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