Exemple #1
0
    } // DiffText


    /// <summary>
    /// If a sequence of modified lines starts with a line that contains the same content
    /// as the line that appends the changes, the difference sequence is modified so that the
    /// appended line and not the starting line is marked as modified.
    /// This leads to more readable diff sequences when comparing text files.
    /// </summary>
    /// <param name="Data">A Diff data buffer containing the identified changes.</param>
    private static void Optimize(DiffData Data) {
      int StartPos, EndPos;

      StartPos = 0;
      while (StartPos < Data.Length) {
        while ((StartPos < Data.Length) && (Data.modified[StartPos] == false))
          StartPos++;
        EndPos = StartPos;
        while ((EndPos < Data.Length) && (Data.modified[EndPos] == true))
          EndPos++;

        if ((EndPos < Data.Length) && (Data.data[StartPos] == Data.data[EndPos])) {
          Data.modified[StartPos] = false;
          Data.modified[EndPos] = true;
        } else {
          StartPos = EndPos;
        } // if
      } // while
    } // Optimize
Exemple #2
0
    } // DiffText


    /// <summary>
    /// Find the difference in 2 text documents, comparing by textlines.
    /// The algorithm itself is comparing 2 arrays of numbers so when comparing 2 text documents
    /// each line is converted into a (hash) number. This hash-value is computed by storing all
    /// textlines into a common hashtable so i can find dublicates in there, and generating a 
    /// new number each time a new textline is inserted.
    /// </summary>
    /// <param name="TextA">A-version of the text (usualy the old one)</param>
    /// <param name="TextB">B-version of the text (usualy the new one)</param>
    /// <param name="trimSpace">When set to true, all leading and trailing whitespace characters are stripped out before the comparation is done.</param>
    /// <param name="ignoreSpace">When set to true, all whitespace characters are converted to a single space character before the comparation is done.</param>
    /// <param name="ignoreCase">When set to true, all characters are converted to their lowercase equivivalence before the comparation is done.</param>
    /// <returns>Returns a array of Items that describe the differences.</returns>
    public static Item[] DiffText(string TextA, string TextB, bool trimSpace, bool ignoreSpace, bool ignoreCase) {
      // prepare the input-text and convert to comparable numbers.
      Hashtable h = new Hashtable(TextA.Length + TextB.Length);

      // The A-Version of the data (original data) to be compared.
      DiffData DataA = new DiffData(DiffCodes(TextA, h, trimSpace, ignoreSpace, ignoreCase));

      // The B-Version of the data (modified data) to be compared.
      DiffData DataB = new DiffData(DiffCodes(TextB, h, trimSpace, ignoreSpace, ignoreCase));

      h = null; // free up hashtable memory (maybe)

      int MAX = DataA.Length + DataB.Length + 1;
      /// 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];

      LCS(DataA, 0, DataA.Length, DataB, 0, DataB.Length, DownVector, UpVector);

      Optimize(DataA);
      Optimize(DataB);
      return CreateDiffs(DataA, DataB);
    } // DiffText
Exemple #3
0
    } // DiffCodes


    /// <summary>
    /// This is the algorithm to find the Shortest Middle Snake (SMS).
    /// </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>
    /// <param name="DownVector">a vector for the (0,0) to (x,y) search. Passed as a parameter for speed reasons.</param>
    /// <param name="UpVector">a vector for the (u,v) to (N,M) search. Passed as a parameter for speed reasons.</param>
    /// <returns>a MiddleSnakeData record containing x,y and u,v</returns>
    private static SMSRD SMS(DiffData DataA, int LowerA, int UpperA, DiffData DataB, int LowerB, int UpperB,
      int[] DownVector, int[] UpVector) {

      SMSRD ret;
      int MAX = DataA.Length + DataB.Length + 1;

      int DownK = LowerA - LowerB; // the k-line to start the forward search
      int UpK = UpperA - UpperB; // the k-line to start the reverse search

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

      // 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