src/main/java/com/sksamuel/diffpatch/DiffMatchPatch.java
public LinkedList<Patch> patch_make(String text1, LinkedList<Diff> diffs) {
    if (text1 == null || diffs == null) {
      throw new IllegalArgumentException("Null inputs. (patch_make)");
    }

    LinkedList<Patch> patches = new LinkedList<Patch>();
    if (diffs.isEmpty()) {
      return patches;  // Get rid of the null case.
    }
    Patch patch = new Patch();
    int char_count1 = 0;  // Number of characters into the text1 string.
    int char_count2 = 0;  // Number of characters into the text2 string.
    // Start with text1 (prepatch_text) and apply the diffs until we arrive at
    // text2 (postpatch_text). We recreate the patches one by one to determine
    // context info.
    String prepatch_text = text1;
    String postpatch_text = text1;
    for (Diff aDiff : diffs) {
      if (patch.diffs.isEmpty() && aDiff.operation != Operation.EQUAL) {
        // A new patch starts here.
        patch.start1 = char_count1;
        patch.start2 = char_count2;
      }

      switch (aDiff.operation) {
      case INSERT:
        patch.diffs.add(aDiff);
        patch.length2 += aDiff.text.length();
        postpatch_text = postpatch_text.substring(0, char_count2)
            + aDiff.text + postpatch_text.substring(char_count2);
        break;
      case DELETE:
        patch.length1 += aDiff.text.length();
        patch.diffs.add(aDiff);
        postpatch_text = postpatch_text.substring(0, char_count2)
            + postpatch_text.substring(char_count2 + aDiff.text.length());
        break;
      case EQUAL:
        if (aDiff.text.length() <= 2 * Patch_Margin
            && !patch.diffs.isEmpty() && aDiff != diffs.getLast()) {
          // Small equality inside a patch.
          patch.diffs.add(aDiff);
          patch.length1 += aDiff.text.length();
          patch.length2 += aDiff.text.length();
        }

        if (aDiff.text.length() >= 2 * Patch_Margin) {
          // Time for a new patch.
          if (!patch.diffs.isEmpty()) {
            patch_addContext(patch, prepatch_text);
            patches.add(patch);
            patch = new Patch();
            // Unlike Unidiff, our patch lists have a rolling context.
            // http://code.google.com/p/google-diff-match-patch/wiki/Unidiff
            // Update prepatch text & pos to reflect the application of the
            // just completed patch.
            prepatch_text = postpatch_text;
            char_count1 = char_count2;
          }
        }
        break;
      }

      // Update the current character count.
      if (aDiff.operation != Operation.INSERT) {
        char_count1 += aDiff.text.length();
      }
      if (aDiff.operation != Operation.DELETE) {
        char_count2 += aDiff.text.length();
      }
    }
    // Pick up the leftover patch if not empty.
    if (!patch.diffs.isEmpty()) {
      patch_addContext(patch, prepatch_text);
      patches.add(patch);
    }

    return patches;
  }
public LinkedList<Patch> patch_make(String text1, LinkedList<Diff> diffs) {
    if (text1 == null || diffs == null) {
      throw new IllegalArgumentException("Null inputs. (patch_make)");
    }

    LinkedList<Patch> patches = new LinkedList<Patch>();
    if (diffs.isEmpty()) {
      return patches;  // Get rid of the null case.
    }
    Patch patch = new Patch();
    int char_count1 = 0;  // Number of characters into the text1 string.
    int char_count2 = 0;  // Number of characters into the text2 string.
    // Start with text1 (prepatch_text) and apply the diffs until we arrive at
    // text2 (postpatch_text). We recreate the patches one by one to determine
    // context info.
    String prepatch_text = text1;
    String postpatch_text = text1;
    for (Diff aDiff : diffs) {
      if (patch.diffs.isEmpty() && aDiff.operation != Operation.EQUAL) {
        // A new patch starts here.
        patch.start1 = char_count1;
        patch.start2 = char_count2;
      }

      switch (aDiff.operation) {
      case INSERT:
        patch.diffs.add(aDiff);
        patch.length2 += aDiff.text.length();
        postpatch_text = postpatch_text.substring(0, char_count2)
            + aDiff.text + postpatch_text.substring(char_count2);
        break;
      case DELETE:
        patch.length1 += aDiff.text.length();
        patch.diffs.add(aDiff);
        postpatch_text = postpatch_text.substring(0, char_count2)
            + postpatch_text.substring(char_count2 + aDiff.text.length());
        break;
      case EQUAL:
        if (aDiff.text.length() <= 2 * Patch_Margin
            && !patch.diffs.isEmpty() && aDiff != diffs.getLast()) {
          // Small equality inside a patch.
          patch.diffs.add(aDiff);
          patch.length1 += aDiff.text.length();
          patch.length2 += aDiff.text.length();
        }

        if (aDiff.text.length() >= 2 * Patch_Margin) {
          // Time for a new patch.
          if (!patch.diffs.isEmpty()) {
            patch_addContext(patch, prepatch_text);
            patches.add(patch);
            patch = new Patch();
            // Unlike Unidiff, our patch lists have a rolling context.
            // http://code.google.com/p/google-diff-match-patch/wiki/Unidiff
            // Update prepatch text & pos to reflect the application of the
            // just completed patch.
            prepatch_text = postpatch_text;
            char_count1 = char_count2;
          }
        }
        break;
      }

      // Update the current character count.
      if (aDiff.operation != Operation.INSERT) {
        char_count1 += aDiff.text.length();
      }
      if (aDiff.operation != Operation.DELETE) {
        char_count2 += aDiff.text.length();
      }
    }
    // Pick up the leftover patch if not empty.
    if (!patch.diffs.isEmpty()) {
      patch_addContext(patch, prepatch_text);
      patches.add(patch);
    }

    return patches;
  }
Compute a list of patches to turn text1 into text2.
text2 is not provided, diffs are the delta between text1 and text2.
@param text1 Old text.
@param diffs Array of Diff objects for text1 to text2.
@return LinkedList of Patch objects.