bite-objc

Bite is a functional enumeration library built on top of NSFastEnumeration, providing functions like take:, filter:, and map:. While many Foundation collections already provide similar operations, Bite lets you do them without introducing large or mutable intermediates.

Concept based on the Bite Java library.

Usage

Installation

pod 'Bite', '~> 0.2'

#import <Bite/Bite.h>

Creating a bite

BITEEnumerator *bite = BITE(myArray);
BITEEnumerator *bite2 = BITE(myArray, 2); // Never enumerate over more than two elements at a time.

for (id obj in BITE(myArray)) {
    // Use directly in a for-in block.
}

Creating a recursive bite

BITEEnumerator *bite = BITE_INTO(self, @selector(parentViewController));

for (id viewController in bite) {
    if ([viewController isKindOfClass:[MyViewController class]]) {
        return viewController;
    }
}

Recursive bites iterate until they reach a nil value.

Chaining bites

BITEEnumerator *bite = [BITE(myArray) filter^BOOL(id obj) { return [obj size].width < 100; }];
BITEEnumerator *bite2 = [bite skip:5];

for (id obj in [bite2 take:5]) {
    [self doSomething:obj];
}

Transforms

• - (BITEEnumerator *)take:(NSUInteger)count Stops iterating after count elements are iterated.

• - (BITEEnumerator *)skip:(NSUInteger)count Skips over count elements.

• - (BITEEnumerator *)map:(id (^)(id obj))mappingFunction Has NSExpression versions. Passes each element through a mapping function and iterates the results.

• - (BITEEnumerator *)mapWithKeyPath:(NSString *)keyPath Same as map: but selects a key path from each element.

• - (BITEEnumerator *)filter:(BOOL (^)(id obj))test Has NSPredicate versions. Only iterates elements that pass a test. Useful for nil filtering before generating a collection.

• - (BITEEnumerator *)choke:(NSUInteger)choke Decreases the number of elements that are loaded into the fast-enumeration buffer.
• - (BITEEnumerator *)except:(id)obj Filters out elements that are equal to the given object.
• - (BITEEnumerator *)until:(BOOL (^)(id obj))test Has NSPredicate versions. Stops iterating when the test passes.
• - (BITEEnumerator *)and:(id<NSFastEnumeration>)enumerator Concatenates this enumerator with another.
• - (BITEEnumerator *)andObject:(id)obj Concatenates this enumerator with a single element.

Evaluating/Collecting

• - (NSUInteger)count Returns the number of elements in the enumerator.
• - (NSArray *)array Creates an array.
• - (NSSet *)set Creates a set.
• - (NSDictionary *)dictionaryWithKeyPath:(NSString *)keyPath valuePath:(NSString *)valuePath Creates a dictionary using key paths for the keys and values.
• - (NSDictionary *)dictionaryWithPairs Creates a dictionary using the path _1 for the key and _2 for the value. To be used with PAIR/BITE_TUPLE.

• - (NSString *)joinedByString:(NSString *)separator Joins the elements in the enumerator with a separator.

• - (BOOL)any:(BOOL (^)(id obj))test Has NSPredicate versions. Returns YES if any item in the enumerator passes the test and stops iterating. It chokes the buffer to one element to limit execution.

• - (BOOL)all:(BOOL (^)(id obj))test Has NSPredicate versions. Returns YES if all items in the enumerator pass the test. Returns NO and stops iterating as soon as the test fails. It chokes the buffer to one element to limit execution.

• - (id)first:(out BOOL *)exists Returns the first item or nil if the enumerator is empty. Optionally outputs whether or not an item was returned to exists in cases where nil is a valid enumerated item.

• - (id)last:(out BOOL *)exists Returns the last item or nil if the enumerator is empty. Optionally outputs whether or not an item was returned to exists in cases where nil is a valid enumerated item.

• - (id)foldLeft:(id)initial func:(id (^)(id acc, id obj))func Folds left with an initial accumulator value.

• - (id)foldRight:(id)initial func:(id (^)(id obj, id acc))func Folds right with an initial accumulator value.

• - (id)reduceLeft:(id (^)(id acc, id obj))func Reduces left.

• - (id)reduceRight:(id (^)(id obj, id acc))func Reduces right.

Tuples

BITETuple contains indexed properties _1, _2, _3 which can be created with the overloaded BITE_TUPLE function. Shorthand macros exist if you define BITE_SHORTHAND before importing bite:

id a = BITE_TUPLE(@1);
id b = BITE_TUPLE(@1, @2);
id c = BITE_TUPLE(@1, @2, @3);
// or
id d = MONAD(@1);
id e = PAIR(@1, @2);
id f = TREBLE(@1, @2, @3);

NSParameterAssert([e _2] == [f _2]);

Examples

1. Creating a dictionary from an object using blocks and tuples.

   NSDictionary *networkUsersForSites = [[[BITE(networkUsers) filter:^BOOL(StacManNetworkUser *user) {
       return user.siteUrl != nil;
   }] map:^id(StacManNetworkUser *user) {
       return PAIR(user.siteUrl, user);
   }] dictionaryWithPairs];

2. Creating the same with predicates and key paths:

   NSDictionary *networkUsersForSites = [[BITE(networkUsers) filterWithFormat:@"siteUrl != nil"]
                                                            dictionaryWithKeyPath:@"siteUrl" valuePath:@"self"];

3. Finding the parent table view for a cell.

   UITableView *tableView = [[BITE_INTO(cell, @selector(superview))
                              filterWithFormat:@"self isKindOfClass: %@", [UITableView class]]
                             first:NULL];