[f0fd47] | 1 | #ifndef CACHE_IMPLEMENTATION_H |
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| 2 | #define CACHE_IMPLEMENTATION_H |
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| 3 | |
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[3d9165] | 4 | #include <cstdio> // for sprintf |
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| 5 | #include <iostream> |
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| 6 | |
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[f0fd47] | 7 | template<class KeyClass, class ValueClass> |
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| 8 | Cache<KeyClass, ValueClass>::Cache (const int maxEntries, const int maxWeight) |
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| 9 | { |
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| 10 | _maxEntries = maxEntries; |
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| 11 | _maxWeight = maxWeight; |
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| 12 | _rank.clear(); |
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| 13 | _key.clear(); |
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| 14 | _value.clear(); |
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| 15 | _weights.clear(); |
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| 16 | _itKey = _key.end(); /* referring to past-the-end element in the list */ |
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| 17 | _itValue = _value.end(); /* referring to past-the-end element in the list */ |
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| 18 | _weight = 0; |
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| 19 | } |
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| 20 | |
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| 21 | template<class KeyClass, class ValueClass> |
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| 22 | int Cache<KeyClass, ValueClass>::getWeight() const |
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| 23 | { |
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| 24 | return _weight; |
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| 25 | } |
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| 26 | |
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| 27 | template<class KeyClass, class ValueClass> |
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| 28 | int Cache<KeyClass, ValueClass>::getNumberOfEntries() const |
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| 29 | { |
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| 30 | return _rank.size(); |
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| 31 | } |
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| 32 | |
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| 33 | template<class KeyClass, class ValueClass> |
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| 34 | void Cache<KeyClass, ValueClass>::clear() |
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| 35 | { |
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| 36 | _rank.clear(); |
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| 37 | _key.clear(); |
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| 38 | _value.clear(); |
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| 39 | _weights.clear(); |
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| 40 | } |
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| 41 | |
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| 42 | template<class KeyClass, class ValueClass> |
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| 43 | Cache<KeyClass, ValueClass>::~Cache() |
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| 44 | { |
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| 45 | _rank.clear(); |
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| 46 | _key.clear(); |
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| 47 | _value.clear(); |
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| 48 | _weights.clear(); |
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| 49 | } |
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| 50 | |
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| 51 | template<class KeyClass, class ValueClass> |
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| 52 | bool Cache<KeyClass, ValueClass>::hasKey (const KeyClass& key) const |
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| 53 | { |
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| 54 | _itKey = _key.end(); // referring to past-the-end element in the list |
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| 55 | typename list<KeyClass>::const_iterator itKey; |
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| 56 | _itValue = _value.begin(); |
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| 57 | /* As _key is a sorted list, the following could actually be implemented |
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| 58 | in logarithmic time, by bisection. However, for lists this does not work. |
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| 59 | But often, we can still terminate the linear loop before having visited |
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| 60 | all elements. */ |
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| 61 | for (itKey = _key.begin(); itKey != _key.end(); itKey++) |
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| 62 | { |
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| 63 | int c = key.compare(*itKey); |
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| 64 | if (c == 0) |
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| 65 | { |
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| 66 | _itKey = itKey; |
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| 67 | return true; |
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| 68 | } |
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| 69 | if (c == -1) return false; |
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| 70 | _itValue++; |
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| 71 | } |
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| 72 | return false; |
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| 73 | } |
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| 74 | |
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| 75 | template<class KeyClass, class ValueClass> |
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| 76 | ValueClass Cache<KeyClass, ValueClass>::getValue (const KeyClass& key) const |
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| 77 | { |
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| 78 | if (_itKey == _key.end()) |
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| 79 | /* _itKey refers to past-the-end element in the list; |
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| 80 | thus, getValue has been called although hasKey |
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| 81 | produced no match */ |
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| 82 | assert(false); |
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| 83 | |
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| 84 | return *_itValue; |
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| 85 | } |
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| 86 | |
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| 87 | template<class KeyClass, class ValueClass> |
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| 88 | bool Cache<KeyClass, ValueClass>::shrink(const KeyClass& key) |
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| 89 | { |
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| 90 | /* We need to return true iff the pair with given key needed to |
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| 91 | be erased during the shrinking procedure. So far, we assume no: */ |
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| 92 | bool result = false; |
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| 93 | /* Shrink until both bounds will be met again: */ |
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| 94 | while (int(_key.size()) > _maxEntries || _weight > _maxWeight) |
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| 95 | { |
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| 96 | if (deleteLast(key)) result = true; |
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| 97 | } |
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| 98 | return result; |
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| 99 | } |
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| 100 | |
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| 101 | template<class KeyClass, class ValueClass> |
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| 102 | int Cache<KeyClass, ValueClass>::getMaxNumberOfEntries() const |
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| 103 | { |
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| 104 | return _maxEntries; |
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| 105 | } |
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| 106 | |
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| 107 | template<class KeyClass, class ValueClass> |
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| 108 | int Cache<KeyClass, ValueClass>::getMaxWeight() const |
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| 109 | { |
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| 110 | return _maxWeight; |
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| 111 | } |
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| 112 | |
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| 113 | template<class KeyClass, class ValueClass> |
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| 114 | bool Cache<KeyClass, ValueClass>::deleteLast(const KeyClass& key) |
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| 115 | { |
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| 116 | if (_rank.size() == 0) |
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| 117 | { |
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| 118 | return false; /* nothing to do */ |
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| 119 | }; |
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| 120 | /* We need to perform the following (empty) loop in order to |
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| 121 | obtain a forward-iterator pointing to the last entry of _rank. |
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| 122 | Note: We cannot use rbegin() because we need the iterator for |
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| 123 | erasing the last entry which is only implemented for forward |
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| 124 | iterators by std::list. */ |
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| 125 | list<int>::iterator itRank; |
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| 126 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) { } |
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| 127 | itRank--; /* Now, this forward iterator points to the last list entry. */ |
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| 128 | int deleteIndex = *itRank; /* index of (_key, _value)-pair with worst, |
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| 129 | i.e., highest _rank */ |
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| 130 | bool result = false; |
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| 131 | |
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| 132 | /* now delete entries in _key and _value with index deleteIndex */ |
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| 133 | int k = 0; |
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| 134 | typename list<KeyClass>::iterator itKey; |
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| 135 | typename list<ValueClass>::iterator itValue = _value.begin(); |
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| 136 | typename list<int>::iterator itWeights = _weights.begin(); |
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| 137 | for (itKey = _key.begin(); itKey != _key.end(); itKey++) |
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| 138 | { |
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| 139 | if (k == deleteIndex) |
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| 140 | { |
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| 141 | result = (key.compare(*itKey) == 0); |
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| 142 | break; |
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| 143 | } |
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| 144 | itValue++; |
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| 145 | itWeights++; |
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| 146 | k++; |
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| 147 | } |
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| 148 | _key.erase(itKey); |
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| 149 | int deleteWeight = *itWeights; |
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| 150 | _value.erase(itValue); |
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| 151 | _weights.erase(itWeights); |
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| 152 | |
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| 153 | /* adjust total weight of this cache */ |
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| 154 | _weight -= deleteWeight; |
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| 155 | |
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| 156 | /* now delete last entry of _rank and decrement all those indices |
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| 157 | // in _rank by 1 which are larger than deleteIndex */ |
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| 158 | _rank.erase(itRank); |
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| 159 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 160 | { |
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| 161 | if (*itRank > deleteIndex) *itRank -= 1; |
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| 162 | } |
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| 163 | |
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| 164 | return result; |
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| 165 | } |
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| 166 | |
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| 167 | template<class KeyClass, class ValueClass> |
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| 168 | bool Cache<KeyClass, ValueClass>::put (const KeyClass& key, |
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| 169 | const ValueClass& value) |
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| 170 | { |
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| 171 | bool keyWasContained = false; |
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| 172 | int oldIndexInKey = -1; |
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| 173 | int newIndexInKey = _key.size(); /* default to enter new (key, value)-pair |
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| 174 | is at the end of the two lists; |
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| 175 | only used in the case |
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| 176 | keyWasContained == false */ |
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| 177 | int k = 0; |
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| 178 | typename list<KeyClass>::iterator itKey; |
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| 179 | // itOldValue will later only be used in the case keyWasContained == true: */ |
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| 180 | typename list<ValueClass>::iterator itOldValue = _value.begin(); |
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| 181 | /* itOldWeights will later only be used in the case |
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| 182 | keyWasContained == true */ |
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| 183 | typename list<int>::iterator itOldWeights = _weights.begin(); |
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| 184 | for (itKey = _key.begin(); itKey != _key.end(); itKey++) |
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| 185 | { |
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| 186 | int c = key.compare(*itKey); |
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| 187 | if (c == -1) |
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| 188 | { |
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| 189 | newIndexInKey = k; |
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| 190 | break; |
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| 191 | } |
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| 192 | if (c == 0) |
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| 193 | { |
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| 194 | keyWasContained = true; |
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| 195 | oldIndexInKey = k; |
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| 196 | break; |
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| 197 | } |
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| 198 | itOldValue++; |
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| 199 | itOldWeights++; |
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| 200 | k++; |
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| 201 | } |
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| 202 | int utility = value.getUtility(); |
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| 203 | int newWeight = value.getWeight(); |
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| 204 | k = 0; |
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| 205 | typename list<ValueClass>::iterator itValue = _value.begin(); |
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| 206 | for (itValue = _value.begin(); itValue != _value.end(); itValue++) |
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| 207 | { |
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| 208 | if (itValue->getUtility() > utility) k++; |
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| 209 | } |
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| 210 | int newIndexInRank = k; |
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| 211 | |
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| 212 | if (keyWasContained) |
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| 213 | { |
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| 214 | /* There was already a pair of the form (key --> *). */ |
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| 215 | |
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| 216 | /*adjusting the weight of the cache */ |
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| 217 | ValueClass oldValue = *itOldValue; |
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| 218 | _weight += newWeight - *itOldWeights; |
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| 219 | |
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| 220 | /* overwriting old value by argument value */ |
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| 221 | itOldValue = _value.erase(itOldValue); |
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| 222 | itOldWeights = _weights.erase(itOldWeights); |
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| 223 | ValueClass myValueCopy = value; |
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| 224 | _value.insert(itOldValue, myValueCopy); |
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| 225 | _weights.insert(itOldWeights, newWeight); |
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| 226 | |
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| 227 | int oldIndexInRank = -1; |
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| 228 | /* oldIndexInRank is to be the position in _rank such that |
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| 229 | _rank[oldIndexInRank] == oldIndexInKey, i.e. |
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| 230 | _key[_rank[oldIndexInRank]] == key: */ |
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| 231 | list<int>::iterator itRank; |
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| 232 | k = 0; |
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| 233 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 234 | { |
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| 235 | if (*itRank == oldIndexInKey) |
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| 236 | { |
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| 237 | oldIndexInRank = k; |
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| 238 | } |
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| 239 | k++; |
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| 240 | } |
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| 241 | /* Although the key stays the same, the ranking of the (key --> value) |
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| 242 | pair may be completely different from before. Thus, we need to repair |
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| 243 | the entries of _rank: */ |
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| 244 | if (oldIndexInRank < newIndexInRank) |
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| 245 | { /* first insert, then erase */ |
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| 246 | k = 0; |
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| 247 | /* insert 'oldIndexInKey' at new position 'newIndexInRank': */ |
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| 248 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 249 | { |
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| 250 | if (k == newIndexInRank) break; |
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| 251 | k++; |
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| 252 | } |
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| 253 | _rank.insert(itRank, oldIndexInKey); /* note that this may also insert |
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| 254 | at position itRank == _rank.end(), |
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| 255 | i.e. when above loop did not |
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| 256 | terminate because of a 'break' |
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| 257 | statement */ |
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| 258 | k = 0; |
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| 259 | /* erase 'oldIndexInKey' at old position 'oldIndexInRank': */ |
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| 260 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 261 | { |
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| 262 | if (k == oldIndexInRank) |
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| 263 | { |
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| 264 | _rank.erase(itRank); |
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| 265 | break; |
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| 266 | } |
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| 267 | k++; |
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| 268 | } |
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| 269 | } |
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| 270 | else |
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| 271 | { /* oldIndexInRank >= newIndexInRank */ |
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| 272 | if (oldIndexInRank > newIndexInRank) |
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| 273 | { /* first erase, then insert */ |
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| 274 | k = 0; |
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| 275 | /* erase 'oldIndexInKey' at old position 'oldIndexInRank': */ |
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| 276 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 277 | { |
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| 278 | if (k == oldIndexInRank) |
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| 279 | { |
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| 280 | _rank.erase(itRank); |
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| 281 | break; |
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| 282 | } |
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| 283 | k++; |
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| 284 | } |
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| 285 | k = 0; |
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| 286 | /* insert 'oldIndexInKey' at new position 'newIndexInRank': */ |
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| 287 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 288 | { |
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| 289 | if (k == newIndexInRank) |
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| 290 | { |
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| 291 | _rank.insert(itRank, oldIndexInKey); |
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| 292 | break; |
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| 293 | } |
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| 294 | k++; |
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| 295 | } |
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| 296 | } |
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| 297 | } |
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| 298 | } |
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| 299 | else |
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| 300 | { |
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| 301 | /* There is no pair of the form (key --> *). We are about to insert |
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| 302 | a completely new (key, value)-pair. |
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| 303 | After this "else" branch, we shall have _key[newIndexInKey] = key; |
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| 304 | _value[newIndexInKey] = value. Note that, after the above computation, |
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| 305 | newIndexInKey contains the correct target position. |
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| 306 | Let's make room for the assignment |
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| 307 | _rank[newIndexInRank] := newIndexInKey: */ |
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| 308 | list<int>::iterator itRank; |
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| 309 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 310 | { |
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| 311 | if (newIndexInKey <= *itRank) |
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| 312 | { |
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| 313 | *itRank += 1; |
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| 314 | } |
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| 315 | } |
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| 316 | k = 0; |
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| 317 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 318 | { |
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| 319 | if (k == newIndexInRank) break; |
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| 320 | k++; |
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| 321 | } |
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| 322 | _rank.insert(itRank, newIndexInKey); |
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| 323 | /* let's insert new key and new value at index newIndexInKey: */ |
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| 324 | itValue = _value.begin(); |
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| 325 | typename list<int>::iterator itWeights = _weights.begin(); |
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| 326 | k = 0; |
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| 327 | for (itKey = _key.begin(); itKey != _key.end(); itKey++) |
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| 328 | { |
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| 329 | if (k == newIndexInKey) break; |
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| 330 | itValue++; |
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| 331 | itWeights++; |
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| 332 | k++; |
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| 333 | } |
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| 334 | KeyClass myKeyCopy = key; |
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| 335 | ValueClass myValueCopy = value; |
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| 336 | _key.insert(itKey, myKeyCopy); |
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| 337 | _value.insert(itValue, myValueCopy); |
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| 338 | _weights.insert(itWeights, newWeight); |
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| 339 | /* adjusting the total weight of the cache: */ |
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| 340 | _weight += newWeight; |
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| 341 | }; |
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| 342 | /* We may now have to shrink the cache: */ |
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| 343 | bool result = shrink(key); /* true iff shrinking deletes the |
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| 344 | new (key, value)-pair */ |
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| 345 | |
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| 346 | assert(_rank.size() == _key.size()); |
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| 347 | assert(_rank.size() == _value.size()); |
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| 348 | return !result; /* true iff the new (key --> value) pair is |
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| 349 | actually in the cache now */ |
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| 350 | } |
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| 351 | |
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| 352 | template<class KeyClass, class ValueClass> |
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| 353 | string Cache<KeyClass, ValueClass>::toString() const |
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| 354 | { |
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| 355 | char h[10]; |
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| 356 | string s = "Cache:"; |
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| 357 | s += "\n entries: "; |
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| 358 | sprintf(h, "%d", getNumberOfEntries()); s += h; |
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| 359 | s += " of at most "; |
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| 360 | sprintf(h, "%d", getMaxNumberOfEntries()); s += h; |
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| 361 | s += "\n weight: "; |
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| 362 | sprintf(h, "%d", getWeight()); s += h; |
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| 363 | s += " of at most "; |
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| 364 | sprintf(h, "%d", getMaxWeight()); s += h; |
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| 365 | if (_key.size() == 0) |
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| 366 | { |
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| 367 | s += "\n no pairs, i.e. cache is empty"; |
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| 368 | } |
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| 369 | else |
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| 370 | { |
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| 371 | int k = 1; |
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| 372 | s += "\n (key --> value) pairs in ascending order of keys:"; |
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| 373 | typename list<KeyClass>::const_iterator itKey; |
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| 374 | typename list<ValueClass>::const_iterator itValue = _value.begin(); |
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| 375 | for (itKey = _key.begin(); itKey != _key.end(); itKey++) |
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| 376 | { |
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| 377 | s += "\n "; |
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| 378 | sprintf(h, "%d", k); s += h; |
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| 379 | s += ". "; |
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| 380 | s += itKey->toString(); |
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| 381 | s += " --> "; |
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| 382 | s += itValue->toString(); |
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| 383 | itValue++; |
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| 384 | k++; |
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| 385 | } |
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| 386 | s += "\n (key --> value) pairs in descending order of ranks:"; |
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| 387 | list<int>::const_iterator itRank; |
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| 388 | int r = 1; |
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| 389 | for (itRank = _rank.begin(); itRank != _rank.end(); itRank++) |
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| 390 | { |
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| 391 | int index = *itRank; |
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| 392 | itValue = _value.begin(); |
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| 393 | k = 0; |
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| 394 | for (itKey = _key.begin(); itKey != _key.end(); itKey++) |
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| 395 | { |
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| 396 | if (k == index) break; |
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| 397 | k++; |
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| 398 | itValue++; |
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| 399 | } |
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| 400 | s += "\n "; |
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| 401 | sprintf(h, "%d", r); s += h; |
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| 402 | s += ". "; |
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| 403 | s += itKey->toString(); |
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| 404 | s += " --> "; |
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| 405 | s += itValue->toString(); |
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| 406 | r++; |
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| 407 | } |
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| 408 | } |
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| 409 | return s; |
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| 410 | } |
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| 411 | |
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| 412 | template<class KeyClass, class ValueClass> |
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| 413 | void Cache<KeyClass, ValueClass>::print() const |
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| 414 | { |
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| 415 | cout << this->toString(); |
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| 416 | } |
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| 417 | |
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| 418 | template<class KeyClass, class ValueClass> |
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| 419 | Cache<KeyClass, ValueClass>::Cache() { } |
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| 420 | |
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| 421 | template<class KeyClass, class ValueClass> |
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| 422 | Cache<KeyClass, ValueClass>::Cache(const Cache& c) |
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| 423 | { |
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| 424 | _rank = c._rank; |
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| 425 | _value = c._value; |
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| 426 | _weights = c._weights; |
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| 427 | _key = c._key; |
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| 428 | _weight = c._weight; |
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| 429 | _maxEntries = c._maxEntries; |
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| 430 | _maxWeight = c._maxWeight; |
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| 431 | } |
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| 432 | |
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| 433 | #endif |
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| 434 | /* CACHE_IMPLEMENTATION_H */ |
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