mirror of https://github.com/OpenTTD/OpenTTD.git
102 lines
3.8 KiB
C++
102 lines
3.8 KiB
C++
/* $Id$ */
|
|
|
|
/** @file fixedsizearray.hpp A fixed size array that doesn't create items until needed. */
|
|
|
|
#ifndef FIXEDSIZEARRAY_HPP
|
|
#define FIXEDSIZEARRAY_HPP
|
|
|
|
|
|
/** fixed size array
|
|
* Upon construction it preallocates fixed size block of memory
|
|
* for all items, but doesn't construct them. Item's construction
|
|
* is delayed. */
|
|
template <class Titem_, int Tcapacity_>
|
|
struct CFixedSizeArrayT {
|
|
/** the only member of fixed size array is pointer to the block
|
|
* of C array of items. Header can be found on the offset -sizeof(CHdr). */
|
|
Titem_ *m_items;
|
|
|
|
/** header for fixed size array */
|
|
struct CHdr
|
|
{
|
|
int m_num_items; ///< number of items in the array
|
|
int m_ref_cnt; ///< block reference counter (used by copy constructor and by destructor)
|
|
};
|
|
|
|
/* make types and constants visible from outside */
|
|
typedef Titem_ Titem; // type of array item
|
|
|
|
static const int Tcapacity = Tcapacity_; // the array capacity (maximum size)
|
|
static const int TitemSize = sizeof(Titem_); // size of item
|
|
static const int ThdrSize = sizeof(CHdr); // size of header
|
|
|
|
/** Default constructor. Preallocate space for items and header, then initialize header. */
|
|
CFixedSizeArrayT()
|
|
{
|
|
/* allocate block for header + items (don't construct items) */
|
|
m_items = (Titem*)((MallocT<int8>(ThdrSize + Tcapacity * sizeof(Titem))) + ThdrSize);
|
|
SizeRef() = 0; // initial number of items
|
|
RefCnt() = 1; // initial reference counter
|
|
}
|
|
|
|
/** Copy constructor. Preallocate space for items and header, then initialize header. */
|
|
CFixedSizeArrayT(const CFixedSizeArrayT<Titem_, Tcapacity_>& src)
|
|
{
|
|
/* share block (header + items) with the source array */
|
|
m_items = src.m_items;
|
|
RefCnt()++; // now we share block with the source
|
|
}
|
|
|
|
/** destroy remaining items and free the memory block */
|
|
~CFixedSizeArrayT()
|
|
{
|
|
/* release one reference to the shared block */
|
|
if ((--RefCnt()) > 0) return; // and return if there is still some owner
|
|
|
|
Clear();
|
|
/* free the memory block occupied by items */
|
|
free(((int8*)m_items) - ThdrSize);
|
|
m_items = NULL;
|
|
}
|
|
|
|
/** Clear (destroy) all items */
|
|
FORCEINLINE void Clear()
|
|
{
|
|
/* walk through all allocated items backward and destroy them */
|
|
for (Titem *pItem = &m_items[Size() - 1]; pItem >= m_items; pItem--) {
|
|
pItem->~Titem_();
|
|
}
|
|
/* number of items become zero */
|
|
SizeRef() = 0;
|
|
}
|
|
|
|
protected:
|
|
/** return reference to the array header (non-const) */
|
|
FORCEINLINE CHdr& Hdr() { return *(CHdr*)(((int8*)m_items) - ThdrSize); }
|
|
/** return reference to the array header (const) */
|
|
FORCEINLINE const CHdr& Hdr() const { return *(CHdr*)(((int8*)m_items) - ThdrSize); }
|
|
/** return reference to the block reference counter */
|
|
FORCEINLINE int& RefCnt() { return Hdr().m_ref_cnt; }
|
|
/** return reference to number of used items */
|
|
FORCEINLINE int& SizeRef() { return Hdr().m_num_items; }
|
|
public:
|
|
/** return number of used items */
|
|
FORCEINLINE int Size() const { return Hdr().m_num_items; }
|
|
/** return true if array is full */
|
|
FORCEINLINE bool IsFull() const { return Size() >= Tcapacity; };
|
|
/** return true if array is empty */
|
|
FORCEINLINE bool IsEmpty() const { return Size() <= 0; };
|
|
/** index validation */
|
|
FORCEINLINE void CheckIdx(int idx) const { assert(idx >= 0); assert(idx < Size()); }
|
|
/** add (allocate), but don't construct item */
|
|
FORCEINLINE Titem& AddNC() { assert(!IsFull()); return m_items[SizeRef()++]; }
|
|
/** add and construct item using default constructor */
|
|
FORCEINLINE Titem& Add() { Titem& item = AddNC(); new(&item)Titem; return item; }
|
|
/** return item by index (non-const version) */
|
|
FORCEINLINE Titem& operator [] (int idx) { CheckIdx(idx); return m_items[idx]; }
|
|
/** return item by index (const version) */
|
|
FORCEINLINE const Titem& operator [] (int idx) const { CheckIdx(idx); return m_items[idx]; }
|
|
};
|
|
|
|
#endif /* FIXEDSIZEARRAY_HPP */
|