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✏️ Editing: createWrapper.js

var baseSetData = require('./baseSetData'),
    createBindWrapper = require('./createBindWrapper'),
    createHybridWrapper = require('./createHybridWrapper'),
    createPartialWrapper = require('./createPartialWrapper'),
    getData = require('./getData'),
    mergeData = require('./mergeData'),
    setData = require('./setData');

/** Used to compose bitmasks for wrapper metadata. */
var BIND_FLAG = 1,
    BIND_KEY_FLAG = 2,
    PARTIAL_FLAG = 32,
    PARTIAL_RIGHT_FLAG = 64;

/** Used as the `TypeError` message for "Functions" methods. */
var FUNC_ERROR_TEXT = 'Expected a function';

/* Native method references for those with the same name as other `lodash` methods. */
var nativeMax = Math.max;

/**
 * Creates a function that either curries or invokes `func` with optional
 * `this` binding and partially applied arguments.
 *
 * @private
 * @param {Function|string} func The function or method name to reference.
 * @param {number} bitmask The bitmask of flags.
 *  The bitmask may be composed of the following flags:
 *     1 - `_.bind`
 *     2 - `_.bindKey`
 *     4 - `_.curry` or `_.curryRight` of a bound function
 *     8 - `_.curry`
 *    16 - `_.curryRight`
 *    32 - `_.partial`
 *    64 - `_.partialRight`
 *   128 - `_.rearg`
 *   256 - `_.ary`
 * @param {*} [thisArg] The `this` binding of `func`.
 * @param {Array} [partials] The arguments to be partially applied.
 * @param {Array} [holders] The `partials` placeholder indexes.
 * @param {Array} [argPos] The argument positions of the new function.
 * @param {number} [ary] The arity cap of `func`.
 * @param {number} [arity] The arity of `func`.
 * @returns {Function} Returns the new wrapped function.
 */
function createWrapper(func, bitmask, thisArg, partials, holders, argPos, ary, arity) {
  var isBindKey = bitmask & BIND_KEY_FLAG;
  if (!isBindKey && typeof func != 'function') {
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  var length = partials ? partials.length : 0;
  if (!length) {
    bitmask &= ~(PARTIAL_FLAG | PARTIAL_RIGHT_FLAG);
    partials = holders = undefined;
  }
  length -= (holders ? holders.length : 0);
  if (bitmask & PARTIAL_RIGHT_FLAG) {
    var partialsRight = partials,
        holdersRight = holders;

partials = holders = undefined;
  }
  var data = isBindKey ? undefined : getData(func),
      newData = [func, bitmask, thisArg, partials, holders, partialsRight, holdersRight, argPos, ary, arity];

if (data) {
    mergeData(newData, data);
    bitmask = newData[1];
    arity = newData[9];
  }
  newData[9] = arity == null
    ? (isBindKey ? 0 : func.length)
    : (nativeMax(arity - length, 0) || 0);

if (bitmask == BIND_FLAG) {
    var result = createBindWrapper(newData[0], newData[2]);
  } else if ((bitmask == PARTIAL_FLAG || bitmask == (BIND_FLAG | PARTIAL_FLAG)) && !newData[4].length) {
    result = createPartialWrapper.apply(undefined, newData);
  } else {
    result = createHybridWrapper.apply(undefined, newData);
  }
  var setter = data ? baseSetData : setData;
  return setter(result, newData);
}

module.exports = createWrapper;

MR SKB