Test exercise - caching class with FIFO

gistfile1.txt

//
//  main.m
//  CacheImpl
//
//  Created by lim on 3/26/19.
//  Copyright © 2019 lim. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface CacheItem : NSObject

@property (strong) NSString *string;
@property (assign) NSInteger first;
@property (assign) NSInteger second;

- (instancetype) initWithString:(NSString *) string first:(NSInteger)first second:(NSInteger)second;

@end

@implementation CacheItem

- (instancetype) initWithString:(NSString *) string first:(NSInteger)first second:(NSInteger)second {
    self = [super init];
    if (self) {
        self.string = string;
        self.first = first;
        self.second = second;
    }
    return self;
}

- (NSString *)description {
    return [NSString stringWithFormat:@"\"%@\", %li, %li", self.string, self.first, self.second];
}

@end

@interface CacheContainer : NSObject

- (instancetype) initWithCapacity:(NSInteger) capacity;

- (void)put:(NSString *)uri item:(NSObject *)item;

- (NSObject *)get:(NSString *)uri;

@end

@interface CacheContainer ()

@property (assign) NSInteger capacity;
@property (assign) NSInteger index;
@property (strong) NSMutableDictionary *storage;
@property (strong) NSMutableDictionary *indexes;

@end

@implementation CacheContainer

- (instancetype) initWithCapacity:(NSInteger) capacity {
    self = [super init];
    if (self) {
        self.capacity = capacity;
        self.storage = [NSMutableDictionary dictionary];
        self.indexes = [NSMutableDictionary dictionary];
    }
    return self;
}

- (void)put:(NSString *)uri item:(NSObject *)item {
    @synchronized (self.storage) {
        if (self.storage.count >= self.capacity) {
            NSString *keyToRemove = self.indexes[@(self.index - self.capacity)];
            if (keyToRemove) {
                [self.storage removeObjectForKey:keyToRemove];
                [self.indexes removeObjectForKey:@(self.index - self.capacity)];
            }
        }
        
        self.storage[uri] = item;
        self.indexes[@(self.index)] = uri;
        
        self.index++;
    }
}

- (NSObject *)get:(NSString *)uri {
    @synchronized (self.storage) {
        return self.storage[uri];
    }
}

@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        CacheContainer *cc = [[CacheContainer alloc] initWithCapacity:3];
        [cc put:@"uri1" item:[[CacheItem alloc] initWithString:@"1" first:1 second:1]];
        [cc put:@"uri2" item:[[CacheItem alloc] initWithString:@"2" first:2 second:2]];
        [cc put:@"uri3" item:[[CacheItem alloc] initWithString:@"3" first:3 second:3]];
        
        NSLog(@"%@", [cc get:@"uri1"]);
        NSLog(@"%@", [cc get:@"uri2"]);
        NSLog(@"%@", [cc get:@"uri3"]);

        [cc put:@"uri4" item:[[CacheItem alloc] initWithString:@"4" first:4 second:4]];

        NSLog(@"%@", [cc get:@"uri1"]);
        NSLog(@"%@", [cc get:@"uri2"]);
        NSLog(@"%@", [cc get:@"uri3"]);
        NSLog(@"%@", [cc get:@"uri4"]);
    }
    return 0;
}