UsageEnvironment/include/HashTable.hh

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// Copyright (c) 1996-2008 Live Networks, Inc.  All rights reserved.
// Generic Hash Table
// C++ header

#ifndef _HASH_TABLE_HH
#define _HASH_TABLE_HH

#ifndef _BOOLEAN_HH
#include "Boolean.hh"
#endif

class HashTable {
    public:
        virtual ~HashTable();

        // The following must be implemented by a particular
        // implementation (subclass):
        static HashTable* create(int keyType);

        virtual void* Add(char const* key, void* value) = 0;
                // Returns the old value if different, otherwise 0
        virtual Boolean Remove(char const* key) = 0;
        virtual void* Lookup(char const* key) const = 0;
                // Returns 0 if not found
        virtual unsigned numEntries() const = 0;
        Boolean IsEmpty() const { return numEntries() == 0; }

        // Used to iterate through the members of the table:
        class Iterator {
            public:
                // The following must be implemented by a particular
                // implementation (subclass):
                static Iterator* create(HashTable& hashTable);

                virtual ~Iterator();

                virtual void* next(char const*& key) = 0; // returns 0 if none

            protected:
                Iterator(); // abstract base class
        };

        // A shortcut that can be used to successively remove each of
        // the entries in the table (e.g., so that their values can be
        // deleted, if they happen to be pointers to allocated memory).
        void* RemoveNext();

    protected:
        HashTable(); // abstract base class
};

// Warning: The following are deliberately the same as in
// Tcl's hash table implementation
int const STRING_HASH_KEYS = 0;
int const ONE_WORD_HASH_KEYS = 1;

#endif

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