[2674] | 1 | /* |
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| 2 | * Licensed to the Apache Software Foundation (ASF) under one or more |
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| 3 | * contributor license agreements. See the NOTICE file distributed with |
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| 4 | * this work for additional information regarding copyright ownership. |
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| 5 | * The ASF licenses this file to You under the Apache License, Version 2.0 |
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| 6 | * (the "License"); you may not use this file except in compliance with |
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| 7 | * the License. You may obtain a copy of the License at |
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| 8 | * |
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| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 10 | * |
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| 11 | * Unless required by applicable law or agreed to in writing, software |
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| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 14 | * See the License for the specific language governing permissions and |
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| 15 | * limitations under the License. |
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| 16 | */ |
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| 17 | |
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| 18 | /* |
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| 19 | * $Id: StringPool.hpp 568078 2007-08-21 11:43:25Z amassari $ |
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| 20 | */ |
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| 21 | |
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| 22 | #if !defined(STRINGPOOL_HPP) |
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| 23 | #define STRINGPOOL_HPP |
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| 24 | |
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| 25 | #include <xercesc/util/RefHashTableOf.hpp> |
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| 26 | |
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| 27 | #include <xercesc/internal/XSerializable.hpp> |
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| 28 | |
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| 29 | XERCES_CPP_NAMESPACE_BEGIN |
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| 30 | |
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| 31 | // |
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| 32 | // This class implements a string pool, in which strings can be added and |
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| 33 | // given a unique id by which they can be refered. It has to provide fast |
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| 34 | // access both mapping from a string to its id and mapping from an id to |
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| 35 | // its string. This requires that it provide two separate data structures. |
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| 36 | // The map one is a hash table for quick storage and look up by name. The |
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| 37 | // other is an array ordered by unique id which maps to the element in the |
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| 38 | // hash table. |
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| 39 | // |
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| 40 | // This works because strings cannot be removed from the pool once added, |
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| 41 | // other than flushing it completely, and because ids are assigned |
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| 42 | // sequentially from 1. |
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| 43 | // |
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| 44 | class XMLUTIL_EXPORT XMLStringPool : public XSerializable, public XMemory |
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| 45 | { |
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| 46 | public : |
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| 47 | // ----------------------------------------------------------------------- |
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| 48 | // Constructors and Destructor |
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| 49 | // ----------------------------------------------------------------------- |
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| 50 | XMLStringPool |
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| 51 | ( |
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| 52 | const unsigned int modulus = 109 |
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| 53 | , MemoryManager* const manager = XMLPlatformUtils::fgMemoryManager |
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| 54 | ); |
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| 55 | virtual ~XMLStringPool(); |
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| 56 | |
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| 57 | |
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| 58 | // ----------------------------------------------------------------------- |
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| 59 | // Pool management methods |
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| 60 | // ----------------------------------------------------------------------- |
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| 61 | virtual unsigned int addOrFind(const XMLCh* const newString); |
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| 62 | virtual bool exists(const XMLCh* const newString) const; |
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| 63 | virtual bool exists(const unsigned int id) const; |
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| 64 | virtual void flushAll(); |
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| 65 | virtual unsigned int getId(const XMLCh* const toFind) const; |
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| 66 | virtual const XMLCh* getValueForId(const unsigned int id) const; |
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| 67 | virtual unsigned int getStringCount() const; |
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| 68 | |
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| 69 | /*** |
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| 70 | * Support for Serialization/De-serialization |
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| 71 | ***/ |
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| 72 | DECL_XSERIALIZABLE(XMLStringPool) |
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| 73 | |
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| 74 | XMLStringPool(MemoryManager* const manager); |
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| 75 | |
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| 76 | private : |
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| 77 | // ----------------------------------------------------------------------- |
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| 78 | // Private data types |
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| 79 | // ----------------------------------------------------------------------- |
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| 80 | struct PoolElem |
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| 81 | { |
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| 82 | unsigned int fId; |
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| 83 | XMLCh* fString; |
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| 84 | }; |
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| 85 | |
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| 86 | // ----------------------------------------------------------------------- |
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| 87 | // Unimplemented constructors and operators |
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| 88 | // ----------------------------------------------------------------------- |
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| 89 | XMLStringPool(const XMLStringPool&); |
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| 90 | XMLStringPool& operator=(const XMLStringPool&); |
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| 91 | |
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| 92 | |
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| 93 | // ----------------------------------------------------------------------- |
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| 94 | // Private helper methods |
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| 95 | // ----------------------------------------------------------------------- |
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| 96 | unsigned int addNewEntry(const XMLCh* const newString); |
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| 97 | |
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| 98 | |
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| 99 | // ----------------------------------------------------------------------- |
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| 100 | // Private data members |
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| 101 | // |
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| 102 | // fIdMap |
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| 103 | // This is an array of pointers to the pool elements. It is ordered |
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| 104 | // by unique id, so using an id to index it gives instant access to |
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| 105 | // the string of that id. This is grown as required. |
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| 106 | // |
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| 107 | // fHashTable |
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| 108 | // This is the hash table used to store and quickly access the |
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| 109 | // strings. |
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| 110 | // |
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| 111 | // fMapCapacity |
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| 112 | // The current capacity of the id map. When the current id hits this |
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| 113 | // value the map must must be expanded. |
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| 114 | // |
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| 115 | // ----------------------------------------------------------------------- |
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| 116 | MemoryManager* fMemoryManager; |
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| 117 | PoolElem** fIdMap; |
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| 118 | RefHashTableOf<PoolElem>* fHashTable; |
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| 119 | unsigned int fMapCapacity; |
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| 120 | |
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| 121 | protected: |
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| 122 | // protected data members |
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| 123 | // fCurId |
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| 124 | // This is the counter used to assign unique ids. It is just bumped |
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| 125 | // up one for each new string added. |
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| 126 | unsigned int fCurId; |
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| 127 | }; |
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| 128 | |
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| 129 | |
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| 130 | // Provid inline versions of some of the simple functions to improve performance. |
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| 131 | inline unsigned int XMLStringPool::addOrFind(const XMLCh* const newString) |
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| 132 | { |
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| 133 | PoolElem* elemToFind = fHashTable->get(newString); |
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| 134 | if (elemToFind) |
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| 135 | return elemToFind->fId; |
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| 136 | |
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| 137 | return addNewEntry(newString); |
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| 138 | } |
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| 139 | |
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| 140 | inline unsigned int XMLStringPool::getId(const XMLCh* const toFind) const |
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| 141 | { |
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| 142 | PoolElem* elemToFind = fHashTable->get(toFind); |
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| 143 | if (elemToFind) |
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| 144 | return elemToFind->fId; |
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| 145 | |
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| 146 | // Not found, so return zero, which is never a legal id |
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| 147 | return 0; |
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| 148 | } |
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| 149 | |
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| 150 | inline bool XMLStringPool::exists(const XMLCh* const newString) const |
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| 151 | { |
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| 152 | return fHashTable->containsKey(newString); |
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| 153 | } |
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| 154 | |
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| 155 | inline bool XMLStringPool::exists(const unsigned int id) const |
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| 156 | { |
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| 157 | if (!id || (id >= fCurId)) |
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| 158 | return false; |
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| 159 | |
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| 160 | return true; |
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| 161 | } |
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| 162 | |
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| 163 | inline const XMLCh* XMLStringPool::getValueForId(const unsigned int id) const |
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| 164 | { |
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| 165 | if (!id || (id >= fCurId)) |
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| 166 | ThrowXMLwithMemMgr(IllegalArgumentException, XMLExcepts::StrPool_IllegalId, fMemoryManager); |
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| 167 | |
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| 168 | // Just index the id map and return that element's string |
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| 169 | return fIdMap[id]->fString; |
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| 170 | } |
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| 171 | |
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| 172 | inline unsigned int XMLStringPool::getStringCount() const |
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| 173 | { |
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| 174 | return fCurId-1; |
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| 175 | } |
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| 176 | |
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| 177 | XERCES_CPP_NAMESPACE_END |
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| 178 | |
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| 179 | #endif |
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