[176] | 1 | /* |
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| 2 | |
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| 3 | Heap Layers: An Extensible Memory Allocation Infrastructure |
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| 4 | |
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| 5 | Copyright (C) 2000-2003 by Emery Berger |
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| 6 | http://www.cs.umass.edu/~emery |
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| 7 | emery@cs.umass.edu |
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| 8 | |
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| 9 | This program is free software; you can redistribute it and/or modify |
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| 10 | it under the terms of the GNU General Public License as published by |
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| 11 | the Free Software Foundation; either version 2 of the License, or |
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| 12 | (at your option) any later version. |
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| 13 | |
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| 14 | This program is distributed in the hope that it will be useful, |
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| 15 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 17 | GNU General Public License for more details. |
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| 18 | |
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| 19 | You should have received a copy of the GNU General Public License |
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| 20 | along with this program; if not, write to the Free Software |
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| 21 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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| 22 | |
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| 23 | */ |
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| 24 | |
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| 25 | #ifndef _DYNARRAY_H_ |
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| 26 | #define _DYNARRAY_H_ |
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| 27 | |
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| 28 | #include <assert.h> |
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| 29 | #include <stdlib.h> |
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| 30 | |
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| 31 | /** |
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| 32 | * @class DynamicArray |
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| 33 | * @brief A dynamic array that grows to fit any index for assignment. |
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| 34 | * |
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| 35 | * This array also features a clear() method, |
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| 36 | * to free the entire array, and a trim(n) method, |
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| 37 | * which tells the array it is no bigger than n elements. |
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| 38 | */ |
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| 39 | |
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| 40 | namespace HL { |
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| 41 | |
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| 42 | template <class ObjType> |
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| 43 | class DynamicArray { |
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| 44 | public: |
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| 45 | DynamicArray (void) |
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| 46 | : internalArray (NULL), |
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| 47 | internalArrayLength (0) |
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| 48 | {} |
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| 49 | |
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| 50 | ~DynamicArray (void) |
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| 51 | { |
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| 52 | clear(); |
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| 53 | } |
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| 54 | |
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| 55 | /// Clear deletes everything in the array. |
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| 56 | inline void clear (void) { |
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| 57 | if (internalArray != NULL) { |
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| 58 | delete internalArray; |
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| 59 | internalArray = NULL; |
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| 60 | internalArrayLength = 0; |
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| 61 | //printf ("\ninternalArrayLength %x = %d\n", this, internalArrayLength); |
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| 62 | } |
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| 63 | } |
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| 64 | |
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| 65 | /// Read-only access to an array element; asserts that index is in range. |
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| 66 | inline const ObjType& operator[] (int index) const { |
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| 67 | assert (index < internalArrayLength); |
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| 68 | assert (index >= 0); |
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| 69 | return internalArray[index]; |
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| 70 | } |
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| 71 | |
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| 72 | /// Access an array index by reference, growing the array if necessary. |
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| 73 | inline ObjType& operator[] (int index) { |
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| 74 | assert (index >= 0); |
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| 75 | if (index >= internalArrayLength) { |
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| 76 | |
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| 77 | // This index is beyond the current size of the array. |
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| 78 | // Grow the array by doubling and copying the old array into the new. |
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| 79 | |
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| 80 | const int newSize = index * 2 + 1; |
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| 81 | ObjType * arr = new ObjType[newSize]; |
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| 82 | #if MALLOC_TRACE |
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| 83 | printf ("m %x %d\n", arr, newSize * sizeof(ObjType)); |
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| 84 | #endif |
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| 85 | if (internalArray != NULL) { |
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| 86 | memcpy (arr, internalArray, internalArrayLength * sizeof(ObjType)); |
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| 87 | delete internalArray; |
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| 88 | #if MALLOC_TRACE |
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| 89 | printf ("f %x\n", internalArray); |
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| 90 | #endif |
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| 91 | } |
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| 92 | internalArray = arr; |
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| 93 | internalArrayLength = newSize; |
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| 94 | //printf ("\ninternalArrayLength %x = %d\n", this, internalArrayLength); |
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| 95 | } |
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| 96 | return internalArray[index]; |
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| 97 | } |
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| 98 | |
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| 99 | /** |
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| 100 | * Trim informs the array that it is now only nelts long |
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| 101 | * as far as the client is concerned. This may trigger |
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| 102 | * shrinking of the array. |
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| 103 | */ |
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| 104 | inline void trim (int nelts) { |
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| 105 | |
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| 106 | // Halve the array if the number of elements |
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| 107 | // drops below one-fourth of the array size. |
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| 108 | |
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| 109 | if (internalArray != NULL) { |
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| 110 | if (nelts * 4 < internalArrayLength) { |
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| 111 | const int newSize = nelts * 2; |
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| 112 | ObjType * arr = new ObjType[newSize]; |
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| 113 | #if MALLOC_TRACE |
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| 114 | printf ("m %x %d\n", arr, newSize * sizeof(ObjType)); |
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| 115 | #endif |
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| 116 | memcpy (arr, internalArray, sizeof(ObjType) * nelts); |
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| 117 | delete internalArray; |
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| 118 | #if MALLOC_TRACE |
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| 119 | printf ("f %x\n", internalArray); |
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| 120 | #endif |
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| 121 | internalArray = arr; |
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| 122 | internalArrayLength = newSize; |
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| 123 | } |
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| 124 | assert (nelts <= internalArrayLength); |
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| 125 | } |
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| 126 | } |
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| 127 | |
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| 128 | |
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| 129 | private: |
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| 130 | |
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| 131 | /// The pointer to the current array. |
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| 132 | ObjType * internalArray; |
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| 133 | |
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| 134 | /// The length of the internal array, in elements. |
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| 135 | int internalArrayLength; |
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| 136 | }; |
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| 137 | |
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| 138 | }; |
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| 139 | |
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| 140 | #endif |
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