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+// Tencent is pleased to support the open source community by making RapidJSON available.
+//
+// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
+//
+// Licensed under the MIT License (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+// http://opensource.org/licenses/MIT
+//
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+#ifndef RAPIDJSON_INTERNAL_STACK_H_
+#define RAPIDJSON_INTERNAL_STACK_H_
+
+#include "../allocators.h"
+#include "swap.h"
+
+#if defined(__clang__)
+RAPIDJSON_DIAG_PUSH
+RAPIDJSON_DIAG_OFF(c++98-compat)
+#endif
+
+RAPIDJSON_NAMESPACE_BEGIN
+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) {
+ }
+
+#if RAPIDJSON_HAS_CXX11_RVALUE_REFS
+ Stack(Stack&& rhs)
+ : allocator_(rhs.allocator_),
+ ownAllocator_(rhs.ownAllocator_),
+ stack_(rhs.stack_),
+ stackTop_(rhs.stackTop_),
+ stackEnd_(rhs.stackEnd_),
+ initialCapacity_(rhs.initialCapacity_)
+ {
+ rhs.allocator_ = 0;
+ rhs.ownAllocator_ = 0;
+ rhs.stack_ = 0;
+ rhs.stackTop_ = 0;
+ rhs.stackEnd_ = 0;
+ rhs.initialCapacity_ = 0;
+ }
+#endif
+
+ ~Stack() {
+ Destroy();
+ }
+
+#if RAPIDJSON_HAS_CXX11_RVALUE_REFS
+ Stack& operator=(Stack&& rhs) {
+ if (&rhs != this)
+ {
+ Destroy();
+
+ allocator_ = rhs.allocator_;
+ ownAllocator_ = rhs.ownAllocator_;
+ stack_ = rhs.stack_;
+ stackTop_ = rhs.stackTop_;
+ stackEnd_ = rhs.stackEnd_;
+ initialCapacity_ = rhs.initialCapacity_;
+
+ rhs.allocator_ = 0;
+ rhs.ownAllocator_ = 0;
+ rhs.stack_ = 0;
+ rhs.stackTop_ = 0;
+ rhs.stackEnd_ = 0;
+ rhs.initialCapacity_ = 0;
+ }
+ return *this;
+ }
+#endif
+
+ void Swap(Stack& rhs) RAPIDJSON_NOEXCEPT {
+ internal::Swap(allocator_, rhs.allocator_);
+ internal::Swap(ownAllocator_, rhs.ownAllocator_);
+ internal::Swap(stack_, rhs.stack_);
+ internal::Swap(stackTop_, rhs.stackTop_);
+ internal::Swap(stackEnd_, rhs.stackEnd_);
+ internal::Swap(initialCapacity_, rhs.initialCapacity_);
+ }
+
+ 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 void Reserve(size_t count = 1) {
+ // Expand the stack if needed
+ if (RAPIDJSON_UNLIKELY(stackTop_ + sizeof(T) * count > stackEnd_))
+ Expand<T>(count);
+ }
+
+ template<typename T>
+ RAPIDJSON_FORCEINLINE T* Push(size_t count = 1) {
+ Reserve<T>(count);
+ return PushUnsafe<T>(count);
+ }
+
+ template<typename T>
+ RAPIDJSON_FORCEINLINE T* PushUnsafe(size_t count = 1) {
+ RAPIDJSON_ASSERT(stackTop_ + sizeof(T) * count <= stackEnd_);
+ 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>
+ const T* Top() const {
+ RAPIDJSON_ASSERT(GetSize() >= sizeof(T));
+ return reinterpret_cast<T*>(stackTop_ - sizeof(T));
+ }
+
+ template<typename T>
+ T* End() { return reinterpret_cast<T*>(stackTop_); }
+
+ template<typename T>
+ const T* End() const { return reinterpret_cast<T*>(stackTop_); }
+
+ template<typename T>
+ T* Bottom() { return reinterpret_cast<T*>(stack_); }
+
+ template<typename T>
+ const T* Bottom() const { return reinterpret_cast<T*>(stack_); }
+
+ bool HasAllocator() const {
+ return allocator_ != 0;
+ }
+
+ Allocator& GetAllocator() {
+ RAPIDJSON_ASSERT(allocator_);
+ 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;
+ if (stack_ == 0) {
+ if (!allocator_)
+ ownAllocator_ = allocator_ = RAPIDJSON_NEW(Allocator());
+ newCapacity = initialCapacity_;
+ } else {
+ newCapacity = GetCapacity();
+ newCapacity += (newCapacity + 1) / 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_ = static_cast<char*>(allocator_->Realloc(stack_, GetCapacity(), newCapacity));
+ stackTop_ = stack_ + size;
+ stackEnd_ = stack_ + newCapacity;
+ }
+
+ void Destroy() {
+ Allocator::Free(stack_);
+ RAPIDJSON_DELETE(ownAllocator_); // Only delete if it is owned by the stack
+ }
+
+ // 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
+RAPIDJSON_NAMESPACE_END
+
+#if defined(__clang__)
+RAPIDJSON_DIAG_POP
+#endif
+
+#endif // RAPIDJSON_STACK_H_