COBasicSequence.m

//
//  COBasicSequence.m
//  DevelopmentApp
//
//  Created by Stanislaw Pankevich on 24/10/15.
//  Copyright © 2015 Stanislaw Pankevich. All rights reserved.
//

#import "Sequence.h"
#import <CompositeOperations/COSimpleOperation.h>

// COS - composite operation step
#define COSInitial @"NSNull"
#define COSFinal nil
#define COS(name) NSStringFromClass([name class]) ?: COSInitial

typedef id (^Generator)(id);

@interface Operation1 : COSimpleOperation; @end
@interface Operation2 : COSimpleOperation; @end
@interface Operation3 : COSimpleOperation; @end

@implementation Operation1
- (void)main { [self finishWithResult:@(1)]; }
@end

@implementation Operation2
- (void)main { [self finishWithResult:@(2)]; }
@end

@implementation Operation3;
- (void)main { [self finishWithResult:@(3)]; }
@end

@interface Sequence ()
@end

@implementation Sequence

- (NSDictionary *)map {
    return @{
        COSInitial: ^id(id _){
            return [Operation1 new];
        },

        COS(Operation1): ^id(id _){
            return [Operation2 new];
        },

        COS(Operation2): ^id(id _){
            return [Operation3 new];
        },

        COS(Operation3): ^id(id _){
            return COSFinal;
        },
    };
}

- (NSOperation<COOperation> *)nextOperationAfterOperation:(NSOperation<COOperation> *)previousOperationOrNil {

    NSString *step = COS([previousOperationOrNil class]);

    Generator generator = self.map[step];
    NSAssert(generator, nil);

    id nextOperation = generator(previousOperationOrNil);

    return nextOperation;
}

@end