OOFilteringEnumerator.h

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/*
 
OOFilteringEnumerator.h
By Jens Ayton
 
NSEnumerator which takes an existing enumerator and filters out the objects
that return NO from a given method. The method may take 0 or 1 arguments
 
Example of use:
    NSArray         *cats = [self cats];
    NSEnumerator    *happyCatEnum = [[cats objectEnumerator] filteredWithSelector:@selector(isHappy)];
    id              happyCat = nil;
    
    while ((happyCat = [happyCatEnum nextObject]))
    {
        ...
    }
 
Filters can be trivially chained. For instance, to get happy red cats, use:
    NSEnumeratore   *happyRedCatEnum = [[[cats objectEnumerator]
                                        filteredWithSelector:@selector(isHappy)]
                                        filteredWithSelector:@selector(hasColor:)
                                                 andArgument:[NSColor redColor]];
 
Objects that do not respond to the filter selector are treated as if they had
returned NO.
 
Bonus feature: adds NSArray-like (but non-exception-throwing)
makeObjectsPerformSelector: to all enumerators.
 
 
Copyright (C) 2008-2013 Jens Ayton
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 
*/
 
#import "OOCocoa.h"
 
 
@interface OOFilteringEnumerator: NSEnumerator
{
@private
    NSEnumerator        *_underlyingEnum;
    SEL                 _selector;
    id                  _argument;
    BOOL                _takesArgument;
}
 
+ (id) filterEnumerator:(NSEnumerator *)enumerator withSelector:(SEL)selector;
+ (id) filterEnumerator:(NSEnumerator *)enumerator withSelector:(SEL)selector andArgument:(id)argument;
 
- (id) initWithUnderlyingEnumerator:(NSEnumerator *)enumerator
                       withSelector:(SEL)selector
                     takingArgument:(BOOL)takesArgument
                      argumentValue:(id)argument;
 
@end
 
 
@interface NSEnumerator (OOFilteringEnumerator)
 
- (id) filteredWithSelector:(SEL)selector;
- (id) filteredWithSelector:(SEL)selector andArgument:(id)argument;
 
@end
 
 
@interface NSArray (OOFilteringEnumerator)
 
- (id) objectEnumeratorFilteredWithSelector:(SEL)selector;
- (id) objectEnumeratorFilteredWithSelector:(SEL)selector andArgument:(id)argument;
 
@end
 
 
@interface NSSet (OOFilteringEnumerator)
 
- (id) objectEnumeratorFilteredWithSelector:(SEL)selector;
- (id) objectEnumeratorFilteredWithSelector:(SEL)selector andArgument:(id)argument;
 
@end
 
 
@interface NSDictionary (OOFilteringEnumerator)
 
- (id) objectEnumeratorFilteredWithSelector:(SEL)selector;
- (id) objectEnumeratorFilteredWithSelector:(SEL)selector andArgument:(id)argument;
 
- (id) keyEnumeratorFilteredWithSelector:(SEL)selector;
- (id) keyEnumeratorFilteredWithSelector:(SEL)selector andArgument:(id)argument;
 
@end
 
 
@interface NSEnumerator (OOMakeObjectsPerformSelector)
 
- (void)makeObjectsPerformSelector:(SEL)selector;
- (void)makeObjectsPerformSelector:(SEL)selector withObject:(id)argument;
 
@end