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//
// GTMNSEnumerator+Filter.m
//
// Copyright 2007-2009 Google Inc.
//
// Licensed 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 "GTMNSEnumerator+Filter.h"
#import "GTMDebugSelectorValidation.h"
#import "GTMDefines.h"
#if GTM_IPHONE_SDK
#import <objc/message.h>
#import <objc/runtime.h>
#else
#import <objc/objc-runtime.h>
#endif
// a private subclass of NSEnumerator that does all the work.
// public interface just returns one of these.
// This top level class contains all the additional boilerplate. Specific
// behavior is in the subclasses.
@interface GTMEnumeratorPrivateBase : NSEnumerator {
@protected
NSEnumerator *base_;
SEL operation_; // either a predicate or a transform depending on context.
id target_; // may be nil
id object_; // may be nil
}
@end
@interface GTMEnumeratorPrivateBase (SubclassesMustProvide)
- (BOOL)filterObject:(id)obj returning:(id *)resultp;
@end
@implementation GTMEnumeratorPrivateBase
- (id)initWithBase:(NSEnumerator *)base
sel:(SEL)filter
target:(id)optionalTarget
object:(id)optionalOther {
self = [super init];
if (self) {
// someone would have to subclass or directly create an object of this
// class, and this class is private to this impl.
_GTMDevAssert(base, @"can't initWithBase: a nil base enumerator");
base_ = [base retain];
operation_ = filter;
target_ = [optionalTarget retain];
object_ = [optionalOther retain];
}
return self;
}
// we don't provide an init because this base class is private to this
// impl, and no one would be able to create it (if they do, they get whatever
// they happens...).
- (void)dealloc {
[base_ release];
[target_ release];
[object_ release];
[super dealloc];
}
- (id)nextObject {
for (id obj = [base_ nextObject]; obj; obj = [base_ nextObject]) {
id result = nil;
if ([self filterObject:obj returning:&result]) {
return result;
}
}
return nil;
}
@end
// a transformer, for each item in the enumerator, returns a f(item).
@interface GTMEnumeratorTransformer : GTMEnumeratorPrivateBase
@end
@implementation GTMEnumeratorTransformer
- (BOOL)filterObject:(id)obj returning:(id *)resultp {
*resultp = [obj performSelector:operation_ withObject:object_];
return nil != *resultp;
}
@end
// a transformer, for each item in the enumerator, returns a f(item).
// a target transformer swaps the target and the argument.
@interface GTMEnumeratorTargetTransformer : GTMEnumeratorPrivateBase
@end
@implementation GTMEnumeratorTargetTransformer
- (BOOL)filterObject:(id)obj returning:(id *)resultp {
*resultp = [target_ performSelector:operation_
withObject:obj
withObject:object_];
return nil != *resultp;
}
@end
// a filter, for each item in the enumerator, if(f(item)) { returns item. }
@interface GTMEnumeratorFilter : GTMEnumeratorPrivateBase
@end
@implementation GTMEnumeratorFilter
// We must take care here, since Intel leaves junk in high bytes of return
// register for predicates that return BOOL.
// For details see:
// http://developer.apple.com/legacy/mac/library/documentation/MacOSX/Conceptual/universal_binary/universal_binary_tips/universal_binary_tips.html#//apple_ref/doc/uid/TP40002217-CH239-280661
// and
// http://www.red-sweater.com/blog/320/abusing-objective-c-with-class#comment-83187
- (BOOL)filterObject:(id)obj returning:(id *)resultp {
*resultp = obj;
return ((BOOL (*)(id, SEL, id))objc_msgSend)(obj, operation_, object_);
}
@end
// a target filter, for each item in the enumerator, if(f(item)) { returns item. }
// a target transformer swaps the target and the argument.
@interface GTMEnumeratorTargetFilter : GTMEnumeratorPrivateBase
@end
@implementation GTMEnumeratorTargetFilter
// We must take care here, since Intel leaves junk in high bytes of return
// register for predicates that return BOOL.
// For details see:
// http://developer.apple.com/legacy/mac/library/documentation/MacOSX/Conceptual/universal_binary/universal_binary_tips/universal_binary_tips.html#//apple_ref/doc/uid/TP40002217-CH239-280661
// and
// http://www.red-sweater.com/blog/320/abusing-objective-c-with-class#comment-83187
- (BOOL)filterObject:(id)obj returning:(id *)resultp {
*resultp = obj;
return ((BOOL (*)(id, SEL, id, id))objc_msgSend)(target_, operation_, obj, object_);
}
@end
@implementation NSEnumerator (GTMEnumeratorFilterAdditions)
- (NSEnumerator *)gtm_filteredEnumeratorByMakingEachObjectPerformSelector:(SEL)selector
withObject:(id)argument {
return [[[GTMEnumeratorFilter alloc] initWithBase:self
sel:selector
target:nil
object:argument] autorelease];
}
- (NSEnumerator *)gtm_enumeratorByMakingEachObjectPerformSelector:(SEL)selector
withObject:(id)argument {
return [[[GTMEnumeratorTransformer alloc] initWithBase:self
sel:selector
target:nil
object:argument] autorelease];
}
- (NSEnumerator *)gtm_filteredEnumeratorByTarget:(id)target
performOnEachSelector:(SEL)predicate {
// make sure the object impls this selector taking an object as an arg.
GTMAssertSelectorNilOrImplementedWithReturnTypeAndArguments(target, predicate,
@encode(BOOL),
@encode(id),
NULL);
return [[[GTMEnumeratorTargetFilter alloc] initWithBase:self
sel:predicate
target:target
object:nil] autorelease];
}
- (NSEnumerator *)gtm_filteredEnumeratorByTarget:(id)target
performOnEachSelector:(SEL)predicate
withObject:(id)object {
// make sure the object impls this selector taking an object as an arg.
GTMAssertSelectorNilOrImplementedWithReturnTypeAndArguments(target, predicate,
@encode(BOOL),
@encode(id),
@encode(id),
NULL);
return [[[GTMEnumeratorTargetFilter alloc] initWithBase:self
sel:predicate
target:target
object:object] autorelease];
}
- (NSEnumerator *)gtm_enumeratorByTarget:(id)target
performOnEachSelector:(SEL)selector {
// make sure the object impls this selector taking an object as an arg.
GTMAssertSelectorNilOrImplementedWithReturnTypeAndArguments(target, selector,
@encode(id),
@encode(id),
NULL);
return [[[GTMEnumeratorTargetTransformer alloc] initWithBase:self
sel:selector
target:target
object:nil]
autorelease];
}
- (NSEnumerator *)gtm_enumeratorByTarget:(id)target
performOnEachSelector:(SEL)selector
withObject:(id)object {
// make sure the object impls this selector taking an object as an arg.
GTMAssertSelectorNilOrImplementedWithReturnTypeAndArguments(target, selector,
@encode(id),
@encode(id),
@encode(id),
NULL);
return [[[GTMEnumeratorTargetTransformer alloc] initWithBase:self
sel:selector
target:target
object:object]
autorelease];
}
@end
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