/**
 *  $Id: helpers.js 156 2006-12-23 08:48:25Z wingedfox $
 *  $HeadURL: https://svn.debugger.ru/repos/jslibs/BrowserExtensions/trunk/helpers.js $
 *
 *  File contains differrent helper functions
 * 
 * @author Ilya Lebedev <ilya@lebedev.net>
 * @license LGPL
 * @version $Rev: 156 $
 */
//-----------------------------------------------------------------------------
//  Variable/property checks
//-----------------------------------------------------------------------------
/**
 *  Checks if property is undefined
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isUndefined (prop /* :Object */) /* :Boolean */ {
  return (typeof prop == 'undefined');
}
/**
 *  Checks if property is function
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isFunction (prop /* :Object */) /* :Boolean */ {
  return (typeof prop == 'function');
}
/**
 *  Checks if property is string
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isString (prop /* :Object */) /* :Boolean */ {
  return (typeof prop == 'string');
}
/**
 *  Checks if property is number
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isNumber (prop /* :Object */) /* :Boolean */ {
  return (typeof prop == 'number');
}
/**
 *  Checks if property is the calculable number
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isNumeric (prop /* :Object */) /* :Boolean */ {
  return isNumber(prop)&&!isNaN(prop)&&isFinite(prop);
}
/**
 *  Checks if property is array
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isArray (prop /* :Object */) /* :Boolean */ {
  return (prop instanceof Array);
}
/**
 *  Checks if property is regexp
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isRegExp (prop /* :Object */) /* :Boolean */ {
  return (prop instanceof RegExp);
}
/**
 *  Checks if property is a boolean value
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isBoolean (prop /* :Object */) /* :Boolean */ {
  return ('boolean' == typeof prop);
}
/**
 *  Checks if property is a scalar value (value that could be used as the hash key)
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isScalar (prop /* :Object */) /* :Boolean */ {
  return isNumeric(prop)||isString(prop);
}
/**
 *  Checks if property is empty
 *
 *  @param {Object} prop value to check
 *  @return {Boolean} true if matched
 *  @scope public
 */
function isEmpty (prop /* :Object */) /* :Boolean */ {
  if (isBoolean(prop)) return false;
  if (isRegExp(prop) && new RegExp("").toString() == prop.toString()) return true;
  if (isString(prop) || isNumber(prop)) return !prop;
  if (Boolean(prop)&&false != prop) {
    for (var i in prop) if(prop.hasOwnProperty(i)) return false
  }
  return true;
}

/*
*  Checks if property is derived from prototype, applies method if it is not exists
*
*  @param string property name
*  @return bool true if prototyped
*  @access public
*/
if ('undefined' == typeof Object.hasOwnProperty) {
  Object.prototype.hasOwnProperty = function (prop) {
    return !('undefined' == typeof this[prop] || this.constructor && this.constructor.prototype[prop] && this[prop] === this.constructor.prototype[prop]);
  }
}