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#ifndef RAPIDJSON_INTERNAL_STACK_H_
#define RAPIDJSON_INTERNAL_STACK_H_
namespace rapidjson {
namespace internal {
///////////////////////////////////////////////////////////////////////////////
// Stack
//! A type-unsafe stack for storing different types of data.
/*! \tparam Allocator Allocator for allocating stack memory.
*/
template <typename Allocator>
class Stack {
public:
Stack(Allocator* allocator, size_t stack_capacity) : allocator_(allocator), own_allocator_(0), stack_(0), stack_top_(0), stack_end_(0), stack_capacity_(stack_capacity) {
RAPIDJSON_ASSERT(stack_capacity_ > 0);
if (!allocator_)
own_allocator_ = allocator_ = new Allocator();
stack_top_ = stack_ = (char*)allocator_->Malloc(stack_capacity_);
stack_end_ = stack_ + stack_capacity_;
}
~Stack() {
Allocator::Free(stack_);
delete own_allocator_; // Only delete if it is owned by the stack
}
void Clear() { /*stack_top_ = 0;*/ stack_top_ = stack_; }
template<typename T>
T* Push(size_t count = 1) {
// Expand the stack if needed
if (stack_top_ + sizeof(T) * count >= stack_end_) {
size_t new_capacity = stack_capacity_ * 2;
size_t size = GetSize();
size_t new_size = GetSize() + sizeof(T) * count;
if (new_capacity < new_size)
new_capacity = new_size;
stack_ = (char*)allocator_->Realloc(stack_, stack_capacity_, new_capacity);
stack_capacity_ = new_capacity;
stack_top_ = stack_ + size;
stack_end_ = stack_ + stack_capacity_;
}
T* ret = (T*)stack_top_;
stack_top_ += sizeof(T) * count;
return ret;
}
template<typename T>
T* Pop(size_t count) {
RAPIDJSON_ASSERT(GetSize() >= count * sizeof(T));
stack_top_ -= count * sizeof(T);
return (T*)stack_top_;
}
template<typename T>
T* Top() {
RAPIDJSON_ASSERT(GetSize() >= sizeof(T));
return (T*)(stack_top_ - sizeof(T));
}
template<typename T>
T* Bottom() { return (T*)stack_; }
Allocator& GetAllocator() { return *allocator_; }
size_t GetSize() const { return stack_top_ - stack_; }
size_t GetCapacity() const { return stack_capacity_; }
private:
Allocator* allocator_;
Allocator* own_allocator_;
char *stack_;
char *stack_top_;
char *stack_end_;
size_t stack_capacity_;
};
} // namespace internal
} // namespace rapidjson
#endif // RAPIDJSON_STACK_H_
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