1 // Copyright 2008 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #ifndef V8_HASHMAP_H_ 29 #define V8_HASHMAP_H_ 30 31 namespace v8 { 32 namespace internal { 33 34 35 // Allocator defines the memory allocator interface 36 // used by HashMap and implements a default allocator. 37 class Allocator BASE_EMBEDDED { 38 public: ~Allocator()39 virtual ~Allocator() {} New(size_t size)40 virtual void* New(size_t size) { return Malloced::New(size); } Delete(void * p)41 virtual void Delete(void* p) { Malloced::Delete(p); } 42 }; 43 44 45 class HashMap { 46 public: 47 static Allocator DefaultAllocator; 48 49 typedef bool (*MatchFun) (void* key1, void* key2); 50 51 // Dummy constructor. This constructor doesn't set up the hash 52 // map properly so don't use it unless you have good reason (e.g., 53 // you know that the HashMap will never be used). 54 HashMap(); 55 56 // initial_capacity is the size of the initial hash map; 57 // it must be a power of 2 (and thus must not be 0). 58 explicit HashMap(MatchFun match, 59 Allocator* allocator = &DefaultAllocator, 60 uint32_t initial_capacity = 8); 61 62 ~HashMap(); 63 64 // HashMap entries are (key, value, hash) triplets. 65 // Some clients may not need to use the value slot 66 // (e.g. implementers of sets, where the key is the value). 67 struct Entry { 68 void* key; 69 void* value; 70 uint32_t hash; // the full hash value for key 71 }; 72 73 // If an entry with matching key is found, Lookup() 74 // returns that entry. If no matching entry is found, 75 // but insert is set, a new entry is inserted with 76 // corresponding key, key hash, and NULL value. 77 // Otherwise, NULL is returned. 78 Entry* Lookup(void* key, uint32_t hash, bool insert); 79 80 // Removes the entry with matching key. 81 void Remove(void* key, uint32_t hash); 82 83 // Empties the hash map (occupancy() == 0). 84 void Clear(); 85 86 // The number of (non-empty) entries in the table. occupancy()87 uint32_t occupancy() const { return occupancy_; } 88 89 // The capacity of the table. The implementation 90 // makes sure that occupancy is at most 80% of 91 // the table capacity. capacity()92 uint32_t capacity() const { return capacity_; } 93 94 // Iteration 95 // 96 // for (Entry* p = map.Start(); p != NULL; p = map.Next(p)) { 97 // ... 98 // } 99 // 100 // If entries are inserted during iteration, the effect of 101 // calling Next() is undefined. 102 Entry* Start() const; 103 Entry* Next(Entry* p) const; 104 105 private: 106 Allocator* allocator_; 107 MatchFun match_; 108 Entry* map_; 109 uint32_t capacity_; 110 uint32_t occupancy_; 111 map_end()112 Entry* map_end() const { return map_ + capacity_; } 113 Entry* Probe(void* key, uint32_t hash); 114 void Initialize(uint32_t capacity); 115 void Resize(); 116 }; 117 118 119 } } // namespace v8::internal 120 121 #endif // V8_HASHMAP_H_ 122