
/**!
 * is
 * the definitive JavaScript type testing library
 * 
 * @copyright 2013 Enrico Marino
 * @license MIT
 */

var objProto = Object.prototype;
var owns = objProto.hasOwnProperty;
var toString = objProto.toString;
var isActualNaN = function (value) {
  return value !== value;
};
var NON_HOST_TYPES = {
  "boolean": 1,
  "number": 1,
  "string": 1,
  "undefined": 1
};

/**
 * Expose `is`
 */

var is = module.exports = {};

/**
 * Test general.
 */

/**
 * is.type
 * Test if `value` is a type of `type`.
 *
 * @param {Mixed} value value to test
 * @param {String} type type
 * @return {Boolean} true if `value` is a type of `type`, false otherwise
 * @api public
 */

is.a =
is.type = function (value, type) {
  return typeof value === type;
};

/**
 * is.defined
 * Test if `value` is defined.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if 'value' is defined, false otherwise
 * @api public
 */

is.defined = function (value) {
  return value !== undefined;
};

/**
 * is.empty
 * Test if `value` is empty.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is empty, false otherwise
 * @api public
 */

is.empty = function (value) {
  var type = toString.call(value);
  var key;

  if ('[object Array]' === type || '[object Arguments]' === type) {
    return value.length === 0;
  }

  if ('[object Object]' === type) {
    for (key in value) if (owns.call(value, key)) return false;
    return true;
  }

  if ('[object String]' === type) {
    return '' === value;
  }

  return false;
};

/**
 * is.equal
 * Test if `value` is equal to `other`.
 *
 * @param {Mixed} value value to test
 * @param {Mixed} other value to compare with
 * @return {Boolean} true if `value` is equal to `other`, false otherwise
 */

is.equal = function (value, other) {
  var strictlyEqual = value === other;
  if (strictlyEqual) {
    return true;
  }

  var type = toString.call(value);
  var key;

  if (type !== toString.call(other)) {
    return false;
  }

  if ('[object Object]' === type) {
    for (key in value) {
      if (!is.equal(value[key], other[key]) || !(key in other)) {
        return false;
      }
    }
    for (key in other) {
      if (!is.equal(value[key], other[key]) || !(key in value)) {
        return false;
      }
    }
    return true;
  }

  if ('[object Array]' === type) {
    key = value.length;
    if (key !== other.length) {
      return false;
    }
    while (--key) {
      if (!is.equal(value[key], other[key])) {
        return false;
      }
    }
    return true;
  }

  if ('[object Function]' === type) {
    return value.prototype === other.prototype;
  }

  if ('[object Date]' === type) {
    return value.getTime() === other.getTime();
  }

  return strictlyEqual;
};

/**
 * is.hosted
 * Test if `value` is hosted by `host`.
 *
 * @param {Mixed} value to test
 * @param {Mixed} host host to test with
 * @return {Boolean} true if `value` is hosted by `host`, false otherwise
 * @api public
 */

is.hosted = function (value, host) {
  var type = typeof host[value];
  return type === 'object' ? !!host[value] : !NON_HOST_TYPES[type];
};

/**
 * is.instance
 * Test if `value` is an instance of `constructor`.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an instance of `constructor`
 * @api public
 */

is.instance = is['instanceof'] = function (value, constructor) {
  return value instanceof constructor;
};

/**
 * is.null
 * Test if `value` is null.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is null, false otherwise
 * @api public
 */

is['null'] = function (value) {
  return value === null;
};

/**
 * is.undef
 * Test if `value` is undefined.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is undefined, false otherwise
 * @api public
 */

is.undef = is['undefined'] = function (value) {
  return value === undefined;
};

/**
 * Test arguments.
 */

/**
 * is.args
 * Test if `value` is an arguments object.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an arguments object, false otherwise
 * @api public
 */

is.args = is['arguments'] = function (value) {
  var isStandardArguments = '[object Arguments]' === toString.call(value);
  var isOldArguments = !is.array(value) && is.arraylike(value) && is.object(value) && is.fn(value.callee);
  return isStandardArguments || isOldArguments;
};

/**
 * Test array.
 */

/**
 * is.array
 * Test if 'value' is an array.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an array, false otherwise
 * @api public
 */

is.array = function (value) {
  return '[object Array]' === toString.call(value);
};

/**
 * is.arguments.empty
 * Test if `value` is an empty arguments object.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an empty arguments object, false otherwise
 * @api public
 */
is.args.empty = function (value) {
  return is.args(value) && value.length === 0;
};

/**
 * is.array.empty
 * Test if `value` is an empty array.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an empty array, false otherwise
 * @api public
 */
is.array.empty = function (value) {
  return is.array(value) && value.length === 0;
};

/**
 * is.arraylike
 * Test if `value` is an arraylike object.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an arguments object, false otherwise
 * @api public
 */

is.arraylike = function (value) {
  return !!value && !is.boolean(value)
    && owns.call(value, 'length')
    && isFinite(value.length)
    && is.number(value.length)
    && value.length >= 0;
};

/**
 * Test boolean.
 */

/**
 * is.boolean
 * Test if `value` is a boolean.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is a boolean, false otherwise
 * @api public
 */

is.boolean = function (value) {
  return '[object Boolean]' === toString.call(value);
};

/**
 * is.false
 * Test if `value` is false.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is false, false otherwise
 * @api public
 */

is['false'] = function (value) {
  return is.boolean(value) && (value === false || value.valueOf() === false);
};

/**
 * is.true
 * Test if `value` is true.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is true, false otherwise
 * @api public
 */

is['true'] = function (value) {
  return is.boolean(value) && (value === true || value.valueOf() === true);
};

/**
 * Test date.
 */

/**
 * is.date
 * Test if `value` is a date.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is a date, false otherwise
 * @api public
 */

is.date = function (value) {
  return '[object Date]' === toString.call(value);
};

/**
 * Test element.
 */

/**
 * is.element
 * Test if `value` is an html element.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an HTML Element, false otherwise
 * @api public
 */

is.element = function (value) {
  return value !== undefined
    && typeof HTMLElement !== 'undefined'
    && value instanceof HTMLElement
    && value.nodeType === 1;
};

/**
 * Test error.
 */

/**
 * is.error
 * Test if `value` is an error object.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an error object, false otherwise
 * @api public
 */

is.error = function (value) {
  return '[object Error]' === toString.call(value);
};

/**
 * Test function.
 */

/**
 * is.fn / is.function (deprecated)
 * Test if `value` is a function.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is a function, false otherwise
 * @api public
 */

is.fn = is['function'] = function (value) {
  var isAlert = typeof window !== 'undefined' && value === window.alert;
  return isAlert || '[object Function]' === toString.call(value);
};

/**
 * Test number.
 */

/**
 * is.number
 * Test if `value` is a number.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is a number, false otherwise
 * @api public
 */

is.number = function (value) {
  return '[object Number]' === toString.call(value);
};

/**
 * is.infinite
 * Test if `value` is positive or negative infinity.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is positive or negative Infinity, false otherwise
 * @api public
 */
is.infinite = function (value) {
  return value === Infinity || value === -Infinity;
};

/**
 * is.decimal
 * Test if `value` is a decimal number.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is a decimal number, false otherwise
 * @api public
 */

is.decimal = function (value) {
  return is.number(value) && !isActualNaN(value) && !is.infinite(value) && value % 1 !== 0;
};

/**
 * is.divisibleBy
 * Test if `value` is divisible by `n`.
 *
 * @param {Number} value value to test
 * @param {Number} n dividend
 * @return {Boolean} true if `value` is divisible by `n`, false otherwise
 * @api public
 */

is.divisibleBy = function (value, n) {
  var isDividendInfinite = is.infinite(value);
  var isDivisorInfinite = is.infinite(n);
  var isNonZeroNumber = is.number(value) && !isActualNaN(value) && is.number(n) && !isActualNaN(n) && n !== 0;
  return isDividendInfinite || isDivisorInfinite || (isNonZeroNumber && value % n === 0);
};

/**
 * is.int
 * Test if `value` is an integer.
 *
 * @param value to test
 * @return {Boolean} true if `value` is an integer, false otherwise
 * @api public
 */

is.int = function (value) {
  return is.number(value) && !isActualNaN(value) && value % 1 === 0;
};

/**
 * is.maximum
 * Test if `value` is greater than 'others' values.
 *
 * @param {Number} value value to test
 * @param {Array} others values to compare with
 * @return {Boolean} true if `value` is greater than `others` values
 * @api public
 */

is.maximum = function (value, others) {
  if (isActualNaN(value)) {
    throw new TypeError('NaN is not a valid value');
  } else if (!is.arraylike(others)) {
    throw new TypeError('second argument must be array-like');
  }
  var len = others.length;

  while (--len >= 0) {
    if (value < others[len]) {
      return false;
    }
  }

  return true;
};

/**
 * is.minimum
 * Test if `value` is less than `others` values.
 *
 * @param {Number} value value to test
 * @param {Array} others values to compare with
 * @return {Boolean} true if `value` is less than `others` values
 * @api public
 */

is.minimum = function (value, others) {
  if (isActualNaN(value)) {
    throw new TypeError('NaN is not a valid value');
  } else if (!is.arraylike(others)) {
    throw new TypeError('second argument must be array-like');
  }
  var len = others.length;

  while (--len >= 0) {
    if (value > others[len]) {
      return false;
    }
  }

  return true;
};

/**
 * is.nan
 * Test if `value` is not a number.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is not a number, false otherwise
 * @api public
 */

is.nan = function (value) {
  return !is.number(value) || value !== value;
};

/**
 * is.even
 * Test if `value` is an even number.
 *
 * @param {Number} value value to test
 * @return {Boolean} true if `value` is an even number, false otherwise
 * @api public
 */

is.even = function (value) {
  return is.infinite(value) || (is.number(value) && value === value && value % 2 === 0);
};

/**
 * is.odd
 * Test if `value` is an odd number.
 *
 * @param {Number} value value to test
 * @return {Boolean} true if `value` is an odd number, false otherwise
 * @api public
 */

is.odd = function (value) {
  return is.infinite(value) || (is.number(value) && value === value && value % 2 !== 0);
};

/**
 * is.ge
 * Test if `value` is greater than or equal to `other`.
 *
 * @param {Number} value value to test
 * @param {Number} other value to compare with
 * @return {Boolean}
 * @api public
 */

is.ge = function (value, other) {
  if (isActualNaN(value) || isActualNaN(other)) {
    throw new TypeError('NaN is not a valid value');
  }
  return !is.infinite(value) && !is.infinite(other) && value >= other;
};

/**
 * is.gt
 * Test if `value` is greater than `other`.
 *
 * @param {Number} value value to test
 * @param {Number} other value to compare with
 * @return {Boolean}
 * @api public
 */

is.gt = function (value, other) {
  if (isActualNaN(value) || isActualNaN(other)) {
    throw new TypeError('NaN is not a valid value');
  }
  return !is.infinite(value) && !is.infinite(other) && value > other;
};

/**
 * is.le
 * Test if `value` is less than or equal to `other`.
 *
 * @param {Number} value value to test
 * @param {Number} other value to compare with
 * @return {Boolean} if 'value' is less than or equal to 'other'
 * @api public
 */

is.le = function (value, other) {
  if (isActualNaN(value) || isActualNaN(other)) {
    throw new TypeError('NaN is not a valid value');
  }
  return !is.infinite(value) && !is.infinite(other) && value <= other;
};

/**
 * is.lt
 * Test if `value` is less than `other`.
 *
 * @param {Number} value value to test
 * @param {Number} other value to compare with
 * @return {Boolean} if `value` is less than `other`
 * @api public
 */

is.lt = function (value, other) {
  if (isActualNaN(value) || isActualNaN(other)) {
    throw new TypeError('NaN is not a valid value');
  }
  return !is.infinite(value) && !is.infinite(other) && value < other;
};

/**
 * is.within
 * Test if `value` is within `start` and `finish`.
 *
 * @param {Number} value value to test
 * @param {Number} start lower bound
 * @param {Number} finish upper bound
 * @return {Boolean} true if 'value' is is within 'start' and 'finish'
 * @api public
 */
is.within = function (value, start, finish) {
  if (isActualNaN(value) || isActualNaN(start) || isActualNaN(finish)) {
    throw new TypeError('NaN is not a valid value');
  } else if (!is.number(value) || !is.number(start) || !is.number(finish)) {
    throw new TypeError('all arguments must be numbers');
  }
  var isAnyInfinite = is.infinite(value) || is.infinite(start) || is.infinite(finish);
  return isAnyInfinite || (value >= start && value <= finish);
};

/**
 * Test object.
 */

/**
 * is.object
 * Test if `value` is an object.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is an object, false otherwise
 * @api public
 */

is.object = function (value) {
  return value && '[object Object]' === toString.call(value);
};

/**
 * is.hash
 * Test if `value` is a hash - a plain object literal.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is a hash, false otherwise
 * @api public
 */

is.hash = function (value) {
  return is.object(value) && value.constructor === Object && !value.nodeType && !value.setInterval;
};

/**
 * Test regexp.
 */

/**
 * is.regexp
 * Test if `value` is a regular expression.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if `value` is a regexp, false otherwise
 * @api public
 */

is.regexp = function (value) {
  return '[object RegExp]' === toString.call(value);
};

/**
 * Test string.
 */

/**
 * is.string
 * Test if `value` is a string.
 *
 * @param {Mixed} value value to test
 * @return {Boolean} true if 'value' is a string, false otherwise
 * @api public
 */

is.string = function (value) {
  return '[object String]' === toString.call(value);
};

