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| | | /********** |
| | | This library is free software; you can redistribute it and/or modify it under |
| | | the terms of the GNU Lesser General Public License as published by the |
| | | Free Software Foundation; either version 3 of the License, or (at your |
| | | option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.) |
| | | |
| | | This library is distributed in the hope that it will be useful, but WITHOUT |
| | | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
| | | FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for |
| | | more details. |
| | | |
| | | You should have received a copy of the GNU Lesser General Public License |
| | | along with this library; if not, write to the Free Software Foundation, Inc., |
| | | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| | | **********/ |
| | | // Copyright (c) 1996-2017 Live Networks, Inc. All rights reserved. |
| | | // Basic Hash Table implementation |
| | | // C++ header |
| | | |
| | | #ifndef _BASIC_HASH_TABLE_HH |
| | | #define _BASIC_HASH_TABLE_HH |
| | | |
| | | #ifndef _HASH_TABLE_HH |
| | | #include "HashTable.hh" |
| | | #endif |
| | | #ifndef _NET_COMMON_H |
| | | #include <NetCommon.h> // to ensure that "uintptr_t" is defined |
| | | #endif |
| | | |
| | | // A simple hash table implementation, inspired by the hash table |
| | | // implementation used in Tcl 7.6: <http://www.tcl.tk/> |
| | | |
| | | #define SMALL_HASH_TABLE_SIZE 4 |
| | | |
| | | class BasicHashTable: public HashTable { |
| | | private: |
| | | class TableEntry; // forward |
| | | |
| | | public: |
| | | BasicHashTable(int keyType); |
| | | virtual ~BasicHashTable(); |
| | | |
| | | // Used to iterate through the members of the table: |
| | | class Iterator; friend class Iterator; // to make Sun's C++ compiler happy |
| | | class Iterator: public HashTable::Iterator { |
| | | public: |
| | | Iterator(BasicHashTable const& table); |
| | | |
| | | private: // implementation of inherited pure virtual functions |
| | | void* next(char const*& key); // returns 0 if none |
| | | |
| | | private: |
| | | BasicHashTable const& fTable; |
| | | unsigned fNextIndex; // index of next bucket to be enumerated after this |
| | | TableEntry* fNextEntry; // next entry in the current bucket |
| | | }; |
| | | |
| | | private: // implementation of inherited pure virtual functions |
| | | virtual void* Add(char const* key, void* value); |
| | | // Returns the old value if different, otherwise 0 |
| | | virtual Boolean Remove(char const* key); |
| | | virtual void* Lookup(char const* key) const; |
| | | // Returns 0 if not found |
| | | virtual unsigned numEntries() const; |
| | | |
| | | private: |
| | | class TableEntry { |
| | | public: |
| | | TableEntry* fNext; |
| | | char const* key; |
| | | void* value; |
| | | }; |
| | | |
| | | TableEntry* lookupKey(char const* key, unsigned& index) const; |
| | | // returns entry matching "key", or NULL if none |
| | | Boolean keyMatches(char const* key1, char const* key2) const; |
| | | // used to implement "lookupKey()" |
| | | |
| | | TableEntry* insertNewEntry(unsigned index, char const* key); |
| | | // creates a new entry, and inserts it in the table |
| | | void assignKey(TableEntry* entry, char const* key); |
| | | // used to implement "insertNewEntry()" |
| | | |
| | | void deleteEntry(unsigned index, TableEntry* entry); |
| | | void deleteKey(TableEntry* entry); |
| | | // used to implement "deleteEntry()" |
| | | |
| | | void rebuild(); // rebuilds the table as its size increases |
| | | |
| | | unsigned hashIndexFromKey(char const* key) const; |
| | | // used to implement many of the routines above |
| | | |
| | | unsigned randomIndex(uintptr_t i) const { |
| | | return (unsigned)(((i*1103515245) >> fDownShift) & fMask); |
| | | } |
| | | |
| | | private: |
| | | TableEntry** fBuckets; // pointer to bucket array |
| | | TableEntry* fStaticBuckets[SMALL_HASH_TABLE_SIZE];// used for small tables |
| | | unsigned fNumBuckets, fNumEntries, fRebuildSize, fDownShift, fMask; |
| | | int fKeyType; |
| | | }; |
| | | |
| | | #endif |