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| 1 | |
| 2 /* | |
| 3 * Copyright 2010 Google Inc. | |
| 4 * | |
| 5 * Use of this source code is governed by a BSD-style license that can be | |
| 6 * found in the LICENSE file. | |
| 7 */ | |
| 8 | |
| 9 | |
| 10 | |
| 11 #ifndef GrTHashTable_DEFINED | |
| 12 #define GrTHashTable_DEFINED | |
| 13 | |
| 14 #include "GrTypes.h" | |
| 15 #include "SkTDArray.h" | |
| 16 | |
| 17 /** | |
| 18 * Key needs | |
| 19 * static bool Equals(const Entry&, const Key&); | |
| 20 * static bool LessThan(const Entry&, const Key&); | |
| 21 * static bool Equals(const Entry&, const Entry&); for SK_DEBUG if GrTHashT
able::validate() is called | |
| 22 * static bool LessThan(const Entry&, const Entry&); for SK_DEBUG if GrTHas
hTable::validate() is called | |
| 23 * uint32_t getHash() const; | |
| 24 * | |
| 25 * Allows duplicate key entries but on find you may get | |
| 26 * any of the duplicate entries returned. | |
| 27 */ | |
| 28 template <typename T, typename Key, size_t kHashBits> class GrTHashTable { | |
| 29 public: | |
| 30 GrTHashTable() { this->clearHash(); } | |
| 31 ~GrTHashTable() {} | |
| 32 | |
| 33 int count() const { return fSorted.count(); } | |
| 34 | |
| 35 struct Any { | |
| 36 // Return the first resource that matches the key. | |
| 37 bool operator()(const T*) const { return true; } | |
| 38 }; | |
| 39 | |
| 40 T* find(const Key& key) const { return this->find(key, Any()); } | |
| 41 template <typename Filter> T* find(const Key&, Filter filter) const; | |
| 42 | |
| 43 // return true if key was unique when inserted. | |
| 44 bool insert(const Key&, T*); | |
| 45 void remove(const Key&, const T*); | |
| 46 | |
| 47 void deleteAll(); | |
| 48 | |
| 49 #ifdef SK_DEBUG | |
| 50 void validate() const; | |
| 51 bool contains(T*) const; | |
| 52 #endif | |
| 53 | |
| 54 // testing | |
| 55 const SkTDArray<T*>& getArray() const { return fSorted; } | |
| 56 SkTDArray<T*>& getArray() { return fSorted; } | |
| 57 private: | |
| 58 void clearHash() { sk_bzero(fHash, sizeof(fHash)); } | |
| 59 | |
| 60 enum { | |
| 61 kHashCount = 1 << kHashBits, | |
| 62 kHashMask = kHashCount - 1 | |
| 63 }; | |
| 64 static unsigned hash2Index(intptr_t hash) { | |
| 65 #if 0 | |
| 66 if (sizeof(hash) == 8) { | |
| 67 hash ^= hash >> 32; | |
| 68 } | |
| 69 #endif | |
| 70 hash ^= hash >> 16; | |
| 71 if (kHashBits <= 8) { | |
| 72 hash ^= hash >> 8; | |
| 73 } | |
| 74 return hash & kHashMask; | |
| 75 } | |
| 76 | |
| 77 mutable T* fHash[kHashCount]; | |
| 78 SkTDArray<T*> fSorted; | |
| 79 | |
| 80 // search fSorted, and return the found index, or ~index of where it | |
| 81 // should be inserted | |
| 82 int searchArray(const Key&) const; | |
| 83 }; | |
| 84 | |
| 85 /////////////////////////////////////////////////////////////////////////////// | |
| 86 | |
| 87 template <typename T, typename Key, size_t kHashBits> | |
| 88 int GrTHashTable<T, Key, kHashBits>::searchArray(const Key& key) const { | |
| 89 int count = fSorted.count(); | |
| 90 if (0 == count) { | |
| 91 // we should insert it at 0 | |
| 92 return ~0; | |
| 93 } | |
| 94 | |
| 95 const T* const* array = fSorted.begin(); | |
| 96 int high = count - 1; | |
| 97 int low = 0; | |
| 98 while (high > low) { | |
| 99 int index = (low + high) >> 1; | |
| 100 if (Key::LessThan(*array[index], key)) { | |
| 101 low = index + 1; | |
| 102 } else { | |
| 103 high = index; | |
| 104 } | |
| 105 } | |
| 106 | |
| 107 // check if we found it | |
| 108 if (Key::Equals(*array[high], key)) { | |
| 109 // above search should have found the first occurrence if there | |
| 110 // are multiple. | |
| 111 SkASSERT(0 == high || Key::LessThan(*array[high - 1], key)); | |
| 112 return high; | |
| 113 } | |
| 114 | |
| 115 // now return the ~ of where we should insert it | |
| 116 if (Key::LessThan(*array[high], key)) { | |
| 117 high += 1; | |
| 118 } | |
| 119 return ~high; | |
| 120 } | |
| 121 | |
| 122 template <typename T, typename Key, size_t kHashBits> | |
| 123 template <typename Filter> | |
| 124 T* GrTHashTable<T, Key, kHashBits>::find(const Key& key, Filter filter) const { | |
| 125 | |
| 126 int hashIndex = hash2Index(key.getHash()); | |
| 127 T* elem = fHash[hashIndex]; | |
| 128 | |
| 129 if (NULL != elem && Key::Equals(*elem, key) && filter(elem)) { | |
| 130 return elem; | |
| 131 } | |
| 132 | |
| 133 // bsearch for the key in our sorted array | |
| 134 int index = this->searchArray(key); | |
| 135 if (index < 0) { | |
| 136 return NULL; | |
| 137 } | |
| 138 | |
| 139 const T* const* array = fSorted.begin(); | |
| 140 | |
| 141 // above search should have found the first occurrence if there | |
| 142 // are multiple. | |
| 143 SkASSERT(0 == index || Key::LessThan(*array[index - 1], key)); | |
| 144 | |
| 145 for ( ; index < count() && Key::Equals(*array[index], key); ++index) { | |
| 146 if (filter(fSorted[index])) { | |
| 147 // update the hash | |
| 148 fHash[hashIndex] = fSorted[index]; | |
| 149 return fSorted[index]; | |
| 150 } | |
| 151 } | |
| 152 | |
| 153 return NULL; | |
| 154 } | |
| 155 | |
| 156 template <typename T, typename Key, size_t kHashBits> | |
| 157 bool GrTHashTable<T, Key, kHashBits>::insert(const Key& key, T* elem) { | |
| 158 int index = this->searchArray(key); | |
| 159 bool first = index < 0; | |
| 160 if (first) { | |
| 161 // turn it into the actual index | |
| 162 index = ~index; | |
| 163 } | |
| 164 // add it to our array | |
| 165 *fSorted.insert(index) = elem; | |
| 166 // update our hash table (overwrites any dupe's position in the hash) | |
| 167 fHash[hash2Index(key.getHash())] = elem; | |
| 168 return first; | |
| 169 } | |
| 170 | |
| 171 template <typename T, typename Key, size_t kHashBits> | |
| 172 void GrTHashTable<T, Key, kHashBits>::remove(const Key& key, const T* elem) { | |
| 173 int index = hash2Index(key.getHash()); | |
| 174 if (fHash[index] == elem) { | |
| 175 fHash[index] = NULL; | |
| 176 } | |
| 177 | |
| 178 // remove from our sorted array | |
| 179 index = this->searchArray(key); | |
| 180 SkASSERT(index >= 0); | |
| 181 // if there are multiple matches searchArray will give us the first match | |
| 182 // march forward until we find elem. | |
| 183 while (elem != fSorted[index]) { | |
| 184 ++index; | |
| 185 SkASSERT(index < fSorted.count()); | |
| 186 } | |
| 187 SkASSERT(elem == fSorted[index]); | |
| 188 fSorted.remove(index); | |
| 189 } | |
| 190 | |
| 191 template <typename T, typename Key, size_t kHashBits> | |
| 192 void GrTHashTable<T, Key, kHashBits>::deleteAll() { | |
| 193 fSorted.deleteAll(); | |
| 194 this->clearHash(); | |
| 195 } | |
| 196 | |
| 197 #ifdef SK_DEBUG | |
| 198 template <typename T, typename Key, size_t kHashBits> | |
| 199 void GrTHashTable<T, Key, kHashBits>::validate() const { | |
| 200 int count = fSorted.count(); | |
| 201 for (int i = 1; i < count; i++) { | |
| 202 SkASSERT(Key::LessThan(*fSorted[i - 1], *fSorted[i]) || | |
| 203 Key::Equals(*fSorted[i - 1], *fSorted[i])); | |
| 204 } | |
| 205 } | |
| 206 | |
| 207 template <typename T, typename Key, size_t kHashBits> | |
| 208 bool GrTHashTable<T, Key, kHashBits>::contains(T* elem) const { | |
| 209 int index = fSorted.find(elem); | |
| 210 return index >= 0; | |
| 211 } | |
| 212 | |
| 213 #endif | |
| 214 | |
| 215 #endif | |
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