/*********************************************************************
 * NAN - Native Abstractions for Node.js
 *
 * Copyright (c) 2016 NAN contributors:
 *   - Rod Vagg <https://github.com/rvagg>
 *   - Benjamin Byholm <https://github.com/kkoopa>
 *   - Trevor Norris <https://github.com/trevnorris>
 *   - Nathan Rajlich <https://github.com/TooTallNate>
 *   - Brett Lawson <https://github.com/brett19>
 *   - Ben Noordhuis <https://github.com/bnoordhuis>
 *   - David Siegel <https://github.com/agnat>
 *
 * MIT License <https://github.com/nodejs/nan/blob/master/LICENSE.md>
 *
 * Version 2.3.5: current Node 6.2.0, Node 12: 0.12.14, Node 10: 0.10.45, iojs: 3.3.1
 *
 * See https://github.com/nodejs/nan for the latest update to this file
 **********************************************************************************/

#ifndef NAN_H_
#define NAN_H_

#include <node_version.h>

#define NODE_0_10_MODULE_VERSION 11
#define NODE_0_12_MODULE_VERSION 14
#define ATOM_0_21_MODULE_VERSION 41
#define IOJS_1_0_MODULE_VERSION  42
#define IOJS_1_1_MODULE_VERSION  43
#define IOJS_2_0_MODULE_VERSION  44
#define IOJS_3_0_MODULE_VERSION  45
#define NODE_4_0_MODULE_VERSION  46
#define NODE_5_0_MODULE_VERSION  47
#define NODE_6_0_MODULE_VERSION  48

#ifdef _MSC_VER
# define NAN_HAS_CPLUSPLUS_11 (_MSC_VER >= 1800)
#else
# define NAN_HAS_CPLUSPLUS_11 (__cplusplus >= 201103L)
#endif

#if NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION && !NAN_HAS_CPLUSPLUS_11
# error This version of node/NAN/v8 requires a C++11 compiler
#endif

#include <uv.h>
#include <node.h>
#include <node_buffer.h>
#include <node_object_wrap.h>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#if defined(_MSC_VER)
# pragma warning( push )
# pragma warning( disable : 4530 )
# include <string>
# include <vector>
# pragma warning( pop )
#else
# include <string>
# include <vector>
#endif

// uv helpers
#ifdef UV_VERSION_MAJOR
# ifndef UV_VERSION_PATCH
#  define UV_VERSION_PATCH 0
# endif
# define NAUV_UVVERSION ((UV_VERSION_MAJOR << 16) | \
                         (UV_VERSION_MINOR <<  8) | \
                         (UV_VERSION_PATCH))
#else
# define NAUV_UVVERSION 0x000b00
#endif

#if NAUV_UVVERSION < 0x000b0b
# ifdef WIN32
#  include <windows.h>
# else
#  include <pthread.h>
# endif
#endif

namespace Nan {

#define NAN_INLINE inline  // TODO(bnoordhuis) Remove in v3.0.0.

#if defined(__GNUC__) && \
    !(defined(V8_DISABLE_DEPRECATIONS) && V8_DISABLE_DEPRECATIONS)
# define NAN_DEPRECATED __attribute__((deprecated))
#elif defined(_MSC_VER) && \
    !(defined(V8_DISABLE_DEPRECATIONS) && V8_DISABLE_DEPRECATIONS)
# define NAN_DEPRECATED __declspec(deprecated)
#else
# define NAN_DEPRECATED
#endif

#if NAN_HAS_CPLUSPLUS_11
# define NAN_DISALLOW_ASSIGN(CLASS) void operator=(const CLASS&) = delete;
# define NAN_DISALLOW_COPY(CLASS) CLASS(const CLASS&) = delete;
# define NAN_DISALLOW_MOVE(CLASS)                                              \
    CLASS(CLASS&&) = delete;  /* NOLINT(build/c++11) */                        \
    void operator=(CLASS&&) = delete;
#else
# define NAN_DISALLOW_ASSIGN(CLASS) void operator=(const CLASS&);
# define NAN_DISALLOW_COPY(CLASS) CLASS(const CLASS&);
# define NAN_DISALLOW_MOVE(CLASS)
#endif

#define NAN_DISALLOW_ASSIGN_COPY(CLASS)                                        \
    NAN_DISALLOW_ASSIGN(CLASS)                                                 \
    NAN_DISALLOW_COPY(CLASS)

#define NAN_DISALLOW_ASSIGN_MOVE(CLASS)                                        \
    NAN_DISALLOW_ASSIGN(CLASS)                                                 \
    NAN_DISALLOW_MOVE(CLASS)

#define NAN_DISALLOW_COPY_MOVE(CLASS)                                          \
    NAN_DISALLOW_COPY(CLASS)                                                   \
    NAN_DISALLOW_MOVE(CLASS)

#define NAN_DISALLOW_ASSIGN_COPY_MOVE(CLASS)                                   \
    NAN_DISALLOW_ASSIGN(CLASS)                                                 \
    NAN_DISALLOW_COPY(CLASS)                                                   \
    NAN_DISALLOW_MOVE(CLASS)

#define TYPE_CHECK(T, S)                                                       \
    while (false) {                                                            \
      *(static_cast<T *volatile *>(0)) = static_cast<S*>(0);                   \
    }

//=== RegistrationFunction =====================================================

#if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
  typedef v8::Handle<v8::Object> ADDON_REGISTER_FUNCTION_ARGS_TYPE;
#else
  typedef v8::Local<v8::Object> ADDON_REGISTER_FUNCTION_ARGS_TYPE;
#endif

#define NAN_MODULE_INIT(name)                                                  \
    void name(Nan::ADDON_REGISTER_FUNCTION_ARGS_TYPE target)

//=== CallbackInfo =============================================================

#include "nan_callbacks.h"  // NOLINT(build/include)

//==============================================================================

#if (NODE_MODULE_VERSION < NODE_0_12_MODULE_VERSION)
typedef v8::Script             UnboundScript;
typedef v8::Script             BoundScript;
#else
typedef v8::UnboundScript      UnboundScript;
typedef v8::Script             BoundScript;
#endif

#if (NODE_MODULE_VERSION < ATOM_0_21_MODULE_VERSION)
typedef v8::String::ExternalAsciiStringResource
    ExternalOneByteStringResource;
#else
typedef v8::String::ExternalOneByteStringResource
    ExternalOneByteStringResource;
#endif

#if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)
template<typename T>
class NonCopyablePersistentTraits :
    public v8::NonCopyablePersistentTraits<T> {};
template<typename T>
class CopyablePersistentTraits :
    public v8::CopyablePersistentTraits<T> {};

template<typename T>
class PersistentBase :
    public v8::PersistentBase<T> {};

template<typename T, typename M = v8::NonCopyablePersistentTraits<T> >
class Persistent;
#else
template<typename T> class NonCopyablePersistentTraits;
template<typename T> class PersistentBase;
template<typename T, typename P> class WeakCallbackData;
template<typename T, typename M = NonCopyablePersistentTraits<T> >
class Persistent;
#endif  // NODE_MODULE_VERSION

#if defined(V8_MAJOR_VERSION) && (V8_MAJOR_VERSION > 4 ||                      \
  (V8_MAJOR_VERSION == 4 && defined(V8_MINOR_VERSION) && V8_MINOR_VERSION >= 3))
# include "nan_maybe_43_inl.h"  // NOLINT(build/include)
#else
# include "nan_maybe_pre_43_inl.h"  // NOLINT(build/include)
#endif

#include "nan_converters.h"  // NOLINT(build/include)
#include "nan_new.h"  // NOLINT(build/include)

#if NAUV_UVVERSION < 0x000b17
#define NAUV_WORK_CB(func) \
    void func(uv_async_t *async, int)
#else
#define NAUV_WORK_CB(func) \
    void func(uv_async_t *async)
#endif

#if NAUV_UVVERSION >= 0x000b0b

typedef uv_key_t nauv_key_t;

inline int nauv_key_create(nauv_key_t *key) {
  return uv_key_create(key);
}

inline void nauv_key_delete(nauv_key_t *key) {
  uv_key_delete(key);
}

inline void* nauv_key_get(nauv_key_t *key) {
  return uv_key_get(key);
}

inline void nauv_key_set(nauv_key_t *key, void *value) {
  uv_key_set(key, value);
}

#else

/* Implement thread local storage for older versions of libuv.
 * This is essentially a backport of libuv commit 5d2434bf
 * written by Ben Noordhuis, adjusted for names and inline.
 */

#ifndef WIN32

typedef pthread_key_t nauv_key_t;

inline int nauv_key_create(nauv_key_t* key) {
  return -pthread_key_create(key, NULL);
}

inline void nauv_key_delete(nauv_key_t* key) {
  if (pthread_key_delete(*key))
    abort();
}

inline void* nauv_key_get(nauv_key_t* key) {
  return pthread_getspecific(*key);
}

inline void nauv_key_set(nauv_key_t* key, void* value) {
  if (pthread_setspecific(*key, value))
    abort();
}

#else

typedef struct {
  DWORD tls_index;
} nauv_key_t;

inline int nauv_key_create(nauv_key_t* key) {
  key->tls_index = TlsAlloc();
  if (key->tls_index == TLS_OUT_OF_INDEXES)
    return UV_ENOMEM;
  return 0;
}

inline void nauv_key_delete(nauv_key_t* key) {
  if (TlsFree(key->tls_index) == FALSE)
    abort();
  key->tls_index = TLS_OUT_OF_INDEXES;
}

inline void* nauv_key_get(nauv_key_t* key) {
  void* value = TlsGetValue(key->tls_index);
  if (value == NULL)
    if (GetLastError() != ERROR_SUCCESS)
      abort();
  return value;
}

inline void nauv_key_set(nauv_key_t* key, void* value) {
  if (TlsSetValue(key->tls_index, value) == FALSE)
    abort();
}

#endif
#endif

#if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
template<typename T>
v8::Local<T> New(v8::Handle<T>);
#endif

#if defined(V8_MAJOR_VERSION) && (V8_MAJOR_VERSION > 4 ||                      \
  (V8_MAJOR_VERSION == 4 && defined(V8_MINOR_VERSION) && V8_MINOR_VERSION >= 3))
  typedef v8::WeakCallbackType WeakCallbackType;
#else
struct WeakCallbackType {
  enum E {kParameter, kInternalFields};
  E type;
  WeakCallbackType(E other) : type(other) {}  // NOLINT(runtime/explicit)
  inline bool operator==(E other) { return other == this->type; }
  inline bool operator!=(E other) { return !operator==(other); }
};
#endif

template<typename P> class WeakCallbackInfo;

#if NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION
# include "nan_persistent_12_inl.h"  // NOLINT(build/include)
#else
# include "nan_persistent_pre_12_inl.h"  // NOLINT(build/include)
#endif

namespace imp {
  static const size_t kMaxLength = 0x3fffffff;
  // v8::String::REPLACE_INVALID_UTF8 was introduced
  // in node.js v0.10.29 and v0.8.27.
#if NODE_MAJOR_VERSION > 0 || \
    NODE_MINOR_VERSION > 10 || \
    NODE_MINOR_VERSION == 10 && NODE_PATCH_VERSION >= 29 || \
    NODE_MINOR_VERSION == 8 && NODE_PATCH_VERSION >= 27
  static const unsigned kReplaceInvalidUtf8 = v8::String::REPLACE_INVALID_UTF8;
#else
  static const unsigned kReplaceInvalidUtf8 = 0;
#endif
}  // end of namespace imp

//=== HandleScope ==============================================================

class HandleScope {
  v8::HandleScope scope;

 public:
#if NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION
  inline HandleScope() : scope(v8::Isolate::GetCurrent()) {}
  inline static int NumberOfHandles() {
    return v8::HandleScope::NumberOfHandles(v8::Isolate::GetCurrent());
  }
#else
  inline HandleScope() : scope() {}
  inline static int NumberOfHandles() {
    return v8::HandleScope::NumberOfHandles();
  }
#endif

 private:
  // Make it hard to create heap-allocated or illegal handle scopes by
  // disallowing certain operations.
  HandleScope(const HandleScope &);
  void operator=(const HandleScope &);
  void *operator new(size_t size);
  void operator delete(void *, size_t);
};

class EscapableHandleScope {
 public:
#if NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION
  inline EscapableHandleScope() : scope(v8::Isolate::GetCurrent()) {}

  inline static int NumberOfHandles() {
    return v8::EscapableHandleScope::NumberOfHandles(v8::Isolate::GetCurrent());
  }

  template<typename T>
  inline v8::Local<T> Escape(v8::Local<T> value) {
    return scope.Escape(value);
  }

 private:
  v8::EscapableHandleScope scope;
#else
  inline EscapableHandleScope() : scope() {}

  inline static int NumberOfHandles() {
    return v8::HandleScope::NumberOfHandles();
  }

  template<typename T>
  inline v8::Local<T> Escape(v8::Local<T> value) {
    return scope.Close(value);
  }

 private:
  v8::HandleScope scope;
#endif

 private:
  // Make it hard to create heap-allocated or illegal handle scopes by
  // disallowing certain operations.
  EscapableHandleScope(const EscapableHandleScope &);
  void operator=(const EscapableHandleScope &);
  void *operator new(size_t size);
  void operator delete(void *, size_t);
};

//=== TryCatch =================================================================

class TryCatch {
  v8::TryCatch try_catch_;
  friend void FatalException(const TryCatch&);

 public:
#if NODE_MODULE_VERSION > NODE_0_12_MODULE_VERSION
  TryCatch() : try_catch_(v8::Isolate::GetCurrent()) {}
#endif

  inline bool HasCaught() const { return try_catch_.HasCaught(); }

  inline bool CanContinue() const { return try_catch_.CanContinue(); }

  inline v8::Local<v8::Value> ReThrow() {
#if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    return New(try_catch_.ReThrow());
#else
    return try_catch_.ReThrow();
#endif
  }

  inline v8::Local<v8::Value> Exception() const {
    return try_catch_.Exception();
  }

#if defined(V8_MAJOR_VERSION) && (V8_MAJOR_VERSION > 4 ||                      \
  (V8_MAJOR_VERSION == 4 && defined(V8_MINOR_VERSION) && V8_MINOR_VERSION >= 3))
  inline v8::MaybeLocal<v8::Value> StackTrace() const {
    return try_catch_.StackTrace(GetCurrentContext());
  }
#else
  inline MaybeLocal<v8::Value> StackTrace() const {
    return MaybeLocal<v8::Value>(try_catch_.StackTrace());
  }
#endif

  inline v8::Local<v8::Message> Message() const {
    return try_catch_.Message();
  }

  inline void Reset() { try_catch_.Reset(); }

  inline void SetVerbose(bool value) { try_catch_.SetVerbose(value); }

  inline void SetCaptureMessage(bool value) {
    try_catch_.SetCaptureMessage(value);
  }
};

//============ =================================================================

/* node 0.12  */
#if NODE_MODULE_VERSION >= NODE_0_12_MODULE_VERSION
  inline
  void SetCounterFunction(v8::CounterLookupCallback cb) {
    v8::Isolate::GetCurrent()->SetCounterFunction(cb);
  }

  inline
  void SetCreateHistogramFunction(v8::CreateHistogramCallback cb) {
    v8::Isolate::GetCurrent()->SetCreateHistogramFunction(cb);
  }

  inline
  void SetAddHistogramSampleFunction(v8::AddHistogramSampleCallback cb) {
    v8::Isolate::GetCurrent()->SetAddHistogramSampleFunction(cb);
  }

#if defined(V8_MAJOR_VERSION) && (V8_MAJOR_VERSION > 4 ||                      \
  (V8_MAJOR_VERSION == 4 && defined(V8_MINOR_VERSION) && V8_MINOR_VERSION >= 3))
  inline bool IdleNotification(int idle_time_in_ms) {
    return v8::Isolate::GetCurrent()->IdleNotificationDeadline(
        idle_time_in_ms * 0.001);
  }
# else
  inline bool IdleNotification(int idle_time_in_ms) {
    return v8::Isolate::GetCurrent()->IdleNotification(idle_time_in_ms);
  }
#endif

  inline void LowMemoryNotification() {
    v8::Isolate::GetCurrent()->LowMemoryNotification();
  }

  inline void ContextDisposedNotification() {
    v8::Isolate::GetCurrent()->ContextDisposedNotification();
  }
#else
  inline
  void SetCounterFunction(v8::CounterLookupCallback cb) {
    v8::V8::SetCounterFunction(cb);
  }

  inline
  void SetCreateHistogramFunction(v8::CreateHistogramCallback cb) {
    v8::V8::SetCreateHistogramFunction(cb);
  }

  inline
  void SetAddHistogramSampleFunction(v8::AddHistogramSampleCallback cb) {
    v8::V8::SetAddHistogramSampleFunction(cb);
  }

  inline bool IdleNotification(int idle_time_in_ms) {
    return v8::V8::IdleNotification(idle_time_in_ms);
  }

  inline void LowMemoryNotification() {
    v8::V8::LowMemoryNotification();
  }

  inline void ContextDisposedNotification() {
    v8::V8::ContextDisposedNotification();
  }
#endif

#if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)  // Node 0.12
  inline v8::Local<v8::Primitive> Undefined() {
# if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    EscapableHandleScope scope;
    return scope.Escape(New(v8::Undefined(v8::Isolate::GetCurrent())));
# else
    return v8::Undefined(v8::Isolate::GetCurrent());
# endif
  }

  inline v8::Local<v8::Primitive> Null() {
# if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    EscapableHandleScope scope;
    return scope.Escape(New(v8::Null(v8::Isolate::GetCurrent())));
# else
    return v8::Null(v8::Isolate::GetCurrent());
# endif
  }

  inline v8::Local<v8::Boolean> True() {
# if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    EscapableHandleScope scope;
    return scope.Escape(New(v8::True(v8::Isolate::GetCurrent())));
# else
    return v8::True(v8::Isolate::GetCurrent());
# endif
  }

  inline v8::Local<v8::Boolean> False() {
# if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    EscapableHandleScope scope;
    return scope.Escape(New(v8::False(v8::Isolate::GetCurrent())));
# else
    return v8::False(v8::Isolate::GetCurrent());
# endif
  }

  inline v8::Local<v8::String> EmptyString() {
    return v8::String::Empty(v8::Isolate::GetCurrent());
  }

  inline int AdjustExternalMemory(int bc) {
    return static_cast<int>(
        v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(bc));
  }

  inline void SetTemplate(
      v8::Local<v8::Template> templ
    , const char *name
    , v8::Local<v8::Data> value) {
    templ->Set(v8::Isolate::GetCurrent(), name, value);
  }

  inline void SetTemplate(
      v8::Local<v8::Template> templ
    , v8::Local<v8::String> name
    , v8::Local<v8::Data> value
    , v8::PropertyAttribute attributes) {
    templ->Set(name, value, attributes);
  }

  inline v8::Local<v8::Context> GetCurrentContext() {
    return v8::Isolate::GetCurrent()->GetCurrentContext();
  }

  inline void* GetInternalFieldPointer(
      v8::Local<v8::Object> object
    , int index) {
    return object->GetAlignedPointerFromInternalField(index);
  }

  inline void SetInternalFieldPointer(
      v8::Local<v8::Object> object
    , int index
    , void* value) {
    object->SetAlignedPointerInInternalField(index, value);
  }

# define NAN_GC_CALLBACK(name)                                                 \
    void name(v8::Isolate *isolate, v8::GCType type, v8::GCCallbackFlags flags)

#if NODE_MODULE_VERSION <= NODE_4_0_MODULE_VERSION
  typedef v8::Isolate::GCEpilogueCallback GCEpilogueCallback;
  typedef v8::Isolate::GCPrologueCallback GCPrologueCallback;
#else
  typedef v8::Isolate::GCCallback GCEpilogueCallback;
  typedef v8::Isolate::GCCallback GCPrologueCallback;
#endif

  inline void AddGCEpilogueCallback(
      GCEpilogueCallback callback
    , v8::GCType gc_type_filter = v8::kGCTypeAll) {
    v8::Isolate::GetCurrent()->AddGCEpilogueCallback(callback, gc_type_filter);
  }

  inline void RemoveGCEpilogueCallback(
      GCEpilogueCallback callback) {
    v8::Isolate::GetCurrent()->RemoveGCEpilogueCallback(callback);
  }

  inline void AddGCPrologueCallback(
      GCPrologueCallback callback
    , v8::GCType gc_type_filter = v8::kGCTypeAll) {
    v8::Isolate::GetCurrent()->AddGCPrologueCallback(callback, gc_type_filter);
  }

  inline void RemoveGCPrologueCallback(
      GCPrologueCallback callback) {
    v8::Isolate::GetCurrent()->RemoveGCPrologueCallback(callback);
  }

  inline void GetHeapStatistics(
      v8::HeapStatistics *heap_statistics) {
    v8::Isolate::GetCurrent()->GetHeapStatistics(heap_statistics);
  }

# define X(NAME)                                                               \
    inline v8::Local<v8::Value> NAME(const char *msg) {                    \
      EscapableHandleScope scope;                                              \
      return scope.Escape(v8::Exception::NAME(New(msg).ToLocalChecked()));     \
    }                                                                          \
                                                                               \
    inline                                                                 \
    v8::Local<v8::Value> NAME(v8::Local<v8::String> msg) {                     \
      return v8::Exception::NAME(msg);                                         \
    }                                                                          \
                                                                               \
    inline void Throw ## NAME(const char *msg) {                           \
      HandleScope scope;                                                       \
      v8::Isolate::GetCurrent()->ThrowException(                               \
          v8::Exception::NAME(New(msg).ToLocalChecked()));                     \
    }                                                                          \
                                                                               \
    inline void Throw ## NAME(v8::Local<v8::String> msg) {                 \
      HandleScope scope;                                                       \
      v8::Isolate::GetCurrent()->ThrowException(                               \
          v8::Exception::NAME(msg));                                           \
    }

  X(Error)
  X(RangeError)
  X(ReferenceError)
  X(SyntaxError)
  X(TypeError)

# undef X

  inline void ThrowError(v8::Local<v8::Value> error) {
    v8::Isolate::GetCurrent()->ThrowException(error);
  }

  inline MaybeLocal<v8::Object> NewBuffer(
      char *data
    , size_t length
#if NODE_MODULE_VERSION > IOJS_2_0_MODULE_VERSION
    , node::Buffer::FreeCallback callback
#else
    , node::smalloc::FreeCallback callback
#endif
    , void *hint
  ) {
    // arbitrary buffer lengths requires
    // NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION
    assert(length <= imp::kMaxLength && "too large buffer");
#if NODE_MODULE_VERSION > IOJS_2_0_MODULE_VERSION
    return node::Buffer::New(
        v8::Isolate::GetCurrent(), data, length, callback, hint);
#else
    return MaybeLocal<v8::Object>(node::Buffer::New(
        v8::Isolate::GetCurrent(), data, length, callback, hint));
#endif
  }

  inline MaybeLocal<v8::Object> CopyBuffer(
      const char *data
    , uint32_t size
  ) {
    // arbitrary buffer lengths requires
    // NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION
    assert(size <= imp::kMaxLength && "too large buffer");
#if NODE_MODULE_VERSION > IOJS_2_0_MODULE_VERSION
    return node::Buffer::Copy(
        v8::Isolate::GetCurrent(), data, size);
#else
    return MaybeLocal<v8::Object>(node::Buffer::New(
        v8::Isolate::GetCurrent(), data, size));
#endif
  }

  inline MaybeLocal<v8::Object> NewBuffer(uint32_t size) {
    // arbitrary buffer lengths requires
    // NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION
    assert(size <= imp::kMaxLength && "too large buffer");
#if NODE_MODULE_VERSION > IOJS_2_0_MODULE_VERSION
    return node::Buffer::New(
        v8::Isolate::GetCurrent(), size);
#else
    return MaybeLocal<v8::Object>(node::Buffer::New(
        v8::Isolate::GetCurrent(), size));
#endif
  }

  inline MaybeLocal<v8::Object> NewBuffer(
      char* data
    , uint32_t size
  ) {
    // arbitrary buffer lengths requires
    // NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION
    assert(size <= imp::kMaxLength && "too large buffer");
#if NODE_MODULE_VERSION > IOJS_2_0_MODULE_VERSION
    return node::Buffer::New(v8::Isolate::GetCurrent(), data, size);
#else
    return MaybeLocal<v8::Object>(
        node::Buffer::Use(v8::Isolate::GetCurrent(), data, size));
#endif
  }

#if defined(V8_MAJOR_VERSION) && (V8_MAJOR_VERSION > 4 ||                      \
  (V8_MAJOR_VERSION == 4 && defined(V8_MINOR_VERSION) && V8_MINOR_VERSION >= 3))
  inline MaybeLocal<v8::String>
  NewOneByteString(const uint8_t * value, int length = -1) {
    return v8::String::NewFromOneByte(v8::Isolate::GetCurrent(), value,
          v8::NewStringType::kNormal, length);
  }

  inline MaybeLocal<BoundScript> CompileScript(
      v8::Local<v8::String> s
    , const v8::ScriptOrigin& origin
  ) {
    v8::ScriptCompiler::Source source(s, origin);
    return v8::ScriptCompiler::Compile(GetCurrentContext(), &source);
  }

  inline MaybeLocal<BoundScript> CompileScript(
      v8::Local<v8::String> s
  ) {
    v8::ScriptCompiler::Source source(s);
    return v8::ScriptCompiler::Compile(GetCurrentContext(), &source);
  }

  inline MaybeLocal<v8::Value> RunScript(
      v8::Local<UnboundScript> script
  ) {
    return script->BindToCurrentContext()->Run(GetCurrentContext());
  }

  inline MaybeLocal<v8::Value> RunScript(
      v8::Local<BoundScript> script
  ) {
    return script->Run(GetCurrentContext());
  }
#else
  inline MaybeLocal<v8::String>
  NewOneByteString(const uint8_t * value, int length = -1) {
    return MaybeLocal<v8::String>(
        v8::String::NewFromOneByte(
            v8::Isolate::GetCurrent()
          , value
          , v8::String::kNormalString, length));
  }

  inline MaybeLocal<BoundScript> CompileScript(
      v8::Local<v8::String> s
    , const v8::ScriptOrigin& origin
  ) {
    v8::ScriptCompiler::Source source(s, origin);
    return MaybeLocal<BoundScript>(
        v8::ScriptCompiler::Compile(v8::Isolate::GetCurrent(), &source));
  }

  inline MaybeLocal<BoundScript> CompileScript(
      v8::Local<v8::String> s
  ) {
    v8::ScriptCompiler::Source source(s);
    return MaybeLocal<BoundScript>(
        v8::ScriptCompiler::Compile(v8::Isolate::GetCurrent(), &source));
  }

  inline MaybeLocal<v8::Value> RunScript(
      v8::Local<UnboundScript> script
  ) {
    return MaybeLocal<v8::Value>(script->BindToCurrentContext()->Run());
  }

  inline MaybeLocal<v8::Value> RunScript(
      v8::Local<BoundScript> script
  ) {
    return MaybeLocal<v8::Value>(script->Run());
  }
#endif

  inline v8::Local<v8::Value> MakeCallback(
      v8::Local<v8::Object> target
    , v8::Local<v8::Function> func
    , int argc
    , v8::Local<v8::Value>* argv) {
#if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    return New(node::MakeCallback(
        v8::Isolate::GetCurrent(), target, func, argc, argv));
#else
    return node::MakeCallback(
        v8::Isolate::GetCurrent(), target, func, argc, argv);
#endif
  }

  inline v8::Local<v8::Value> MakeCallback(
      v8::Local<v8::Object> target
    , v8::Local<v8::String> symbol
    , int argc
    , v8::Local<v8::Value>* argv) {
#if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    return New(node::MakeCallback(
        v8::Isolate::GetCurrent(), target, symbol, argc, argv));
#else
    return node::MakeCallback(
        v8::Isolate::GetCurrent(), target, symbol, argc, argv);
#endif
  }

  inline v8::Local<v8::Value> MakeCallback(
      v8::Local<v8::Object> target
    , const char* method
    , int argc
    , v8::Local<v8::Value>* argv) {
#if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    return New(node::MakeCallback(
        v8::Isolate::GetCurrent(), target, method, argc, argv));
#else
    return node::MakeCallback(
        v8::Isolate::GetCurrent(), target, method, argc, argv);
#endif
  }

  inline void FatalException(const TryCatch& try_catch) {
    node::FatalException(v8::Isolate::GetCurrent(), try_catch.try_catch_);
  }

  inline v8::Local<v8::Value> ErrnoException(
          int errorno
       ,  const char* syscall = NULL
       ,  const char* message = NULL
       ,  const char* path = NULL) {
    return node::ErrnoException(v8::Isolate::GetCurrent(), errorno, syscall,
            message, path);
  }

  NAN_DEPRECATED inline v8::Local<v8::Value> NanErrnoException(
          int errorno
       ,  const char* syscall = NULL
       ,  const char* message = NULL
       ,  const char* path = NULL) {
    return ErrnoException(errorno, syscall, message, path);
  }

  template<typename T>
  inline void SetIsolateData(
      v8::Isolate *isolate
    , T *data
  ) {
      isolate->SetData(0, data);
  }

  template<typename T>
  inline T *GetIsolateData(
      v8::Isolate *isolate
  ) {
      return static_cast<T*>(isolate->GetData(0));
  }

class Utf8String {
 public:
  inline explicit Utf8String(v8::Local<v8::Value> from) :
      length_(0), str_(str_st_) {
    if (!from.IsEmpty()) {
      v8::Local<v8::String> string = from->ToString();
      if (!string.IsEmpty()) {
        size_t len = 3 * string->Length() + 1;
        assert(len <= INT_MAX);
        if (len > sizeof (str_st_)) {
          str_ = static_cast<char*>(malloc(len));
          assert(str_ != 0);
        }
        const int flags =
            v8::String::NO_NULL_TERMINATION | imp::kReplaceInvalidUtf8;
        length_ = string->WriteUtf8(str_, static_cast<int>(len), 0, flags);
        str_[length_] = '\0';
      }
    }
  }

  inline int length() const {
    return length_;
  }

  inline char* operator*() { return str_; }
  inline const char* operator*() const { return str_; }

  inline ~Utf8String() {
    if (str_ != str_st_) {
      free(str_);
    }
  }

 private:
  NAN_DISALLOW_ASSIGN_COPY_MOVE(Utf8String)

  int length_;
  char *str_;
  char str_st_[1024];
};

#else  // Node 0.8 and 0.10
  inline v8::Local<v8::Primitive> Undefined() {
    EscapableHandleScope scope;
    return scope.Escape(New(v8::Undefined()));
  }

  inline v8::Local<v8::Primitive> Null() {
    EscapableHandleScope scope;
    return scope.Escape(New(v8::Null()));
  }

  inline v8::Local<v8::Boolean> True() {
    EscapableHandleScope scope;
    return scope.Escape(New(v8::True()));
  }

  inline v8::Local<v8::Boolean> False() {
    EscapableHandleScope scope;
    return scope.Escape(New(v8::False()));
  }

  inline v8::Local<v8::String> EmptyString() {
    return v8::String::Empty();
  }

  inline int AdjustExternalMemory(int bc) {
    return static_cast<int>(v8::V8::AdjustAmountOfExternalAllocatedMemory(bc));
  }

  inline void SetTemplate(
      v8::Local<v8::Template> templ
    , const char *name
    , v8::Local<v8::Data> value) {
    templ->Set(name, value);
  }

  inline void SetTemplate(
      v8::Local<v8::Template> templ
    , v8::Local<v8::String> name
    , v8::Local<v8::Data> value
    , v8::PropertyAttribute attributes) {
    templ->Set(name, value, attributes);
  }

  inline v8::Local<v8::Context> GetCurrentContext() {
    return v8::Context::GetCurrent();
  }

  inline void* GetInternalFieldPointer(
      v8::Local<v8::Object> object
    , int index) {
    return object->GetPointerFromInternalField(index);
  }

  inline void SetInternalFieldPointer(
      v8::Local<v8::Object> object
    , int index
    , void* value) {
    object->SetPointerInInternalField(index, value);
  }

# define NAN_GC_CALLBACK(name)                                                 \
    void name(v8::GCType type, v8::GCCallbackFlags flags)

  inline void AddGCEpilogueCallback(
    v8::GCEpilogueCallback callback
  , v8::GCType gc_type_filter = v8::kGCTypeAll) {
    v8::V8::AddGCEpilogueCallback(callback, gc_type_filter);
  }
  inline void RemoveGCEpilogueCallback(
    v8::GCEpilogueCallback callback) {
    v8::V8::RemoveGCEpilogueCallback(callback);
  }
  inline void AddGCPrologueCallback(
    v8::GCPrologueCallback callback
  , v8::GCType gc_type_filter = v8::kGCTypeAll) {
    v8::V8::AddGCPrologueCallback(callback, gc_type_filter);
  }
  inline void RemoveGCPrologueCallback(
    v8::GCPrologueCallback callback) {
    v8::V8::RemoveGCPrologueCallback(callback);
  }
  inline void GetHeapStatistics(
    v8::HeapStatistics *heap_statistics) {
    v8::V8::GetHeapStatistics(heap_statistics);
  }

# define X(NAME)                                                               \
    inline v8::Local<v8::Value> NAME(const char *msg) {                    \
      EscapableHandleScope scope;                                              \
      return scope.Escape(v8::Exception::NAME(New(msg).ToLocalChecked()));     \
    }                                                                          \
                                                                               \
    inline                                                                 \
    v8::Local<v8::Value> NAME(v8::Local<v8::String> msg) {                     \
      return v8::Exception::NAME(msg);                                         \
    }                                                                          \
                                                                               \
    inline void Throw ## NAME(const char *msg) {                           \
      HandleScope scope;                                                       \
      v8::ThrowException(v8::Exception::NAME(New(msg).ToLocalChecked()));      \
    }                                                                          \
                                                                               \
    inline                                                                 \
    void Throw ## NAME(v8::Local<v8::String> errmsg) {                         \
      v8::ThrowException(v8::Exception::NAME(errmsg));                         \
    }

  X(Error)
  X(RangeError)
  X(ReferenceError)
  X(SyntaxError)
  X(TypeError)

# undef X

  inline void ThrowError(v8::Local<v8::Value> error) {
    v8::ThrowException(error);
  }

  inline MaybeLocal<v8::Object> NewBuffer(
      char *data
    , size_t length
    , node::Buffer::free_callback callback
    , void *hint
  ) {
    EscapableHandleScope scope;
    // arbitrary buffer lengths requires
    // NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION
    assert(length <= imp::kMaxLength && "too large buffer");
    return MaybeLocal<v8::Object>(scope.Escape(
        New(node::Buffer::New(data, length, callback, hint)->handle_)));
  }

  inline MaybeLocal<v8::Object> CopyBuffer(
      const char *data
    , uint32_t size
  ) {
    EscapableHandleScope scope;
    // arbitrary buffer lengths requires
    // NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION
    assert(size <= imp::kMaxLength && "too large buffer");
#if NODE_MODULE_VERSION >= NODE_0_10_MODULE_VERSION
    return MaybeLocal<v8::Object>(
        scope.Escape(New(node::Buffer::New(data, size)->handle_)));
#else
    return MaybeLocal<v8::Object>(scope.Escape(
        New(node::Buffer::New(const_cast<char*>(data), size)->handle_)));
#endif
  }

  inline MaybeLocal<v8::Object> NewBuffer(uint32_t size) {
    // arbitrary buffer lengths requires
    // NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION
    EscapableHandleScope scope;
    assert(size <= imp::kMaxLength && "too large buffer");
    return MaybeLocal<v8::Object>(
        scope.Escape(New(node::Buffer::New(size)->handle_)));
  }

  inline void FreeData(char *data, void *hint) {
    (void) hint;  // unused
    delete[] data;
  }

  inline MaybeLocal<v8::Object> NewBuffer(
      char* data
    , uint32_t size
  ) {
    EscapableHandleScope scope;
    // arbitrary buffer lengths requires
    // NODE_MODULE_VERSION >= IOJS_3_0_MODULE_VERSION
    assert(size <= imp::kMaxLength && "too large buffer");
    return MaybeLocal<v8::Object>(scope.Escape(New(
        node::Buffer::New(data, size, FreeData, NULL)->handle_)));
  }

namespace imp {
inline void
widenString(std::vector<uint16_t> *ws, const uint8_t *s, int l) {
  size_t len = static_cast<size_t>(l);
  if (l < 0) {
    len = strlen(reinterpret_cast<const char*>(s));
  }
  assert(len <= INT_MAX && "string too long");
  ws->resize(len);
  std::copy(s, s + len, ws->begin());  // NOLINT(build/include_what_you_use)
}
}  // end of namespace imp

  inline MaybeLocal<v8::String>
  NewOneByteString(const uint8_t * value, int length = -1) {
    std::vector<uint16_t> wideString;  // NOLINT(build/include_what_you_use)
    imp::widenString(&wideString, value, length);
    return imp::Factory<v8::String>::return_t(v8::String::New(
        &wideString.front(), static_cast<int>(wideString.size())));
  }

  inline MaybeLocal<BoundScript> CompileScript(
      v8::Local<v8::String> s
    , const v8::ScriptOrigin& origin
  ) {
    return MaybeLocal<BoundScript>(
        v8::Script::Compile(s, const_cast<v8::ScriptOrigin *>(&origin)));
  }

  inline MaybeLocal<BoundScript> CompileScript(
    v8::Local<v8::String> s
  ) {
    return MaybeLocal<BoundScript>(v8::Script::Compile(s));
  }

  inline
  MaybeLocal<v8::Value> RunScript(v8::Local<v8::Script> script) {
    return MaybeLocal<v8::Value>(script->Run());
  }

  inline v8::Local<v8::Value> MakeCallback(
      v8::Local<v8::Object> target
    , v8::Local<v8::Function> func
    , int argc
    , v8::Local<v8::Value>* argv) {
    return New(node::MakeCallback(target, func, argc, argv));
  }

  inline v8::Local<v8::Value> MakeCallback(
      v8::Local<v8::Object> target
    , v8::Local<v8::String> symbol
    , int argc
    , v8::Local<v8::Value>* argv) {
    return New(node::MakeCallback(target, symbol, argc, argv));
  }

  inline v8::Local<v8::Value> MakeCallback(
      v8::Local<v8::Object> target
    , const char* method
    , int argc
    , v8::Local<v8::Value>* argv) {
    return New(node::MakeCallback(target, method, argc, argv));
  }

  inline void FatalException(const TryCatch& try_catch) {
    node::FatalException(const_cast<v8::TryCatch &>(try_catch.try_catch_));
  }

  inline v8::Local<v8::Value> ErrnoException(
          int errorno
       ,  const char* syscall = NULL
       ,  const char* message = NULL
       ,  const char* path = NULL) {
    return node::ErrnoException(errorno, syscall, message, path);
  }

  NAN_DEPRECATED inline v8::Local<v8::Value> NanErrnoException(
          int errorno
       ,  const char* syscall = NULL
       ,  const char* message = NULL
       ,  const char* path = NULL) {
    return ErrnoException(errorno, syscall, message, path);
  }


  template<typename T>
  inline void SetIsolateData(
      v8::Isolate *isolate
    , T *data
  ) {
      isolate->SetData(data);
  }

  template<typename T>
  inline T *GetIsolateData(
      v8::Isolate *isolate
  ) {
      return static_cast<T*>(isolate->GetData());
  }

class Utf8String {
 public:
  inline explicit Utf8String(v8::Local<v8::Value> from) :
      length_(0), str_(str_st_) {
    if (!from.IsEmpty()) {
      v8::Local<v8::String> string = from->ToString();
      if (!string.IsEmpty()) {
        size_t len = 3 * string->Length() + 1;
        assert(len <= INT_MAX);
        if (len > sizeof (str_st_)) {
          str_ = static_cast<char*>(malloc(len));
          assert(str_ != 0);
        }
        const int flags =
            v8::String::NO_NULL_TERMINATION | imp::kReplaceInvalidUtf8;
        length_ = string->WriteUtf8(str_, static_cast<int>(len), 0, flags);
        str_[length_] = '\0';
      }
    }
  }

  inline int length() const {
    return length_;
  }

  inline char* operator*() { return str_; }
  inline const char* operator*() const { return str_; }

  inline ~Utf8String() {
    if (str_ != str_st_) {
      free(str_);
    }
  }

 private:
  NAN_DISALLOW_ASSIGN_COPY_MOVE(Utf8String)

  int length_;
  char *str_;
  char str_st_[1024];
};

#endif  // NODE_MODULE_VERSION

typedef void (*FreeCallback)(char *data, void *hint);

typedef const FunctionCallbackInfo<v8::Value>& NAN_METHOD_ARGS_TYPE;
typedef void NAN_METHOD_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Value>& NAN_GETTER_ARGS_TYPE;
typedef void NAN_GETTER_RETURN_TYPE;

typedef const PropertyCallbackInfo<void>& NAN_SETTER_ARGS_TYPE;
typedef void NAN_SETTER_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Value>&
    NAN_PROPERTY_GETTER_ARGS_TYPE;
typedef void NAN_PROPERTY_GETTER_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Value>&
    NAN_PROPERTY_SETTER_ARGS_TYPE;
typedef void NAN_PROPERTY_SETTER_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Array>&
    NAN_PROPERTY_ENUMERATOR_ARGS_TYPE;
typedef void NAN_PROPERTY_ENUMERATOR_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Boolean>&
    NAN_PROPERTY_DELETER_ARGS_TYPE;
typedef void NAN_PROPERTY_DELETER_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Integer>&
    NAN_PROPERTY_QUERY_ARGS_TYPE;
typedef void NAN_PROPERTY_QUERY_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Value>& NAN_INDEX_GETTER_ARGS_TYPE;
typedef void NAN_INDEX_GETTER_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Value>& NAN_INDEX_SETTER_ARGS_TYPE;
typedef void NAN_INDEX_SETTER_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Array>&
    NAN_INDEX_ENUMERATOR_ARGS_TYPE;
typedef void NAN_INDEX_ENUMERATOR_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Boolean>&
    NAN_INDEX_DELETER_ARGS_TYPE;
typedef void NAN_INDEX_DELETER_RETURN_TYPE;

typedef const PropertyCallbackInfo<v8::Integer>&
    NAN_INDEX_QUERY_ARGS_TYPE;
typedef void NAN_INDEX_QUERY_RETURN_TYPE;

#define NAN_METHOD(name)                                                       \
    Nan::NAN_METHOD_RETURN_TYPE name(Nan::NAN_METHOD_ARGS_TYPE info)
#define NAN_GETTER(name)                                                       \
    Nan::NAN_GETTER_RETURN_TYPE name(                                          \
        v8::Local<v8::String> property                                         \
      , Nan::NAN_GETTER_ARGS_TYPE info)
#define NAN_SETTER(name)                                                       \
    Nan::NAN_SETTER_RETURN_TYPE name(                                          \
        v8::Local<v8::String> property                                         \
      , v8::Local<v8::Value> value                                             \
      , Nan::NAN_SETTER_ARGS_TYPE info)
#define NAN_PROPERTY_GETTER(name)                                              \
    Nan::NAN_PROPERTY_GETTER_RETURN_TYPE name(                                 \
        v8::Local<v8::String> property                                         \
      , Nan::NAN_PROPERTY_GETTER_ARGS_TYPE info)
#define NAN_PROPERTY_SETTER(name)                                              \
    Nan::NAN_PROPERTY_SETTER_RETURN_TYPE name(                                 \
        v8::Local<v8::String> property                                         \
      , v8::Local<v8::Value> value                                             \
      , Nan::NAN_PROPERTY_SETTER_ARGS_TYPE info)
#define NAN_PROPERTY_ENUMERATOR(name)                                          \
    Nan::NAN_PROPERTY_ENUMERATOR_RETURN_TYPE name(                             \
        Nan::NAN_PROPERTY_ENUMERATOR_ARGS_TYPE info)
#define NAN_PROPERTY_DELETER(name)                                             \
    Nan::NAN_PROPERTY_DELETER_RETURN_TYPE name(                                \
        v8::Local<v8::String> property                                         \
      , Nan::NAN_PROPERTY_DELETER_ARGS_TYPE info)
#define NAN_PROPERTY_QUERY(name)                                               \
    Nan::NAN_PROPERTY_QUERY_RETURN_TYPE name(                                  \
        v8::Local<v8::String> property                                         \
      , Nan::NAN_PROPERTY_QUERY_ARGS_TYPE info)
# define NAN_INDEX_GETTER(name)                                                \
    Nan::NAN_INDEX_GETTER_RETURN_TYPE name(                                    \
        uint32_t index                                                         \
      , Nan::NAN_INDEX_GETTER_ARGS_TYPE info)
#define NAN_INDEX_SETTER(name)                                                 \
    Nan::NAN_INDEX_SETTER_RETURN_TYPE name(                                    \
        uint32_t index                                                         \
      , v8::Local<v8::Value> value                                             \
      , Nan::NAN_INDEX_SETTER_ARGS_TYPE info)
#define NAN_INDEX_ENUMERATOR(name)                                             \
    Nan::NAN_INDEX_ENUMERATOR_RETURN_TYPE                                      \
    name(Nan::NAN_INDEX_ENUMERATOR_ARGS_TYPE info)
#define NAN_INDEX_DELETER(name)                                                \
    Nan::NAN_INDEX_DELETER_RETURN_TYPE name(                                   \
        uint32_t index                                                         \
      , Nan::NAN_INDEX_DELETER_ARGS_TYPE info)
#define NAN_INDEX_QUERY(name)                                                  \
    Nan::NAN_INDEX_QUERY_RETURN_TYPE name(                                     \
        uint32_t index                                                         \
      , Nan::NAN_INDEX_QUERY_ARGS_TYPE info)

class Callback {
 public:
  Callback() {
    HandleScope scope;
    v8::Local<v8::Object> obj = New<v8::Object>();
    handle.Reset(obj);
  }

  explicit Callback(const v8::Local<v8::Function> &fn) {
    HandleScope scope;
    v8::Local<v8::Object> obj = New<v8::Object>();
    handle.Reset(obj);
    SetFunction(fn);
  }

  ~Callback() {
    if (handle.IsEmpty()) return;
    handle.Reset();
  }

  bool operator==(const Callback &other) const {
    HandleScope scope;
    v8::Local<v8::Value> a = New(handle)->Get(kCallbackIndex);
    v8::Local<v8::Value> b = New(other.handle)->Get(kCallbackIndex);
    return a->StrictEquals(b);
  }

  bool operator!=(const Callback &other) const {
    return !this->operator==(other);
  }

  inline
  v8::Local<v8::Function> operator*() const { return this->GetFunction(); }

  inline v8::Local<v8::Value> operator()(
      v8::Local<v8::Object> target
    , int argc = 0
    , v8::Local<v8::Value> argv[] = 0) const {
    return this->Call(target, argc, argv);
  }

  inline v8::Local<v8::Value> operator()(
      int argc = 0
    , v8::Local<v8::Value> argv[] = 0) const {
    return this->Call(argc, argv);
  }

  inline void SetFunction(const v8::Local<v8::Function> &fn) {
    HandleScope scope;
    Set(New(handle), kCallbackIndex, fn);
  }

  inline v8::Local<v8::Function> GetFunction() const {
    EscapableHandleScope scope;
    return scope.Escape(New(handle)->Get(kCallbackIndex)
        .As<v8::Function>());
  }

  inline bool IsEmpty() const {
    HandleScope scope;
    return New(handle)->Get(kCallbackIndex)->IsUndefined();
  }

  inline v8::Local<v8::Value>
  Call(v8::Local<v8::Object> target
     , int argc
     , v8::Local<v8::Value> argv[]) const {
#if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)
    v8::Isolate *isolate = v8::Isolate::GetCurrent();
    return Call_(isolate, target, argc, argv);
#else
    return Call_(target, argc, argv);
#endif
  }

  inline v8::Local<v8::Value>
  Call(int argc, v8::Local<v8::Value> argv[]) const {
#if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)
    v8::Isolate *isolate = v8::Isolate::GetCurrent();
    return Call_(isolate, isolate->GetCurrentContext()->Global(), argc, argv);
#else
    return Call_(v8::Context::GetCurrent()->Global(), argc, argv);
#endif
  }

 private:
  NAN_DISALLOW_ASSIGN_COPY_MOVE(Callback)
  Persistent<v8::Object> handle;
  static const uint32_t kCallbackIndex = 0;

#if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)
  v8::Local<v8::Value> Call_(v8::Isolate *isolate
                           , v8::Local<v8::Object> target
                           , int argc
                           , v8::Local<v8::Value> argv[]) const {
    EscapableHandleScope scope;

    v8::Local<v8::Function> callback = New(handle)->
        Get(kCallbackIndex).As<v8::Function>();
# if NODE_MODULE_VERSION < IOJS_3_0_MODULE_VERSION
    return scope.Escape(New(node::MakeCallback(
        isolate
      , target
      , callback
      , argc
      , argv
    )));
# else
    return scope.Escape(node::MakeCallback(
        isolate
      , target
      , callback
      , argc
      , argv
    ));
# endif
  }
#else
  v8::Local<v8::Value> Call_(v8::Local<v8::Object> target
                           , int argc
                           , v8::Local<v8::Value> argv[]) const {
    EscapableHandleScope scope;

    v8::Local<v8::Function> callback = New(handle)->
        Get(kCallbackIndex).As<v8::Function>();
    return scope.Escape(New(node::MakeCallback(
        target
      , callback
      , argc
      , argv
    )));
  }
#endif
};

/* abstract */ class AsyncWorker {
 public:
  explicit AsyncWorker(Callback *callback_)
      : callback(callback_), errmsg_(NULL) {
    request.data = this;

    HandleScope scope;
    v8::Local<v8::Object> obj = New<v8::Object>();
    persistentHandle.Reset(obj);
  }

  virtual ~AsyncWorker() {
    HandleScope scope;

    if (!persistentHandle.IsEmpty())
      persistentHandle.Reset();
    delete callback;
    delete[] errmsg_;
  }

  virtual void WorkComplete() {
    HandleScope scope;

    if (errmsg_ == NULL)
      HandleOKCallback();
    else
      HandleErrorCallback();
    delete callback;
    callback = NULL;
  }

  inline void SaveToPersistent(
      const char *key, const v8::Local<v8::Value> &value) {
    HandleScope scope;
    New(persistentHandle)->Set(New(key).ToLocalChecked(), value);
  }

  inline void SaveToPersistent(
      const v8::Local<v8::String> &key, const v8::Local<v8::Value> &value) {
    HandleScope scope;
    New(persistentHandle)->Set(key, value);
  }

  inline void SaveToPersistent(
      uint32_t index, const v8::Local<v8::Value> &value) {
    HandleScope scope;
    New(persistentHandle)->Set(index, value);
  }

  inline v8::Local<v8::Value> GetFromPersistent(const char *key) const {
    EscapableHandleScope scope;
    return scope.Escape(
        New(persistentHandle)->Get(New(key).ToLocalChecked()));
  }

  inline v8::Local<v8::Value>
  GetFromPersistent(const v8::Local<v8::String> &key) const {
    EscapableHandleScope scope;
    return scope.Escape(New(persistentHandle)->Get(key));
  }

  inline v8::Local<v8::Value> GetFromPersistent(uint32_t index) const {
    EscapableHandleScope scope;
    return scope.Escape(New(persistentHandle)->Get(index));
  }

  virtual void Execute() = 0;

  uv_work_t request;

  virtual void Destroy() {
      delete this;
  }

 protected:
  Persistent<v8::Object> persistentHandle;
  Callback *callback;

  virtual void HandleOKCallback() {
    callback->Call(0, NULL);
  }

  virtual void HandleErrorCallback() {
    HandleScope scope;

    v8::Local<v8::Value> argv[] = {
      v8::Exception::Error(New<v8::String>(ErrorMessage()).ToLocalChecked())
    };
    callback->Call(1, argv);
  }

  void SetErrorMessage(const char *msg) {
    delete[] errmsg_;

    size_t size = strlen(msg) + 1;
    errmsg_ = new char[size];
    memcpy(errmsg_, msg, size);
  }

  const char* ErrorMessage() const {
    return errmsg_;
  }

 private:
  NAN_DISALLOW_ASSIGN_COPY_MOVE(AsyncWorker)
  char *errmsg_;
};

/* abstract */ class AsyncProgressWorker : public AsyncWorker {
 public:
  explicit AsyncProgressWorker(Callback *callback_)
      : AsyncWorker(callback_), asyncdata_(NULL), asyncsize_(0) {
    async = new uv_async_t;
    uv_async_init(
        uv_default_loop()
      , async
      , AsyncProgress_
    );
    async->data = this;

    uv_mutex_init(&async_lock);
  }

  virtual ~AsyncProgressWorker() {
    uv_mutex_destroy(&async_lock);

    delete[] asyncdata_;
  }

  void WorkProgress() {
    uv_mutex_lock(&async_lock);
    char *data = asyncdata_;
    size_t size = asyncsize_;
    asyncdata_ = NULL;
    uv_mutex_unlock(&async_lock…