diff/lib/index.es6.js

function Diff() {}
Diff.prototype = {
  diff: function diff(oldString, newString) {
    var options = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : {};
    var callback = options.callback;

    if (typeof options === 'function') {
      callback = options;
      options = {};
    }

    this.options = options;
    var self = this;

    function done(value) {
      if (callback) {
        setTimeout(function () {
          callback(undefined, value);
        }, 0);
        return true;
      } else {
        return value;
      }
    } // Allow subclasses to massage the input prior to running


    oldString = this.castInput(oldString);
    newString = this.castInput(newString);
    oldString = this.removeEmpty(this.tokenize(oldString));
    newString = this.removeEmpty(this.tokenize(newString));
    var newLen = newString.length,
        oldLen = oldString.length;
    var editLength = 1;
    var maxEditLength = newLen + oldLen;
    var bestPath = [{
      newPos: -1,
      components: []
    }]; // Seed editLength = 0, i.e. the content starts with the same values

    var oldPos = this.extractCommon(bestPath[0], newString, oldString, 0);

    if (bestPath[0].newPos + 1 >= newLen && oldPos + 1 >= oldLen) {
      // Identity per the equality and tokenizer
      return done([{
        value: this.join(newString),
        count: newString.length
      }]);
    } // Main worker method. checks all permutations of a given edit length for acceptance.


    function execEditLength() {
      for (var diagonalPath = -1 * editLength; diagonalPath <= editLength; diagonalPath += 2) {
        var basePath = void 0;

        var addPath = bestPath[diagonalPath - 1],
            removePath = bestPath[diagonalPath + 1],
            _oldPos = (removePath ? removePath.newPos : 0) - diagonalPath;

        if (addPath) {
          // No one else is going to attempt to use this value, clear it
          bestPath[diagonalPath - 1] = undefined;
        }

        var canAdd = addPath && addPath.newPos + 1 < newLen,
            canRemove = removePath && 0 <= _oldPos && _oldPos < oldLen;

        if (!canAdd && !canRemove) {
          // If this path is a terminal then prune
          bestPath[diagonalPath] = undefined;
          continue;
        } // Select the diagonal that we want to branch from. We select the prior
        // path whose position in the new string is the farthest from the origin
        // and does not pass the bounds of the diff graph


        if (!canAdd || canRemove && addPath.newPos < removePath.newPos) {
          basePath = clonePath(removePath);
          self.pushComponent(basePath.components, undefined, true);
        } else {
          basePath = addPath; // No need to clone, we've pulled it from the list

          basePath.newPos++;
          self.pushComponent(basePath.components, true, undefined);
        }

        _oldPos = self.extractCommon(basePath, newString, oldString, diagonalPath); // If we have hit the end of both strings, then we are done

        if (basePath.newPos + 1 >= newLen && _oldPos + 1 >= oldLen) {
          return done(buildValues(self, basePath.components, newString, oldString, self.useLongestToken));
        } else {
          // Otherwise track this path as a potential candidate and continue.
          bestPath[diagonalPath] = basePath;
        }
      }

      editLength++;
    } // Performs the length of edit iteration. Is a bit fugly as this has to support the
    // sync and async mode which is never fun. Loops over execEditLength until a value
    // is produced.


    if (callback) {
      (function exec() {
        setTimeout(function () {
          // This should not happen, but we want to be safe.

          /* istanbul ignore next */
          if (editLength > maxEditLength) {
            return callback();
          }

          if (!execEditLength()) {
            exec();
          }
        }, 0);
      })();
    } else {
      while (editLength <= maxEditLength) {
        var ret = execEditLength();

        if (ret) {
          return ret;
        }
      }
    }
  },
  pushComponent: function pushComponent(components, added, removed) {
    var last = components[components.length - 1];

    if (last && last.added === added && last.removed === removed) {
      // We need to clone here as the component clone operation is just
      // as shallow array clone
      components[components.length - 1] = {
        count: last.count + 1,
        added: added,
        removed: removed
      };
    } else {
      components.push({
        count: 1,
        added: added,
        removed: removed
      });
    }
  },
  extractCommon: function extractCommon(basePath, newString, oldString, diagonalPath) {
    var newLen = newString.length,
        oldLen = oldString.length,
        newPos = basePath.newPos,
        oldPos = newPos - diagonalPath,
        commonCount = 0;

    while (newPos + 1 < newLen && oldPos + 1 < oldLen && this.equals(newString[newPos + 1], oldString[oldPos + 1])) {
      newPos++;
      oldPos++;
      commonCount++;
    }

    if (commonCount) {
      basePath.components.push({
        count: commonCount
      });
    }

    basePath.newPos = newPos;
    return oldPos;
  },
  equals: function equals(left, right) {
    if (this.options.comparator) {
      return this.options.comparator(left, right);
    } else {
      return left === right || this.options.ignoreCase && left.toLowerCase() === right.toLowerCase();
    }
  },
  removeEmpty: function removeEmpty(array) {
    var ret = [];

    for (var i = 0; i < array.length; i++) {
      if (array[i]) {
        ret.push(array[i]);
      }
    }

    return ret;
  },
  castInput: function castInput(value) {
    return value;
  },
  tokenize: function tokenize(value) {
    return value.split('');
  },
  join: function join(chars) {
    return chars.join('');
  }
};

function buildValues(diff, components, newString, oldString, useLongestToken) {
  var componentPos = 0,
      componentLen = components.length,
      newPos = 0,
      oldPos = 0;

  for (; componentPos < componentLen; componentPos++) {
    var component = components[componentPos];

    if (!component.removed) {
      if (!component.added && useLongestToken) {
        var value = newString.slice(newPos, newPos + component.count);
        value = value.map(function (value, i) {
          var oldValue = oldString[oldPos + i];
          return oldValue.length > value.length ? oldValue : value;
        });
        component.value = diff.join(value);
      } else {
        component.value = diff.join(newString.slice(newPos, newPos + component.count));
      }

      newPos += component.count; // Common case

      if (!component.added) {
        oldPos += component.count;
      }
    } else {
      component.value = diff.join(oldString.slice(oldPos, oldPos + component.count));
      oldPos += component.count; // Reverse add and remove so removes are output first to match common convention
      // The diffing algorithm is tied to add then remove output and this is the simplest
      // route to get the desired output with minimal overhead.

      if (componentPos && components[componentPos - 1].added) {
        var tmp = components[componentPos - 1];
        components[componentPos - 1] = components[componentPos];
        components[componentPos] = tmp;
      }
    }
  } // Special case handle for when one terminal is ignored (i.e. whitespace).
  // For this case we merge the terminal into the prior string and drop the change.
  // This is only available for string mode.


  var lastComponent = components[componentLen - 1];

  if (componentLen > 1 && typeof lastComponent.value === 'string' && (lastComponent.added || lastComponent.removed) && diff.equals('', lastComponent.value)) {
    components[componentLen - 2].value += lastComponent.value;
    components.pop();
  }

  return components;
}

function clonePath(path) {
  return {
    newPos: path.newPos,
    components: path.components.slice(0)
  };
}

var characterDiff = new Diff();
function diffChars(oldStr, newStr, options) {
  return characterDiff.diff(oldStr, newStr, options);
}

function generateOptions(options, defaults) {
  if (typeof options === 'function') {
    defaults.callback = options;
  } else if (options) {
    for (var name in options) {
      /* istanbul ignore else */
      if (options.hasOwnProperty(name)) {
        defaults[name] = options[name];
      }
    }
  }

  return defaults;
}

//
// Ranges and exceptions:
// Latin-1 Supplement, 0080–00FF
//  - U+00D7  × Multiplication sign
//  - U+00F7  ÷ Division sign
// Latin Extended-A, 0100–017F
// Latin Extended-B, 0180–024F
// IPA Extensions, 0250–02AF
// Spacing Modifier Letters, 02B0–02FF
//  - U+02C7  ˇ &#711;  Caron
//  - U+02D8  ˘ &#728;  Breve
//  - U+02D9  ˙ &#729;  Dot Above
//  - U+02DA  ˚ &#730;  Ring Above
//  - U+02DB  ˛ &#731;  Ogonek
//  - U+02DC  ˜ &#732;  Small Tilde
//  - U+02DD  ˝ &#733;  Double Acute Accent
// Latin Extended Additional, 1E00–1EFF

var extendedWordChars = /^[A-Za-z\xC0-\u02C6\u02C8-\u02D7\u02DE-\u02FF\u1E00-\u1EFF]+$/;
var reWhitespace = /\S/;
var wordDiff = new Diff();

wordDiff.equals = function (left, right) {
  if (this.options.ignoreCase) {
    left = left.toLowerCase();
    right = right.toLowerCase();
  }

  return left === right || this.options.ignoreWhitespace && !reWhitespace.test(left) && !reWhitespace.test(right);
};

wordDiff.tokenize = function (value) {
  // All whitespace symbols except newline group into one token, each newline - in separate token
  var tokens = value.split(/([^\S\r\n]+|[()[\]{}'"\r\n]|\b)/); // Join the boundary splits that we do not consider to be boundaries. This is primarily the extended Latin character set.

  for (var i = 0; i < tokens.length - 1; i++) {
    // If we have an empty string in the next field and we have only word chars before and after, merge
    if (!tokens[i + 1] && tokens[i + 2] && extendedWordChars.test(tokens[i]) && extendedWordChars.test(tokens[i + 2])) {
      tokens[i] += tokens[i + 2];
      tokens.splice(i + 1, 2);
      i--;
    }
  }

  return tokens;
};

function diffWords(oldStr, newStr, options) {
  options = generateOptions(options, {
    ignoreWhitespace: true
  });
  return wordDiff.diff(oldStr, newStr, options);
}
function diffWordsWithSpace(oldStr, newStr, options) {
  return wordDiff.diff(oldStr, newStr, options);
}

var lineDiff = new Diff();

lineDiff.tokenize = function (value) {
  var retLines = [],
      linesAndNewlines = value.split(/(\n|\r\n)/); // Ignore the final empty token that occurs if the string ends with a new line

  if (!linesAndNewlines[linesAndNewlines.length - 1]) {
    linesAndNewlines.pop();
  } // Merge the content and line separators into single tokens


  for (var i = 0; i < linesAndNewlines.length; i++) {
    var line = linesAndNewlines[i];

    if (i % 2 && !this.options.newlineIsToken) {
      retLines[retLines.length - 1] += line;
    } else {
      if (this.options.ignoreWhitespace) {
        line = line.trim();
      }

      retLines.push(line);
    }
  }

  return retLines;
};

function diffLines(oldStr, newStr, callback) {
  return lineDiff.diff(oldStr, newStr, callback);
}
function diffTrimmedLines(oldStr, newStr, callback) {
  var options = generateOptions(callback, {
    ignoreWhitespace: true
  });
  return lineDiff.diff(oldStr, newStr, options);
}

var sentenceDiff = new Diff();

sentenceDiff.tokenize = function (value) {
  return value.split(/(\S.+?[.!?])(?=\s+|$)/);
};

function diffSentences(oldStr, newStr, callback) {
  return sentenceDiff.diff(oldStr, newStr, callback);
}

var cssDiff = new Diff();

cssDiff.tokenize = function (value) {
  return value.split(/([{}:;,]|\s+)/);
};

function diffCss(oldStr, newStr, callback) {
  return cssDiff.diff(oldStr, newStr, callback);
}

function _typeof(obj) {
  "@babel/helpers - typeof";

  if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") {
    _typeof = function (obj) {
      return typeof obj;
    };
  } else {
    _typeof = function (obj) {
      return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
    };
  }

  return _typeof(obj);
}

function _toConsumableArray(arr) {
  return _arrayWithoutHoles(arr) || _iterableToArray(arr) || _unsupportedIterableToArray(arr) || _nonIterableSpread();
}

function _arrayWithoutHoles(arr) {
  if (Array.isArray(arr)) return _arrayLikeToArray(arr);
}

function _iterableToArray(iter) {
  if (typeof Symbol !== "undefined" && Symbol.iterator in Object(iter)) return Array.from(iter);
}

function _unsupportedIterableToArray(o, minLen) {
  if (!o) return;
  if (typeof o === "string") return _arrayLikeToArray(o, minLen);
  var n = Object.prototype.toString.call(o).slice(8, -1);
  if (n === "Object" && o.constructor) n = o.constructor.name;
  if (n === "Map" || n === "Set") return Array.from(o);
  if (n === "Arguments" || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(n)) return _arrayLikeToArray(o, minLen);
}

function _arrayLikeToArray(arr, len) {
  if (len == null || len > arr.length) len = arr.length;

  for (var i = 0, arr2 = new Array(len); i < len; i++) arr2[i] = arr[i];

  return arr2;
}

function _nonIterableSpread() {
  throw new TypeError("Invalid attempt to spread non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method.");
}

var objectPrototypeToString = Object.prototype.toString;
var jsonDiff = new Diff(); // Discriminate between two lines of pretty-printed, serialized JSON where one of them has a
// dangling comma and the other doesn't. Turns out including the dangling comma yields the nicest output:

jsonDiff.useLongestToken = true;
jsonDiff.tokenize = lineDiff.tokenize;

jsonDiff.castInput = function (value) {
  var _this$options = this.options,
      undefinedReplacement = _this$options.undefinedReplacement,
      _this$options$stringi = _this$options.stringifyReplacer,
      stringifyReplacer = _this$options$stringi === void 0 ? function (k, v) {
    return typeof v === 'undefined' ? undefinedReplacement : v;
  } : _this$options$stringi;
  return typeof value === 'string' ? value : JSON.stringify(canonicalize(value, null, null, stringifyReplacer), stringifyReplacer, '  ');
};

jsonDiff.equals = function (left, right) {
  return Diff.prototype.equals.call(jsonDiff, left.replace(/,([\r\n])/g, '$1'), right.replace(/,([\r\n])/g, '$1'));
};

function diffJson(oldObj, newObj, options) {
  return jsonDiff.diff(oldObj, newObj, options);
} // This function handles the presence of circular references by bailing out when encountering an
// object that is already on the "stack" of items being processed. Accepts an optional replacer

function canonicalize(obj, stack, replacementStack, replacer, key) {
  stack = stack || [];
  replacementStack = replacementStack || [];

  if (replacer) {
    obj = replacer(key, obj);
  }

  var i;

  for (i = 0; i < stack.length; i += 1) {
    if (stack[i] === obj) {
      return replacementStack[i];
    }
  }

  var canonicalizedObj;

  if ('[object Array]' === objectPrototypeToString.call(obj)) {
    stack.push(obj);
    canonicalizedObj = new Array(obj.length);
    replacementStack.push(canonicalizedObj);

    for (i = 0; i < obj.length; i += 1) {
      canonicalizedObj[i] = canonicalize(obj[i], stack, replacementStack, replacer, key);
    }

    stack.pop();
    replacementStack.pop();
    return canonicalizedObj;
  }

  if (obj && obj.toJSON) {
    obj = obj.toJSON();
  }

  if (_typeof(obj) === 'object' && obj !== null) {
    stack.push(obj);
    canonicalizedObj = {};
    replacementStack.push(canonicalizedObj);

    var sortedKeys = [],
        _key;

    for (_key in obj) {
      /* istanbul ignore else */
      if (obj.hasOwnProperty(_key)) {
        sortedKeys.push(_key);
      }
    }

    sortedKeys.sort();

    for (i = 0; i < sortedKeys.length; i += 1) {
      _key = sortedKeys[i];
      canonicalizedObj[_key] = canonicalize(obj[_key], stack, replacementStack, replacer, _key);
    }

    stack.pop();
    replacementStack.pop();
  } else {
    canonicalizedObj = obj;
  }

  return canonicalizedObj;
}

var arrayDiff = new Diff();

arrayDiff.tokenize = function (value) {
  return value.slice();
};

arrayDiff.join = arrayDiff.removeEmpty = function (value) {
  return value;
};

function diffArrays(oldArr, newArr, callback) {
  return arrayDiff.diff(oldArr, newArr, callback);
}

function parsePatch(uniDiff) {
  var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {};
  var diffstr = uniDiff.split(/\r\n|[\n\v\f\r\x85]/),
      delimiters = uniDiff.match(/\r\n|[\n\v\f\r\x85]/g) || [],
      list = [],
      i = 0;

  function parseIndex() {
    var index = {};
    list.push(index); // Parse diff metadata

    while (i < diffstr.length) {
      var line = diffstr[i]; // File header found, end parsing diff metadata

      if (/^(\-\-\-|\+\+\+|@@)\s/.test(line)) {
        break;
      } // Diff index


      var header = /^(?:Index:|diff(?: -r \w+)+)\s+(.+?)\s*$/.exec(line);

      if (header) {
        index.index = header[1];
      }

      i++;
    } // Parse file headers if they are defined. Unified diff requires them, but
    // there's no technical issues to have an isolated hunk without file header


    parseFileHeader(index);
    parseFileHeader(index); // Parse hunks

    index.hunks = [];

    while (i < diffstr.length) {
      var _line = diffstr[i];

      if (/^(Index:|diff|\-\-\-|\+\+\+)\s/.test(_line)) {
        break;
      } else if (/^@@/.test(_line)) {
        index.hunks.push(parseHunk());
      } else if (_line && options.strict) {
        // Ignore unexpected content unless in strict mode
        throw new Error('Unknown line ' + (i + 1) + ' ' + JSON.stringify(_line));
      } else {
        i++;
      }
    }
  } // Parses the --- and +++ headers, if none are found, no lines
  // are consumed.


  function parseFileHeader(index) {
    var fileHeader = /^(---|\+\+\+)\s+(.*)$/.exec(diffstr[i]);

    if (fileHeader) {
      var keyPrefix = fileHeader[1] === '---' ? 'old' : 'new';
      var data = fileHeader[2].split('\t', 2);
      var fileName = data[0].replace(/\\\\/g, '\\');

      if (/^".*"$/.test(fileName)) {
        fileName = fileName.substr(1, fileName.length - 2);
      }

      index[keyPrefix + 'FileName'] = fileName;
      index[keyPrefix + 'Header'] = (data[1] || '').trim();
      i++;
    }
  } // Parses a hunk
  // This assumes that we are at the start of a hunk.


  function parseHunk() {
    var chunkHeaderIndex = i,
        chunkHeaderLine = diffstr[i++],
        chunkHeader = chunkHeaderLine.split(/@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@/);
    var hunk = {
      oldStart: +chunkHeader[1],
      oldLines: typeof chunkHeader[2] === 'undefined' ? 1 : +chunkHeader[2],
      newStart: +chunkHeader[3],
      newLines: typeof chunkHeader[4] === 'undefined' ? 1 : +chunkHeader[4],
      lines: [],
      linedelimiters: []
    }; // Unified Diff Format quirk: If the chunk size is 0,
    // the first number is one lower than one would expect.
    // https://www.artima.com/weblogs/viewpost.jsp?thread=164293

    if (hunk.oldLines === 0) {
      hunk.oldStart += 1;
    }

    if (hunk.newLines === 0) {
      hunk.newStart += 1;
    }

    var addCount = 0,
        removeCount = 0;

    for (; i < diffstr.length; i++) {
      // Lines starting with '---' could be mistaken for the "remove line" operation
      // But they could be the header for the next file. Therefore prune such cases out.
      if (diffstr[i].indexOf('--- ') === 0 && i + 2 < diffstr.length && diffstr[i + 1].indexOf('+++ ') === 0 && diffstr[i + 2].indexOf('@@') === 0) {
        break;
      }

      var operation = diffstr[i].length == 0 && i != diffstr.length - 1 ? ' ' : diffstr[i][0];

      if (operation === '+' || operation === '-' || operation === ' ' || operation === '\\') {
        hunk.lines.push(diffstr[i]);
        hunk.linedelimiters.push(delimiters[i] || '\n');

        if (operation === '+') {
          addCount++;
        } else if (operation === '-') {
          removeCount++;
        } else if (operation === ' ') {
          addCount++;
          removeCount++;
        }
      } else {
        break;
      }
    } // Handle the empty block count case


    if (!addCount && hunk.newLines === 1) {
      hunk.newLines = 0;
    }

    if (!removeCount && hunk.oldLines === 1) {
      hunk.oldLines = 0;
    } // Perform optional sanity checking


    if (options.strict) {
      if (addCount !== hunk.newLines) {
        throw new Error('Added line count did not match for hunk at line ' + (chunkHeaderIndex + 1));
      }

      if (removeCount !== hunk.oldLines) {
        throw new Error('Removed line count did not match for hunk at line ' + (chunkHeaderIndex + 1));
      }
    }

    return hunk;
  }

  while (i < diffstr.length) {
    parseIndex();
  }

  return list;
}

// Iterator that traverses in the range of [min, max], stepping
// by distance from a given start position. I.e. for [0, 4], with
// start of 2, this will iterate 2, 3, 1, 4, 0.
function distanceIterator (start, minLine, maxLine) {
  var wantForward = true,
      backwardExhausted = false,
      forwardExhausted = false,
      localOffset = 1;
  return function iterator() {
    if (wantForward && !forwardExhausted) {
      if (backwardExhausted) {
        localOffset++;
      } else {
        wantForward = false;
      } // Check if trying to fit beyond text length, and if not, check it fits
      // after offset location (or desired location on first iteration)


      if (start + localOffset <= maxLine) {
        return localOffset;
      }

      forwardExhausted = true;
    }

    if (!backwardExhausted) {
      if (!forwardExhausted) {
        wantForward = true;
      } // Check if trying to fit before text beginning, and if not, check it fits
      // before offset location


      if (minLine <= start - localOffset) {
        return -localOffset++;
      }

      backwardExhausted = true;
      return iterator();
    } // We tried to fit hunk before text beginning and beyond text length, then
    // hunk can't fit on the text. Return undefined

  };
}

function applyPatch(source, uniDiff) {
  var options = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : {};

  if (typeof uniDiff === 'string') {
    uniDiff = parsePatch(uniDiff);
  }

  if (Array.isArray(uniDiff)) {
    if (uniDiff.length > 1) {
      throw new Error('applyPatch only works with a single input.');
    }

    uniDiff = uniDiff[0];
  } // Apply the diff to the input


  var lines = source.split(/\r\n|[\n\v\f\r\x85]/),
      delimiters = source.match(/\r\n|[\n\v\f\r\x85]/g) || [],
      hunks = uniDiff.hunks,
      compareLine = options.compareLine || function (lineNumber, line, operation, patchContent) {
    return line === patchContent;
  },
      errorCount = 0,
      fuzzFactor = options.fuzzFactor || 0,
      minLine = 0,
      offset = 0,
      removeEOFNL,
      addEOFNL;
  /**
   * Checks if the hunk exactly fits on the provided location
   */


  function hunkFits(hunk, toPos) {
    for (var j = 0; j < hunk.lines.length; j++) {
      var line = hunk.lines[j],
          operation = line.length > 0 ? line[0] : ' ',
          content = line.length > 0 ? line.substr(1) : line;

      if (operation === ' ' || operation === '-') {
        // Context sanity check
        if (!compareLine(toPos + 1, lines[toPos], operation, content)) {
          errorCount++;

          if (errorCount > fuzzFactor) {
            return false;
          }
        }

        toPos++;
      }
    }

    return true;
  } // Search best fit offsets for each hunk based on the previous ones


  for (var i = 0; i < hunks.length; i++) {
    var hunk = hunks[i],
        maxLine = lines.length - hunk.oldLines,
        localOffset = 0,
        toPos = offset + hunk.oldStart - 1;
    var iterator = distanceIterator(toPos, minLine, maxLine);

    for (; localOffset !== undefined; localOffset = iterator()) {
      if (hunkFits(hunk, toPos + localOffset)) {
        hunk.offset = offset += localOffset;
        break;
      }
    }

    if (localOffset === undefined) {
      return false;
    } // Set lower text limit to end of the current hunk, so next ones don't try
    // to fit over already patched text


    minLine = hunk.offset + hunk.oldStart + hunk.oldLines;
  } // Apply patch hunks


  var diffOffset = 0;

  for (var _i = 0; _i < hunks.length; _i++) {
    var _hunk = hunks[_i],
        _toPos = _hunk.oldStart + _hunk.offset + diffOffset - 1;

    diffOffset += _hunk.newLines - _hunk.oldLines;

    for (var j = 0; j < _hunk.lines.length; j++) {
      var line = _hunk.lines[j],
          operation = line.length > 0 ? line[0] : ' ',
          content = line.length > 0 ? line.substr(1) : line,
          delimiter = _hunk.linedelimiters[j];

      if (operation === ' ') {
        _toPos++;
      } else if (operation === '-') {
        lines.splice(_toPos, 1);
        delimiters.splice(_toPos, 1);
        /* istanbul ignore else */
      } else if (operation === '+') {
        lines.splice(_toPos, 0, content);
        delimiters.splice(_toPos, 0, delimiter);
        _toPos++;
      } else if (operation === '\\') {
        var previousOperation = _hunk.lines[j - 1] ? _hunk.lines[j - 1][0] : null;

        if (previousOperation === '+') {
          removeEOFNL = true;
        } else if (previousOperation === '-') {
          addEOFNL = true;
        }
      }
    }
  } // Handle EOFNL insertion/removal


  if (removeEOFNL) {
    while (!lines[lines.length - 1]) {
      lines.pop();
      delimiters.pop();
    }
  } else if (addEOFNL) {
    lines.push('');
    delimiters.push('\n');
  }

  for (var _k = 0; _k < lines.length - 1; _k++) {
    lines[_k] = lines[_k] + delimiters[_k];
  }

  return lines.join('');
} // Wrapper that supports multiple file patches via callbacks.

function applyPatches(uniDiff, options) {
  if (typeof uniDiff === 'string') {
    uniDiff = parsePatch(uniDiff);
  }

  var currentIndex = 0;

  function processIndex() {
    var index = uniDiff[currentIndex++];

    if (!index) {
      return options.complete();
    }

    options.loadFile(index, function (err, data) {
      if (err) {
        return options.complete(err);
      }

      var updatedContent = applyPatch(data, index, options);
      options.patched(index, updatedContent, function (err) {
        if (err) {
          return options.complete(err);
        }

        processIndex();
      });
    });
  }

  processIndex();
}

function structuredPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader, options) {
  if (!options) {
    options = {};
  }

  if (typeof options.context === 'undefined') {
    options.context = 4;
  }

  var diff = diffLines(oldStr, newStr, options);
  diff.push({
    value: '',
    lines: []
  }); // Append an empty value to make cleanup easier

  function contextLines(lines) {
    return lines.map(function (entry) {
      return ' ' + entry;
    });
  }

  var hunks = [];
  var oldRangeStart = 0,
      newRangeStart = 0,
      curRange = [],
      oldLine = 1,
      newLine = 1;

  var _loop = function _loop(i) {
    var current = diff[i],
        lines = current.lines || current.value.replace(/\n$/, '').split('\n');
    current.lines = lines;

    if (current.added || current.removed) {
      var _curRange;

      // If we have previous context, start with that
      if (!oldRangeStart) {
        var prev = diff[i - 1];
        oldRangeStart = oldLine;
        newRangeStart = newLine;

        if (prev) {
          curRange = options.context > 0 ? contextLines(prev.lines.slice(-options.context)) : [];
          oldRangeStart -= curRange.length;
          newRangeStart -= curRange.length;
        }
      } // Output our changes


      (_curRange = curRange).push.apply(_curRange, _toConsumableArray(lines.map(function (entry) {
        return (current.added ? '+' : '-') + entry;
      }))); // Track the updated file position


      if (current.added) {
        newLine += lines.length;
      } else {
        oldLine += lines.length;
      }
    } else {
      // Identical context lines. Track line changes
      if (oldRangeStart) {
        // Close out any changes that have been output (or join overlapping)
        if (lines.length <= options.context * 2 && i < diff.length - 2) {
          var _curRange2;

          // Overlapping
          (_curRange2 = curRange).push.apply(_curRange2, _toConsumableArray(contextLines(lines)));
        } else {
          var _curRange3;

          // end the range and output
          var contextSize = Math.min(lines.length, options.context);

          (_curRange3 = curRange).push.apply(_curRange3, _toConsumableArray(contextLines(lines.slice(0, contextSize))));

          var hunk = {
            oldStart: oldRangeStart,
            oldLines: oldLine - oldRangeStart + contextSize,
            newStart: newRangeStart,
            newLines: newLine - newRangeStart + contextSize,
            lines: curRange
          };

          if (i >= diff.length - 2 && lines.length <= options.context) {
            // EOF is inside this hunk
            var oldEOFNewline = /\n$/.test(oldStr);
            var newEOFNewline = /\n$/.test(newStr);
            var noNlBeforeAdds = lines.length == 0 && curRange.length > hunk.oldLines;

            if (!oldEOFNewline && noNlBeforeAdds && oldStr.length > 0) {
              // special case: old has no eol and no trailing context; no-nl can end up before adds
              // however, if the old file is empty, do not output the no-nl line
              curRange.splice(hunk.oldLines, 0, '\\ No newline at end of file');
            }

            if (!oldEOFNewline && !noNlBeforeAdds || !newEOFNewline) {
              curRange.push('\\ No newline at end of file');
            }
          }

          hunks.push(hunk);
          oldRangeStart = 0;
          newRangeStart = 0;
          curRange = [];
        }
      }

      oldLine += lines.length;
      newLine += lines.length;
    }
  };

  for (var i = 0; i < diff.length; i++) {
    _loop(i);
  }

  return {
    oldFileName: oldFileName,
    newFileName: newFileName,
    oldHeader: oldHeader,
    newHeader: newHeader,
    hunks: hunks
  };
}
function formatPatch(diff) {
  var ret = [];

  if (diff.oldFileName == diff.newFileName) {
    ret.push('Index: ' + diff.oldFileName);
  }

  ret.push('===================================================================');
  ret.push('--- ' + diff.oldFileName + (typeof diff.oldHeader === 'undefined' ? '' : '\t' + diff.oldHeader));
  ret.push('+++ ' + diff.newFileName + (typeof diff.newHeader === 'undefined' ? '' : '\t' + diff.newHeader));

  for (var i = 0; i < diff.hunks.length; i++) {
    var hunk = diff.hunks[i]; // Unified Diff Format quirk: If the chunk size is 0,
    // the first number is one lower than one would expect.
    // https://www.artima.com/weblogs/viewpost.jsp?thread=164293

    if (hunk.oldLines === 0) {
      hunk.oldStart -= 1;
    }

    if (hunk.newLines === 0) {
      hunk.newStart -= 1;
    }

    ret.push('@@ -' + hunk.oldStart + ',' + hunk.oldLines + ' +' + hunk.newStart + ',' + hunk.newLines + ' @@');
    ret.push.apply(ret, hunk.lines);
  }

  return ret.join('\n') + '\n';
}
function createTwoFilesPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader, options) {
  return formatPatch(structuredPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader, options));
}
function createPatch(fileName, oldStr, newStr, oldHeader, newHeader, options) {
  return createTwoFilesPatch(fileName, fileName, oldStr, newStr, oldHeader, newHeader, options);
}

function arrayEqual(a, b) {
  if (a.length !== b.length) {
    return false;
  }

  return arrayStartsWith(a, b);
}
function arrayStartsWith(array, start) {
  if (start.length > array.length) {
    return false;
  }

  for (var i = 0; i < start.length; i++) {
    if (start[i] !== array[i]) {
      return false;
    }
  }

  return true;
}

function calcLineCount(hunk) {
  var _calcOldNewLineCount = calcOldNewLineCount(hunk.lines),
      oldLines = _calcOldNewLineCount.oldLines,
      newLines = _calcOldNewLineCount.newLines;

  if (oldLines !== undefined) {
    hunk.oldLines = oldLines;
  } else {
    delete hunk.oldLines;
  }

  if (newLines !== undefined) {
    hunk.newLines = newLines;
  } else {
    delete hunk.newLines;
  }
}
function merge(mine, theirs, base) {
  mine = loadPatch(mine, base);
  theirs = loadPatch(theirs, base);
  var ret = {}; // For index we just let it pass through as it doesn't have any necessary meaning.
  // Leaving sanity checks on this to the API consumer that may know more about the
  // meaning in their own context.

  if (mine.index || theirs.index) {
    ret.index = mine.index || theirs.index;
  }

  if (mine.newFileName || theirs.newFileName) {
    if (!fileNameChanged(mine)) {
      // No header or no change in ours, use theirs (and ours if theirs does not exist)
      ret.oldFileName = theirs.oldFileName || mine.oldFileName;
      ret.newFileName = theirs.newFileName || mine.newFileName;
      ret.oldHeader = theirs.oldHeader || mine.oldHeader;
      ret.newHeader = theirs.newHeader || mine.newHeader;
    } else if (!fileNameChanged(theirs)) {
      // No header or no change in theirs, use ours
      ret.oldFileName = mine.oldFileName;
      ret.newFileName = mine.newFileName;
      ret.oldHeader = mine.oldHeader;
      ret.newHeader = mine.newHeader;
    } else {
      // Both changed... figure it out
      ret.oldFileName = selectField(ret, mine.oldFileName, theirs.oldFileName);
      ret.newFileName = selectField(ret, mine.newFileName, theirs.newFileName);
      ret.oldHeader = selectField(ret, mine.oldHeader, theirs.oldHeader);
      ret.newHeader = selectField(ret, mine.newHeader, theirs.newHeader);
    }
  }

  ret.hunks = [];
  var mineIndex = 0,
      theirsIndex = 0,
      mineOffset = 0,
      theirsOffset = 0;

  while (mineIndex < mine.hunks.length || theirsIndex < theirs.hunks.length) {
    var mineCurrent = mine.hunks[mineIndex] || {
      oldStart: Infinity
    },
        theirsCurrent = theirs.hunks[theirsIndex] || {
      oldStart: Infinity
    };

    if (hunkBefore(mineCurrent, theirsCurrent)) {
      // This patch does not overlap with any of the others, yay.
      ret.hunks.push(cloneHunk(mineCurrent, mineOffset));
      mineIndex++;
      theirsOffset += mineCurrent.newLines - mineCurrent.oldLines;
    } else if (hunkBefore(theirsCurrent, mineCurrent)) {
      // This patch does not overlap with any of the others, yay.
      ret.hunks.push(cloneHunk(theirsCurrent, theirsOffset));
      theirsIndex++;
      mineOffset += theirsCurrent.newLines - theirsCurrent.oldLines;
    } else {
      // Overlap, merge as best we can
      var mergedHunk = {
        oldStart: Math.min(mineCurrent.oldStart, theirsCurrent.oldStart),
        oldLines: 0,
        newStart: Math.min(mineCurrent.newStart + mineOffset, theirsCurrent.oldStart + theirsOffset),
        newLines: 0,
        lines: []
      };
      mergeLines(mergedHunk, mineCurrent.oldStart, mineCurrent.lines, theirsCurrent.oldStart, theirsCurrent.lines);
      theirsIndex++;
      mineIndex++;
      ret.hunks.push(mergedHunk);
    }
  }

  return ret;
}

function loadPatch(param, base) {
  if (typeof param === 'string') {
    if (/^@@/m.test(param) || /^Index:/m.test(param)) {
      return parsePatch(param)[0];
    }

    if (!base) {
      throw new Error('Must provide a base reference or pass in a patch');
    }

    return structuredPatch(undefined, undefined, base, param);
  }

  return param;
}

function fileNameChanged(patch) {
  return patch.newFileName && patch.newFileName !== patch.oldFileName;
}

function selectField(index, mine, theirs) {
  if (mine === theirs) {
    return mine;
  } else {
    index.conflict = true;
    return {
      mine: mine,
      theirs: theirs
    };
  }
}

function hunkBefore(test, check) {
  return test.oldStart < check.oldStart && test.oldStart + test.oldLines < check.oldStart;
}

function cloneHunk(hunk, offset) {
  return {
    oldStart: hunk.oldStart,
    oldLines: hunk.oldLines,
    newStart: hunk.newStart + offset,
    newLines: hunk.newLines,
    lines: hunk.lines
  };
}

function mergeLines(hunk, mineOffset, mineLines, theirOffset, theirLines) {
  // This will generally result in a conflicted hunk, but there are cases where the context
  // is the only overlap where we can successfully merge the content here.
  var mine = {
    offset: mineOffset,
    lines: mineLines,
    index: 0
  },
      their = {
    offset: theirOffset,
    lines: theirLines,
    index: 0
  }; // Handle any leading content

  insertLeading(hunk, mine, their);
  insertLeading(hunk, their, mine); // Now in the overlap content. Scan through and select the best changes from each.

  while (mine.index < mine.lines.length && their.index < their.lines.length) {
    var mineCurrent = mine.lines[mine.index],
        theirCurrent = their.lines[their.index];

    if ((mineCurrent[0] === '-' || mineCurrent[0] === '+') && (theirCurrent[0] === '-' || theirCurrent[0] === '+')) {
      // Both modified ...
      mutualChange(hunk, mine, their);
    } else if (mineCurrent[0] === '+' && theirCurrent[0] === ' ') {
      var _hunk$lines;

      // Mine inserted
      (_hunk$lines = hunk.lines).push.apply(_hunk$lines, _toConsumableArray(collectChange(mine)));
    } else if (theirCurrent[0] === '+' && mineCurrent[0] === ' ') {
      var _hunk$lines2;

      // Theirs inserted
      (_hunk$lines2 = hunk.lines).push.apply(_hunk$lines2, _toConsumableArray(collectChange(their)));
    } else if (mineCurrent[0] === '-' && theirCurrent[0] === ' ') {
      // Mine removed or edited
      removal(hunk, mine, their);
    } else if (theirCurrent[0] === '-' && mineCurrent[0] === ' ') {
      // Their removed or edited
      removal(hunk, their, mine, true);
    } else if (mineCurrent === theirCurrent) {
      // Context identity
      hunk.lines.push(mineCurrent);
      mine.index++;
      their.index++;
    } else {
      // Context mismatch
      conflict(hunk, collectChange(mine), collectChange(their));
    }
  } // Now push anything that may be remaining


  insertTrailing(hunk, mine);
  insertTrailing(hunk, their);
  calcLineCount(hunk);
}

function mutualChange(hunk, mine, their) {
  var myChanges = collectChange(mine),
      theirChanges = collectChange(their);

  if (allRemoves(myChanges) && allRemoves(theirChanges)) {
    // Special case for remove changes that are supersets of one another
    if (arrayStartsWith(myChanges, theirChanges) && skipRemoveSuperset(their, myChanges, myChanges.length - theirChanges.length)) {
      var _hunk$lines3;

      (_hunk$lines3 = hunk.lines).push.apply(_hunk$lines3, _toConsumableArray(myChanges));

      return;
    } else if (arrayStartsWith(theirChanges, myChanges) && skipRemoveSuperset(mine, theirChanges, theirChanges.length - myChanges.length)) {
      var _hunk$lines4;

      (_hunk$lines4 = hunk.lines).push.apply(_hunk$lines4, _toConsumableArray(theirChanges));

      return;
    }
  } else if (arrayEqual(myChanges, theirChanges)) {
    var _hunk$lines5;

    (_hunk$lines5 = hunk.lines).push.apply(_hunk$lines5, _toConsumableArray(myChanges));

    return;
  }

  conflict(hunk, myChanges, theirChanges);
}

function removal(hunk, mine, their, swap) {
  var myChanges = collectChange(mine),
      theirChanges = collectContext(their, myChanges);

  if (theirChanges.merged) {
    var _hunk$lines6;

    (_hunk$lines6 = hunk.lines).push.apply(_hunk$lines6, _toConsumableArray(theirChanges.merged));
  } else {
    conflict(hunk, swap ? theirChanges : myChanges, swap ? myChanges : theirChanges);
  }
}

function conflict(hunk, mine, their) {
  hunk.conflict = true;
  hunk.lines.push({
    conflict: true,
    mine: mine,
    theirs: their
  });
}

function insertLeading(hunk, insert, their) {
  while (insert.offset < their.offset && insert.index < insert.lines.length) {
    var line = insert.lines[insert.index++];
    hunk.lines.push(line);
    insert.offset++;
  }
}

function insertTrailing(hunk, insert) {
  while (insert.index < insert.lines.length) {
    var line = insert.lines[insert.index++];
    hunk.lines.push(line);
  }
}

function collectChange(state) {
  var ret = [],
      operation = state.lines[state.index][0];

  while (state.index < state.lines.length) {
    var line = state.lines[state.index]; // Group additions that are immediately after subtractions and treat them as one "atomic" modify change.

    if (operation === '-' && line[0] === '+') {
      operation = '+';
    }

    if (operation === line[0]) {
      ret.push(line);
      state.index++;
    } else {
      break;
    }
  }

  return ret;
}

function collectContext(state, matchChanges) {
  var changes = [],
      merged = [],
      matchIndex = 0,
      contextChanges = false,
      conflicted = false;

  while (matchIndex < matchChanges.length && state.index < state.lines.length) {
    var change = state.lines[state.index],
        match = matchChanges[matchIndex]; // Once we've hit our add, then we are done

    if (match[0] === '+') {
      break;
    }

    contextChanges = contextChanges || change[0] !== ' ';
    merged.push(match);
    matchIndex++; // Consume any additions in the other block as a conflict to attempt
    // to pull in the remaining context after this

    if (change[0] === '+') {
      conflicted = true;

      while (change[0] === '+') {
        changes.push(change);
        change = state.lines[++state.index];
      }
    }

    if (match.substr(1) === change.substr(1)) {
      changes.push(change);
      state.index++;
    } else {
      conflicted = true;
    }
  }

  if ((matchChanges[matchIndex] || '')[0] === '+' && contextChanges) {
    conflicted = true;
  }

  if (conflicted) {
    return changes;
  }

  while (matchIndex < matchChanges.length) {
    merged.push(matchChanges[matchIndex++]);
  }

  return {
    merged: merged,
    changes: changes
  };
}

function allRemoves(changes) {
  return changes.reduce(function (prev, change) {
    return prev && change[0] === '-';
  }, true);
}

function skipRemoveSuperset(state, removeChanges, delta) {
  for (var i = 0; i < delta; i++) {
    var changeContent = removeChanges[removeChanges.length - delta + i].substr(1);

    if (state.lines[state.index + i] !== ' ' + changeContent) {
      return false;
    }
  }

  state.index += delta;
  return true;
}

function calcOldNewLineCount(lines) {
  var oldLines = 0;
  var newLines = 0;
  lines.forEach(function (line) {
    if (typeof line !== 'string') {
      var myCount = calcOldNewLineCount(line.mine);
      var theirCount = calcOldNewLineCount(line.theirs);

      if (oldLines !== undefined) {
        if (myCount.oldLines === theirCount.oldLines) {
          oldLines += myCount.oldLines;
        } else {
          oldLines = undefined;
        }
      }

      if (newLines !== undefined) {
        if (myCount.newLines === theirCount.newLines) {
          newLines += myCount.newLines;
        } else {
          newLines = undefined;
        }
      }
    } else {
      if (newLines !== undefined && (line[0] === '+' || line[0] === ' ')) {
        newLines++;
      }

      if (oldLines !== undefined && (line[0] === '-' || line[0] === ' ')) {
        oldLines++;
      }
    }
  });
  return {
    oldLines: oldLines,
    newLines: newLines
  };
}

// See: http://code.google.com/p/google-diff-match-patch/wiki/API
function convertChangesToDMP(changes) {
  var ret = [],
      change,
      operation;

  for (var i = 0; i < changes.length; i++) {
    change = changes[i];

    if (change.added) {
      operation = 1;
    } else if (change.removed) {
      operation = -1;
    } else {
      operation = 0;
    }

    ret.push([operation, change.value]);
  }

  return ret;
}

function convertChangesToXML(changes) {
  var ret = [];

  for (var i = 0; i < changes.length; i++) {
    var change = changes[i];

    if (change.added) {
      ret.push('<ins>');
    } else if (change.removed) {
      ret.push('<del>');
    }

    ret.push(escapeHTML(change.value));

    if (change.added) {
      ret.push('</ins>');
    } else if (change.removed) {
      ret.push('</del>');
    }
  }

  return ret.join('');
}

function escapeHTML(s) {
  var n = s;
  n = n.replace(/&/g, '&amp;');
  n = n.replace(/</g, '&lt;');
  n = n.replace(/>/g, '&gt;');
  n = n.replace(/"/g, '&quot;');
  return n;
}

export { Diff, applyPatch, applyPatches, canonicalize, convertChangesToDMP, convertChangesToXML, createPatch, createTwoFilesPatch, diffArrays, diffChars, diffCss, diffJson, diffLines, diffSentences, diffTrimmedLines, diffWords, diffWordsWithSpace, merge, parsePatch, structuredPatch };