Diff: rapidjson/internal/stack.h

Revision:

0:33d4e66780c0

diff -r 000000000000 -r 33d4e66780c0 rapidjson/internal/stack.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rapidjson/internal/stack.h	Fri Feb 24 11:23:12 2017 -0600
@@ -0,0 +1,230 @@
+// 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_