tasks a-s

Task/Priority-queue/Objective-C/priority-queue.m

@@ -0,0 +1,68 @@
+#import <Foundation/Foundation.h>
+
+const void *PQRetain(CFAllocatorRef allocator, const void *ptr) {
+  return [(id)ptr retain];
+}
+void PQRelease(CFAllocatorRef allocator, const void *ptr) {
+  [(id)ptr release];
+}
+CFComparisonResult PQCompare(const void *ptr1, const void *ptr2, void *unused) {
+  return [(id)ptr1 compare:(id)ptr2];
+}
+
+@interface Task : NSObject {
+  int priority;
+  NSString *name;
+}
+- (id)initWithPriority:(int)p andName:(NSString *)n;
+- (NSComparisonResult)compare:(Task *)other;
+@end
+
+@implementation Task
+- (id)initWithPriority:(int)p andName:(NSString *)n {
+  if ((self = [super init])) {
+    priority = p;
+    name = [n copy];
+  }
+  return self;
+}
+- (void)dealloc {
+  [name release];
+  [super dealloc];
+}
+- (NSString *)description {
+  return [NSString stringWithFormat:@"%d, %@", priority, name];
+}
+- (NSComparisonResult)compare:(Task *)other {
+  if (priority == other->priority)
+    return NSOrderedSame;
+  else if (priority < other->priority)
+    return NSOrderedAscending;
+  else
+    return NSOrderedDescending;
+}
+@end
+
+int main (int argc, const char *argv[]) {
+  NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
+
+  CFBinaryHeapCallBacks callBacks = {0, PQRetain, PQRelease, NULL, PQCompare};
+  CFBinaryHeapRef pq = CFBinaryHeapCreate(NULL, 0, &callBacks, NULL);
+
+  CFBinaryHeapAddValue(pq, [[[Task alloc] initWithPriority:3 andName:@"Clear drains"] autorelease]);
+  CFBinaryHeapAddValue(pq, [[[Task alloc] initWithPriority:4 andName:@"Feed cat"] autorelease]);
+  CFBinaryHeapAddValue(pq, [[[Task alloc] initWithPriority:5 andName:@"Make tea"] autorelease]);
+  CFBinaryHeapAddValue(pq, [[[Task alloc] initWithPriority:1 andName:@"Solve RC tasks"] autorelease]);
+  CFBinaryHeapAddValue(pq, [[[Task alloc] initWithPriority:2 andName:@"Tax return"] autorelease]);
+
+  while (CFBinaryHeapGetCount(pq) != 0) {
+    Task *task = (id)CFBinaryHeapGetMinimum(pq);
+    NSLog(@"%@", task);
+    CFBinaryHeapRemoveMinimumValue(pq);
+  }
+
+  CFRelease(pq);
+
+  [pool drain];
+  return 0;
+}