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// Copyright (C) 2011 Milo Yip
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
#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:
// Optimization note: Do not allocate memory for stack_ in constructor.
// Do it lazily when first Push() -> Expand() -> Resize().
Stack(Allocator* allocator, size_t stackCapacity) : allocator_(allocator), ownAllocator(0), stack_(0), stackTop_(0), stackEnd_(0), initialCapacity_(stackCapacity) {
RAPIDJSON_ASSERT(stackCapacity > 0);
if (!allocator_)
ownAllocator = allocator_ = new Allocator();
}
~Stack() {
Allocator::Free(stack_);
delete ownAllocator; // Only delete if it is owned by the stack
}
void Clear() { stackTop_ = stack_; }
void ShrinkToFit() {
if (Empty()) {
// If the stack is empty, completely deallocate the memory.
Allocator::Free(stack_);
stack_ = 0;
stackTop_ = 0;
stackEnd_ = 0;
}
else
Resize(GetSize());
}
// Optimization note: try to minimize the size of this function for force inline.
// Expansion is run very infrequently, so it is moved to another (probably non-inline) function.
template<typename T>
RAPIDJSON_FORCEINLINE T* Push(size_t count = 1) {
// Expand the stack if needed
if (stackTop_ + sizeof(T) * count >= stackEnd_)
Expand<T>(count);
T* ret = reinterpret_cast<T*>(stackTop_);
stackTop_ += sizeof(T) * count;
return ret;
}
template<typename T>
T* Pop(size_t count) {
RAPIDJSON_ASSERT(GetSize() >= count * sizeof(T));
stackTop_ -= count * sizeof(T);
return reinterpret_cast<T*>(stackTop_);
}
template<typename T>
T* Top() {
RAPIDJSON_ASSERT(GetSize() >= sizeof(T));
return reinterpret_cast<T*>(stackTop_ - sizeof(T));
}
template<typename T>
T* Bottom() { return (T*)stack_; }
Allocator& GetAllocator() { return *allocator_; }
bool Empty() const { return stackTop_ == stack_; }
size_t GetSize() const { return static_cast<size_t>(stackTop_ - stack_); }
size_t GetCapacity() const { return static_cast<size_t>(stackEnd_ - stack_); }
private:
template<typename T>
void Expand(size_t count) {
// Only expand the capacity if the current stack exists. Otherwise just create a stack with initial capacity.
size_t newCapacity = (stack_ == 0) ? initialCapacity_ : GetCapacity() * 2;
size_t newSize = GetSize() + sizeof(T) * count;
if (newCapacity < newSize)
newCapacity = newSize;
Resize(newCapacity);
}
void Resize(size_t newCapacity) {
const size_t size = GetSize(); // Backup the current size
stack_ = (char*)allocator_->Realloc(stack_, GetCapacity(), newCapacity);
stackTop_ = stack_ + size;
stackEnd_ = stack_ + newCapacity;
}
// Prohibit copy constructor & assignment operator.
Stack(const Stack&);
Stack& operator=(const Stack&);
Allocator* allocator_;
Allocator* ownAllocator;
char *stack_;
char *stackTop_;
char *stackEnd_;
size_t initialCapacity_;
};
} // namespace internal
} // namespace rapidjson
#endif // RAPIDJSON_STACK_H_
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