/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Utilities used by various tool commands.

 */

#import "ToolCommon.h"

NS_ASSUME_NONNULL_BEGIN

@interface ToolCommon ()

@property (atomic, strong, readonly ) NSOperationQueue *    queue;

@end

NS_ASSUME_NONNULL_END

@implementation ToolCommon

+ (ToolCommon *)sharedInstance {

    static ToolCommon *     sSharedInstance;

    static dispatch_once_t  sOnceToken;

    dispatch_once(&sOnceToken, ^{

        sSharedInstance = [[ToolCommon alloc] init];

    });

    return sSharedInstance;

}

- (instancetype)init {

    self = [super init];

    if (self != nil) {

        self->_queue = [[NSOperationQueue alloc] init];

    }

    return self;

}

- (void)dealloc {

    assert(NO);

}

- (void)synchronouslyRunOperation:(NSOperation *)op {

    NSParameterAssert(op != nil);

    if (self.debugRunOpOnMainThread) {

        // This is the hacky way we do it to simplify debugging.

        [op main];

    } else {

        // This is how it /should/ be done.

        [self.queue addOperation:op];

        [self.queue waitUntilAllOperationsAreFinished];

    }

}

@end