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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. using namespace std;
  5.  
  6. template<class type, int blockSize>
  7. class idBlockAlloc {
  8. public:
  9.               idBlockAlloc( void );
  10.               ~idBlockAlloc( void );
  11.  
  12.   void          Shutdown( void );
  13.  
  14.   type *          Alloc( void );
  15.   void          Free( type *element );
  16.  
  17.   int            GetTotalCount( void ) const { return total; }
  18.   int            GetAllocCount( void ) const { return active; }
  19.   int            GetFreeCount( void ) const { return total - active; }
  20.  
  21. private:
  22.   typedef struct element_s {
  23.     struct element_s *  next;
  24.     type        t;
  25.   } element_t;
  26.   typedef struct block_s {
  27.     element_t      elements[blockSize];
  28.     struct block_s *  next;
  29.   } block_t;
  30.  
  31.   block_t *        blocks;
  32.   element_t *        free;
  33.   int            total;
  34.   int            active;
  35. };
  36.  
  37. template<class type, int blockSize>
  38. idBlockAlloc<type,blockSize>::idBlockAlloc( void ) {
  39.   blocks = NULL;
  40.   free = NULL;
  41.   total = active = 0;
  42. }
  43.  
  44. template<class type, int blockSize>
  45. idBlockAlloc<type,blockSize>::~idBlockAlloc( void ) {
  46.   Shutdown();
  47. }
  48.  
  49. template<class type, int blockSize>
  50. type *idBlockAlloc<type,blockSize>::Alloc( void ) {
  51.   if ( !free ) {
  52.     block_t *block = new block_t;
  53.     block->next = blocks;
  54.     blocks = block;
  55.     for ( int i = 0; i < blockSize; i++ ) {
  56.       block->elements[i].next = free;
  57.       free = &block->elements[i];
  58.     }
  59.     total += blockSize;
  60.   }
  61.   active++;
  62.   element_t *element = free;
  63.   free = free->next;
  64.   element->next = NULL;
  65.   return &element->t;
  66. }
  67.  
  68. template<class type, int blockSize>
  69. void idBlockAlloc<type,blockSize>::Free( type *t ) {
  70.   element_t *element = (element_t *)( ( (unsigned char *) t ) - ( (int) &((element_t *)0)->t ) );
  71.   element->next = free;
  72.   free = element;
  73.   active--;
  74. }
  75.  
  76. template<class type, int blockSize>
  77. void idBlockAlloc<type,blockSize>::Shutdown( void ) {
  78.   while( blocks ) {
  79.     block_t *block = blocks;
  80.     blocks = blocks->next;
  81.     delete block;
  82.   }
  83.   blocks = NULL;
  84.   free = NULL;
  85.   total = active = 0;
  86. }
  87.  
  88. struct SomeClass{
  89.   SomeClass(){
  90.     cout << "SomeClass()" << endl;
  91.     }
  92.  
  93.   std::vector<int> data;
  94.   };
  95.  
  96. int main() {
  97.   idBlockAlloc<SomeClass,32>  eventAllocator;
  98.   SomeClass* event = eventAllocator.Alloc();
  99.   event->data.push_back(1);
  100.  
  101.   eventAllocator.Free( event );
  102.  
  103.   event = eventAllocator.Alloc();
  104.   event->data.push_back(2);
  105.  
  106.   cout << event->data.size() << endl;
  107.   eventAllocator.Free( event );
  108.   }
  109.  
Success #stdin #stdout 0.01s 2816KB
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Standard input is empty
stdout
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SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
SomeClass()
2
https://ideone.com/oXrf6
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
public

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