105 lines
3.4 KiB
C++
Executable File
105 lines
3.4 KiB
C++
Executable File
/**********
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This library is free software; you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License as published by the
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Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)
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This library is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
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more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this library; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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**********/
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// Copyright (c) 1996-2015 Live Networks, Inc. All rights reserved.
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// Basic Hash Table implementation
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// C++ header
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#ifndef _BASIC_HASH_TABLE_HH
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#define _BASIC_HASH_TABLE_HH
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#ifndef _HASH_TABLE_HH
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#include "HashTable.hh"
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#endif
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#ifndef _NET_COMMON_H
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#include <NetCommon.h> // to ensure that "uintptr_t" is defined
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#endif
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// A simple hash table implementation, inspired by the hash table
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// implementation used in Tcl 7.6: <http://www.tcl.tk/>
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#define SMALL_HASH_TABLE_SIZE 4
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class BasicHashTable: public HashTable {
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private:
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class TableEntry; // forward
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public:
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BasicHashTable(int keyType);
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virtual ~BasicHashTable();
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// Used to iterate through the members of the table:
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class Iterator; friend class Iterator; // to make Sun's C++ compiler happy
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class Iterator: public HashTable::Iterator {
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public:
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Iterator(BasicHashTable const& table);
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private: // implementation of inherited pure virtual functions
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void* next(char const*& key); // returns 0 if none
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private:
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BasicHashTable const& fTable;
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unsigned fNextIndex; // index of next bucket to be enumerated after this
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TableEntry* fNextEntry; // next entry in the current bucket
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};
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private: // implementation of inherited pure virtual functions
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virtual void* Add(char const* key, void* value);
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// Returns the old value if different, otherwise 0
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virtual Boolean Remove(char const* key);
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virtual void* Lookup(char const* key) const;
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// Returns 0 if not found
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virtual unsigned numEntries() const;
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private:
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class TableEntry {
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public:
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TableEntry* fNext;
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char const* key;
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void* value;
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};
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TableEntry* lookupKey(char const* key, unsigned& index) const;
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// returns entry matching "key", or NULL if none
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Boolean keyMatches(char const* key1, char const* key2) const;
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// used to implement "lookupKey()"
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TableEntry* insertNewEntry(unsigned index, char const* key);
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// creates a new entry, and inserts it in the table
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void assignKey(TableEntry* entry, char const* key);
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// used to implement "insertNewEntry()"
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void deleteEntry(unsigned index, TableEntry* entry);
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void deleteKey(TableEntry* entry);
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// used to implement "deleteEntry()"
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void rebuild(); // rebuilds the table as its size increases
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unsigned hashIndexFromKey(char const* key) const;
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// used to implement many of the routines above
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unsigned randomIndex(uintptr_t i) const {
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return (unsigned)(((i*1103515245) >> fDownShift) & fMask);
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}
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private:
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TableEntry** fBuckets; // pointer to bucket array
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TableEntry* fStaticBuckets[SMALL_HASH_TABLE_SIZE];// used for small tables
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unsigned fNumBuckets, fNumEntries, fRebuildSize, fDownShift, fMask;
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int fKeyType;
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};
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#endif
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