audacia/src/MemoryX.h

#ifndef __AUDACITY_MEMORY_X_H__
#define __AUDACITY_MEMORY_X_H__

// C++ standard header <memory> with a few extensions
#include <memory>

#ifndef safenew
#define safenew new
#endif

// Conditional compilation switch indicating whether to rely on
// std:: containers knowing about rvalue references
#undef __AUDACITY_OLD_STD__

#if defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED <= __MAC_10_6

#define __AUDACITY_OLD_STD__

#include <math.h>
inline long long int llrint(float __x) { return __builtin_llrintf(__x); }
inline long long int llrint(double __x) { return __builtin_llrintl(__x); }
inline long long int llrint(long double __x) { return __builtin_llrintl(__x); }

#include <cmath>
using std::isnan;
using std::isinf;

// Need this to define move() and forward()
#include <tr1/type_traits>

// To define make_shared
#include <tr1/memory>

namespace std {
   using std::tr1::shared_ptr;
   using std::tr1::weak_ptr;
   using std::tr1::static_pointer_cast;
   using std::tr1::remove_reference;
   using std::tr1::is_unsigned;

   template<typename X> struct default_delete
   {
      default_delete() {}
      
      // Allow copy from other deleter classes
      template<typename Y>
      default_delete(const default_delete<Y>& that)
      {
         // Break compilation if Y* does not convert to X*
         // I should figure out the right use of enable_if instead
         // Note: YPtr avoids bogus compiler warning for C99 compound literals
         using YPtr = Y*;
         static_assert((static_cast<X*>(YPtr{}), true),
                       "Pointer types not convertible");
      }
      
      inline void operator() (void *p) const
      {
         delete static_cast<X*>(p);
      }
   };
   
   // Specialization for arrays
   template<typename X> struct default_delete<X[]>
   {
      // Do not allow copy from other deleter classes
      inline void operator() (void *p) const
      {
         delete[] static_cast<X*>(p);
      }
   };

   struct nullptr_t
   {
      void* __lx;

      struct __nat {int __for_bool_;};

      nullptr_t() : __lx(0) {}
      nullptr_t(int __nat::*) : __lx(0) {}

      operator int __nat::*() const {return 0;}

      template <class _Tp>
         operator _Tp* () const {return 0;}

      template <class _Tp, class _Up>
         operator _Tp _Up::* () const {return 0;}

      friend bool operator==(nullptr_t, nullptr_t) {return true;}
      friend bool operator!=(nullptr_t, nullptr_t) {return false;}
      friend bool operator<(nullptr_t, nullptr_t) {return false;}
      friend bool operator<=(nullptr_t, nullptr_t) {return true;}
      friend bool operator>(nullptr_t, nullptr_t) {return false;}
      friend bool operator>=(nullptr_t, nullptr_t) {return true;}
   };

   inline nullptr_t __get_nullptr_t() {return nullptr_t(0);}

   #define nullptr std::__get_nullptr_t()

   // "Cast" anything as an rvalue reference.
   template<typename T> inline typename remove_reference<T>::type&& move(T&& t)
   { return static_cast<typename std::remove_reference<T>::type&&>(t); }

   template<typename T, typename D = default_delete<T>> class unique_ptr
      : private D // use empty base optimization
   {
   public:
      // Default constructor
      unique_ptr() {}
      
      // Implicit constrution from nullptr
      unique_ptr(nullptr_t) {}

      // Explicit constructor from pointer and optional deleter
      explicit unique_ptr(T *p_)
         : p{ p_ } {}
      explicit unique_ptr(T *p_, const D &d)
         : D(d), p{ p_ } {}
      // Template constructors for upcasting
      template<typename U>
      explicit unique_ptr(U* p_)
         : p{ p_ } {}
      template<typename U>
      explicit unique_ptr(U* p_, const D& d)
         : D(d), p{ p_ } {}

      // Copy is disallowed
      unique_ptr(const unique_ptr &) PROHIBITED;
      unique_ptr& operator= (const unique_ptr &) PROHIBITED;

      // But move is allowed!
      unique_ptr(unique_ptr &&that)
         : D(move(that.get_deleter())), p{ that.release() } { }
      unique_ptr& operator= (unique_ptr &&that)
      {
         if (this != &that) {
            get_deleter()(p);
            ((D&)*this) = move(that.get_deleter());
            p = that.release();
         }
         return *this;
      }

      // Assign null
      unique_ptr& operator= (nullptr_t)
      {
         get_deleter()(p);
         p = nullptr;
         return *this;
      }

      // Template versions of move for upcasting
      template<typename U, typename E>
      unique_ptr(unique_ptr<U, E> &&that)
         : D(move(that.get_deleter())), p{ that.release() } { }
      template<typename U, typename E>
      unique_ptr& operator= (unique_ptr<U, E> &&that)
      {
         // Skip the self-assignment test -- self-assignment should go to the non-template overload
         get_deleter()(p);
         p = that.release();
         get_deleter() = move(that.get_deleter());
         return *this;
      }
      
      D& get_deleter() { return *this; }
      const D& get_deleter() const { return *this; }

      ~unique_ptr() { get_deleter()(p); }

      T* operator -> () const { return p; }
      T& operator * () const { return *p; }
      T* get() const { return p; }

      // So you can say if(p)
      explicit operator bool() const { return p != nullptr; }

      // Give up ownership, don't destroy
      T* release() { T* result = p; p = nullptr; return result; }

      void reset(T* __p = nullptr)
      {
         T* old__p = p;
         p = __p;
         if (old__p != nullptr)
         {
            get_deleter()(old__p);
         }
      }

      void swap(unique_ptr& that)
      {
         std::swap(p, that.p);
         std::swap(get_deleter(), that.get_deleter());
      }

   private:
      T *p{};
   };

   // Now specialize the class for array types
   template<typename T, typename D> class unique_ptr<T[], D>
      : private D // use empty base optimization
   {
   public:
      // Default constructor
      unique_ptr() {}

      // Implicit constrution from nullptr
      unique_ptr(nullptr_t) {}
      
      // Explicit constructor from pointer
      explicit unique_ptr(T *p_)
         : p{ p_ } {}
      explicit unique_ptr(T *p_, const D &d)
         : D( d ), p{ p_ } {}
      // NO template constructor for upcasting!

      // Copy is disallowed
      unique_ptr(const unique_ptr &) PROHIBITED;
      unique_ptr& operator= (const unique_ptr &)PROHIBITED;

      // But move is allowed!
      unique_ptr(unique_ptr &&that)
         : D( move(that.get_deleter()) ), p{ that.release() } { }
      unique_ptr& operator= (unique_ptr &&that)
      {
         if (this != &that) {
            get_deleter()(p);
            p = that.release();
            ((D&)*this) = move(that.get_deleter());
         }
         return *this;
      }

      // Assign null
      unique_ptr& operator= (nullptr_t)
      {
         get_deleter()(p);
         p = nullptr;
         return *this;
      }
      
      D& get_deleter() { return *this; }
      const D& get_deleter() const { return *this; }

      // NO template versions of move for upcasting!

      ~unique_ptr() { get_deleter()(p); }

      // No operator ->, but [] instead
      T& operator [] (size_t n) const { return p[n]; }

      T& operator * () const { return *p; }
      T* get() const { return p; }

      // So you can say if(p)
      explicit operator bool() const { return p != nullptr; }

      // Give up ownership, don't destroy
      T* release() { T* result = p; p = nullptr; return result; }

      void reset(T* __p = nullptr)
      {
         T* old__p = p;
         p = __p;
         if (old__p != nullptr)
         {
            get_deleter()(old__p);
         }
      }

      void swap(unique_ptr& that)
      {
         std::swap(p, that.p);
         std::swap(get_deleter(), that.get_deleter());
      }

   private:
      T *p{};
   };

   // Equality operators for unique_ptr, don't need the specializations for array case
   template<typename U, typename E>
   inline bool operator== (nullptr_t, const unique_ptr<U, E>& ptr)
   {
      return ptr.get() == nullptr;
   }
   template<typename U, typename E>
   inline bool operator== (const unique_ptr<U, E>& ptr, nullptr_t)
   {
      return ptr.get() == nullptr;
   }
   template<typename U, typename E, typename V, typename F>
   inline bool operator == (const unique_ptr<U, E> &ptr1,
                            const unique_ptr<V, F> &ptr2)
   {
      return ptr1.get() == ptr2.get();
   }

   template<typename U, typename E> inline bool operator != (nullptr_t, const unique_ptr<U, E> &ptr) { return !(ptr == nullptr); }
   template<typename U, typename E> inline bool operator != (const unique_ptr<U, E> &ptr, nullptr_t) { return !(ptr == nullptr); }
   template<typename U, typename E, typename V, typename F> inline bool operator != (const unique_ptr<U, E>& ptr1, const unique_ptr<V, F> &ptr2)
   { return !(ptr1 == ptr2); }

   // Forward -- pass along rvalue references as rvalue references, anything else as it is
   // (Because the appropriate overload is taken, and "reference collapse" applies to the return type)
   template<typename T> inline T&& forward(typename remove_reference<T>::type& t)
   { return static_cast<T&&>(t); }
   template<typename T> inline T&& forward(typename remove_reference<T>::type&& t)
   { return static_cast<T&&>(t); }

   // We need make_shared for ourselves, because the library doesn't use variadics
   template<typename X, typename... Args> inline shared_ptr<X> make_shared(Args&&... args)
   {
      return shared_ptr<X>{ safenew X(forward<Args>(args)...) };
   }
   // From LLVM c++11 and modified

   #include <cstddef>

   template<class _Ep>
   class initializer_list
   {
       const _Ep* __begin_;
       size_t    __size_;

       initializer_list(const _Ep* __b, size_t __s)
           : __begin_(__b),
             __size_(__s)
           {}
   public:
       typedef _Ep        value_type;
       typedef const _Ep& reference;
       typedef const _Ep& const_reference;
       typedef size_t    size_type;

       typedef const _Ep* iterator;
       typedef const _Ep* const_iterator;

       initializer_list() : __begin_(nullptr), __size_(0) {}

       size_t    size()  const {return __size_;}

       const _Ep* begin() const {return __begin_;}

       const _Ep* end()   const {return __begin_ + __size_;}
   };

   template<class _Ep>
   inline
   const _Ep*
   begin(initializer_list<_Ep> __il)
   {
       return __il.begin();
   }

   template<class _Ep>
   inline
   const _Ep*
   end(initializer_list<_Ep> __il)
   {
       return __il.end();
   }
}

#endif

#if !(_MSC_VER >= 1800 || __cplusplus >= 201402L)
/* replicate the very useful C++14 make_unique for those build environments
that don't implement it yet.
typical useage:
auto p = std::make_unique<Myclass>(ctorArg1, ctorArg2, ... ctorArgN);
p->DoSomething();
auto q = std::make_unique<Myclass[]>(count);
q[0].DoSomethingElse();

The first hides naked NEW and DELETE from the source code.
The second hides NEW[] and DELETE[].  Both of course ensure destruction if
you don't use something like std::move(p) or q.release().  Both expressions require
that you identify the type only once, which is brief and less error prone.

(Whereas this omission of [] might invite a runtime error:
std::unique_ptr<Myclass> q { safenew Myclass[count] }; )

Some C++11 tricks needed here are (1) variadic argument lists and
(2) making the compile-time dispatch work correctly.  You can't have
a partially specialized template function, but you get the effect of that
by other metaprogramming means.
*/

namespace std {
   // For overloading resolution
   template <typename X> struct __make_unique_result {
      using scalar_case = unique_ptr<X>;
   };

   // Partial specialization of the struct for array case
   template <typename X> struct __make_unique_result<X[]> {
      using array_case = unique_ptr<X[]>;
      using element = X;
   };

   // Now the scalar version of unique_ptr
   template<typename X, typename... Args> inline
      typename __make_unique_result<X>::scalar_case
      make_unique(Args&&... args)
   {
      return typename __make_unique_result<X>::scalar_case
      { safenew X(forward<Args>(args)...) };
   }

   // Now the array version of unique_ptr
   // The compile-time dispatch trick is that the non-existence
   // of the scalar_case type makes the above overload
   // unavailable when the template parameter is explicit
   template<typename X> inline
      typename __make_unique_result<X>::array_case
      make_unique(size_t count)
   {
      return typename __make_unique_result<X>::array_case
      { safenew typename __make_unique_result<X>::element[count] };
   }
}
#endif

/*
 * ArrayOf<X>
 * Not to be confused with std::array (which takes a fixed size) or std::vector
 * This maintains a pointer allocated by NEW X[].  It's cheap: only one pointer,
 * with no size and capacity information for resizing as for vector, and if X is
 * a built-in numeric or pointer type, by default there is no zero filling at
 * allocation time.
 */

template<typename X>
class ArrayOf : public std::unique_ptr<X[]>
{
public:
   ArrayOf() {}

   template<typename Integral>
   explicit ArrayOf(Integral count, bool initialize = false)
   {
      static_assert(std::is_unsigned<Integral>::value, "Unsigned arguments only");
      reinit(count, initialize);
   }

   ArrayOf(const ArrayOf&) PROHIBITED;
   ArrayOf(ArrayOf&& that)
      : std::unique_ptr < X[] >
         (std::move((std::unique_ptr < X[] >&)(that)))
   {
   }
   ArrayOf& operator= (ArrayOf &&that)
   {
      std::unique_ptr<X[]>::operator=(std::move(that));
      return *this;
   }
   ArrayOf& operator= (std::unique_ptr<X[]> &&that)
   {
      std::unique_ptr<X[]>::operator=(std::move(that));
      return *this;
   }

   template< typename Integral >
   void reinit(Integral count,
               bool initialize = false)
   {
      static_assert(std::is_unsigned<Integral>::value, "Unsigned arguments only");
      if (initialize)
         // Initialize elements (usually, to zero for a numerical type)
         std::unique_ptr<X[]>::reset(safenew X[count]{});
      else
         // Avoid the slight initialization overhead
         std::unique_ptr<X[]>::reset(safenew X[count]);
   }
};

/*
 * ArraysOf<X>
 * This simplifies arrays of arrays, each array separately allocated with NEW[]
 * But it might be better to use std::Array<ArrayOf<X>, N> for some small constant N
 * Or use just one array when sub-arrays have a common size and are not large.
 */
template<typename X>
class ArraysOf : public ArrayOf<ArrayOf<X>>
{
public:
   ArraysOf() {}

   template<typename Integral>
   explicit ArraysOf(Integral N)
      : ArrayOf<ArrayOf<X>>( N )
   {}

   template<typename Integral1, typename Integral2 >
   ArraysOf(Integral1 N, Integral2 M, bool initialize = false)
   : ArrayOf<ArrayOf<X>>( N )
   {
      static_assert(std::is_unsigned<Integral1>::value, "Unsigned arguments only");
      static_assert(std::is_unsigned<Integral2>::value, "Unsigned arguments only");
      for (size_t ii = 0; ii < N; ++ii)
         (*this)[ii] = ArrayOf<X>{ M, initialize };
   }

   ArraysOf(const ArraysOf&) PROHIBITED;
   ArraysOf& operator= (ArraysOf&& that)
   {
      ArrayOf<ArrayOf<X>>::operator=(std::move(that));
      return *this;
   }

   using ArrayOf<ArrayOf<X>>::reinit;

   template<typename Integral1, typename Integral2 >
   void reinit(Integral1 countN, Integral2 countM, bool initialize = false)
   {
      static_assert(std::is_unsigned<Integral1>::value, "Unsigned arguments only");
      static_assert(std::is_unsigned<Integral2>::value, "Unsigned arguments only");
      reinit(countN, false);
      for (size_t ii = 0; ii < countN; ++ii)
         (*this)[ii].reinit(countM, initialize);
   }
};

/*
 * template class Maybe<X>
 * Can be used for monomorphic objects that are stack-allocable, but only conditionally constructed.
 * You might also use it as a member.
 * Initialize with create(), then use like a smart pointer,
 * with *, ->, get(), reset(), or in if()
 */

// Placement-NEW is used below, and that does not cooperate with the DEBUG_NEW for Visual Studio
#ifdef _DEBUG
#ifdef _MSC_VER
#undef new
#endif
#endif

template<typename X>
class Maybe {
public:

   // Construct as NULL
   Maybe() {}

   // Supply the copy and move, so you might use this as a class member too
   Maybe(const Maybe &that)
   {
      if (that.get())
         create(*that);
   }

   Maybe& operator= (const Maybe &that)
   {
      if (this != &that) {
         if (that.get())
            create(*that);
         else
            reset();
      }
      return *this;
   }

   Maybe(Maybe &&that)
   {
      if (that.get())
         create(::std::move(*that));
   }

   Maybe& operator= (Maybe &&that)
   {
      if (this != &that) {
         if (that.get())
            create(::std::move(*that));
         else
            reset();
      }
      return *this;
   }

   // Make an object in the buffer, passing constructor arguments,
   // but destroying any previous object first
   // Note that if constructor throws, we remain in a consistent
   // NULL state -- giving exception safety but only weakly
   // (previous value was lost if present)
   template<typename... Args>
   void create(Args&&... args)
   {
      // Lose any old value
      reset();
      // Create NEW value
      pp = safenew(address()) X(std::forward<Args>(args)...);
   }

   // Destroy any object that was built in it
   ~Maybe()
   {
      reset();
   }

   // Pointer-like operators

   // Dereference, with the usual bad consequences if NULL
   X &operator* () const
   {
      return *pp;
   }

   X *operator-> () const
   {
      return pp;
   }

   X* get() const
   {
      return pp;
   }

   void reset()
   {
      if (pp)
         pp->~X(), pp = nullptr;
   }

   // So you can say if(ptr)
   explicit operator bool() const
   {
      return pp != nullptr;
   }

private:
   X* address()
   {
      return reinterpret_cast<X*>(&storage);
   }

   // Data
#if 0
   typename ::std::aligned_storage<
      sizeof(X)
      // , alignof(X) // Not here yet in all compilers
   >::type storage{};
#else
   union {
      double d;
      char storage[sizeof(X)];
   };
#endif
   X* pp{ nullptr };
};

// Restore definition of debug new
#ifdef _DEBUG
#ifdef _MSC_VER
#undef THIS_FILE
static char*THIS_FILE = __FILE__;
#define new new(_NORMAL_BLOCK, THIS_FILE, __LINE__)
#endif
#endif

// Frequently, we need to use a vector or list of unique_ptr if we can, but default
// to shared_ptr if we can't (because containers know how to copy elements only,
// not move them).
#ifdef __AUDACITY_OLD_STD__
template<typename T> using movable_ptr = std::shared_ptr<T>;
template<typename T, typename Deleter> using movable_ptr_with_deleter_base = std::shared_ptr<T>;
#else
template<typename T> using movable_ptr = std::unique_ptr<T>;
template<typename T, typename Deleter> using movable_ptr_with_deleter_base = std::unique_ptr<T, Deleter>;
#endif

template<typename T, typename... Args>
inline movable_ptr<T> make_movable(Args&&... args)
{
   return std::
#ifdef __AUDACITY_OLD_STD__
      make_shared
#else
      make_unique
#endif
      <T>(std::forward<Args>(args)...);
}

template<typename T, typename Deleter> class movable_ptr_with_deleter
   : public movable_ptr_with_deleter_base < T, Deleter >
{
public:
   // Do not expose a constructor that takes only a pointer without deleter
   // That is important when implemented with shared_ptr
   movable_ptr_with_deleter() {};
   movable_ptr_with_deleter(T* p, const Deleter &d)
      : movable_ptr_with_deleter_base<T, Deleter>( p, d ) {}

#ifdef __AUDACITY_OLD_STD__

   // copy
   movable_ptr_with_deleter(const movable_ptr_with_deleter &that)
      : movable_ptr_with_deleter_base < T, Deleter > ( that )
   {
   }

   movable_ptr_with_deleter &operator= (const movable_ptr_with_deleter& that)
   {
      if (this != &that) {
         ((movable_ptr_with_deleter_base<T, Deleter>&)(*this)) =
            that;
      }
      return *this;
   }

#else

   // move
   movable_ptr_with_deleter(movable_ptr_with_deleter &&that)
      : movable_ptr_with_deleter_base < T, Deleter > ( std::move(that) )
   {
   }

   movable_ptr_with_deleter &operator= (movable_ptr_with_deleter&& that)
   {
      if (this != &that) {
         ((movable_ptr_with_deleter_base<T, Deleter>&)(*this)) =
         std::move(that);
      }
      return *this;
   }

#endif
};

template<typename T, typename Deleter, typename... Args>
inline movable_ptr_with_deleter<T, Deleter>
make_movable_with_deleter(const Deleter &d, Args&&... args)
{
   return movable_ptr_with_deleter<T, Deleter>(safenew T(std::forward<Args>(args)...), d);
}

/*
 * A deleter class to supply the second template parameter of unique_ptr for
 * classes like wxWindow that should be sent a message called Destroy rather
 * than be deleted directly
 */
template <typename T>
struct Destroyer {
   void operator () (T *p) const { if (p) p->Destroy(); }
};

/*
 * a convenience for using Destroyer
 */
template <typename T>
using Destroy_ptr = std::unique_ptr<T, Destroyer<T>>;

/*
 * "finally" as in The C++ Programming Language, 4th ed., p. 358
 * Useful for defining ad-hoc RAII actions.
 * typical usage:
 * auto cleanup = finally([&]{ ... code; ... });
 */

// Construct this from any copyable function object, such as a lambda
template <typename F>
struct Final_action {
   Final_action(F f) : clean( f ) {}
   ~Final_action() { clean(); }
   F clean;
};

// Function template with type deduction lets you construct Final_action
// without typing any angle brackets
template <typename F>
Final_action<F> finally (F f)
{
   return Final_action<F>(f);
}

/*
 * Set a variable temporarily in a scope
 */
template< typename T >
struct RestoreValue {
   T oldValue;
   void operator () ( T *p ) const { if (p) *p = oldValue; }
};

template< typename T >
class ValueRestorer : public std::unique_ptr< T, RestoreValue<T> >
{
   using std::unique_ptr< T, RestoreValue<T> >::reset; // make private
   // But release() remains public and can be useful to commit a changed value
public:
   explicit ValueRestorer( T &var )
      : std::unique_ptr< T, RestoreValue<T> >( &var, { var } )
   {}
   explicit ValueRestorer( T &var, const T& newValue )
      : std::unique_ptr< T, RestoreValue<T> >( &var, { var } )
   { var = newValue; }
   ValueRestorer(ValueRestorer &&that)
      : std::unique_ptr < T, RestoreValue<T> > ( std::move(that) ) {};
   ValueRestorer & operator= (ValueRestorer &&that)
   {
      if (this != &that)
         std::unique_ptr < T, RestoreValue<T> >::operator=(std::move(that));
      return *this;
   }
};

// inline functions provide convenient parameter type deduction
template< typename T >
ValueRestorer< T > valueRestorer( T& var )
{ return ValueRestorer< T >{ var }; }

template< typename T >
ValueRestorer< T > valueRestorer( T& var, const T& newValue )
{ return ValueRestorer< T >{ var, newValue }; }

/*
 * A convenience for use with range-for
 */
template <typename Iterator>
struct IteratorRange : public std::pair<Iterator, Iterator> {
   IteratorRange (Iterator &&a, Iterator &&b)
      : std::pair<Iterator, Iterator> ( std::move(a), std::move(b) ) {}

   Iterator begin() const { return this->first; }
   Iterator end() const { return this->second; }
};

#endif // __AUDACITY_MEMORY_X_H__