extend the reverse path.
				for(int k = UpK - D; k <= UpK + D; k += 2) {
					// Debug.Write(0, "SMS", "extend reverse path " + k.ToString());

					// find the only or better starting point
					int x, y;
					if(k == UpK + D) {
						x = UpVector[UpOffset + k - 1]; // up
					}
					else {
						x = UpVector[UpOffset + k + 1] - 1; // left
						if((k > UpK - D) && (UpVector[UpOffset + k - 1] < x))
							x = UpVector[UpOffset + k - 1]; // up
					} // if
					y = x - k;

					while((x > LowerA) && (y > LowerB) && (DataA.data[x - 1] == DataB.data[y - 1])) {
						x--; y--; // diagonal
					}
					UpVector[UpOffset + k] = x;

					// overlap ?
					if(!oddDelta && (DownK - D <= k) && (k <= DownK + D)) {
						if(UpVector[UpOffset + k] <= DownVector[DownOffset + k]) {
							ret.x = DownVector[DownOffset + k];
							ret.y = DownVector[DownOffset + k] - k;
							// ret.u = UpVector[UpOffset + k];     // 2002.09.20: no need for 2 points 
							// ret.v = UpVector[UpOffset + k] - k;
							return (ret);
						} // if
					} // if

				} // for k

			} // for D

			throw new ApplicationException("the algorithm should never come here.");
		} // SMS


		/// <summary>
		/// This is the divide-and-conquer implementation of the longes common-subsequence (LCS) 
		/// algorithm.
		/// The published algorithm passes recursively parts of the A and B sequences.
		/// To avoid copying these arrays the lower and upper bounds are passed while the sequences stay constant.
		/// </summary>
		/// <param name="DataA">sequence A</param>
		/// <param name="LowerA">lower bound of the actual range in DataA</param>
		/// <param name="UpperA">upper bound of the actual range in DataA (exclusive)</param>
		/// <param name="DataB">sequence B</param>
		/// <param name="LowerB">lower bound of the actual range in DataB</param>
		/// <param name="UpperB">upper bound of the actual range in DataB (exclusive)</param>
		private static void LCS(DiffData DataA, int LowerA, int UpperA, DiffData DataB, int LowerB, int UpperB) {
			// Debug.Write(2, "LCS", String.Format("Analyse the box: A[{0}-{1}] to B[{2}-{3}]", LowerA, UpperA, LowerB, UpperB));

			// Fast walkthrough equal lines at the start
			while(LowerA < UpperA && LowerB < UpperB && DataA.data[LowerA] == DataB.data[LowerB]) {
				LowerA++; LowerB++;
			}

			// Fast walkthrough equal lines at the end
			while(LowerA < UpperA && LowerB < UpperB && DataA.data[UpperA - 1] == DataB.data[UpperB - 1]) {
				--UpperA; --UpperB;
			}

			if(LowerA == UpperA) {
				// mark as inserted lines.
				while(LowerB < UpperB)
					DataB.modified[LowerB++] = true;

			}
			else if(LowerB == UpperB) {
				// mark as deleted lines.
				while(LowerA < UpperA)
					DataA.modified[LowerA++] = true;

			}
			else {
				// Find the middle snakea and length of an optimal path for A and B
				SMSRD smsrd = SMS(DataA, LowerA, UpperA, DataB, LowerB, UpperB);
				// Debug.Write(2, "MiddleSnakeData", String.Format("{0},{1}", smsrd.x, smsrd.y));

				// The path is from LowerX to (x,y) and (x,y) ot UpperX
				LCS(DataA, LowerA, smsrd.x, DataB, LowerB, smsrd.y);
				LCS(DataA, smsrd.x, UpperA, DataB, smsrd.y, UpperB);  // 2002.09.20: no need for 2 points 
			}
		} // LCS()


		/// <summary>Scan the tables of which lines are inserted and deleted,
		/// producing an edit script in forward order.  
		/// </summary>
		/// dynamic array
		private static Item[] CreateDiffs(DiffData DataA, DiffData DataB) {
			ArrayList a = new ArrayList();
			Item aItem;
			Item[] result;

			int StartA, StartB;
			int LineA, LineB;

			LineA = 0;
			LineB = 0;
			while(LineA < DataA.Length || LineB < DataB.Length) {
				if((LineA < DataA.Length) && (!DataA.modified[LineA])
				  && (LineB < DataB.Length) && (!DataB.modified[LineB])) {
					// equal lines
					LineA++;
					LineB++;

				}
				else {
					// maybe deleted and/or inserted lines
					StartA = LineA;
					StartB = LineB;

					while(LineA < DataA.Length && (LineB >= DataB.Length || DataA.modified[LineA]))
						// while (LineA < DataA.Length && DataA.modified[LineA])
						LineA++;

					while(LineB < DataB.Length && (LineA >= DataA.Length || DataB.modified[LineB]))
						// while (LineB < DataB.Length && DataB.modified[LineB])
						LineB++;

					if((StartA < LineA) || (StartB < LineB)) {
						// store a new difference-item
						aItem = new Item();
						aItem.StartA = StartA;
						aItem.StartB = StartB;
						aItem.deletedA = LineA - StartA;
						aItem.insertedB = LineB - StartB;
						a.Add(aItem);
					} // if
				} // if
			} // while

			result = new Item[a.Count];
			a.CopyTo(result);

			return (result);
		}

	} // class Diff

	/// <summary>Data on one input file being compared.  
	/// </summary>
	internal class DiffData {

		/// <summary>Number of elements (lines).</summary>
		internal int Length;

		/// <summary>Buffer of numbers that will be compared.</summary>
		internal int[] data;

		/// <summary>
		/// Array of booleans that flag for modified data.
		/// This is the result of the diff.
		/// This means deletedA in the first Data or inserted in the second Data.
		/// </summary>
		internal bool[] modified;

		/// <summary>
		/// Initialize the Diff-Data buffer.
		/// </summary>
		/// <param name="data">reference to the buffer</param>
		internal DiffData(int[] initData) {
			data = initData;
			Length = initData.Length;
			modified = new bool[Length + 2];
		} // DiffData

	} // class DiffData

}