/*
 * Copyright 2017 Google
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import "FEmptyNode.h"
#import "FChildrenNode.h"

@implementation FEmptyNode

+ (id<FNode>) emptyNode {
    static FChildrenNode* empty = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        empty = [[FChildrenNode alloc] init];
    });
    return empty;
}
@end