ramda.unnest/unnest.js

R.unnest exported as a module

(function (global, factory) {
	typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
	typeof define === 'function' && define.amd ? define(['exports'], factory) :
	(factory((global.R = {})));
}(this, (function (exports) { 'use strict';

function _identity(x) { return x; }

function _isPlaceholder(a) {
  return a != null &&
         typeof a === 'object' &&
         a['@@functional/placeholder'] === true;
}

/**
 * Optimized internal one-arity curry function.
 *
 * @private
 * @category Function
 * @param {Function} fn The function to curry.
 * @return {Function} The curried function.
 */
function _curry1(fn) {
  return function f1(a) {
    if (arguments.length === 0 || _isPlaceholder(a)) {
      return f1;
    } else {
      return fn.apply(this, arguments);
    }
  };
}

/**
 * Optimized internal two-arity curry function.
 *
 * @private
 * @category Function
 * @param {Function} fn The function to curry.
 * @return {Function} The curried function.
 */
function _curry2(fn) {
  return function f2(a, b) {
    switch (arguments.length) {
      case 0:
        return f2;
      case 1:
        return _isPlaceholder(a) ? f2
             : _curry1(function(_b) { return fn(a, _b); });
      default:
        return _isPlaceholder(a) && _isPlaceholder(b) ? f2
             : _isPlaceholder(a) ? _curry1(function(_a) { return fn(_a, b); })
             : _isPlaceholder(b) ? _curry1(function(_b) { return fn(a, _b); })
             : fn(a, b);
    }
  };
}

/**
 * Tests whether or not an object is an array.
 *
 * @private
 * @param {*} val The object to test.
 * @return {Boolean} `true` if `val` is an array, `false` otherwise.
 * @example
 *
 *      _isArray([]); //=> true
 *      _isArray(null); //=> false
 *      _isArray({}); //=> false
 */
var _isArray = Array.isArray || function _isArray(val) {
  return (val != null &&
          val.length >= 0 &&
          Object.prototype.toString.call(val) === '[object Array]');
};

function _isTransformer(obj) {
  return obj != null && typeof obj['@@transducer/step'] === 'function';
}

/**
 * Returns a function that dispatches with different strategies based on the
 * object in list position (last argument). If it is an array, executes [fn].
 * Otherwise, if it has a function with one of the given method names, it will
 * execute that function (functor case). Otherwise, if it is a transformer,
 * uses transducer [xf] to return a new transformer (transducer case).
 * Otherwise, it will default to executing [fn].
 *
 * @private
 * @param {Array} methodNames properties to check for a custom implementation
 * @param {Function} xf transducer to initialize if object is transformer
 * @param {Function} fn default ramda implementation
 * @return {Function} A function that dispatches on object in list position
 */
function _dispatchable(methodNames, xf, fn) {
  return function() {
    if (arguments.length === 0) {
      return fn();
    }
    var args = Array.prototype.slice.call(arguments, 0);
    var obj = args.pop();
    if (!_isArray(obj)) {
      var idx = 0;
      while (idx < methodNames.length) {
        if (typeof obj[methodNames[idx]] === 'function') {
          return obj[methodNames[idx]].apply(obj, args);
        }
        idx += 1;
      }
      if (_isTransformer(obj)) {
        var transducer = xf.apply(null, args);
        return transducer(obj);
      }
    }
    return fn.apply(this, arguments);
  };
}

function _isString(x) {
  return Object.prototype.toString.call(x) === '[object String]';
}

/**
 * Tests whether or not an object is similar to an array.
 *
 * @private
 * @category Type
 * @category List
 * @sig * -> Boolean
 * @param {*} x The object to test.
 * @return {Boolean} `true` if `x` has a numeric length property and extreme indices defined; `false` otherwise.
 * @example
 *
 *      _isArrayLike([]); //=> true
 *      _isArrayLike(true); //=> false
 *      _isArrayLike({}); //=> false
 *      _isArrayLike({length: 10}); //=> false
 *      _isArrayLike({0: 'zero', 9: 'nine', length: 10}); //=> true
 */
var _isArrayLike = _curry1(function isArrayLike(x) {
  if (_isArray(x)) { return true; }
  if (!x) { return false; }
  if (typeof x !== 'object') { return false; }
  if (_isString(x)) { return false; }
  if (x.nodeType === 1) { return !!x.length; }
  if (x.length === 0) { return true; }
  if (x.length > 0) {
    return x.hasOwnProperty(0) && x.hasOwnProperty(x.length - 1);
  }
  return false;
});

/**
 * `_makeFlat` is a helper function that returns a one-level or fully recursive
 * function based on the flag passed in.
 *
 * @private
 */
function _makeFlat(recursive) {
  return function flatt(list) {
    var value, jlen, j;
    var result = [];
    var idx = 0;
    var ilen = list.length;

    while (idx < ilen) {
      if (_isArrayLike(list[idx])) {
        value = recursive ? flatt(list[idx]) : list[idx];
        j = 0;
        jlen = value.length;
        while (j < jlen) {
          result[result.length] = value[j];
          j += 1;
        }
      } else {
        result[result.length] = list[idx];
      }
      idx += 1;
    }
    return result;
  };
}

function _forceReduced(x) {
  return {
    '@@transducer/value': x,
    '@@transducer/reduced': true
  };
}

function XWrap(fn) {
  this.f = fn;
}
XWrap.prototype['@@transducer/init'] = function() {
  throw new Error('init not implemented on XWrap');
};
XWrap.prototype['@@transducer/result'] = function(acc) { return acc; };
XWrap.prototype['@@transducer/step'] = function(acc, x) {
  return this.f(acc, x);
};

function _xwrap(fn) { return new XWrap(fn); }

function _arity(n, fn) {
  /* eslint-disable no-unused-vars */
  switch (n) {
    case 0: return function() { return fn.apply(this, arguments); };
    case 1: return function(a0) { return fn.apply(this, arguments); };
    case 2: return function(a0, a1) { return fn.apply(this, arguments); };
    case 3: return function(a0, a1, a2) { return fn.apply(this, arguments); };
    case 4: return function(a0, a1, a2, a3) { return fn.apply(this, arguments); };
    case 5: return function(a0, a1, a2, a3, a4) { return fn.apply(this, arguments); };
    case 6: return function(a0, a1, a2, a3, a4, a5) { return fn.apply(this, arguments); };
    case 7: return function(a0, a1, a2, a3, a4, a5, a6) { return fn.apply(this, arguments); };
    case 8: return function(a0, a1, a2, a3, a4, a5, a6, a7) { return fn.apply(this, arguments); };
    case 9: return function(a0, a1, a2, a3, a4, a5, a6, a7, a8) { return fn.apply(this, arguments); };
    case 10: return function(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) { return fn.apply(this, arguments); };
    default: throw new Error('First argument to _arity must be a non-negative integer no greater than ten');
  }
}

/**
 * Creates a function that is bound to a context.
 * Note: `R.bind` does not provide the additional argument-binding capabilities of
 * [Function.prototype.bind](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind).
 *
 * @func
 * @memberOf R
 * @since v0.6.0
 * @category Function
 * @category Object
 * @sig (* -> *) -> {*} -> (* -> *)
 * @param {Function} fn The function to bind to context
 * @param {Object} thisObj The context to bind `fn` to
 * @return {Function} A function that will execute in the context of `thisObj`.
 * @see R.partial
 * @example
 *
 *      const log = R.bind(console.log, console);
 *      R.pipe(R.assoc('a', 2), R.tap(log), R.assoc('a', 3))({a: 1}); //=> {a: 3}
 *      // logs {a: 2}
 * @symb R.bind(f, o)(a, b) = f.call(o, a, b)
 */
var bind = _curry2(function bind(fn, thisObj) {
  return _arity(fn.length, function() {
    return fn.apply(thisObj, arguments);
  });
});

function _arrayReduce(xf, acc, list) {
  var idx = 0;
  var len = list.length;
  while (idx < len) {
    acc = xf['@@transducer/step'](acc, list[idx]);
    if (acc && acc['@@transducer/reduced']) {
      acc = acc['@@transducer/value'];
      break;
    }
    idx += 1;
  }
  return xf['@@transducer/result'](acc);
}

function _iterableReduce(xf, acc, iter) {
  var step = iter.next();
  while (!step.done) {
    acc = xf['@@transducer/step'](acc, step.value);
    if (acc && acc['@@transducer/reduced']) {
      acc = acc['@@transducer/value'];
      break;
    }
    step = iter.next();
  }
  return xf['@@transducer/result'](acc);
}

function _methodReduce(xf, acc, obj, methodName) {
  return xf['@@transducer/result'](obj[methodName](bind(xf['@@transducer/step'], xf), acc));
}

var symIterator = (typeof Symbol !== 'undefined') ? Symbol.iterator : '@@iterator';

function _reduce(fn, acc, list) {
  if (typeof fn === 'function') {
    fn = _xwrap(fn);
  }
  if (_isArrayLike(list)) {
    return _arrayReduce(fn, acc, list);
  }
  if (typeof list['fantasy-land/reduce'] === 'function') {
    return _methodReduce(fn, acc, list, 'fantasy-land/reduce');
  }
  if (list[symIterator] != null) {
    return _iterableReduce(fn, acc, list[symIterator]());
  }
  if (typeof list.next === 'function') {
    return _iterableReduce(fn, acc, list);
  }
  if (typeof list.reduce === 'function') {
    return _methodReduce(fn, acc, list, 'reduce');
  }

  throw new TypeError('reduce: list must be array or iterable');
}

var _xfBase = {
  init: function() {
    return this.xf['@@transducer/init']();
  },
  result: function(result) {
    return this.xf['@@transducer/result'](result);
  }
};

var preservingReduced = function(xf) {
  return {
    '@@transducer/init': _xfBase.init,
    '@@transducer/result': function(result) {
      return xf['@@transducer/result'](result);
    },
    '@@transducer/step': function(result, input) {
      var ret = xf['@@transducer/step'](result, input);
      return ret['@@transducer/reduced'] ? _forceReduced(ret) : ret;
    }
  };
};

var _flatCat = function _xcat(xf) {
  var rxf = preservingReduced(xf);
  return {
    '@@transducer/init': _xfBase.init,
    '@@transducer/result': function(result) {
      return rxf['@@transducer/result'](result);
    },
    '@@transducer/step': function(result, input) {
      return !_isArrayLike(input) ? _reduce(rxf, result, [input]) : _reduce(rxf, result, input);
    }
  };
};

function _map(fn, functor) {
  var idx = 0;
  var len = functor.length;
  var result = Array(len);
  while (idx < len) {
    result[idx] = fn(functor[idx]);
    idx += 1;
  }
  return result;
}

function XMap(f, xf) {
  this.xf = xf;
  this.f = f;
}
XMap.prototype['@@transducer/init'] = _xfBase.init;
XMap.prototype['@@transducer/result'] = _xfBase.result;
XMap.prototype['@@transducer/step'] = function(result, input) {
  return this.xf['@@transducer/step'](result, this.f(input));
};

var _xmap = _curry2(function _xmap(f, xf) { return new XMap(f, xf); });

/**
 * Internal curryN function.
 *
 * @private
 * @category Function
 * @param {Number} length The arity of the curried function.
 * @param {Array} received An array of arguments received thus far.
 * @param {Function} fn The function to curry.
 * @return {Function} The curried function.
 */
function _curryN(length, received, fn) {
  return function() {
    var combined = [];
    var argsIdx = 0;
    var left = length;
    var combinedIdx = 0;
    while (combinedIdx < received.length || argsIdx < arguments.length) {
      var result;
      if (combinedIdx < received.length &&
          (!_isPlaceholder(received[combinedIdx]) ||
           argsIdx >= arguments.length)) {
        result = received[combinedIdx];
      } else {
        result = arguments[argsIdx];
        argsIdx += 1;
      }
      combined[combinedIdx] = result;
      if (!_isPlaceholder(result)) {
        left -= 1;
      }
      combinedIdx += 1;
    }
    return left <= 0 ? fn.apply(this, combined)
                     : _arity(left, _curryN(length, combined, fn));
  };
}

/**
 * Returns a curried equivalent of the provided function, with the specified
 * arity. The curried function has two unusual capabilities. First, its
 * arguments needn't be provided one at a time. If `g` is `R.curryN(3, f)`, the
 * following are equivalent:
 *
 *   - `g(1)(2)(3)`
 *   - `g(1)(2, 3)`
 *   - `g(1, 2)(3)`
 *   - `g(1, 2, 3)`
 *
 * Secondly, the special placeholder value [`R.__`](#__) may be used to specify
 * "gaps", allowing partial application of any combination of arguments,
 * regardless of their positions. If `g` is as above and `_` is [`R.__`](#__),
 * the following are equivalent:
 *
 *   - `g(1, 2, 3)`
 *   - `g(_, 2, 3)(1)`
 *   - `g(_, _, 3)(1)(2)`
 *   - `g(_, _, 3)(1, 2)`
 *   - `g(_, 2)(1)(3)`
 *   - `g(_, 2)(1, 3)`
 *   - `g(_, 2)(_, 3)(1)`
 *
 * @func
 * @memberOf R
 * @since v0.5.0
 * @category Function
 * @sig Number -> (* -> a) -> (* -> a)
 * @param {Number} length The arity for the returned function.
 * @param {Function} fn The function to curry.
 * @return {Function} A new, curried function.
 * @see R.curry
 * @example
 *
 *      const sumArgs = (...args) => R.sum(args);
 *
 *      const curriedAddFourNumbers = R.curryN(4, sumArgs);
 *      const f = curriedAddFourNumbers(1, 2);
 *      const g = f(3);
 *      g(4); //=> 10
 */
var curryN = _curry2(function curryN(length, fn) {
  if (length === 1) {
    return _curry1(fn);
  }
  return _arity(length, _curryN(length, [], fn));
});

function _has(prop, obj) {
  return Object.prototype.hasOwnProperty.call(obj, prop);
}

var toString = Object.prototype.toString;
var _isArguments = (function() {
  return toString.call(arguments) === '[object Arguments]' ?
    function _isArguments(x) { return toString.call(x) === '[object Arguments]'; } :
    function _isArguments(x) { return _has('callee', x); };
}());

// cover IE < 9 keys issues
var hasEnumBug = !({toString: null}).propertyIsEnumerable('toString');
var nonEnumerableProps = ['constructor', 'valueOf', 'isPrototypeOf', 'toString',
                          'propertyIsEnumerable', 'hasOwnProperty', 'toLocaleString'];
// Safari bug
var hasArgsEnumBug = (function() {
  'use strict';
  return arguments.propertyIsEnumerable('length');
}());

var contains = function contains(list, item) {
  var idx = 0;
  while (idx < list.length) {
    if (list[idx] === item) {
      return true;
    }
    idx += 1;
  }
  return false;
};

/**
 * Returns a list containing the names of all the enumerable own properties of
 * the supplied object.
 * Note that the order of the output array is not guaranteed to be consistent
 * across different JS platforms.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig {k: v} -> [k]
 * @param {Object} obj The object to extract properties from
 * @return {Array} An array of the object's own properties.
 * @see R.keysIn, R.values
 * @example
 *
 *      R.keys({a: 1, b: 2, c: 3}); //=> ['a', 'b', 'c']
 */
var keys = typeof Object.keys === 'function' && !hasArgsEnumBug ?
  _curry1(function keys(obj) {
    return Object(obj) !== obj ? [] : Object.keys(obj);
  }) :
  _curry1(function keys(obj) {
    if (Object(obj) !== obj) {
      return [];
    }
    var prop, nIdx;
    var ks = [];
    var checkArgsLength = hasArgsEnumBug && _isArguments(obj);
    for (prop in obj) {
      if (_has(prop, obj) && (!checkArgsLength || prop !== 'length')) {
        ks[ks.length] = prop;
      }
    }
    if (hasEnumBug) {
      nIdx = nonEnumerableProps.length - 1;
      while (nIdx >= 0) {
        prop = nonEnumerableProps[nIdx];
        if (_has(prop, obj) && !contains(ks, prop)) {
          ks[ks.length] = prop;
        }
        nIdx -= 1;
      }
    }
    return ks;
  });

/**
 * Takes a function and
 * a [functor](https://github.com/fantasyland/fantasy-land#functor),
 * applies the function to each of the functor's values, and returns
 * a functor of the same shape.
 *
 * Ramda provides suitable `map` implementations for `Array` and `Object`,
 * so this function may be applied to `[1, 2, 3]` or `{x: 1, y: 2, z: 3}`.
 *
 * Dispatches to the `map` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * Also treats functions as functors and will compose them together.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Functor f => (a -> b) -> f a -> f b
 * @param {Function} fn The function to be called on every element of the input `list`.
 * @param {Array} list The list to be iterated over.
 * @return {Array} The new list.
 * @see R.transduce, R.addIndex
 * @example
 *
 *      const double = x => x * 2;
 *
 *      R.map(double, [1, 2, 3]); //=> [2, 4, 6]
 *
 *      R.map(double, {x: 1, y: 2, z: 3}); //=> {x: 2, y: 4, z: 6}
 * @symb R.map(f, [a, b]) = [f(a), f(b)]
 * @symb R.map(f, { x: a, y: b }) = { x: f(a), y: f(b) }
 * @symb R.map(f, functor_o) = functor_o.map(f)
 */
var map = _curry2(_dispatchable(['fantasy-land/map', 'map'], _xmap, function map(fn, functor) {
  switch (Object.prototype.toString.call(functor)) {
    case '[object Function]':
      return curryN(functor.length, function() {
        return fn.call(this, functor.apply(this, arguments));
      });
    case '[object Object]':
      return _reduce(function(acc, key) {
        acc[key] = fn(functor[key]);
        return acc;
      }, {}, keys(functor));
    default:
      return _map(fn, functor);
  }
}));

var _xchain = _curry2(function _xchain(f, xf) {
  return map(f, _flatCat(xf));
});

/**
 * `chain` maps a function over a list and concatenates the results. `chain`
 * is also known as `flatMap` in some libraries.
 *
 * Dispatches to the `chain` method of the second argument, if present,
 * according to the [FantasyLand Chain spec](https://github.com/fantasyland/fantasy-land#chain).
 *
 * If second argument is a function, `chain(f, g)(x)` is equivalent to `f(g(x), x)`.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category List
 * @sig Chain m => (a -> m b) -> m a -> m b
 * @param {Function} fn The function to map with
 * @param {Array} list The list to map over
 * @return {Array} The result of flat-mapping `list` with `fn`
 * @example
 *
 *      const duplicate = n => [n, n];
 *      R.chain(duplicate, [1, 2, 3]); //=> [1, 1, 2, 2, 3, 3]
 *
 *      R.chain(R.append, R.head)([1, 2, 3]); //=> [1, 2, 3, 1]
 */
var chain = _curry2(_dispatchable(['fantasy-land/chain', 'chain'], _xchain, function chain(fn, monad) {
  if (typeof monad === 'function') {
    return function(x) { return fn(monad(x))(x); };
  }
  return _makeFlat(false)(map(fn, monad));
}));

/**
 * Shorthand for `R.chain(R.identity)`, which removes one level of nesting from
 * any [Chain](https://github.com/fantasyland/fantasy-land#chain).
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category List
 * @sig Chain c => c (c a) -> c a
 * @param {*} list
 * @return {*}
 * @see R.flatten, R.chain
 * @example
 *
 *      R.unnest([1, [2], [[3]]]); //=> [1, 2, [3]]
 *      R.unnest([[1, 2], [3, 4], [5, 6]]); //=> [1, 2, 3, 4, 5, 6]
 */
var unnest = chain(_identity);

exports.unnest = unnest;

Object.defineProperty(exports, '__esModule', { value: true });

})));