1  var LodashWrapper = require('./_LodashWrapper'),
 2      flatRest = require('./_flatRest'),
 3      getData = require('./_getData'),
 4      getFuncName = require('./_getFuncName'),
 5      isArray = require('./isArray'),
 6      isLaziable = require('./_isLaziable');
 7  
 8  /** Error message constants. */
 9  var FUNC_ERROR_TEXT = 'Expected a function';
10  
11  /** Used to compose bitmasks for function metadata. */
12  var WRAP_CURRY_FLAG = 8,
13      WRAP_PARTIAL_FLAG = 32,
14      WRAP_ARY_FLAG = 128,
15      WRAP_REARG_FLAG = 256;
16  
17  /**
18   * Creates a `_.flow` or `_.flowRight` function.
19   *
20   * @private
21   * @param {boolean} [fromRight] Specify iterating from right to left.
22   * @returns {Function} Returns the new flow function.
23   */
24  function createFlow(fromRight) {
25    return flatRest(function(funcs) {
26      var length = funcs.length,
27          index = length,
28          prereq = LodashWrapper.prototype.thru;
29  
30      if (fromRight) {
31        funcs.reverse();
32      }
33      while (index--) {
34        var func = funcs[index];
35        if (typeof func != 'function') {
36          throw new TypeError(FUNC_ERROR_TEXT);
37        }
38        if (prereq && !wrapper && getFuncName(func) == 'wrapper') {
39          var wrapper = new LodashWrapper([], true);
40        }
41      }
42      index = wrapper ? index : length;
43      while (++index < length) {
44        func = funcs[index];
45  
46        var funcName = getFuncName(func),
47            data = funcName == 'wrapper' ? getData(func) : undefined;
48  
49        if (data && isLaziable(data[0]) &&
50              data[1] == (WRAP_ARY_FLAG | WRAP_CURRY_FLAG | WRAP_PARTIAL_FLAG | WRAP_REARG_FLAG) &&
51              !data[4].length && data[9] == 1
52            ) {
53          wrapper = wrapper[getFuncName(data[0])].apply(wrapper, data[3]);
54        } else {
55          wrapper = (func.length == 1 && isLaziable(func))
56            ? wrapper[funcName]()
57            : wrapper.thru(func);
58        }
59      }
60      return function() {
61        var args = arguments,
62            value = args[0];
63  
64        if (wrapper && args.length == 1 && isArray(value)) {
65          return wrapper.plant(value).value();
66        }
67        var index = 0,
68            result = length ? funcs[index].apply(this, args) : value;
69  
70        while (++index < length) {
71          result = funcs[index].call(this, result);
72        }
73        return result;
74      };
75    });
76  }
77  
78  module.exports = createFlow;