// $Id:$
# ifndef CPPAD_POD_VECTOR_INCLUDED
# define CPPAD_POD_VECTOR_INCLUDED

/* --------------------------------------------------------------------------
CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-14 Bradley M. Bell

CppAD is distributed under multiple licenses. This distribution is under
the terms of the 
                    GNU General Public License Version 3.

A copy of this license is included in the COPYING file of this distribution.
Please visit http://www.coin-or.org/CppAD/ for information on other licenses.
-------------------------------------------------------------------------- */

# if CPPAD_CSTDINT_HAS_8_TO_64
# include <cstdint>
# endif
# include <algorithm>
# include <cppad/thread_alloc.hpp>
# include <cppad/local/cppad_assert.hpp>
# include <cppad/local/op_code.hpp>

namespace CppAD { // BEGIN_CPPAD_NAMESPACE
/*!
\file pod_vector.hpp
File used to define pod_vector class
*/

/*
A list of which Types pod_vector<Type> consideres to be plain old data
*/
/// default value is false
template <class Type> inline bool is_pod(void)           { return false; }   
/// system pod types so far:
template <> inline bool is_pod<bool>(void)               { return true; }
template <> inline bool is_pod<float>(void)              { return true; }
template <> inline bool is_pod<double>(void)             { return true; }
# if CPPAD_CSTDINT_HAS_8_TO_64
template <> inline bool is_pod<int8_t>(void)             { return true;  }  
template <> inline bool is_pod<int16_t>(void)            { return true;  }  
template <> inline bool is_pod<int32_t>(void)            { return true;  }  
template <> inline bool is_pod<int64_t>(void)            { return true;  }  
//
template <> inline bool is_pod<uint8_t>(void)            { return true;  }  
template <> inline bool is_pod<uint16_t>(void)           { return true;  }  
template <> inline bool is_pod<uint32_t>(void)           { return true;  }  
template <> inline bool is_pod<uint64_t>(void)           { return true;  }  
# else // CPPAD_CSTDINT_HAS_8_TO_64
template <> inline bool is_pod<char>(void)               { return true; }
template <> inline bool is_pod<short int>(void)          { return true; }
template <> inline bool is_pod<int>(void)                { return true; }
//
template <> inline bool is_pod<unsigned char>(void)      { return true; }
template <> inline bool is_pod<unsigned short int>(void) { return true; }
template <> inline bool is_pod<unsigned int>(void)       { return true; }
/*
  This line:

  template <> inline bool is_pod<size_t>(void)             { return true; }

  is a re-definition *if* 'size_t' is equal to 'unsigned int'.
  To avoid this issue we will assume that 'size_t' is always an alias to one
  of the unsigned integer types, although this is not guarantied to be correct:
  http://stackoverflow.com/questions/23749822/is-size-t-guaranteed-to-be-an-alias-type-to-one-of-integer-types
  FIXME: throw a compile time error if assumption is wrong.
 */
template <> inline bool is_pod<unsigned long int>(void)  { return true; }

# endif // CPPAD_CSTDINT_HAS_8_TO_64

/// CppAD pod types so far: 
template <> inline bool is_pod<OpCode>(void)             { return true; }

// ---------------------------------------------------------------------------
/*!
A vector class with Type element that does not use element constructors
or destructors when Type is Plain Old Data (pod).
*/
template <class Type>
class pod_vector {
private:
	/// maximum number of elements that should ever be in this vector
	size_t max_length_;
	/// number of elements currently in this vector
	size_t length_;
	/// maximum number of Type elements current allocation can hold
	size_t capacity_;
	/// pointer to the first type elements 
	/// (not defined and should not be used when capacity_ = 0)
	Type   *data_;
	/// do not use the copy constructor
	explicit pod_vector(const pod_vector& )
	{	CPPAD_ASSERT_UNKNOWN(false); }
public:
	/// Constructors set capacity, length, and data to zero.
	///
	/// \param max_length
	/// value for maximum number of elements in this vector.
	inline pod_vector(
		size_t max_length = std::numeric_limits<size_t>::max()
	) 
	: max_length_(max_length), length_(0), capacity_(0), data_(CPPAD_NULL)
	{ }
	// ----------------------------------------------------------------------
	/// Destructor: returns allocated memory to \c thread_alloc; 
	/// see \c extend.  If this is not plain old data, 
	/// the destructor for each element is called.
	~pod_vector(void)
	{	if( capacity_ > 0 )
		{	void* v_ptr = reinterpret_cast<void*>( data_ );
			if( ! is_pod<Type>() )
			{	// call destructor for each element
				size_t i;
				for(i = 0; i < capacity_; i++)
					(data_ + i)->~Type();
			}
			thread_alloc::return_memory(v_ptr); 
		}
	}
	// ----------------------------------------------------------------------
	/// current number of elements in this vector.
	inline size_t size(void) const
	{	return length_; }
	/// current capacity (amount of allocated storage) for this vector.
	inline size_t capacity(void) const
	{	return capacity_; }
	/// current data pointer, no longer valid after any of the following:
	/// extend, erase, operator=, and ~pod_vector. 
	/// Take extreem care when using this function.
	inline Type* data(void)
	{	return data_; }
	/// const version of \c data pointer
	inline const Type* data(void) const
	{	return data_; }
	// ----------------------------------------------------------------------
	/*!
	Increase the number of elements the end of this vector. 

	\param n
	is the number of elements to add to end of this vector.

	\return
	is the number  of elements in the vector before \c extend was extended.

	- If \c Type is plain old data, new elements are not initialized; 
	i.e., their constructor is not called. Otherwise, the constructor
	is called for each new element.

	- This is the only routine that allocates memory for \c pod_vector.
	and it uses thread_alloc for this allocation, hence this determines
	which thread corresponds to this vector (when in parallel mode).

	- If the resulting length of the vector would be more than \c max_length_,
	and \c NDEBUG is not defined, a CPPAD_ASSERT is generated.
	*/
	inline size_t extend(size_t n)
	{	size_t old_length   = length_;
		length_            += n;
		CPPAD_ASSERT_KNOWN(
			length_ <= max_length_ ,
			"pod_vector.hpp: attempt to create to large a vector.\n"
			"If Type is CPPAD_TYPE_ADDR_TYPE, tape is too long for Type."
		);
		// check if we can use current memory
		if( capacity_ >= length_ )
			return old_length;

		// save more old information
		size_t old_capacity = capacity_;
		Type* old_data      = data_;

		// get new memory and set capacity
		size_t length_bytes = length_ * sizeof(Type);
		size_t capacity_bytes;
		void* v_ptr = thread_alloc::get_memory(length_bytes, capacity_bytes);
		capacity_   = capacity_bytes / sizeof(Type);
		data_       = reinterpret_cast<Type*>(v_ptr);
		CPPAD_ASSERT_UNKNOWN( length_ <= capacity_ );

		size_t i;
		if( ! is_pod<Type>() )
		{	// call constructor for each new element
			for(i = 0; i < capacity_; i++)
				new(data_ + i) Type();
		}
		
		// copy old data to new data
		for(i = 0; i < old_length; i++)
			data_[i] = old_data[i];

		// return old memory to available pool
		if( old_capacity > 0 )
		{	v_ptr = reinterpret_cast<void*>( old_data );
			if( ! is_pod<Type>() )
			{	for(i = 0; i < old_capacity; i++)
					(old_data + i)->~Type();
			} 
			thread_alloc::return_memory(v_ptr); 
		}

		// return value for extend(n) is the old length
		return old_length;
	}
	// ----------------------------------------------------------------------
	/// non-constant element access; i.e., we can change this element value
	Type& operator[](
		/// element index, must be less than length
		size_t i
	)
	{	CPPAD_ASSERT_UNKNOWN( i < length_ );
		return data_[i]; 
	}
	// ----------------------------------------------------------------------
	/// constant element access; i.e., we cannot change this element value
	const Type& operator[](
		/// element index, must be less than length
		size_t i
	) const
	{	CPPAD_ASSERT_UNKNOWN( i < length_ );
		return data_[i]; 
	}
	// ----------------------------------------------------------------------
	/*!
 	Remove all the elements from this vector but leave the capacity
	and data pointer as is.

	*/
	void erase(void)
	{	length_ = 0;
		return;
	}	
	// ----------------------------------------------------------------------
	/*!
 	Remove all the elements from this vector and delete its memory.
	*/
	void free(void)
	{	if( capacity_ > 0 )
		{	void* v_ptr = reinterpret_cast<void*>( data_ );
			if( ! is_pod<Type>() )
			{	// call destructor for each element
				size_t i;
				for(i = 0; i < capacity_; i++)
					(data_ + i)->~Type();
			}
			thread_alloc::return_memory(v_ptr); 
		}
		data_     = CPPAD_NULL;
		capacity_ = 0;
		length_   = 0;
	}
	/// vector assignment operator
	/// If the resulting length of the vector would be more than 
	/// \c max_length_, and \c NDEBUG is not defined, 
	/// a CPPAD_ASSERT is generated.
	void operator=(
		/// right hand size of the assingment operation
		const pod_vector& x
	)
	{	size_t i;
	
		if( x.length_ <= capacity_ )
		{	// use existing allocation for this vector
			length_ = x.length_;
			CPPAD_ASSERT_KNOWN(
				length_ <= max_length_ ,
				"pod_vector.hpp: attempt to create to large a vector.\n"
				"If Type is CPPAD_TYPE_ADDR_TYPE, tape long for Type."
			);
		}
		else
		{	// free old memory and get new memory of sufficient length
			if( capacity_ > 0 )
			{	void* v_ptr = reinterpret_cast<void*>( data_ );
				if( ! is_pod<Type>() )
				{	// call destructor for each element
					for(i = 0; i < capacity_; i++)
						(data_ + i)->~Type();
				}
				thread_alloc::return_memory(v_ptr); 
			}
			length_ = capacity_ = 0;
			extend( x.length_ );
		}
		CPPAD_ASSERT_UNKNOWN( length_   == x.length_ );
		for(i = 0; i < length_; i++)
		{	data_[i] = x.data_[i]; }
	}
	/*!
	Swap all properties of this vector with another.

	\param other
	is the other vector that we are swapping this vector with.
 	*/
	void swap(pod_vector& other)
	{	std::swap(capacity_, other.capacity_);
		std::swap(length_,   other.length_);
		std::swap(data_,     other.data_);
	}
};

} // END_CPPAD_NAMESPACE
# endif
