Provide StdAllocator, STL compatible, for use with STL types.

include/rapidjson/allocators.h

@@ -17,6 +17,8 @@
 
 #include "rapidjson.h"
 
+#include <memory>
+
 RAPIDJSON_NAMESPACE_BEGIN
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -89,7 +91,14 @@ public:
         }
         return RAPIDJSON_REALLOC(originalPtr, newSize);
     }
-    static void Free(void *ptr) { RAPIDJSON_FREE(ptr); }
+    static void Free(void *ptr) RAPIDJSON_NOEXCEPT { RAPIDJSON_FREE(ptr); }
+
+    bool operator==(const CrtAllocator&) const RAPIDJSON_NOEXCEPT {
+        return true;
+    }
+    bool operator!=(const CrtAllocator&) const RAPIDJSON_NOEXCEPT {
+        return false;
+    }
 };
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -113,6 +122,36 @@ public:
 */
 template <typename BaseAllocator = CrtAllocator>
 class MemoryPoolAllocator {
+    //! Chunk header for perpending to each chunk.
+    /*! Chunks are stored as a singly linked list.
+    */
+    struct ChunkHeader {
+        size_t capacity;    //!< Capacity of the chunk in bytes (excluding the header itself).
+        size_t size;        //!< Current size of allocated memory in bytes.
+        ChunkHeader *next;  //!< Next chunk in the linked list.
+    };
+
+    struct SharedData {
+        ChunkHeader *chunkHead;  //!< Head of the chunk linked-list. Only the head chunk serves allocation.
+        BaseAllocator* ownBaseAllocator; //!< base allocator created by this object.
+        size_t refcount;
+        bool ownBuffer;
+    };
+
+    static const size_t SIZEOF_SHARED_DATA = RAPIDJSON_ALIGN(sizeof(SharedData));
+    static const size_t SIZEOF_CHUNK_HEADER = RAPIDJSON_ALIGN(sizeof(ChunkHeader));
+
+    static inline ChunkHeader *GetChunkHead(SharedData *shared)
+    {
+        return reinterpret_cast<ChunkHeader*>(reinterpret_cast<uint8_t*>(shared) + SIZEOF_SHARED_DATA);
+    }
+    static inline uint8_t *GetChunkBuffer(SharedData *shared)
+    {
+        return reinterpret_cast<uint8_t*>(shared->chunkHead) + SIZEOF_CHUNK_HEADER;
+    }
+
+    static const size_t kDefaultChunkCapacity = RAPIDJSON_ALLOCATOR_DEFAULT_CHUNK_CAPACITY; //!< Default chunk capacity.
+
 public:
     static const bool kNeedFree = false;    //!< Tell users that no need to call Free() with this allocator. (concept Allocator)
 
@@ -120,9 +159,26 @@ public:
     /*! \param chunkSize The size of memory chunk. The default is kDefaultChunkSize.
         \param baseAllocator The allocator for allocating memory chunks.
     */
+    explicit
     MemoryPoolAllocator(size_t chunkSize = kDefaultChunkCapacity, BaseAllocator* baseAllocator = 0) : 
-        chunkHead_(0), chunk_capacity_(chunkSize), userBuffer_(0), baseAllocator_(baseAllocator), ownBaseAllocator_(0)
+        chunk_capacity_(chunkSize),
+        baseAllocator_(baseAllocator ? baseAllocator : RAPIDJSON_NEW(BaseAllocator)()),
+        shared_(static_cast<SharedData*>(baseAllocator_ ? baseAllocator_->Malloc(SIZEOF_SHARED_DATA + SIZEOF_CHUNK_HEADER) : 0))
     {
+        RAPIDJSON_ASSERT(baseAllocator_ != 0);
+        RAPIDJSON_ASSERT(shared_ != 0);
+        if (baseAllocator) {
+            shared_->ownBaseAllocator = 0;
+        }
+        else {
+            shared_->ownBaseAllocator = baseAllocator_;
+        }
+        shared_->chunkHead = GetChunkHead(shared_);
+        shared_->chunkHead->capacity = 0;
+        shared_->chunkHead->size = 0;
+        shared_->chunkHead->next = 0;
+        shared_->ownBuffer = true;
+        shared_->refcount = 1;
     }
 
     //! Constructor with user-supplied buffer.
@@ -136,41 +192,77 @@ public:
         \param baseAllocator The allocator for allocating memory chunks.
     */
     MemoryPoolAllocator(void *buffer, size_t size, size_t chunkSize = kDefaultChunkCapacity, BaseAllocator* baseAllocator = 0) :
-        chunkHead_(0), chunk_capacity_(chunkSize), userBuffer_(buffer), baseAllocator_(baseAllocator), ownBaseAllocator_(0)
+        chunk_capacity_(chunkSize),
+        baseAllocator_(baseAllocator),
+        shared_(static_cast<SharedData*>(AlignBuffer(buffer, size)))
     {
-        RAPIDJSON_ASSERT(buffer != 0);
+        RAPIDJSON_ASSERT(size >= SIZEOF_SHARED_DATA + SIZEOF_CHUNK_HEADER);
-        RAPIDJSON_ASSERT(size > sizeof(ChunkHeader));
+        shared_->chunkHead = GetChunkHead(shared_);
-        chunkHead_ = reinterpret_cast<ChunkHeader*>(buffer);
+        shared_->chunkHead->capacity = size - SIZEOF_SHARED_DATA - SIZEOF_CHUNK_HEADER;
-        chunkHead_->capacity = size - sizeof(ChunkHeader);
+        shared_->chunkHead->size = 0;
-        chunkHead_->size = 0;
+        shared_->chunkHead->next = 0;
-        chunkHead_->next = 0;
+        shared_->ownBaseAllocator = 0;
+        shared_->ownBuffer = false;
+        shared_->refcount = 1;
+    }
+
+    MemoryPoolAllocator(const MemoryPoolAllocator& rhs) RAPIDJSON_NOEXCEPT :
+        chunk_capacity_(rhs.chunk_capacity_),
+        baseAllocator_(rhs.baseAllocator_),
+        shared_(rhs.shared_)
+    {
+        RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0);
+        ++shared_->refcount;
+    }
+    MemoryPoolAllocator& operator=(const MemoryPoolAllocator& rhs) RAPIDJSON_NOEXCEPT
+    {
+        RAPIDJSON_NOEXCEPT_ASSERT(rhs.shared_->refcount > 0);
+        ++rhs.shared_->refcount;
+
+        this->~MemoryPoolAllocator();
+        baseAllocator_ = rhs.baseAllocator_;
+        chunk_capacity_ = rhs.chunk_capacity_;
+        shared_ = rhs.shared_;
+        return *this;
     }
 
     //! Destructor.
     /*! This deallocates all memory chunks, excluding the user-supplied buffer.
     */
-    ~MemoryPoolAllocator() {
+    ~MemoryPoolAllocator() RAPIDJSON_NOEXCEPT {
+        if (shared_->refcount > 1) {
+            --shared_->refcount;
+            return;
+        }
         Clear();
-        RAPIDJSON_DELETE(ownBaseAllocator_);
+        BaseAllocator *a = shared_->ownBaseAllocator;
+        if (shared_->ownBuffer) {
+            baseAllocator_->Free(shared_);
+        }
+        RAPIDJSON_DELETE(a);
     }
 
-    //! Deallocates all memory chunks, excluding the user-supplied buffer.
+    //! Deallocates all memory chunks, excluding the first/user one.
-    void Clear() {
+    void Clear() RAPIDJSON_NOEXCEPT {
-        while (chunkHead_ && chunkHead_ != userBuffer_) {
+        RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0);
-            ChunkHeader* next = chunkHead_->next;
+        for (;;) {
-            baseAllocator_->Free(chunkHead_);
+            ChunkHeader* c = shared_->chunkHead;
-            chunkHead_ = next;
+            if (!c->next) {
+                break;
+            }
+            shared_->chunkHead = c->next;
+            baseAllocator_->Free(c);
         }
-        if (chunkHead_ && chunkHead_ == userBuffer_)
+        shared_->chunkHead->size = 0;
-            chunkHead_->size = 0; // Clear user buffer
     }
 
     //! Computes the total capacity of allocated memory chunks.
     /*! \return total capacity in bytes.
     */
-    size_t Capacity() const {
+    size_t Capacity() const RAPIDJSON_NOEXCEPT {
+        RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0);
         size_t capacity = 0;
-        for (ChunkHeader* c = chunkHead_; c != 0; c = c->next)
+        for (ChunkHeader* c = shared_->chunkHead; c != 0; c = c->next)
             capacity += c->capacity;
         return capacity;
     }
@@ -178,25 +270,35 @@ public:
     //! Computes the memory blocks allocated.
     /*! \return total used bytes.
     */
-    size_t Size() const {
+    size_t Size() const RAPIDJSON_NOEXCEPT {
+        RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0);
         size_t size = 0;
-        for (ChunkHeader* c = chunkHead_; c != 0; c = c->next)
+        for (ChunkHeader* c = shared_->chunkHead; c != 0; c = c->next)
             size += c->size;
         return size;
     }
 
+    //! Whether the allocator is shared.
+    /*! \return true or false.
+    */
+    bool Shared() const RAPIDJSON_NOEXCEPT {
+        RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0);
+        return shared_->refcount > 1;
+    }
+
     //! Allocates a memory block. (concept Allocator)
     void* Malloc(size_t size) {
+        RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0);
         if (!size)
             return NULL;
 
         size = RAPIDJSON_ALIGN(size);
-        if (chunkHead_ == 0 || chunkHead_->size + size > chunkHead_->capacity)
+        if (RAPIDJSON_UNLIKELY(shared_->chunkHead->size + size > shared_->chunkHead->capacity))
             if (!AddChunk(chunk_capacity_ > size ? chunk_capacity_ : size))
                 return NULL;
 
-        void *buffer = reinterpret_cast<char *>(chunkHead_) + RAPIDJSON_ALIGN(sizeof(ChunkHeader)) + chunkHead_->size;
+        void *buffer = GetChunkBuffer(shared_) + shared_->chunkHead->size;
-        chunkHead_->size += size;
+        shared_->chunkHead->size += size;
         return buffer;
     }
 
@@ -205,6 +307,7 @@ public:
         if (originalPtr == 0)
             return Malloc(newSize);
 
+        RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0);
         if (newSize == 0)
             return NULL;
 
@@ -216,10 +319,10 @@ public:
             return originalPtr;
 
         // Simply expand it if it is the last allocation and there is sufficient space
-        if (originalPtr == reinterpret_cast<char *>(chunkHead_) + RAPIDJSON_ALIGN(sizeof(ChunkHeader)) + chunkHead_->size - originalSize) {
+        if (originalPtr == GetChunkBuffer(shared_) + shared_->chunkHead->size - originalSize) {
             size_t increment = static_cast<size_t>(newSize - originalSize);
-            if (chunkHead_->size + increment <= chunkHead_->capacity) {
+            if (shared_->chunkHead->size + increment <= shared_->chunkHead->capacity) {
-                chunkHead_->size += increment;
+                shared_->chunkHead->size += increment;
                 return originalPtr;
             }
         }
@@ -235,50 +338,264 @@ public:
     }
 
     //! Frees a memory block (concept Allocator)
-    static void Free(void *ptr) { (void)ptr; } // Do nothing
+    static void Free(void *ptr) RAPIDJSON_NOEXCEPT { (void)ptr; } // Do nothing
+
+    //! Compare (equality) with another MemoryPoolAllocator
+    bool operator==(const MemoryPoolAllocator& rhs) const RAPIDJSON_NOEXCEPT {
+        RAPIDJSON_NOEXCEPT_ASSERT(shared_->refcount > 0);
+        RAPIDJSON_NOEXCEPT_ASSERT(rhs.shared_->refcount > 0);
+        return shared_ == rhs.shared_;
+    }
+    //! Compare (inequality) with another MemoryPoolAllocator
+    bool operator!=(const MemoryPoolAllocator& rhs) const RAPIDJSON_NOEXCEPT {
+        return !operator==(rhs);
+    }
 
 private:
-    //! Copy constructor is not permitted.
-    MemoryPoolAllocator(const MemoryPoolAllocator& rhs) /* = delete */;
-    //! Copy assignment operator is not permitted.
-    MemoryPoolAllocator& operator=(const MemoryPoolAllocator& rhs) /* = delete */;
-
     //! Creates a new chunk.
     /*! \param capacity Capacity of the chunk in bytes.
         \return true if success.
     */
     bool AddChunk(size_t capacity) {
         if (!baseAllocator_)
-            ownBaseAllocator_ = baseAllocator_ = RAPIDJSON_NEW(BaseAllocator)();
+            shared_->ownBaseAllocator = baseAllocator_ = RAPIDJSON_NEW(BaseAllocator)();
-        if (ChunkHeader* chunk = reinterpret_cast<ChunkHeader*>(baseAllocator_->Malloc(RAPIDJSON_ALIGN(sizeof(ChunkHeader)) + capacity))) {
+        if (ChunkHeader* chunk = static_cast<ChunkHeader*>(baseAllocator_->Malloc(SIZEOF_CHUNK_HEADER + capacity))) {
             chunk->capacity = capacity;
             chunk->size = 0;
-            chunk->next = chunkHead_;
+            chunk->next = shared_->chunkHead;
-            chunkHead_ =  chunk;
+            shared_->chunkHead = chunk;
             return true;
         }
         else
             return false;
     }
 
-    static const int kDefaultChunkCapacity = RAPIDJSON_ALLOCATOR_DEFAULT_CHUNK_CAPACITY; //!< Default chunk capacity.
+    static inline void* AlignBuffer(void* buf, size_t &size)
+    {
+        RAPIDJSON_NOEXCEPT_ASSERT(buf != 0);
+        const uintptr_t mask = sizeof(void*) - 1;
+        const uintptr_t ubuf = reinterpret_cast<uintptr_t>(buf);
+        if (RAPIDJSON_UNLIKELY(ubuf & mask)) {
+            const uintptr_t abuf = (ubuf + mask) & ~mask;
+            RAPIDJSON_ASSERT(size >= abuf - ubuf);
+            buf = reinterpret_cast<void*>(abuf);
+            size -= abuf - ubuf;
+        }
+        return buf;
+    }
 
-    //! Chunk header for perpending to each chunk.
+    size_t chunk_capacity_;     //!< The minimum capacity of chunk when they are allocated.
-    /*! Chunks are stored as a singly linked list.
+    BaseAllocator* baseAllocator_;  //!< base allocator for allocating memory chunks.
-    */
+    SharedData *shared_;        //!< The shared data of the allocator
-    struct ChunkHeader {
+};
-        size_t capacity;    //!< Capacity of the chunk in bytes (excluding the header itself).
+
-        size_t size;        //!< Current size of allocated memory in bytes.
+
-        ChunkHeader *next;  //!< Next chunk in the linked list.
+template<typename T, typename A>
+inline T* Realloc(A& a, T* old_p, size_t old_n, size_t new_n)
+{
+    RAPIDJSON_NOEXCEPT_ASSERT(old_n <= SIZE_MAX / sizeof(T) && new_n <= SIZE_MAX / sizeof(T));
+    return static_cast<T*>(a.Realloc(old_p, old_n * sizeof(T), new_n * sizeof(T)));
+}
+
+template<typename T, typename A>
+inline T *Malloc(A& a, size_t n = 1)
+{
+    return Realloc<T, A>(a, NULL, 0, n);
+}
+
+template<typename T, typename A>
+inline void Free(A& a, T *p, size_t n = 1)
+{
+    static_cast<void>(Realloc<T, A>(a, p, n, 0));
+}
+
+
+#ifdef __GNUC__
+RAPIDJSON_DIAG_PUSH
+RAPIDJSON_DIAG_OFF(effc++) // std::allocator can safely be inherited
+#endif
+
+template <typename T, typename BaseAllocator = CrtAllocator>
+class StdAllocator :
+    public std::allocator<T>
+{
+    typedef std::allocator<T> allocator_type;
+
+public:
+    typedef BaseAllocator BaseAllocatorType;
+
+    StdAllocator() RAPIDJSON_NOEXCEPT :
+        allocator_type(),
+        baseAllocator_()
+    { }
+
+    StdAllocator(const StdAllocator& rhs) RAPIDJSON_NOEXCEPT :
+        allocator_type(rhs),
+        baseAllocator_(rhs.baseAllocator_)
+    { }
+
+    template<typename U>
+    StdAllocator(const StdAllocator<U, BaseAllocator>& rhs) RAPIDJSON_NOEXCEPT :
+        allocator_type(rhs),
+        baseAllocator_(rhs.baseAllocator_)
+    { }
+
+    /* implicit */
+    StdAllocator(const BaseAllocator& allocator) RAPIDJSON_NOEXCEPT :
+        allocator_type(),
+        baseAllocator_(allocator)
+    { }
+
+    ~StdAllocator() RAPIDJSON_NOEXCEPT
+    { }
+
+    typedef typename allocator_type::value_type       value_type;
+    typedef typename allocator_type::pointer          pointer;
+    typedef typename allocator_type::const_pointer    const_pointer;
+    typedef typename allocator_type::reference        reference;
+    typedef typename allocator_type::const_reference  const_reference;
+    typedef typename allocator_type::size_type        size_type;
+    typedef typename allocator_type::difference_type  difference_type;
+
+    template<typename U>
+    struct rebind {
+        typedef StdAllocator<U, BaseAllocator> other;
     };
 
-    ChunkHeader *chunkHead_;    //!< Head of the chunk linked-list. Only the head chunk serves allocation.
+#if RAPIDJSON_HAS_CXX11
-    size_t chunk_capacity_;     //!< The minimum capacity of chunk when they are allocated.
+    using allocator_type::max_size;
-    void *userBuffer_;          //!< User supplied buffer.
+    using allocator_type::address;
-    BaseAllocator* baseAllocator_;  //!< base allocator for allocating memory chunks.
+    using allocator_type::construct;
-    BaseAllocator* ownBaseAllocator_;   //!< base allocator created by this object.
+    using allocator_type::destroy;
+#else
+    size_t max_size() const RAPIDJSON_NOEXCEPT
+    {
+        return allocator_type::max_size();
+    }
+
+    pointer address(reference r) const RAPIDJSON_NOEXCEPT
+    {
+        return allocator_type::address(r);
+    }
+    const_pointer address(const_reference r) const RAPIDJSON_NOEXCEPT
+    {
+        return allocator_type::address(r);
+    }
+
+    void construct(pointer p, const_reference r)
+    {
+        allocator_type::construct(p, r);
+    }
+    void destroy(pointer p)
+    {
+        allocator_type::destroy(p);
+    }
+#endif
+
+    template <typename U>
+    U* allocate(size_type n = 1, const void* = 0)
+    {
+        return RAPIDJSON_NAMESPACE::Malloc<U>(baseAllocator_, n);
+    }
+    template <typename U>
+    void deallocate(U* p, size_type n = 1)
+    {
+        RAPIDJSON_NAMESPACE::Free<U>(baseAllocator_, p, n);
+    }
+
+    pointer allocate(size_type n = 1, const void* = 0)
+    {
+        return allocate<value_type>(n);
+    }
+    void deallocate(pointer p, size_type n = 1)
+    {
+        deallocate<value_type>(p, n);
+    }
+
+    template<typename U>
+    bool operator==(const StdAllocator<U, BaseAllocator>& rhs) const RAPIDJSON_NOEXCEPT
+    {
+        return baseAllocator_ == rhs.baseAllocator_;
+    }
+    template<typename U>
+    bool operator!=(const StdAllocator<U, BaseAllocator>& rhs) const RAPIDJSON_NOEXCEPT
+    {
+        return !operator==(rhs);
+    }
+
+    //! rapidjson Allocator concept
+    void* Malloc(size_t size)
+    {
+        return baseAllocator_.Malloc(size);
+    }
+    void* Realloc(void* originalPtr, size_t originalSize, size_t newSize)
+    {
+        return baseAllocator_.Realloc(originalPtr, originalSize, newSize);
+    }
+    static void Free(void *ptr) RAPIDJSON_NOEXCEPT
+    {
+        BaseAllocator::Free(ptr);
+    }
+
+private:
+    template <typename, typename>
+    friend class StdAllocator; // access to StdAllocator<!T>.*
+
+    BaseAllocator baseAllocator_;
 };
 
+template <typename BaseAllocator>
+class StdAllocator<void, BaseAllocator> :
+    public std::allocator<void>
+{
+    typedef std::allocator<void> allocator_type;
+
+public:
+    typedef BaseAllocator BaseAllocatorType;
+
+    StdAllocator() RAPIDJSON_NOEXCEPT :
+        allocator_type(),
+        baseAllocator_()
+    { }
+
+    StdAllocator(const StdAllocator& rhs) RAPIDJSON_NOEXCEPT :
+        allocator_type(rhs),
+        baseAllocator_(rhs.baseAllocator_)
+    { }
+
+    template<typename U>
+    StdAllocator(const StdAllocator<U, BaseAllocator>& rhs) RAPIDJSON_NOEXCEPT :
+        allocator_type(rhs),
+        baseAllocator_(rhs.baseAllocator_)
+    { }
+
+    /* implicit */
+    StdAllocator(const BaseAllocator& allocator) RAPIDJSON_NOEXCEPT :
+        allocator_type(),
+        baseAllocator_(allocator)
+    { }
+
+    ~StdAllocator() RAPIDJSON_NOEXCEPT
+    { }
+
+    typedef typename allocator_type::value_type value_type;
+
+    template<typename U>
+    struct rebind {
+        typedef StdAllocator<U, BaseAllocator> other;
+    };
+
+private:
+    template <typename, typename>
+    friend class StdAllocator; // access to StdAllocator<!T>.*
+
+    BaseAllocator baseAllocator_;
+};
+
+#ifdef __GNUC__
+RAPIDJSON_DIAG_POP
+#endif
+
 RAPIDJSON_NAMESPACE_END
 
 #endif // RAPIDJSON_ENCODINGS_H_