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fixedsizearray.hpp
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1 /* $Id: fixedsizearray.hpp 23640 2011-12-20 17:57:56Z truebrain $ */
2
3 /*
4 * This file is part of OpenTTD.
5 * 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.
6 * 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.
7 * 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/>.
8 */
9
12 #ifndef FIXEDSIZEARRAY_HPP
13 #define FIXEDSIZEARRAY_HPP
14
15 #include "../core/alloc_func.hpp"
16
23 template <class T, uint C>
24 struct FixedSizeArray {
25 protected:
27 struct ArrayHeader
28 {
29 uint items;
30 uint reference_count;
31 };
32
33 /* make constants visible from outside */
34 static const uint Tsize = sizeof(T);
35 static const uint HeaderSize = sizeof(ArrayHeader);
36
41 T *data;
42
44 inline ArrayHeader& Hdr() { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
46 inline const ArrayHeader& Hdr() const { return *(ArrayHeader*)(((byte*)data) - HeaderSize); }
48 inline uint& RefCnt() { return Hdr().reference_count; }
50 inline uint& SizeRef() { return Hdr().items; }
51
52 public:
54 FixedSizeArray()
55 {
56 /* Ensure the size won't overflow. */
57 assert_compile(C < (SIZE_MAX - HeaderSize) / Tsize);
58
59 /* allocate block for header + items (don't construct items) */
60 data = (T*)((MallocT<byte>(HeaderSize + C * Tsize)) + HeaderSize);
61 SizeRef() = 0; // initial number of items
62 RefCnt() = 1; // initial reference counter
63 }
64
66 FixedSizeArray(const FixedSizeArray<T, C>& src)
67 {
68 /* share block (header + items) with the source array */
69 data = src.data;
70 RefCnt()++; // now we share block with the source
71 }
72
74 ~FixedSizeArray()
75 {
76 /* release one reference to the shared block */
77 if ((--RefCnt()) > 0) return; // and return if there is still some owner
78
79 Clear();
80 /* free the memory block occupied by items */
81 free(((byte*)data) - HeaderSize);
82 data = NULL;
83 }
84
86 inline void Clear()
87 {
88 /* Walk through all allocated items backward and destroy them
89 * Note: this->Length() can be zero. In that case data[this->Length() - 1] is evaluated unsigned
90 * on some compilers with some architectures. (e.g. gcc with x86) */
91 for (T *pItem = this->data + this->Length() - 1; pItem >= this->data; pItem--) {
92 pItem->~T();
93 }
94 /* number of items become zero */
95 SizeRef() = 0;
96 }
97
99 inline uint Length() const { return Hdr().items; }
101 inline bool IsFull() const { return Length() >= C; }
103 inline bool IsEmpty() const { return Length() <= 0; }
105 inline T *Append() { assert(!IsFull()); return &data[SizeRef()++]; }
107 inline T *AppendC() { T *item = Append(); new(item)T; return item; }
109 inline T& operator [] (uint index) { assert(index < Length()); return data[index]; }
111 inline const T& operator [] (uint index) const { assert(index < Length()); return data[index]; }
112 };
113
114 #endif /* FIXEDSIZEARRAY_HPP */