Function mergeData

lib/web/jshint.js:5725–5778

* Merges the function metadata of `source` into `data`. * * Merging metadata reduces the number of wrappers required to invoke a function. * This is possible because methods like `_.bind`, `_.curry`, and `_.partial` * may be applied regardless of execution order. Methods like `_.

(data, source)

     * @returns {Array} Returns `data`.
     */
    function mergeData(data, source) {
      var bitmask = data[1],
          srcBitmask = source[1],
          newBitmask = bitmask | srcBitmask,
          isCommon = newBitmask < ARY_FLAG;

      var isCombo =
        (srcBitmask == ARY_FLAG && bitmask == CURRY_FLAG) ||
        (srcBitmask == ARY_FLAG && bitmask == REARG_FLAG && data[7].length <= source[8]) ||
        (srcBitmask == (ARY_FLAG | REARG_FLAG) && bitmask == CURRY_FLAG);

      // Exit early if metadata can't be merged.
      if (!(isCommon || isCombo)) {
        return data;
      }
      // Use source `thisArg` if available.
      if (srcBitmask & BIND_FLAG) {
        data[2] = source[2];
        // Set when currying a bound function.
        newBitmask |= (bitmask & BIND_FLAG) ? 0 : CURRY_BOUND_FLAG;
      }
      // Compose partial arguments.
      var value = source[3];
      if (value) {
        var partials = data[3];
        data[3] = partials ? composeArgs(partials, value, source[4]) : arrayCopy(value);
        data[4] = partials ? replaceHolders(data[3], PLACEHOLDER) : arrayCopy(source[4]);
      }
      // Compose partial right arguments.
      value = source[5];
      if (value) {
        partials = data[5];
        data[5] = partials ? composeArgsRight(partials, value, source[6]) : arrayCopy(value);
        data[6] = partials ? replaceHolders(data[5], PLACEHOLDER) : arrayCopy(source[6]);
      }
      // Use source `argPos` if available.
      value = source[7];
      if (value) {
        data[7] = arrayCopy(value);
      }
      // Use source `ary` if it's smaller.
      if (srcBitmask & ARY_FLAG) {
        data[8] = data[8] == null ? source[8] : nativeMin(data[8], source[8]);
      }
      // Use source `arity` if one is not provided.
      if (data[9] == null) {
        data[9] = source[9];
      }
      // Use source `func` and merge bitmasks.
      data[0] = source[0];
      data[1] = newBitmask;

      return data;
    }

    /**
     * A specialized version of `_.pick` that picks `object` properties specified