OpenTTD Source: src/misc/fixedsizearray.hpp Source File

OpenTTD Source 12.2

fixedsizearray.hpp
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1 /*
2 * This file is part of OpenTTD.
3 * 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.
4 * 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.
5 * 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/>.
6 */
7
10 #ifndef FIXEDSIZEARRAY_HPP
11 #define FIXEDSIZEARRAY_HPP
12
13 #include "../core/alloc_func.hpp"
14
21 template <class T, uint C>
22 struct FixedSizeArray {
23 protected:
25 struct ArrayHeader
26 {
27 uint items;
28 uint reference_count;
29 };
30
31 /* make constants visible from outside */
32 static const uint Tsize = sizeof(T);
33 static const uint HeaderSize = sizeof(ArrayHeader);
34
39 T *data;
40
42 inline ArrayHeader& Hdr()
43 {
44 return *(ArrayHeader*)(((byte*)data) - HeaderSize);
45 }
46
48 inline const ArrayHeader& Hdr() const
49 {
50 return *(ArrayHeader*)(((byte*)data) - HeaderSize);
51 }
52
54 inline uint& RefCnt()
55 {
56 return Hdr().reference_count;
57 }
58
60 inline uint& SizeRef()
61 {
62 return Hdr().items;
63 }
64
65 public:
67 FixedSizeArray()
68 {
69 /* Ensure the size won't overflow. */
70 static_assert(C < (SIZE_MAX - HeaderSize) / Tsize);
71
72 /* allocate block for header + items (don't construct items) */
73 data = (T*)((MallocT<byte>(HeaderSize + C * Tsize)) + HeaderSize);
74 SizeRef() = 0; // initial number of items
75 RefCnt() = 1; // initial reference counter
76 }
77
79 FixedSizeArray(const FixedSizeArray<T, C> &src)
80 {
81 /* share block (header + items) with the source array */
82 data = src.data;
83 RefCnt()++; // now we share block with the source
84 }
85
87 ~FixedSizeArray()
88 {
89 /* release one reference to the shared block */
90 if ((--RefCnt()) > 0) return; // and return if there is still some owner
91
92 Clear();
93 /* free the memory block occupied by items */
94 free(((byte*)data) - HeaderSize);
95 data = nullptr;
96 }
97
99 inline void Clear()
100 {
101 /* Walk through all allocated items backward and destroy them
102 * Note: this->Length() can be zero. In that case data[this->Length() - 1] is evaluated unsigned
103 * on some compilers with some architectures. (e.g. gcc with x86) */
104 for (T *pItem = this->data + this->Length() - 1; pItem >= this->data; pItem--) {
105 pItem->~T();
106 }
107 /* number of items become zero */
108 SizeRef() = 0;
109 }
110
112 inline uint Length() const
113 {
114 return Hdr().items;
115 }
116
118 inline bool IsFull() const
119 {
120 return Length() >= C;
121 }
122
124 inline bool IsEmpty() const
125 {
126 return Length() <= 0;
127 }
128
130 inline T *Append()
131 {
132 assert(!IsFull());
133 return &data[SizeRef()++];
134 }
135
137 inline T *AppendC()
138 {
139 T *item = Append();
140 new(item)T;
141 return item;
142 }
144 inline T& operator[](uint index)
145 {
146 assert(index < Length());
147 return data[index];
148 }
149
151 inline const T& operator[](uint index) const
152 {
153 assert(index < Length());
154 return data[index];
155 }
156 };
157
158 #endif /* FIXEDSIZEARRAY_HPP */
FixedSizeArray::FixedSizeArray
FixedSizeArray()
Default constructor.
Definition: fixedsizearray.hpp:67
FixedSizeArray::RefCnt
uint & RefCnt()
return reference to the block reference counter
Definition: fixedsizearray.hpp:54
FixedSizeArray::Clear
void Clear()
Clear (destroy) all items.
Definition: fixedsizearray.hpp:99
FixedSizeArray::HeaderSize
static const uint HeaderSize
size of header
Definition: fixedsizearray.hpp:33
FixedSizeArray::Tsize
static const uint Tsize
size of item
Definition: fixedsizearray.hpp:32
FixedSizeArray::data
T * data
the only member of fixed size array is pointer to the block of C array of items.
Definition: fixedsizearray.hpp:39
FixedSizeArray::FixedSizeArray
FixedSizeArray(const FixedSizeArray< T, C > &src)
Copy constructor.
Definition: fixedsizearray.hpp:79
FixedSizeArray::operator[]
T & operator[](uint index)
return item by index (non-const version)
Definition: fixedsizearray.hpp:144
FixedSizeArray::IsEmpty
bool IsEmpty() const
return true if array is empty
Definition: fixedsizearray.hpp:124
FixedSizeArray::Hdr
const ArrayHeader & Hdr() const
return reference to the array header (const)
Definition: fixedsizearray.hpp:48
FixedSizeArray::ArrayHeader
header for fixed size array
Definition: fixedsizearray.hpp:25
FixedSizeArray::SizeRef
uint & SizeRef()
return reference to number of used items
Definition: fixedsizearray.hpp:60
FixedSizeArray::ArrayHeader::items
uint items
number of items in the array
Definition: fixedsizearray.hpp:27
FixedSizeArray::Append
T * Append()
add (allocate), but don't construct item
Definition: fixedsizearray.hpp:130
FixedSizeArray::IsFull
bool IsFull() const
return true if array is full
Definition: fixedsizearray.hpp:118
FixedSizeArray
fixed size array Upon construction it preallocates fixed size block of memory for all items,...
Definition: fixedsizearray.hpp:22
FixedSizeArray::ArrayHeader::reference_count
uint reference_count
block reference counter (used by copy constructor and by destructor)
Definition: fixedsizearray.hpp:28
FixedSizeArray::~FixedSizeArray
~FixedSizeArray()
destroy remaining items and free the memory block
Definition: fixedsizearray.hpp:87
FixedSizeArray::Length
uint Length() const
return number of used items
Definition: fixedsizearray.hpp:112
FixedSizeArray::Hdr
ArrayHeader & Hdr()
return reference to the array header (non-const)
Definition: fixedsizearray.hpp:42
free
static void free(const void *ptr)
Version of the standard free that accepts const pointers.
Definition: stdafx.h:460
FixedSizeArray::AppendC
T * AppendC()
add and construct item using default constructor
Definition: fixedsizearray.hpp:137