Sources/SPTPersistentCacheObjectDescription.m

/*
 Copyright (c) 2015-2021 Spotify AB.

 Licensed to the Apache Software Foundation (ASF) under one
 or more contributor license agreements.  See the NOTICE file
 distributed with this work for additional information
 regarding copyright ownership.  The ASF licenses this file
 to you 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 "SPTPersistentCacheObjectDescription.h"

id const SPTPersistentCacheObjectDescriptionTerminationSentinel = @"0xDEADC0DE";

NS_INLINE BOOL SPTIsObjectDescriptionTerminationSentinel(id const object)
{
    return object == SPTPersistentCacheObjectDescriptionTerminationSentinel;
}

static void SPTPersistentCacheObjectDescriptionAppendToString(NSMutableString *description, id<NSObject> object, id<NSObject> firstValue, va_list valueKeyPairs)
{
    NSCParameterAssert(description);
    NSCParameterAssert(object);

    id<NSObject> value = firstValue;
    id<NSObject> key = va_arg(valueKeyPairs, id);

    while (!SPTIsObjectDescriptionTerminationSentinel(value) && !SPTIsObjectDescriptionTerminationSentinel(key)) {
        if (value != object && key != object) {
            [description appendFormat:@"; %@ = \"%@\"", key, value];
        }

        value = va_arg(valueKeyPairs, id);
        if (SPTIsObjectDescriptionTerminationSentinel(value)) {
            break;
        }

        key = va_arg(valueKeyPairs, id);
    }

}

NSString *_SPTPersistentCacheObjectDescription(id<NSObject> object, id<NSObject> firstValue, ...)
{
    if (object == nil) {
        return nil;
    }

    NSString * const objectClassName = NSStringFromClass(object.class);
    NSMutableString * const description = [NSMutableString stringWithFormat:@"<%@: %p", objectClassName, (void *)object];

    NSString * (^ const closeAndReturnDescriptionBlock)(void) = ^{
        [description appendString:@">"];
        return [description copy];
    };

    if (SPTIsObjectDescriptionTerminationSentinel(firstValue)) {
        return closeAndReturnDescriptionBlock();
    }

    va_list valueKeyPairs;
    va_start(valueKeyPairs, firstValue);
    SPTPersistentCacheObjectDescriptionAppendToString(description, object, firstValue, valueKeyPairs);
    va_end(valueKeyPairs);

    return closeAndReturnDescriptionBlock();
}