1

/* $Id$ */

     2

     5

#ifndef  FIXEDSIZEARRAY_HPP

     6

#define  FIXEDSIZEARRAY_HPP

     7

     8

     9

/** fixed size array

    10

 *  Upon construction it preallocates fixed size block of memory

    11

 *  for all items, but doesn't construct them. Item's construction

    12

 *  is delayed. */

    13

template <class Titem_, int Tcapacity_>

    14

struct CFixedSizeArrayT {

    15

	/** the only member of fixed size array is pointer to the block

    16

	 *  of C array of items. Header can be found on the offset -sizeof(CHdr). */

    17

	Titem_ *m_items;

    18

    19

	/** header for fixed size array */

    20

	struct CHdr

    21

	{

    22

		int    m_num_items; ///< number of items in the array

    23

		int    m_ref_cnt;   ///< block reference counter (used by copy constructor and by destructor)

    24

	};

    25

    26

	// make types and constants visible from outside

    27

	typedef Titem_ Titem; // type of array item

    28

    29

	static const int Tcapacity = Tcapacity_;     // the array capacity (maximum size)

    30

	static const int TitemSize = sizeof(Titem_); // size of item

    31

	static const int ThdrSize  = sizeof(CHdr);   // size of header

    32

    33

	/** Default constructor. Preallocate space for items and header, then initialize header. */

    34

	CFixedSizeArrayT()

    35

	{

    36

		// allocate block for header + items (don't construct items)

    37

		m_items = (Titem*)(((int8*)malloc(ThdrSize + Tcapacity * sizeof(Titem))) + ThdrSize);

    38

		SizeRef() = 0; // initial number of items

    39

		RefCnt() = 1; // initial reference counter

    40

	}

    41

    42

	/** Copy constructor. Preallocate space for items and header, then initialize header. */

    43

	CFixedSizeArrayT(const CFixedSizeArrayT<Titem_, Tcapacity_>& src)

    44

	{

    45

		// share block (header + items) with the source array

    46

		m_items = src.m_items;

    47

		RefCnt()++; // now we share block with the source

    48

	}

    49

    50

	/** destroy remaining items and free the memory block */

    51

	~CFixedSizeArrayT()

    52

	{

    53

		// release one reference to the shared block

    54

		if ((--RefCnt()) > 0) return; // and return if there is still some owner

    55

    56

		Clear();

    57

		// free the memory block occupied by items

    58

		free(((int8*)m_items) - ThdrSize);

    59

		m_items = NULL;

    60

	}

    61

    62

	/** Clear (destroy) all items */

    63

	FORCEINLINE void Clear()

    64

	{

    65

		// walk through all allocated items backward and destroy them

    66

		for (Titem* pItem = &m_items[Size() - 1]; pItem >= m_items; pItem--) {

    67

			pItem->~Titem_();

    68

		}

    69

		// number of items become zero

    70

		SizeRef() = 0;

    71

	}

    72

    73

protected:

    74

	/** return reference to the array header (non-const) */

    75

	FORCEINLINE CHdr& Hdr() { return *(CHdr*)(((int8*)m_items) - ThdrSize); }

    76

	/** return reference to the array header (const) */

    77

	FORCEINLINE const CHdr& Hdr() const { return *(CHdr*)(((int8*)m_items) - ThdrSize); }

    78

	/** return reference to the block reference counter */

    79

	FORCEINLINE int& RefCnt() { return Hdr().m_ref_cnt; }

    80

	/** return reference to number of used items */

    81

	FORCEINLINE int& SizeRef() { return Hdr().m_num_items; }

    82

public:

    83

	/** return number of used items */

    84

	FORCEINLINE int Size() const { return Hdr().m_num_items; }

    85

	/** return true if array is full */

    86

	FORCEINLINE bool IsFull() const { return Size() >= Tcapacity; };

    87

	/** return true if array is empty */

    88

	FORCEINLINE bool IsEmpty() const { return Size() <= 0; };

    89

	/** index validation */

    90

	FORCEINLINE void CheckIdx(int idx) const { assert(idx >= 0); assert(idx < Size()); }

    91

	/** add (allocate), but don't construct item */

    92

	FORCEINLINE Titem& AddNC() { assert(!IsFull()); return m_items[SizeRef()++]; }

    93

	/** add and construct item using default constructor */

    94

	FORCEINLINE Titem& Add() { Titem& item = AddNC(); new(&item)Titem; return item; }

    95

	/** return item by index (non-const version) */

    96

	FORCEINLINE Titem& operator [] (int idx) { CheckIdx(idx); return m_items[idx]; }

    97

	/** return item by index (const version) */

    98

	FORCEINLINE const Titem& operator [] (int idx) const { CheckIdx(idx); return m_items[idx]; }

    99

};

   100

   101

#endif /* FIXEDSIZEARRAY_HPP */