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#pragma once
#include "globalincs/pstypes.h"
#include <functional>
namespace util {
/**
* @brief A generic heap manager
*
* This class does not allocate memory! It only keeps track of where memory is stored and which memory ranges may be
* reused later. This needs some kind of underlying memory manager before it can do anything.
*/
class HeapAllocator {
public:
/**
* @brief A function that can resize a generic heap structure.
*
* This takes the new size of the heap as its only parameter.
*/
typedef std::function<void(size_t)> HeapResizer;
private:
struct MemoryRange {
size_t offset = 0;
size_t size = 0;
bool operator<(const MemoryRange& other) const;
bool operator==(const MemoryRange& other) const;
};
size_t _heapSize = 0;
size_t _lastSizeIncraese = 0;
HeapResizer _heapResizer;
SCP_vector<MemoryRange> _freeRanges;
SCP_vector<MemoryRange> _allocatedRanges;
void addFreeRange(const MemoryRange& range);
void addAllocatedRange(const MemoryRange& range);
/**
* @brief Checks if all free ranges are merged properly.
*/
void checkRangesMerged();
static bool check_connected_range(const MemoryRange& left, const MemoryRange& right);
public:
explicit HeapAllocator(const HeapResizer& creatorFunction);
~HeapAllocator() = default;
/**
* @brief Allocates the specified amount of memory
* @param size The size of the memory block to allocate
* @return The offset at which the specified amount of memory can be used
*/
size_t allocate(size_t size);
/**
* @brief Frees the memory starting at the specified offset.
* @param offset The offset at which to free memory. This value must have been returned by allocate previously!
*/
void free(size_t offset);
/**
* @brief Retrieves the amount of allocations currently active
* @return The active allocations in this heap.
*/
size_t numAllocations() const;
};
}
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