cleanupSemantic.js

'use strict';

Object.defineProperty(exports, '__esModule', {
  value: true
});
exports.cleanupSemantic = exports.DIFF_INSERT = exports.DIFF_DELETE = exports.DIFF_EQUAL = exports.Diff = void 0;

function _defineProperty(obj, key, value) {
  if (key in obj) {
    Object.defineProperty(obj, key, {
      value: value,
      enumerable: true,
      configurable: true,
      writable: true
    });
  } else {
    obj[key] = value;
  }
  return obj;
}

/**
 * Diff Match and Patch
 * Copyright 2018 The diff-match-patch Authors.
 * https://github.com/google/diff-match-patch
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @fileoverview Computes the difference between two texts to create a patch.
 * Applies the patch onto another text, allowing for errors.
 * @author fraser@google.com (Neil Fraser)
 */

/**
 * CHANGES by pedrottimark to diff_match_patch_uncompressed.ts file:
 *
 * 1. Delete anything not needed to use diff_cleanupSemantic method
 * 2. Convert from prototype properties to var declarations
 * 3. Convert Diff to class from constructor and prototype
 * 4. Add type annotations for arguments and return values
 * 5. Add exports
 */

/**
 * The data structure representing a diff is an array of tuples:
 * [[DIFF_DELETE, 'Hello'], [DIFF_INSERT, 'Goodbye'], [DIFF_EQUAL, ' world.']]
 * which means: delete 'Hello', add 'Goodbye' and keep ' world.'
 */
var DIFF_DELETE = -1;
exports.DIFF_DELETE = DIFF_DELETE;
var DIFF_INSERT = 1;
exports.DIFF_INSERT = DIFF_INSERT;
var DIFF_EQUAL = 0;
/**
 * Class representing one diff tuple.
 * Attempts to look like a two-element array (which is what this used to be).
 * @param {number} op Operation, one of: DIFF_DELETE, DIFF_INSERT, DIFF_EQUAL.
 * @param {string} text Text to be deleted, inserted, or retained.
 * @constructor
 */

exports.DIFF_EQUAL = DIFF_EQUAL;

class Diff {
  constructor(op, text) {
    _defineProperty(this, 0, void 0);

    _defineProperty(this, 1, void 0);

    this[0] = op;
    this[1] = text;
  }
}
/**
 * Determine the common prefix of two strings.
 * @param {string} text1 First string.
 * @param {string} text2 Second string.
 * @return {number} The number of characters common to the start of each
 *     string.
 */

exports.Diff = Diff;

var diff_commonPrefix = function (text1, text2) {
  // Quick check for common null cases.
  if (!text1 || !text2 || text1.charAt(0) != text2.charAt(0)) {
    return 0;
  } // Binary search.
  // Performance analysis: https://neil.fraser.name/news/2007/10/09/

  var pointermin = 0;
  var pointermax = Math.min(text1.length, text2.length);
  var pointermid = pointermax;
  var pointerstart = 0;

  while (pointermin < pointermid) {
    if (
      text1.substring(pointerstart, pointermid) ==
      text2.substring(pointerstart, pointermid)
    ) {
      pointermin = pointermid;
      pointerstart = pointermin;
    } else {
      pointermax = pointermid;
    }

    pointermid = Math.floor((pointermax - pointermin) / 2 + pointermin);
  }

  return pointermid;
};
/**
 * Determine the common suffix of two strings.
 * @param {string} text1 First string.
 * @param {string} text2 Second string.
 * @return {number} The number of characters common to the end of each string.
 */

var diff_commonSuffix = function (text1, text2) {
  // Quick check for common null cases.
  if (
    !text1 ||
    !text2 ||
    text1.charAt(text1.length - 1) != text2.charAt(text2.length - 1)
  ) {
    return 0;
  } // Binary search.
  // Performance analysis: https://neil.fraser.name/news/2007/10/09/

  var pointermin = 0;
  var pointermax = Math.min(text1.length, text2.length);
  var pointermid = pointermax;
  var pointerend = 0;

  while (pointermin < pointermid) {
    if (
      text1.substring(text1.length - pointermid, text1.length - pointerend) ==
      text2.substring(text2.length - pointermid, text2.length - pointerend)
    ) {
      pointermin = pointermid;
      pointerend = pointermin;
    } else {
      pointermax = pointermid;
    }

    pointermid = Math.floor((pointermax - pointermin) / 2 + pointermin);
  }

  return pointermid;
};
/**
 * Determine if the suffix of one string is the prefix of another.
 * @param {string} text1 First string.
 * @param {string} text2 Second string.
 * @return {number} The number of characters common to the end of the first
 *     string and the start of the second string.
 * @private
 */

var diff_commonOverlap_ = function (text1, text2) {
  // Cache the text lengths to prevent multiple calls.
  var text1_length = text1.length;
  var text2_length = text2.length; // Eliminate the null case.

  if (text1_length == 0 || text2_length == 0) {
    return 0;
  } // Truncate the longer string.

  if (text1_length > text2_length) {
    text1 = text1.substring(text1_length - text2_length);
  } else if (text1_length < text2_length) {
    text2 = text2.substring(0, text1_length);
  }

  var text_length = Math.min(text1_length, text2_length); // Quick check for the worst case.

  if (text1 == text2) {
    return text_length;
  } // Start by looking for a single character match
  // and increase length until no match is found.
  // Performance analysis: https://neil.fraser.name/news/2010/11/04/

  var best = 0;
  var length = 1;

  while (true) {
    var pattern = text1.substring(text_length - length);
    var found = text2.indexOf(pattern);

    if (found == -1) {
      return best;
    }

    length += found;

    if (
      found == 0 ||
      text1.substring(text_length - length) == text2.substring(0, length)
    ) {
      best = length;
      length++;
    }
  }
};
/**
 * Reduce the number of edits by eliminating semantically trivial equalities.
 * @param {!Array.<!diff_match_patch.Diff>} diffs Array of diff tuples.
 */

var diff_cleanupSemantic = function (diffs) {
  var changes = false;
  var equalities = []; // Stack of indices where equalities are found.

  var equalitiesLength = 0; // Keeping our own length var is faster in JS.

  /** @type {?string} */

  var lastEquality = null; // Always equal to diffs[equalities[equalitiesLength - 1]][1]

  var pointer = 0; // Index of current position.
  // Number of characters that changed prior to the equality.

  var length_insertions1 = 0;
  var length_deletions1 = 0; // Number of characters that changed after the equality.

  var length_insertions2 = 0;
  var length_deletions2 = 0;

  while (pointer < diffs.length) {
    if (diffs[pointer][0] == DIFF_EQUAL) {
      // Equality found.
      equalities[equalitiesLength++] = pointer;
      length_insertions1 = length_insertions2;
      length_deletions1 = length_deletions2;
      length_insertions2 = 0;
      length_deletions2 = 0;
      lastEquality = diffs[pointer][1];
    } else {
      // An insertion or deletion.
      if (diffs[pointer][0] == DIFF_INSERT) {
        length_insertions2 += diffs[pointer][1].length;
      } else {
        length_deletions2 += diffs[pointer][1].length;
      } // Eliminate an equality that is smaller or equal to the edits on both
      // sides of it.

      if (
        lastEquality &&
        lastEquality.length <=
          Math.max(length_insertions1, length_deletions1) &&
        lastEquality.length <= Math.max(length_insertions2, length_deletions2)
      ) {
        // Duplicate record.
        diffs.splice(
          equalities[equalitiesLength - 1],
          0,
          new Diff(DIFF_DELETE, lastEquality)
        ); // Change second copy to insert.

        diffs[equalities[equalitiesLength - 1] + 1][0] = DIFF_INSERT; // Throw away the equality we just deleted.

        equalitiesLength--; // Throw away the previous equality (it needs to be reevaluated).

        equalitiesLength--;
        pointer = equalitiesLength > 0 ? equalities[equalitiesLength - 1] : -1;
        length_insertions1 = 0; // Reset the counters.

        length_deletions1 = 0;
        length_insertions2 = 0;
        length_deletions2 = 0;
        lastEquality = null;
        changes = true;
      }
    }

    pointer++;
  } // Normalize the diff.

  if (changes) {
    diff_cleanupMerge(diffs);
  }

  diff_cleanupSemanticLossless(diffs); // Find any overlaps between deletions and insertions.
  // e.g: <del>abcxxx</del><ins>xxxdef</ins>
  //   -> <del>abc</del>xxx<ins>def</ins>
  // e.g: <del>xxxabc</del><ins>defxxx</ins>
  //   -> <ins>def</ins>xxx<del>abc</del>
  // Only extract an overlap if it is as big as the edit ahead or behind it.

  pointer = 1;

  while (pointer < diffs.length) {
    if (
      diffs[pointer - 1][0] == DIFF_DELETE &&
      diffs[pointer][0] == DIFF_INSERT
    ) {
      var deletion = diffs[pointer - 1][1];
      var insertion = diffs[pointer][1];
      var overlap_length1 = diff_commonOverlap_(deletion, insertion);
      var overlap_length2 = diff_commonOverlap_(insertion, deletion);

      if (overlap_length1 >= overlap_length2) {
        if (
          overlap_length1 >= deletion.length / 2 ||
          overlap_length1 >= insertion.length / 2
        ) {
          // Overlap found.  Insert an equality and trim the surrounding edits.
          diffs.splice(
            pointer,
            0,
            new Diff(DIFF_EQUAL, insertion.substring(0, overlap_length1))
          );
          diffs[pointer - 1][1] = deletion.substring(
            0,
            deletion.length - overlap_length1
          );
          diffs[pointer + 1][1] = insertion.substring(overlap_length1);
          pointer++;
        }
      } else {
        if (
          overlap_length2 >= deletion.length / 2 ||
          overlap_length2 >= insertion.length / 2
        ) {
          // Reverse overlap found.
          // Insert an equality and swap and trim the surrounding edits.
          diffs.splice(
            pointer,
            0,
            new Diff(DIFF_EQUAL, deletion.substring(0, overlap_length2))
          );
          diffs[pointer - 1][0] = DIFF_INSERT;
          diffs[pointer - 1][1] = insertion.substring(
            0,
            insertion.length - overlap_length2
          );
          diffs[pointer + 1][0] = DIFF_DELETE;
          diffs[pointer + 1][1] = deletion.substring(overlap_length2);
          pointer++;
        }
      }

      pointer++;
    }

    pointer++;
  }
};
/**
 * 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 c<ins>at c</ins>ame. -> The <ins>cat </ins>came.
 * @param {!Array.<!diff_match_patch.Diff>} diffs Array of diff tuples.
 */

exports.cleanupSemantic = diff_cleanupSemantic;

var diff_cleanupSemanticLossless = function (diffs) {
  /**
   * Given two strings, compute a score representing whether the internal
   * boundary falls on logical boundaries.
   * Scores range from 6 (best) to 0 (worst).
   * Closure, but does not reference any external variables.
   * @param {string} one First string.
   * @param {string} two Second string.
   * @return {number} The score.
   * @private
   */
  function diff_cleanupSemanticScore_(one, two) {
    if (!one || !two) {
      // Edges are the best.
      return 6;
    } // Each port of this function behaves slightly differently due to
    // subtle differences in each language's definition of things like
    // 'whitespace'.  Since this function's purpose is largely cosmetic,
    // the choice has been made to use each language's native features
    // rather than force total conformity.

    var char1 = one.charAt(one.length - 1);
    var char2 = two.charAt(0);
    var nonAlphaNumeric1 = char1.match(nonAlphaNumericRegex_);
    var nonAlphaNumeric2 = char2.match(nonAlphaNumericRegex_);
    var whitespace1 = nonAlphaNumeric1 && char1.match(whitespaceRegex_);
    var whitespace2 = nonAlphaNumeric2 && char2.match(whitespaceRegex_);
    var lineBreak1 = whitespace1 && char1.match(linebreakRegex_);
    var lineBreak2 = whitespace2 && char2.match(linebreakRegex_);
    var blankLine1 = lineBreak1 && one.match(blanklineEndRegex_);
    var blankLine2 = lineBreak2 && two.match(blanklineStartRegex_);

    if (blankLine1 || blankLine2) {
      // Five points for blank lines.
      return 5;
    } else if (lineBreak1 || lineBreak2) {
      // Four points for line breaks.
      return 4;
    } else if (nonAlphaNumeric1 && !whitespace1 && whitespace2) {
      // Three points for end of sentences.
      return 3;
    } else if (whitespace1 || whitespace2) {
      // Two points for whitespace.
      return 2;
    } else if (nonAlphaNumeric1 || nonAlphaNumeric2) {
      // One point for non-alphanumeric.
      return 1;
    }

    return 0;
  }

  var pointer = 1; // Intentionally ignore the first and last element (don't need checking).

  while (pointer < diffs.length - 1) {
    if (
      diffs[pointer - 1][0] == DIFF_EQUAL &&
      diffs[pointer + 1][0] == DIFF_EQUAL
    ) {
      // This is a single edit surrounded by equalities.
      var equality1 = diffs[pointer - 1][1];
      var edit = diffs[pointer][1];
      var equality2 = diffs[pointer + 1][1]; // First, shift the edit as far left as possible.

      var commonOffset = diff_commonSuffix(equality1, edit);

      if (commonOffset) {
        var commonString = edit.substring(edit.length - commonOffset);
        equality1 = equality1.substring(0, equality1.length - commonOffset);
        edit = commonString + edit.substring(0, edit.length - commonOffset);
        equality2 = commonString + equality2;
      } // Second, step character by character right, looking for the best fit.

      var bestEquality1 = equality1;
      var bestEdit = edit;
      var bestEquality2 = equality2;
      var bestScore =
        diff_cleanupSemanticScore_(equality1, edit) +
        diff_cleanupSemanticScore_(edit, equality2);

      while (edit.charAt(0) === equality2.charAt(0)) {
        equality1 += edit.charAt(0);
        edit = edit.substring(1) + equality2.charAt(0);
        equality2 = equality2.substring(1);
        var score =
          diff_cleanupSemanticScore_(equality1, edit) +
          diff_cleanupSemanticScore_(edit, equality2); // The >= encourages trailing rather than leading whitespace on edits.

        if (score >= bestScore) {
          bestScore = score;
          bestEquality1 = equality1;
          bestEdit = edit;
          bestEquality2 = equality2;
        }
      }

      if (diffs[pointer - 1][1] != bestEquality1) {
        // We have an improvement, save it back to the diff.
        if (bestEquality1) {
          diffs[pointer - 1][1] = bestEquality1;
        } else {
          diffs.splice(pointer - 1, 1);
          pointer--;
        }

        diffs[pointer][1] = bestEdit;

        if (bestEquality2) {
          diffs[pointer + 1][1] = bestEquality2;
        } else {
          diffs.splice(pointer + 1, 1);
          pointer--;
        }
      }
    }

    pointer++;
  }
}; // Define some regex patterns for matching boundaries.

var nonAlphaNumericRegex_ = /[^a-zA-Z0-9]/;
var whitespaceRegex_ = /\s/;
var linebreakRegex_ = /[\r\n]/;
var blanklineEndRegex_ = /\n\r?\n$/;
var blanklineStartRegex_ = /^\r?\n\r?\n/;
/**
 * Reorder and merge like edit sections.  Merge equalities.
 * Any edit section can move as long as it doesn't cross an equality.
 * @param {!Array.<!diff_match_patch.Diff>} diffs Array of diff tuples.
 */

var diff_cleanupMerge = function (diffs) {
  // Add a dummy entry at the end.
  diffs.push(new Diff(DIFF_EQUAL, ''));
  var pointer = 0;
  var count_delete = 0;
  var count_insert = 0;
  var text_delete = '';
  var text_insert = '';
  var commonlength;

  while (pointer < diffs.length) {
    switch (diffs[pointer][0]) {
      case DIFF_INSERT:
        count_insert++;
        text_insert += diffs[pointer][1];
        pointer++;
        break;

      case DIFF_DELETE:
        count_delete++;
        text_delete += diffs[pointer][1];
        pointer++;
        break;

      case DIFF_EQUAL:
        // Upon reaching an equality, check for prior redundancies.
        if (count_delete + count_insert > 1) {
          if (count_delete !== 0 && count_insert !== 0) {
            // Factor out any common prefixies.
            commonlength = diff_commonPrefix(text_insert, text_delete);

            if (commonlength !== 0) {
              if (
                pointer - count_delete - count_insert > 0 &&
                diffs[pointer - count_delete - count_insert - 1][0] ==
                  DIFF_EQUAL
              ) {
                diffs[
                  pointer - count_delete - count_insert - 1
                ][1] += text_insert.substring(0, commonlength);
              } else {
                diffs.splice(
                  0,
                  0,
                  new Diff(DIFF_EQUAL, text_insert.substring(0, commonlength))
                );
                pointer++;
              }

              text_insert = text_insert.substring(commonlength);
              text_delete = text_delete.substring(commonlength);
            } // Factor out any common suffixies.

            commonlength = diff_commonSuffix(text_insert, text_delete);

            if (commonlength !== 0) {
              diffs[pointer][1] =
                text_insert.substring(text_insert.length - commonlength) +
                diffs[pointer][1];
              text_insert = text_insert.substring(
                0,
                text_insert.length - commonlength
              );
              text_delete = text_delete.substring(
                0,
                text_delete.length - commonlength
              );
            }
          } // Delete the offending records and add the merged ones.

          pointer -= count_delete + count_insert;
          diffs.splice(pointer, count_delete + count_insert);

          if (text_delete.length) {
            diffs.splice(pointer, 0, new Diff(DIFF_DELETE, text_delete));
            pointer++;
          }

          if (text_insert.length) {
            diffs.splice(pointer, 0, new Diff(DIFF_INSERT, text_insert));
            pointer++;
          }

          pointer++;
        } else if (pointer !== 0 && diffs[pointer - 1][0] == DIFF_EQUAL) {
          // Merge this equality with the previous one.
          diffs[pointer - 1][1] += diffs[pointer][1];
          diffs.splice(pointer, 1);
        } else {
          pointer++;
        }

        count_insert = 0;
        count_delete = 0;
        text_delete = '';
        text_insert = '';
        break;
    }
  }

  if (diffs[diffs.length - 1][1] === '') {
    diffs.pop(); // Remove the dummy entry at the end.
  } // Second pass: look for single edits surrounded on both sides by equalities
  // which can be shifted sideways to eliminate an equality.
  // e.g: A<ins>BA</ins>C -> <ins>AB</ins>AC

  var changes = false;
  pointer = 1; // Intentionally ignore the first and last element (don't need checking).

  while (pointer < diffs.length - 1) {
    if (
      diffs[pointer - 1][0] == DIFF_EQUAL &&
      diffs[pointer + 1][0] == DIFF_EQUAL
    ) {
      // This is a single edit surrounded by equalities.
      if (
        diffs[pointer][1].substring(
          diffs[pointer][1].length - diffs[pointer - 1][1].length
        ) == diffs[pointer - 1][1]
      ) {
        // Shift the edit over the previous equality.
        diffs[pointer][1] =
          diffs[pointer - 1][1] +
          diffs[pointer][1].substring(
            0,
            diffs[pointer][1].length - diffs[pointer - 1][1].length
          );
        diffs[pointer + 1][1] = diffs[pointer - 1][1] + diffs[pointer + 1][1];
        diffs.splice(pointer - 1, 1);
        changes = true;
      } else if (
        diffs[pointer][1].substring(0, diffs[pointer + 1][1].length) ==
        diffs[pointer + 1][1]
      ) {
        // Shift the edit over the next equality.
        diffs[pointer - 1][1] += diffs[pointer + 1][1];
        diffs[pointer][1] =
          diffs[pointer][1].substring(diffs[pointer + 1][1].length) +
          diffs[pointer + 1][1];
        diffs.splice(pointer + 1, 1);
        changes = true;
      }
    }

    pointer++;
  } // If shifts were made, the diff needs reordering and another shift sweep.

  if (changes) {
    diff_cleanupMerge(diffs);
  }
};