104 lines
2.5 KiB
C++
104 lines
2.5 KiB
C++
//
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// gs_bucket.h - cpp template implementation of a growable, freeable list
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// Author: Peter Slattery
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// Date: December 30, 2019
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//
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// The key difference between gs_list.h and gs_bucket.h is that gs_bucket.h keeps everything
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// sequential (new elements are appended to the end, free elements are filled in from the end),
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// whereas gs_list.h maintiains a free list and deals with holes in the list
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template <typename T>
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struct gs_bucket_bucket
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{
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T* Contents;
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};
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#define GS_LIST_DEFAULT_BUCKET_SIZE 256
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template <typename T>
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class gs_bucket {
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public:
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u32 BucketSize;
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u32 BucketCount;
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gs_bucket_bucket<T>* Buckets;
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u32 Used;
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void GrowBucket();
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T* GetElementAtIndex(u32 Index);
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T* TakeElement();
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u32 PushElementOnBucket(T Ele);
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void FreeElementAtIndex(u32 Index);
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};
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template <typename T>
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void gs_bucket<T>::GrowBucket()
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{
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if (this->BucketSize == 0)
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{
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this->BucketSize = GS_LIST_DEFAULT_BUCKET_SIZE;
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}
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this->BucketCount += 1;
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this->Buckets = (gs_bucket_bucket<T>*)realloc(this->Buckets, sizeof(gs_bucket_bucket<T>) * this->BucketCount);
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gs_bucket_bucket<T>* NewBucket = this->Buckets + (this->BucketCount - 1);
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NewBucket->Contents = (T*)malloc(sizeof(T) * this->BucketSize);
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}
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template <typename T>
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T* gs_bucket<T>::GetElementAtIndex(u32 Index)
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{
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Assert(Index < this->BucketSize * this->BucketCount);
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Assert(Index < this->Used);
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u32 BucketIndex = Index / this->BucketSize;
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u32 IndexInBucket = Index % this->BucketSize;
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T* Result = this->Buckets[BucketIndex].Contents + IndexInBucket;
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return Result;
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}
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template <typename T>
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T* gs_bucket<T>::TakeElement()
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{
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if (this->Used >= this->BucketSize * this->BucketCount)
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{
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this->GrowBucket();
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}
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u32 Index = this->Used++;
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T* Result = this->GetElementAtIndex(Index);
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return Result;
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}
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template <typename T>
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u32 gs_bucket<T>::PushElementOnBucket(T Ele)
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{
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u32 ResultIndex = 0;
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if (this->Used >= this->BucketSize * this->BucketCount)
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{
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this->GrowBucket();
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}
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ResultIndex = this->Used++;
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T* FreeElement = this->GetElementAtIndex(ResultIndex);
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*FreeElement = Ele;
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return ResultIndex;
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}
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template <typename T>
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void gs_bucket<T>::FreeElementAtIndex(u32 Index)
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{
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Assert(Index < this->BucketSize * this->BucketCount);
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T* ToFillIn = this->GetElementAtIndex(Index);
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T* ToFree = this->GetElementAtIndex(--this->Used);
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*ToFillIn = *ToFree;
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}
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