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/*
* 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 "FLLRBEmptyNode.h"
#import "FLLRBValueNode.h"
@implementation FLLRBEmptyNode
@synthesize key, value, color, left, right;
- (NSString *) description {
return [NSString stringWithFormat:@"[key=%@ val=%@ color=%@]", key, value, (color ? @"true" : @"false")];
}
+ (id)emptyNode
{
static dispatch_once_t pred = 0;
__strong static id _sharedObject = nil;
dispatch_once(&pred, ^{
_sharedObject = [[self alloc] init]; // or some other init method
});
return _sharedObject;
}
- (id)copyWith:(id) aKey withValue:(id) aValue withColor:(FLLRBColor*) aColor withLeft:(id<FLLRBNode>)aLeft withRight:(id<FLLRBNode>)aRight {
return self;
}
- (id<FLLRBNode>) insertKey:(id) aKey forValue:(id)aValue withComparator:(NSComparator)aComparator {
FLLRBValueNode* result = [[FLLRBValueNode alloc] initWithKey:aKey withValue:aValue withColor:nil withLeft:nil withRight:nil];
return result;
}
- (id<FLLRBNode>) remove:(id) key withComparator:(NSComparator)aComparator {
return self;
}
- (int) count {
return 0;
}
- (BOOL) isEmpty {
return YES;
}
- (BOOL) inorderTraversal:(BOOL (^)(id key, id value))action {
return NO;
}
- (BOOL) reverseTraversal:(BOOL (^)(id key, id value))action {
return NO;
}
- (id<FLLRBNode>) min {
return self;
}
- (id) minKey {
return nil;
}
- (id) maxKey {
return nil;
}
- (BOOL) isRed {
return NO;
}
- (int) check {
return 0;
}
@end
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