A2DictionaryOfVariableBindings

A2DictionaryOfVariableBindings.h

@import Foundation;

#define A2DictionaryOfVariableBindings(...) _A2DictionaryOfVariableBindings(@"" # __VA_ARGS__, __VA_ARGS__, nil)
extern NSDictionary *_A2DictionaryOfVariableBindings(NSString *commaSeparatedKeysString, id firstValue, ...); // not for direct use

A2DictionaryOfVariableBindings.m

#import "A2DictionaryOfVariableBindings.h"

static NSCharacterSet *commaAndWhitespaceCharacterSet;
static NSCharacterSet *commaAndWhitespaceInvertedCharacterSet;

NSDictionary *_A2DictionaryOfVariableBindings(NSString *commaSeparatedKeysString, id firstValue, ...) {
    if (commaAndWhitespaceCharacterSet == nil) {
        commaAndWhitespaceCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@", \t\n\r\x0B"];
        commaAndWhitespaceInvertedCharacterSet = [commaAndWhitespaceCharacterSet invertedSet];
    }

    NSScanner *scanner = [[NSScanner alloc] initWithString:commaSeparatedKeysString];

    NSMutableArray *keys = [[NSMutableArray alloc] init];

    NSString *key;
    [scanner scanUpToCharactersFromSet:commaAndWhitespaceInvertedCharacterSet intoString:NULL];
    [scanner scanUpToCharactersFromSet:commaAndWhitespaceCharacterSet intoString:&key];

    while (key != nil) {
        NSUInteger lastDotIndex = [key rangeOfString:@"." options:NSBackwardsSearch].location;
        if (lastDotIndex != NSNotFound) {
            key = [key substringFromIndex:lastDotIndex + 1];
        }

        NSCAssert(![keys containsObject:key], @"A2DictionaryOfVariableBindings failed because multiple values have \"%@\" as the last path component", key);
        [keys addObject:key];

        [scanner scanUpToCharactersFromSet:commaAndWhitespaceInvertedCharacterSet intoString:NULL];
        if (![scanner scanUpToCharactersFromSet:commaAndWhitespaceCharacterSet intoString:&key]) {
            key = nil;
        }
    }

    NSMutableArray *values = [NSMutableArray arrayWithCapacity:keys.count];

    va_list ap;
    va_start(ap, firstValue);
    id value = firstValue;
    while (value != nil) {
        [values addObject:value];
        value = va_arg(ap, id);
    }
    va_end(ap);

    NSCAssert(values.count == keys.count, @"Unequal key and value counts. This may be because %@ is nil.", keys[values.count]);
    return [NSDictionary dictionaryWithObjects:values forKeys:keys];
}