var Symbol = require('./internal/Symbol'),
    isSymbol = require('./isSymbol');

/** Used as references for various `Number` constants. */
var INFINITY = 1 / 0;

/** Used to convert symbols to primitives and strings. */
var symbolProto = Symbol ? Symbol.prototype : undefined,
    symbolToString = Symbol ? symbolProto.toString : undefined;

/**
 * Converts `value` to a string if it's not one. An empty string is returned
 * for `null` and `undefined` values. The sign of `-0` is preserved.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to process.
 * @returns {string} Returns the string.
 * @example
 *
 * _.toString(null);
 * // => ''
 *
 * _.toString(-0);
 * // => '-0'
 *
 * _.toString([1, 2, 3]);
 * // => '1,2,3'
 */
function toString(value) {
  // Exit early for strings to avoid a performance hit in some environments.
  if (typeof value == 'string') {
    return value;
  }
  if (value == null) {
    return '';
  }
  if (isSymbol(value)) {
    return Symbol ? symbolToString.call(value) : '';
  }
  var result = (value + '');
  return (result == '0' && (1 / value) == -INFINITY) ? '-0' : result;
}

module.exports = toString;
