function diff_match_patch() {

  // Defaults.
  // Redefine these in your program to override the defaults.

  // Number of seconds to map a diff before giving up (0 for infinity).
  this.Diff_Timeout = 1.0;
  // Cost of an empty edit operation in terms of edit characters.
  this.Diff_EditCost = 4;
  // At what point is no match declared (0.0 = perfection, 1.0 = very loose).
  this.Match_Threshold = 0.5;
  // How far to search for a match (0 = exact location, 1000+ = broad match).
  // A match this many characters away from the expected location will add
  // 1.0 to the score (0.0 is a perfect match).
  this.Match_Distance = 1000;
  // When deleting a large block of text (over ~64 characters), how close does
  // the contents have to match the expected contents. (0.0 = perfection,
  // 1.0 = very loose).  Note that Match_Threshold controls how closely the
  // end points of a delete need to match.
  this.Patch_DeleteThreshold = 0.5;
  // Chunk size for context length.
  this.Patch_Margin = 4;

  // The number of bits in an int.
  this.Match_MaxBits = 32;
}
Class containing the diff, match and patch methods.
@constructor