lodash/lodash._baseisequal/index.js

/**
 * lodash 3.0.0 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.7.0 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var isArray = require('lodash.isarray'),
    isTypedArray = require('lodash.istypedarray'),
    keys = require('lodash.keys');

/** `Object#toString` result references. */
var argsTag = '[object Arguments]',
    arrayTag = '[object Array]',
    boolTag = '[object Boolean]',
    dateTag = '[object Date]',
    errorTag = '[object Error]',
    numberTag = '[object Number]',
    objectTag = '[object Object]',
    regexpTag = '[object RegExp]',
    stringTag = '[object String]';

/**
 * Converts `value` to a string if it is not one. An empty string is returned
 * for `null` or `undefined` values.
 *
 * @private
 * @param {*} value The value to process.
 * @returns {string} Returns the string.
 */
function baseToString(value) {
  if (typeof value == 'string') {
    return value;
  }
  return value == null ? '' : (value + '');
}

/** Used for native method references. */
var objectProto = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty = objectProto.hasOwnProperty;

/**
 * Used to resolve the `toStringTag` of values.
 * See the [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.prototype.tostring)
 * for more details.
 */
var objToString = objectProto.toString;

/**
 * The base implementation of `_.isEqual` without support for `this` binding
 * `customizer` functions.
 *
 * @private
 * @param {*} value The value to compare.
 * @param {*} other The other value to compare.
 * @param {Function} [customizer] The function to customize comparing values.
 * @param {boolean} [isWhere] Specify performing partial comparisons.
 * @param {Array} [stackA] Tracks traversed `value` objects.
 * @param {Array} [stackB] Tracks traversed `other` objects.
 * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
 */
function baseIsEqual(value, other, customizer, isWhere, stackA, stackB) {
  // Exit early for identical values.
  if (value === other) {
    // Treat `+0` vs. `-0` as not equal.
    return value !== 0 || (1 / value == 1 / other);
  }
  var valType = typeof value,
      othType = typeof other;

  // Exit early for unlike primitive values.
  if ((valType != 'function' && valType != 'object' && othType != 'function' && othType != 'object') ||
      value == null || other == null) {
    // Return `false` unless both values are `NaN`.
    return value !== value && other !== other;
  }
  return baseIsEqualDeep(value, other, baseIsEqual, customizer, isWhere, stackA, stackB);
}

/**
 * A specialized version of `baseIsEqual` for arrays and objects which performs
 * deep comparisons and tracks traversed objects enabling objects with circular
 * references to be compared.
 *
 * @private
 * @param {Object} object The object to compare.
 * @param {Object} other The other object to compare.
 * @param {Function} equalFunc The function to determine equivalents of values.
 * @param {Function} [customizer] The function to customize comparing objects.
 * @param {boolean} [isWhere] Specify performing partial comparisons.
 * @param {Array} [stackA=[]] Tracks traversed `value` objects.
 * @param {Array} [stackB=[]] Tracks traversed `other` objects.
 * @returns {boolean} Returns `true` if the objects are equivalent, else `false`.
 */
function baseIsEqualDeep(object, other, equalFunc, customizer, isWhere, stackA, stackB) {
  var objIsArr = isArray(object),
      othIsArr = isArray(other),
      objTag = arrayTag,
      othTag = arrayTag;

  if (!objIsArr) {
    objTag = objToString.call(object);
    if (objTag == argsTag) {
      objTag = objectTag;
    } else if (objTag != objectTag) {
      objIsArr = isTypedArray(object);
    }
  }
  if (!othIsArr) {
    othTag = objToString.call(other);
    if (othTag == argsTag) {
      othTag = objectTag;
    } else if (othTag != objectTag) {
      othIsArr = isTypedArray(other);
    }
  }
  var objIsObj = objTag == objectTag,
      othIsObj = othTag == objectTag,
      isSameTag = objTag == othTag;

  if (isSameTag && !(objIsArr || objIsObj)) {
    return equalByTag(object, other, objTag);
  }
  var valWrapped = objIsObj && hasOwnProperty.call(object, '__wrapped__'),
      othWrapped = othIsObj && hasOwnProperty.call(other, '__wrapped__');

  if (valWrapped || othWrapped) {
    return equalFunc(valWrapped ? object.value() : object, othWrapped ? other.value() : other, customizer, isWhere, stackA, stackB);
  }
  if (!isSameTag) {
    return false;
  }
  // Assume cyclic values are equal.
  // For more information on detecting circular references see https://es5.github.io/#JO.
  stackA || (stackA = []);
  stackB || (stackB = []);

  var length = stackA.length;
  while (length--) {
    if (stackA[length] == object) {
      return stackB[length] == other;
    }
  }
  // Add `object` and `other` to the stack of traversed objects.
  stackA.push(object);
  stackB.push(other);

  var result = (objIsArr ? equalArrays : equalObjects)(object, other, equalFunc, customizer, isWhere, stackA, stackB);

  stackA.pop();
  stackB.pop();

  return result;
}

/**
 * A specialized version of `baseIsEqualDeep` for arrays with support for
 * partial deep comparisons.
 *
 * @private
 * @param {Array} array The array to compare.
 * @param {Array} other The other array to compare.
 * @param {Function} equalFunc The function to determine equivalents of values.
 * @param {Function} [customizer] The function to customize comparing arrays.
 * @param {boolean} [isWhere] Specify performing partial comparisons.
 * @param {Array} [stackA] Tracks traversed `value` objects.
 * @param {Array} [stackB] Tracks traversed `other` objects.
 * @returns {boolean} Returns `true` if the arrays are equivalent, else `false`.
 */
function equalArrays(array, other, equalFunc, customizer, isWhere, stackA, stackB) {
  var index = -1,
      arrLength = array.length,
      othLength = other.length,
      result = true;

  if (arrLength != othLength && !(isWhere && othLength > arrLength)) {
    return false;
  }
  // Deep compare the contents, ignoring non-numeric properties.
  while (result && ++index < arrLength) {
    var arrValue = array[index],
        othValue = other[index];

    result = undefined;
    if (customizer) {
      result = isWhere
        ? customizer(othValue, arrValue, index)
        : customizer(arrValue, othValue, index);
    }
    if (typeof result == 'undefined') {
      // Recursively compare arrays (susceptible to call stack limits).
      if (isWhere) {
        var othIndex = othLength;
        while (othIndex--) {
          othValue = other[othIndex];
          result = (arrValue && arrValue === othValue) || equalFunc(arrValue, othValue, customizer, isWhere, stackA, stackB);
          if (result) {
            break;
          }
        }
      } else {
        result = (arrValue && arrValue === othValue) || equalFunc(arrValue, othValue, customizer, isWhere, stackA, stackB);
      }
    }
  }
  return !!result;
}

/**
 * A specialized version of `baseIsEqualDeep` for comparing objects of
 * the same `toStringTag`.
 *
 * **Note:** This function only supports comparing values with tags of
 * `Boolean`, `Date`, `Error`, `Number`, `RegExp`, or `String`.
 *
 * @private
 * @param {Object} value The object to compare.
 * @param {Object} other The other object to compare.
 * @param {string} tag The `toStringTag` of the objects to compare.
 * @returns {boolean} Returns `true` if the objects are equivalent, else `false`.
 */
function equalByTag(object, other, tag) {
  switch (tag) {
    case boolTag:
    case dateTag:
      // Coerce dates and booleans to numbers, dates to milliseconds and booleans
      // to `1` or `0` treating invalid dates coerced to `NaN` as not equal.
      return +object == +other;

    case errorTag:
      return object.name == other.name && object.message == other.message;

    case numberTag:
      // Treat `NaN` vs. `NaN` as equal.
      return (object != +object)
        ? other != +other
        // But, treat `-0` vs. `+0` as not equal.
        : (object == 0 ? ((1 / object) == (1 / other)) : object == +other);

    case regexpTag:
    case stringTag:
      // Coerce regexes to strings and treat strings primitives and string
      // objects as equal. See https://es5.github.io/#x15.10.6.4 for more details.
      return object == baseToString(other);
  }
  return false;
}

/**
 * A specialized version of `baseIsEqualDeep` for objects with support for
 * partial deep comparisons.
 *
 * @private
 * @param {Object} object The object to compare.
 * @param {Object} other The other object to compare.
 * @param {Function} equalFunc The function to determine equivalents of values.
 * @param {Function} [customizer] The function to customize comparing values.
 * @param {boolean} [isWhere] Specify performing partial comparisons.
 * @param {Array} [stackA] Tracks traversed `value` objects.
 * @param {Array} [stackB] Tracks traversed `other` objects.
 * @returns {boolean} Returns `true` if the objects are equivalent, else `false`.
 */
function equalObjects(object, other, equalFunc, customizer, isWhere, stackA, stackB) {
  var objProps = keys(object),
      objLength = objProps.length,
      othProps = keys(other),
      othLength = othProps.length;

  if (objLength != othLength && !isWhere) {
    return false;
  }
  var hasCtor,
      index = -1;

  while (++index < objLength) {
    var key = objProps[index],
        result = hasOwnProperty.call(other, key);

    if (result) {
      var objValue = object[key],
          othValue = other[key];

      result = undefined;
      if (customizer) {
        result = isWhere
          ? customizer(othValue, objValue, key)
          : customizer(objValue, othValue, key);
      }
      if (typeof result == 'undefined') {
        // Recursively compare objects (susceptible to call stack limits).
        result = (objValue && objValue === othValue) || equalFunc(objValue, othValue, customizer, isWhere, stackA, stackB);
      }
    }
    if (!result) {
      return false;
    }
    hasCtor || (hasCtor = key == 'constructor');
  }
  if (!hasCtor) {
    var objCtor = object.constructor,
        othCtor = other.constructor;

    // Non `Object` object instances with different constructors are not equal.
    if (objCtor != othCtor && ('constructor' in object && 'constructor' in other) &&
        !(typeof objCtor == 'function' && objCtor instanceof objCtor && typeof othCtor == 'function' && othCtor instanceof othCtor)) {
      return false;
    }
  }
  return true;
}

module.exports = baseIsEqual;