path: root/node_modules/locutus/php/xdiff/xdiff_string_diff.js

'use strict';

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

module.exports = function xdiff_string_diff(oldData, newData, contextLines, minimal) {
  // eslint-disable-line camelcase
  //  discuss at: http://locutus.io/php/xdiff_string_diff
  // original by: Brett Zamir (http://brett-zamir.me)
  //    based on: Imgen Tata (http://www.myipdf.com/)
  // bugfixed by: Imgen Tata (http://www.myipdf.com/)
  // improved by: Brett Zamir (http://brett-zamir.me)
  //      note 1: The minimal argument is not currently supported
  //   example 1: xdiff_string_diff('', 'Hello world!')
  //   returns 1: '@@ -0,0 +1,1 @@\n+Hello world!'

  // (This code was done by Imgen Tata; I have only reformatted for use in Locutus)

  // See http://en.wikipedia.org/wiki/Diff#Unified_format
  var i = 0;
  var j = 0;
  var k = 0;
  var oriHunkStart;
  var newHunkStart;
  var oriHunkEnd;
  var newHunkEnd;
  var oriHunkLineNo;
  var newHunkLineNo;
  var oriHunkSize;
  var newHunkSize;
  var MAX_CONTEXT_LINES = Number.POSITIVE_INFINITY; // Potential configuration
  var MIN_CONTEXT_LINES = 0;
  var DEFAULT_CONTEXT_LINES = 3;
  var HEADER_PREFIX = '@@ '; //
  var HEADER_SUFFIX = ' @@';
  var ORIGINAL_INDICATOR = '-';
  var NEW_INDICATOR = '+';
  var RANGE_SEPARATOR = ',';
  var CONTEXT_INDICATOR = ' ';
  var DELETION_INDICATOR = '-';
  var ADDITION_INDICATOR = '+';
  var oriLines;
  var newLines;
  var NEW_LINE = '\n';

  var _trim = function _trim(text) {
    if (typeof text !== 'string') {
      throw new Error('String parameter required');
    }

    return text.replace(/(^\s*)|(\s*$)/g, '');
  };

  var _verifyType = function _verifyType(type) {
    var args = arguments;
    var argsLen = arguments.length;
    var basicTypes = ['number', 'boolean', 'string', 'function', 'object', 'undefined'];
    var basicType;
    var i;
    var j;
    var typeOfType = typeof type === 'undefined' ? 'undefined' : _typeof(type);
    if (typeOfType !== 'string' && typeOfType !== 'function') {
      throw new Error('Bad type parameter');
    }

    if (argsLen < 2) {
      throw new Error('Too few arguments');
    }

    if (typeOfType === 'string') {
      type = _trim(type);

      if (type === '') {
        throw new Error('Bad type parameter');
      }

      for (j = 0; j < basicTypes.length; j++) {
        basicType = basicTypes[j];

        if (basicType === type) {
          for (i = 1; i < argsLen; i++) {
            if (_typeof(args[i]) !== type) {
              throw new Error('Bad type');
            }
          }

          return;
        }
      }

      throw new Error('Bad type parameter');
    }

    // Not basic type. we need to use instanceof operator
    for (i = 1; i < argsLen; i++) {
      if (!(args[i] instanceof type)) {
        throw new Error('Bad type');
      }
    }
  };

  var _hasValue = function _hasValue(array, value) {
    var i;
    _verifyType(Array, array);

    for (i = 0; i < array.length; i++) {
      if (array[i] === value) {
        return true;
      }
    }

    return false;
  };

  var _areTypeOf = function _areTypeOf(type) {
    var args = arguments;
    var argsLen = arguments.length;
    var basicTypes = ['number', 'boolean', 'string', 'function', 'object', 'undefined'];
    var basicType;
    var i;
    var j;
    var typeOfType = typeof type === 'undefined' ? 'undefined' : _typeof(type);

    if (typeOfType !== 'string' && typeOfType !== 'function') {
      throw new Error('Bad type parameter');
    }

    if (argsLen < 2) {
      throw new Error('Too few arguments');
    }

    if (typeOfType === 'string') {
      type = _trim(type);

      if (type === '') {
        return false;
      }

      for (j = 0; j < basicTypes.length; j++) {
        basicType = basicTypes[j];

        if (basicType === type) {
          for (i = 1; i < argsLen; i++) {
            if (_typeof(args[i]) !== type) {
              return false;
            }
          }

          return true;
        }
      }

      throw new Error('Bad type parameter');
    }

    // Not basic type. we need to use instanceof operator
    for (i = 1; i < argsLen; i++) {
      if (!(args[i] instanceof type)) {
        return false;
      }
    }

    return true;
  };

  var _getInitializedArray = function _getInitializedArray(arraySize, initValue) {
    var array = [];
    var i;
    _verifyType('number', arraySize);

    for (i = 0; i < arraySize; i++) {
      array.push(initValue);
    }

    return array;
  };

  var _splitIntoLines = function _splitIntoLines(text) {
    _verifyType('string', text);

    if (text === '') {
      return [];
    }
    return text.split('\n');
  };

  var _isEmptyArray = function _isEmptyArray(obj) {
    return _areTypeOf(Array, obj) && obj.length === 0;
  };

  /**
   * Finds longest common sequence between two sequences
   * @see {@link http://wordaligned.org/articles/longest-common-subsequence}
   */
  var _findLongestCommonSequence = function _findLongestCommonSequence(seq1, seq2, seq1IsInLcs, seq2IsInLcs) {
    if (!_areTypeOf(Array, seq1, seq2)) {
      throw new Error('Array parameters are required');
    }

    // Deal with edge case
    if (_isEmptyArray(seq1) || _isEmptyArray(seq2)) {
      return [];
    }

    // Function to calculate lcs lengths
    var lcsLens = function lcsLens(xs, ys) {
      var i;
      var j;
      var prev;
      var curr = _getInitializedArray(ys.length + 1, 0);

      for (i = 0; i < xs.length; i++) {
        prev = curr.slice(0);
        for (j = 0; j < ys.length; j++) {
          if (xs[i] === ys[j]) {
            curr[j + 1] = prev[j] + 1;
          } else {
            curr[j + 1] = Math.max(curr[j], prev[j + 1]);
          }
        }
      }

      return curr;
    };

    // Function to find lcs and fill in the array to indicate the optimal longest common sequence
    var _findLcs = function _findLcs(xs, xidx, xIsIn, ys) {
      var i;
      var xb;
      var xe;
      var llB;
      var llE;
      var pivot;
      var max;
      var yb;
      var ye;
      var nx = xs.length;
      var ny = ys.length;

      if (nx === 0) {
        return [];
      }
      if (nx === 1) {
        if (_hasValue(ys, xs[0])) {
          xIsIn[xidx] = true;
          return [xs[0]];
        }
        return [];
      }
      i = Math.floor(nx / 2);
      xb = xs.slice(0, i);
      xe = xs.slice(i);
      llB = lcsLens(xb, ys);
      llE = lcsLens(xe.slice(0).reverse(), ys.slice(0).reverse());

      pivot = 0;
      max = 0;
      for (j = 0; j <= ny; j++) {
        if (llB[j] + llE[ny - j] > max) {
          pivot = j;
          max = llB[j] + llE[ny - j];
        }
      }
      yb = ys.slice(0, pivot);
      ye = ys.slice(pivot);
      return _findLcs(xb, xidx, xIsIn, yb).concat(_findLcs(xe, xidx + i, xIsIn, ye));
    };

    // Fill in seq1IsInLcs to find the optimal longest common subsequence of first sequence
    _findLcs(seq1, 0, seq1IsInLcs, seq2);
    // Fill in seq2IsInLcs to find the optimal longest common subsequence
    // of second sequence and return the result
    return _findLcs(seq2, 0, seq2IsInLcs, seq1);
  };

  // First, check the parameters
  if (_areTypeOf('string', oldData, newData) === false) {
    return false;
  }

  if (oldData === newData) {
    return '';
  }

  if (typeof contextLines !== 'number' || contextLines > MAX_CONTEXT_LINES || contextLines < MIN_CONTEXT_LINES) {
    contextLines = DEFAULT_CONTEXT_LINES;
  }

  oriLines = _splitIntoLines(oldData);
  newLines = _splitIntoLines(newData);
  var oriLen = oriLines.length;
  var newLen = newLines.length;
  var oriIsInLcs = _getInitializedArray(oriLen, false);
  var newIsInLcs = _getInitializedArray(newLen, false);
  var lcsLen = _findLongestCommonSequence(oriLines, newLines, oriIsInLcs, newIsInLcs).length;
  var unidiff = '';

  if (lcsLen === 0) {
    // No common sequence
    unidiff = [HEADER_PREFIX, ORIGINAL_INDICATOR, oriLen > 0 ? '1' : '0', RANGE_SEPARATOR, oriLen, ' ', NEW_INDICATOR, newLen > 0 ? '1' : '0', RANGE_SEPARATOR, newLen, HEADER_SUFFIX].join('');

    for (i = 0; i < oriLen; i++) {
      unidiff += NEW_LINE + DELETION_INDICATOR + oriLines[i];
    }

    for (j = 0; j < newLen; j++) {
      unidiff += NEW_LINE + ADDITION_INDICATOR + newLines[j];
    }

    return unidiff;
  }

  var leadingContext = [];
  var trailingContext = [];
  var actualLeadingContext = [];
  var actualTrailingContext = [];

  // Regularize leading context by the contextLines parameter
  var regularizeLeadingContext = function regularizeLeadingContext(context) {
    if (context.length === 0 || contextLines === 0) {
      return [];
    }

    var contextStartPos = Math.max(context.length - contextLines, 0);

    return context.slice(contextStartPos);
  };

  // Regularize trailing context by the contextLines parameter
  var regularizeTrailingContext = function regularizeTrailingContext(context) {
    if (context.length === 0 || contextLines === 0) {
      return [];
    }

    return context.slice(0, Math.min(contextLines, context.length));
  };

  // Skip common lines in the beginning
  while (i < oriLen && oriIsInLcs[i] === true && newIsInLcs[i] === true) {
    leadingContext.push(oriLines[i]);
    i++;
  }

  j = i;
  // The index in the longest common sequence
  k = i;
  oriHunkStart = i;
  newHunkStart = j;
  oriHunkEnd = i;
  newHunkEnd = j;

  while (i < oriLen || j < newLen) {
    while (i < oriLen && oriIsInLcs[i] === false) {
      i++;
    }
    oriHunkEnd = i;

    while (j < newLen && newIsInLcs[j] === false) {
      j++;
    }
    newHunkEnd = j;

    // Find the trailing context
    trailingContext = [];
    while (i < oriLen && oriIsInLcs[i] === true && j < newLen && newIsInLcs[j] === true) {
      trailingContext.push(oriLines[i]);
      k++;
      i++;
      j++;
    }

    if (k >= lcsLen || // No more in longest common lines
    trailingContext.length >= 2 * contextLines) {
      // Context break found
      if (trailingContext.length < 2 * contextLines) {
        // It must be last block of common lines but not a context break
        trailingContext = [];

        // Force break out
        i = oriLen;
        j = newLen;

        // Update hunk ends to force output to the end
        oriHunkEnd = oriLen;
        newHunkEnd = newLen;
      }

      // Output the diff hunk

      // Trim the leading and trailing context block
      actualLeadingContext = regularizeLeadingContext(leadingContext);
      actualTrailingContext = regularizeTrailingContext(trailingContext);

      oriHunkStart -= actualLeadingContext.length;
      newHunkStart -= actualLeadingContext.length;
      oriHunkEnd += actualTrailingContext.length;
      newHunkEnd += actualTrailingContext.length;

      oriHunkLineNo = oriHunkStart + 1;
      newHunkLineNo = newHunkStart + 1;
      oriHunkSize = oriHunkEnd - oriHunkStart;
      newHunkSize = newHunkEnd - newHunkStart;

      // Build header
      unidiff += [HEADER_PREFIX, ORIGINAL_INDICATOR, oriHunkLineNo, RANGE_SEPARATOR, oriHunkSize, ' ', NEW_INDICATOR, newHunkLineNo, RANGE_SEPARATOR, newHunkSize, HEADER_SUFFIX, NEW_LINE].join('');

      // Build the diff hunk content
      while (oriHunkStart < oriHunkEnd || newHunkStart < newHunkEnd) {
        if (oriHunkStart < oriHunkEnd && oriIsInLcs[oriHunkStart] === true && newIsInLcs[newHunkStart] === true) {
          // The context line
          unidiff += CONTEXT_INDICATOR + oriLines[oriHunkStart] + NEW_LINE;
          oriHunkStart++;
          newHunkStart++;
        } else if (oriHunkStart < oriHunkEnd && oriIsInLcs[oriHunkStart] === false) {
          // The deletion line
          unidiff += DELETION_INDICATOR + oriLines[oriHunkStart] + NEW_LINE;
          oriHunkStart++;
        } else if (newHunkStart < newHunkEnd && newIsInLcs[newHunkStart] === false) {
          // The additional line
          unidiff += ADDITION_INDICATOR + newLines[newHunkStart] + NEW_LINE;
          newHunkStart++;
        }
      }

      // Update hunk position and leading context
      oriHunkStart = i;
      newHunkStart = j;
      leadingContext = trailingContext;
    }
  }

  // Trim the trailing new line if it exists
  if (unidiff.length > 0 && unidiff.charAt(unidiff.length) === NEW_LINE) {
    unidiff = unidiff.slice(0, -1);
  }

  return unidiff;
};
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