chain/lodash.js

define(['../internal/LodashWrapper', '../internal/arrayCopy', '../lang/isArray', '../internal/isObjectLike'], function(LodashWrapper, arrayCopy, isArray, isObjectLike) {

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

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

  /**
   * Creates a `lodash` object which wraps `value` to enable intuitive chaining.
   * Methods that operate on and return arrays, collections, and functions can
   * be chained together. Methods that return a boolean or single value will
   * automatically end the chain returning the unwrapped value. Explicit chaining
   * may be enabled using `_.chain`. The execution of chained methods is lazy,
   * that is, execution is deferred until `_#value` is implicitly or explicitly
   * called.
   *
   * Lazy evaluation allows several methods to support shortcut fusion. Shortcut
   * fusion is an optimization that merges iteratees to avoid creating intermediate
   * arrays and reduce the number of iteratee executions.
   *
   * Chaining is supported in custom builds as long as the `_#value` method is
   * directly or indirectly included in the build.
   *
   * In addition to lodash methods, wrappers also have the following `Array` methods:
   * `concat`, `join`, `pop`, `push`, `reverse`, `shift`, `slice`, `sort`, `splice`,
   * and `unshift`
   *
   * The wrapper functions that support shortcut fusion are:
   * `drop`, `dropRight`, `dropRightWhile`, `dropWhile`, `filter`, `first`,
   * `initial`, `last`, `map`, `pluck`, `reject`, `rest`, `reverse`, `slice`,
   * `take`, `takeRight`, `takeRightWhile`, `takeWhile`, and `where`
   *
   * The chainable wrapper functions are:
   * `after`, `ary`, `assign`, `at`, `before`, `bind`, `bindAll`, `bindKey`,
   * `callback`, `chain`, `chunk`, `compact`, `concat`, `constant`, `countBy`,
   * `create`, `curry`, `debounce`, `defaults`, `defer`, `delay`, `difference`,
   * `drop`, `dropRight`, `dropRightWhile`, `dropWhile`, `filter`, `flatten`,
   * `flattenDeep`, `flow`, `flowRight`, `forEach`, `forEachRight`, `forIn`,
   * `forInRight`, `forOwn`, `forOwnRight`, `functions`, `groupBy`, `indexBy`,
   * `initial`, `intersection`, `invert`, `invoke`, `keys`, `keysIn`, `map`,
   * `mapValues`, `matches`, `memoize`, `merge`, `mixin`, `negate`, `noop`,
   * `omit`, `once`, `pairs`, `partial`, `partialRight`, `partition`, `pick`,
   * `pluck`, `property`, `propertyOf`, `pull`, `pullAt`, `push`, `range`,
   * `rearg`, `reject`, `remove`, `rest`, `reverse`, `shuffle`, `slice`, `sort`,
   * `sortBy`, `sortByAll`, `splice`, `take`, `takeRight`, `takeRightWhile`,
   * `takeWhile`, `tap`, `throttle`, `thru`, `times`, `toArray`, `toPlainObject`,
   * `transform`, `union`, `uniq`, `unshift`, `unzip`, `values`, `valuesIn`,
   * `where`, `without`, `wrap`, `xor`, `zip`, and `zipObject`
   *
   * The wrapper functions that are **not** chainable by default are:
   * `attempt`, `camelCase`, `capitalize`, `clone`, `cloneDeep`, `deburr`,
   * `endsWith`, `escape`, `escapeRegExp`, `every`, `find`, `findIndex`, `findKey`,
   * `findLast`, `findLastIndex`, `findLastKey`, `findWhere`, `first`, `has`,
   * `identity`, `includes`, `indexOf`, `isArguments`, `isArray`, `isBoolean`,
   * `isDate`, `isElement`, `isEmpty`, `isEqual`, `isError`, `isFinite`,
   * `isFunction`, `isMatch` , `isNative`, `isNaN`, `isNull`, `isNumber`,
   * `isObject`, `isPlainObject`, `isRegExp`, `isString`, `isUndefined`,
   * `isTypedArray`, `join`, `kebabCase`, `last`, `lastIndexOf`, `max`, `min`,
   * `noConflict`, `now`, `pad`, `padLeft`, `padRight`, `parseInt`, `pop`,
   * `random`, `reduce`, `reduceRight`, `repeat`, `result`, `runInContext`,
   * `shift`, `size`, `snakeCase`, `some`, `sortedIndex`, `sortedLastIndex`,
   * `startsWith`, `template`, `trim`, `trimLeft`, `trimRight`, `trunc`,
   * `unescape`, `uniqueId`, `value`, and `words`
   *
   * The wrapper function `sample` will return a wrapped value when `n` is provided,
   * otherwise an unwrapped value is returned.
   *
   * @name _
   * @constructor
   * @category Chain
   * @param {*} value The value to wrap in a `lodash` instance.
   * @returns {Object} Returns a `lodash` instance.
   * @example
   *
   * var wrapped = _([1, 2, 3]);
   *
   * // returns an unwrapped value
   * wrapped.reduce(function(sum, n) { return sum + n; });
   * // => 6
   *
   * // returns a wrapped value
   * var squares = wrapped.map(function(n) { return n * n; });
   *
   * _.isArray(squares);
   * // => false
   *
   * _.isArray(squares.value());
   * // => true
   */
  function lodash(value) {
    if (isObjectLike(value) && !isArray(value)) {
      if (value instanceof LodashWrapper) {
        return value;
      }
      if (hasOwnProperty.call(value, '__wrapped__')) {
        return new LodashWrapper(value.__wrapped__, value.__chain__, arrayCopy(value.__actions__));
      }
    }
    return new LodashWrapper(value);
  }

  // Ensure `new LodashWrapper` is an instance of `lodash`.
  LodashWrapper.prototype = lodash.prototype;

  return lodash;
});