Function mapSingleChildIntoContext

docs/external/js/react.development.js:1230–1250

(bookKeeping, child, childKey)

  }

  function mapSingleChildIntoContext(bookKeeping, child, childKey) {
    var result = bookKeeping.result,
        keyPrefix = bookKeeping.keyPrefix,
        func = bookKeeping.func,
        context = bookKeeping.context;
    var mappedChild = func.call(context, child, bookKeeping.count++);

    if (Array.isArray(mappedChild)) {
      mapIntoWithKeyPrefixInternal(mappedChild, result, childKey, function (c) {
        return c;
      });
    } else if (mappedChild != null) {
      if (isValidElement(mappedChild)) {
        mappedChild = cloneAndReplaceKey(mappedChild, // Keep both the (mapped) and old keys if they differ, just as
        // traverseAllChildren used to do for objects as children
        keyPrefix + (mappedChild.key && (!child || child.key !== mappedChild.key) ? escapeUserProvidedKey(mappedChild.key) + '/' : '') + childKey);
      }

      result.push(mappedChild);
    }
  }

  function mapIntoWithKeyPrefixInternal(children, array, prefix, func, context) {
    var escapedPrefix = '';