# fixedsizearray.hpp

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    00001 /* $Id: fixedsizearray.hpp 23640 2011-12-20 17:57:56Z truebrain $ */
    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   inline ArrayHeader& Hdr() { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
    00046   inline const ArrayHeader& Hdr() const { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
    00048   inline uint& RefCnt() { return Hdr().reference_count; }
    00050   inline uint& SizeRef() { return Hdr().items; }
    00051
    00052 public:
    00054   FixedSizeArray()
    00055   {
    00056     /* Ensure the size won't overflow. */
    00057     assert_compile(C < (SIZE_MAX - HeaderSize) / Tsize);
    00058
    00059     /* allocate block for header + items (don't construct items) */
    00060     data = (T*)((MallocT<byte>(HeaderSize + C * Tsize)) + HeaderSize);
    00061     SizeRef() = 0; // initial number of items
    00062     RefCnt() = 1; // initial reference counter
    00063   }
    00064
    00066   FixedSizeArray(const FixedSizeArray<T, C>& src)
    00067   {
    00068     /* share block (header + items) with the source array */
    00069     data = src.data;
    00070     RefCnt()++; // now we share block with the source
    00071   }
    00072
    00074   ~FixedSizeArray()
    00075   {
    00076     /* release one reference to the shared block */
    00077     if ((--RefCnt()) > 0) return; // and return if there is still some owner
    00078
    00079     Clear();
    00080     /* free the memory block occupied by items */
    00081     free(((byte*)data) - HeaderSize);
    00082     data = NULL;
    00083   }
    00084
    00086   inline void Clear()
    00087   {
    00088     /* Walk through all allocated items backward and destroy them
    00089      * Note: this->Length() can be zero. In that case data[this->Length() - 1] is evaluated unsigned
    00090      *       on some compilers with some architectures. (e.g. gcc with x86) */
    00091     for (T *pItem = this->data + this->Length() - 1; pItem >= this->data; pItem--) {
    00092       pItem->~T();
    00093     }
    00094     /* number of items become zero */
    00095     SizeRef() = 0;
    00096   }
    00097
    00099   inline uint Length() const { return Hdr().items; }
    00101   inline bool IsFull() const { return Length() >= C; }
    00103   inline bool IsEmpty() const { return Length() <= 0; }
    00105   inline T *Append() { assert(!IsFull()); return &data[SizeRef()++]; }
    00107   inline T *AppendC() { T *item = Append(); new(item)T; return item; }
    00109   inline T& operator [] (uint index) { assert(index < Length()); return data[index]; }
    00111   inline const T& operator [] (uint index) const { assert(index < Length()); return data[index]; }
    00112 };
    00113
    00114 #endif /* FIXEDSIZEARRAY_HPP */