fixedsizearray.hpp

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00001 /* $Id$ */
00002 
00003 /*
00004  * This file is part of OpenTTD.
00005  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
00006  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
00007  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
00008  */
00009 
00012 #ifndef FIXEDSIZEARRAY_HPP
00013 #define FIXEDSIZEARRAY_HPP
00014 
00015 #include "../core/alloc_func.hpp"
00016 
00023 template <class T, uint C>
00024 struct FixedSizeArray {
00025 protected:
00027   struct ArrayHeader
00028   {
00029     uint items;           
00030     uint reference_count; 
00031   };
00032 
00033   /* make constants visible from outside */
00034   static const uint Tsize = sizeof(T);                
00035   static const uint HeaderSize = sizeof(ArrayHeader); 
00036 
00041   T *data;
00042 
00044   FORCEINLINE ArrayHeader& Hdr() { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
00046   FORCEINLINE const ArrayHeader& Hdr() const { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
00048   FORCEINLINE uint& RefCnt() { return Hdr().reference_count; }
00050   FORCEINLINE uint& SizeRef() { return Hdr().items; }
00051 
00052 public:
00054   FixedSizeArray()
00055   {
00056     /* allocate block for header + items (don't construct items) */
00057     data = (T*)((MallocT<byte>(HeaderSize + C * Tsize)) + HeaderSize);
00058     SizeRef() = 0; // initial number of items
00059     RefCnt() = 1; // initial reference counter
00060   }
00061 
00063   FixedSizeArray(const FixedSizeArray<T, C>& src)
00064   {
00065     /* share block (header + items) with the source array */
00066     data = src.data;
00067     RefCnt()++; // now we share block with the source
00068   }
00069 
00071   ~FixedSizeArray()
00072   {
00073     /* release one reference to the shared block */
00074     if ((--RefCnt()) > 0) return; // and return if there is still some owner
00075 
00076     Clear();
00077     /* free the memory block occupied by items */
00078     free(((byte*)data) - HeaderSize);
00079     data = NULL;
00080   }
00081 
00083   FORCEINLINE void Clear()
00084   {
00085     /* Walk through all allocated items backward and destroy them
00086      * Note: this->Length() can be zero. In that case data[this->Length() - 1] is evaluated unsigned
00087      *       on some compilers with some architectures. (e.g. gcc with x86) */
00088     for (T *pItem = this->data + this->Length() - 1; pItem >= this->data; pItem--) {
00089       pItem->~T();
00090     }
00091     /* number of items become zero */
00092     SizeRef() = 0;
00093   }
00094 
00096   FORCEINLINE uint Length() const { return Hdr().items; }
00098   FORCEINLINE bool IsFull() const { return Length() >= C; }
00100   FORCEINLINE bool IsEmpty() const { return Length() <= 0; }
00102   FORCEINLINE T *Append() { assert(!IsFull()); return &data[SizeRef()++]; }
00104   FORCEINLINE T *AppendC() { T *item = Append(); new(item)T; return item; }
00106   FORCEINLINE T& operator [] (uint index) { assert(index < Length()); return data[index]; }
00108   FORCEINLINE const T& operator [] (uint index) const { assert(index < Length()); return data[index]; }
00109 };
00110 
00111 #endif /* FIXEDSIZEARRAY_HPP */

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