# fixedsizearray.hpp

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    00001 /* $Id: fixedsizearray.hpp 18828 2010-01-16 16:44:59Z frosch $ */
    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
    00021 template <class T, uint C>
    00022 struct FixedSizeArray {
    00023 protected:
    00025   struct ArrayHeader
    00026   {
    00027     uint items;
    00028     uint reference_count;
    00029   };
    00030
    00031   /* make constants visible from outside */
    00032   static const uint Tsize = sizeof(T);                // size of item
    00033   static const uint HeaderSize = sizeof(ArrayHeader); // size of header
    00034
    00037   T *data;
    00038
    00040   FORCEINLINE ArrayHeader& Hdr() { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
    00042   FORCEINLINE const ArrayHeader& Hdr() const { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
    00044   FORCEINLINE uint& RefCnt() { return Hdr().reference_count; }
    00046   FORCEINLINE uint& SizeRef() { return Hdr().items; }
    00047
    00048 public:
    00050   FixedSizeArray()
    00051   {
    00052     /* allocate block for header + items (don't construct items) */
    00053     data = (T*)((MallocT<byte>(HeaderSize + C * Tsize)) + HeaderSize);
    00054     SizeRef() = 0; // initial number of items
    00055     RefCnt() = 1; // initial reference counter
    00056   }
    00057
    00059   FixedSizeArray(const FixedSizeArray<T, C>& src)
    00060   {
    00061     /* share block (header + items) with the source array */
    00062     data = src.data;
    00063     RefCnt()++; // now we share block with the source
    00064   }
    00065
    00067   ~FixedSizeArray()
    00068   {
    00069     /* release one reference to the shared block */
    00070     if ((--RefCnt()) > 0) return; // and return if there is still some owner
    00071
    00072     Clear();
    00073     /* free the memory block occupied by items */
    00074     free(((byte*)data) - HeaderSize);
    00075     data = NULL;
    00076   }
    00077
    00079   FORCEINLINE void Clear()
    00080   {
    00081     /* Walk through all allocated items backward and destroy them
    00082      * Note: this->Length() can be zero. In that case data[this->Length() - 1] is evaluated unsigned
    00083      *       on some compilers with some architectures. (e.g. gcc with x86) */
    00084     for (T *pItem = this->data + this->Length() - 1; pItem >= this->data; pItem--) {
    00085       pItem->~T();
    00086     }
    00087     /* number of items become zero */
    00088     SizeRef() = 0;
    00089   }
    00090
    00092   FORCEINLINE uint Length() const { return Hdr().items; }
    00094   FORCEINLINE bool IsFull() const { return Length() >= C; };
    00096   FORCEINLINE bool IsEmpty() const { return Length() <= 0; };
    00098   FORCEINLINE T *Append() { assert(!IsFull()); return &data[SizeRef()++]; }
    00100   FORCEINLINE T *AppendC() { T *item = Append(); new(item)T; return item; }
    00102   FORCEINLINE T& operator [] (uint index) { assert(index < Length()); return data[index]; }
    00104   FORCEINLINE const T& operator [] (uint index) const { assert(index < Length()); return data[index]; }
    00105 };
    00106
    00107 #endif /* FIXEDSIZEARRAY_HPP */