Package com.jsql.model.injection.strategy.blind.patch

Class DiffMatchPatch

java.lang.Object
com.jsql.model.injection.strategy.blind.patch.DiffMatchPatch
public class DiffMatchPatch extends Object
Class containing the diff, match and patch methods. Also contains the behaviour settings.

  • Field Details

    • DIFF_TIMEOUT

      public static final float DIFF_TIMEOUT
      Number of seconds to map a diff before giving up (0 for infinity).
      See Also:

    • DIFF_EDIT_COST

      public static final short DIFF_EDIT_COST
      Cost of an empty edit operation in terms of edit characters.
      See Also:

    • MATCH_THRESHOLD

      public static final float MATCH_THRESHOLD
      At what point is no match declared (0.0 = perfection, 1.0 = very loose).
      See Also:

    • MATCH_DISTANCE

      public static final int MATCH_DISTANCE
      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).
      See Also:

    • PATCH_DELETE_THRESHOLD

      public static final float PATCH_DELETE_THRESHOLD
      When deleting a large block of text (over ~64 characters), how close do the contents have to be 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.
      See Also:

    • PATCH_MARGIN

      public static final short PATCH_MARGIN
      Chunk size for context length.
      See Also:

  • Constructor Details

    • DiffMatchPatch

      public DiffMatchPatch()

  • Method Details

    • diffMain

      public List<Diff> diffMain(String text1, String text2)
      Find the differences between two texts. Run a faster, slightly less optimal diff. This method allows the 'checklines' of diff_main() to be optional. Most of the time checklines is wanted, so default to true.
      Parameters:
      text1 - Old string to be diffed.
      text2 - New string to be diffed.
      Returns:
      Linked List of Diff objects.

    • diffMain

      public LinkedList<Diff> diffMain(String text1, String text2, boolean checklines)
      Find the differences between two texts.
      Parameters:
      text1 - Old string to be diffed.
      text2 - New string to be diffed.
      checklines - Speedup flag. If false, then don't run a line-level diff first to identify the changed areas. If true, then run a faster slightly less optimal diff.
      Returns:
      Linked List of Diff objects.

    • diffBisect

      protected LinkedList<Diff> diffBisect(String text1, String text2, long deadline)
      Find the 'middle snake' of a diff, split the problem in two and return the recursively constructed diff. See Myers 1986 paper: An O(ND) Difference Algorithm and Its Variations.
      Parameters:
      text1 - Old string to be diffed.
      text2 - New string to be diffed.
      deadline - Time at which to bail if not yet complete.
      Returns:
      LinkedList of Diff objects.

    • diffLinesToChars

      protected DiffMatchPatch.LinesToCharsResult diffLinesToChars(String text1, String text2)
      Split two texts into a list of strings. Reduce the texts to a string of hashes where each Unicode character represents one line.
      Parameters:
      text1 - First string.
      text2 - Second string.
      Returns:
      An object containing the encoded text1, the encoded text2 and the List of unique strings. The zeroth element of the List of unique strings is intentionally blank.

    • diffCharsToLines

      protected void diffCharsToLines(List<Diff> diffs, List<String> lineArray)
      Rehydrate the text in a diff from a string of line hashes to real lines of text.
      Parameters:
      diffs - LinkedList of Diff objects.
      lineArray - List of unique strings.

    • diffCommonPrefix

      public int diffCommonPrefix(String text1, String text2)
      Determine the common prefix of two strings
      Parameters:
      text1 - First string.
      text2 - Second string.
      Returns:
      The number of characters common to the start of each string.

    • diffCommonSuffix

      public int diffCommonSuffix(String text1, String text2)
      Determine the common suffix of two strings
      Parameters:
      text1 - First string.
      text2 - Second string.
      Returns:
      The number of characters common to the end of each string.

    • diffCommonOverlap

      protected int diffCommonOverlap(String valueText1, String valueText2)
      Determine if the suffix of one string is the prefix of another.
      Parameters:
      valueText1 - First string.
      valueText2 - Second string.
      Returns:
      The number of characters common to the end of the first string and the start of the second string.

    • diffHalfMatch

      protected String[] diffHalfMatch(String text1, String text2)
      Do the two texts share a substring which is at least half the length of the longer text? This speedup can produce non-minimal diffs.
      Parameters:
      text1 - First string.
      text2 - Second string.
      Returns:
      Five element String array, containing the prefix of text1, the suffix of text1, the prefix of text2, the suffix of text2 and the common middle. Or null if there was no match.

    • diffCleanupSemantic

      public void diffCleanupSemantic(LinkedList<Diff> diffs)
      Reduce the number of edits by eliminating semantically trivial equalities.
      Parameters:
      diffs - LinkedList of Diff objects.

    • diffCleanupSemanticLossless

      public void diffCleanupSemanticLossless(List<Diff> diffs)
      Look for single edits surrounded on both sides by equalities which can be shifted sideways to align the edit to a word boundary. e.g: The cat came. -> The cat came.
      Parameters:
      diffs - LinkedList of Diff objects.

    • diffCleanupEfficiency

      public void diffCleanupEfficiency(LinkedList<Diff> diffs)
      Reduce the number of edits by eliminating operationally trivial equalities.
      Parameters:
      diffs - LinkedList of Diff objects.

    • diffCleanupMerge

      public void diffCleanupMerge(LinkedList<Diff> diffs)
      Reorder and merge like edit sections. Merge equalities. Any edit section can move as long as it doesn't cross an equality.
      Parameters:
      diffs - LinkedList of Diff objects.

    • diffXIndex

      public int diffXIndex(List<Diff> diffs, int loc)
      loc is a location in text1, compute and return the equivalent location in text2. e.g. "The cat" vs "The big cat", 1->1, 5->8
      Parameters:
      diffs - List of Diff objects.
      loc - Location within text1.
      Returns:
      Location within text2.

    • diffPrettyHtml

      public String diffPrettyHtml(List<Diff> diffs)
      Convert a Diff list into a pretty HTML report.
      Parameters:
      diffs - List of Diff objects.
      Returns:
      HTML representation.

    • diffText1

      public String diffText1(List<Diff> diffs)
      Compute and return the source text (all equalities and deletions).
      Parameters:
      diffs - List of Diff objects.
      Returns:
      Source text.

    • diffText2

      public String diffText2(List<Diff> diffs)
      Compute and return the destination text (all equalities and insertions).
      Parameters:
      diffs - List of Diff objects.
      Returns:
      Destination text.

    • diffLevenshtein

      public int diffLevenshtein(List<Diff> diffs)
      Compute the Levenshtein distance; the number of inserted, deleted or substituted characters.
      Parameters:
      diffs - List of Diff objects.
      Returns:
      Number of changes.

    • diffToDelta

      public String diffToDelta(List<Diff> diffs)
      Crush the diff into an encoded string which describes the operations required to transform text1 into text2. E.g. =3\t-2\t+ing -> Keep 3 chars, delete 2 chars, insert 'ing'. Operations are tab-separated. Inserted text is escaped using %xx notation.
      Parameters:
      diffs - Array of Diff objects.
      Returns:
      Delta text.

    • diffFromDelta

      public List<Diff> diffFromDelta(String text1, String delta)
      Given the original text1, and an encoded string which describes the operations required to transform text1 into text2, compute the full diff.
      Parameters:
      text1 - Source string for the diff.
      delta - Delta text.
      Returns:
      Array of Diff objects or null if invalid.

    • matchMain

      public int matchMain(String text, String pattern, int valueLoc)
      Locate the best instance of 'pattern' in 'text' near 'loc'. Returns -1 if no match found.
      Parameters:
      text - The text to search.
      pattern - The pattern to search for.
      valueLoc - The location to search around.
      Returns:
      Best match index or -1.

    • matchBitap

      protected int matchBitap(String text, String pattern, int loc)
      Locate the best instance of 'pattern' in 'text' near 'loc' using the Bitap algorithm. Returns -1 if no match found.
      Parameters:
      text - The text to search.
      pattern - The pattern to search for.
      loc - The location to search around.
      Returns:
      Best match index or -1.

    • matchAlphabet

      protected Map<Character,Integer> matchAlphabet(String pattern)
      Initialise the alphabet for the Bitap algorithm.
      Parameters:
      pattern - The text to encode.
      Returns:
      Hash of character locations.

    • patchAddContext

      protected void patchAddContext(Patch patch, String text)
      Increase the context until it is unique, but don't let the pattern expand beyond Match_MaxBits.
      Parameters:
      patch - The patch to grow.
      text - Source text.

    • patchMake

      public List<Patch> patchMake(String text1, String text2)
      Compute a list of patches to turn text1 into text2. A set of diffs will be computed.
      Parameters:
      text1 - Old text.
      text2 - New text.
      Returns:
      LinkedList of Patch objects.

    • patchMake

      public List<Patch> patchMake(LinkedList<Diff> diffs)
      Compute a list of patches to turn text1 into text2. text1 will be derived from the provided diffs.
      Parameters:
      diffs - Array of Diff objects for text1 to text2.
      Returns:
      LinkedList of Patch objects.

    • patchMake

      public List<Patch> patchMake(String text1, Deque<Diff> diffs)
      Compute a list of patches to turn text1 into text2. text2 is not provided, diffs are the delta between text1 and text2.
      Parameters:
      text1 - Old text.
      diffs - Array of Diff objects for text1 to text2.
      Returns:
      Deque of Patch objects.

    • patchDeepCopy

      public LinkedList<Patch> patchDeepCopy(List<Patch> patches)
      Given an array of patches, return another array that is identical.
      Parameters:
      patches - Array of Patch objects.
      Returns:
      Array of Patch objects.

    • patchApply

      public Object[] patchApply(LinkedList<Patch> valuePatches, String valueText)
      Merge a set of patches onto the text. Return a patched text, as well as an array of true/false values indicating which patches were applied.
      Parameters:
      valuePatches - Array of Patch objects
      valueText - Old text.
      Returns:
      Two element Object array, containing the new text and an array of boolean values.

    • patchAddPadding

      public String patchAddPadding(Deque<Patch> patches)
      Add some padding on text start and end so that edges can match something. Intended to be called only from within patch_apply.
      Parameters:
      patches - Array of Patch objects.
      Returns:
      The padding string added to each side.

    • patchSplitMax

      public void patchSplitMax(List<Patch> patches)
      Look through the patches and break up any which are longer than the maximum limit of the match algorithm. Intended to be called only from within patch_apply.
      Parameters:
      patches - List of Patch objects.

    • patchToText

      public String patchToText(List<Patch> patches)
      Take a list of patches and return a textual representation.
      Parameters:
      patches - List of Patch objects.
      Returns:
      Text representation of patches.

    • patchFromText

      public List<Patch> patchFromText(String textline)
      Parse a textual representation of patches and return a List of Patch objects.
      Parameters:
      textline - Text representation of patches.
      Returns:
      List of Patch objects.