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424 строки
13 KiB
C++
424 строки
13 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is C++ hashtable templates.
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*
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* The Initial Developer of the Original Code is
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* Benjamin Smedberg.
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* Portions created by the Initial Developer are Copyright (C) 2002
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef nsTHashtable_h__
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#define nsTHashtable_h__
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#include "nscore.h"
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#include "pldhash.h"
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#include "nsDebug.h"
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#include NEW_H
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// helper function for nsTHashtable::Clear()
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NS_COM_GLUE PLDHashOperator
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PL_DHashStubEnumRemove(PLDHashTable *table,
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PLDHashEntryHdr *entry,
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PRUint32 ordinal,
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void *userArg);
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/**
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* a base class for templated hashtables.
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*
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* Clients will rarely need to use this class directly. Check the derived
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* classes first, to see if they will meet your needs.
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*
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* @param EntryType the templated entry-type class that is managed by the
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* hashtable. <code>EntryType</code> must extend the following declaration,
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* and <strong>must not declare any virtual functions or derive from classes
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* with virtual functions.</strong> Any vtable pointer would break the
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* PLDHashTable code.
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*<pre> class EntryType : public PLDHashEntryHdr
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* {
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* public: or friend nsTHashtable<EntryType>;
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* // KeyType is what we use when Get()ing or Put()ing this entry
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* // this should either be a simple datatype (PRUint32, nsISupports*) or
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* // a const reference (const nsAString&)
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* typedef something KeyType;
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* // KeyTypePointer is the pointer-version of KeyType, because pldhash.h
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* // requires keys to cast to <code>const void*</code>
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* typedef const something* KeyTypePointer;
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*
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* EntryType(KeyTypePointer aKey);
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*
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* // the copy constructor must be defined, even if AllowMemMove() == true
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* // or you will cause link errors!
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* EntryType(const EntryType& aEnt);
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*
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* // the destructor must be defined... or you will cause link errors!
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* ~EntryType();
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*
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* // KeyEquals(): does this entry match this key?
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* PRBool KeyEquals(KeyTypePointer aKey) const;
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*
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* // KeyToPointer(): Convert KeyType to KeyTypePointer
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* static KeyTypePointer KeyToPointer(KeyType aKey);
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*
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* // HashKey(): calculate the hash number
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* static PLDHashNumber HashKey(KeyTypePointer aKey);
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*
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* // ALLOW_MEMMOVE can we move this class with memmove(), or do we have
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* // to use the copy constructor?
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* enum { ALLOW_MEMMOVE = PR_(TRUE or FALSE) };
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* }</pre>
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*
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* @see nsInterfaceHashtable
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* @see nsDataHashtable
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* @see nsClassHashtable
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* @author "Benjamin Smedberg <bsmedberg@covad.net>"
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*/
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template<class EntryType>
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class nsTHashtable
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{
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public:
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/**
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* A dummy constructor; you must call Init() before using this class.
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*/
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nsTHashtable();
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/**
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* destructor, cleans up and deallocates
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*/
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~nsTHashtable();
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/**
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* Initialize the table. This function must be called before any other
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* class operations. This can fail due to OOM conditions.
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* @param initSize the initial number of buckets in the hashtable, default 16
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* @return PR_TRUE if the class was initialized properly.
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*/
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PRBool Init(PRUint32 initSize = PL_DHASH_MIN_SIZE);
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/**
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* Check whether the table has been initialized. This can be useful for static hashtables.
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* @return the initialization state of the class.
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*/
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PRBool IsInitialized() const { return !!mTable.entrySize; }
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/**
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* Return the generation number for the table. This increments whenever
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* the table data items are moved.
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*/
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PRUint32 GetGeneration() const { return mTable.generation; }
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/**
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* KeyType is typedef'ed for ease of use.
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*/
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typedef typename EntryType::KeyType KeyType;
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/**
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* KeyTypePointer is typedef'ed for ease of use.
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*/
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typedef typename EntryType::KeyTypePointer KeyTypePointer;
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/**
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* Return the number of entries in the table.
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* @return number of entries
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*/
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PRUint32 Count() const { return mTable.entryCount; }
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/**
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* Get the entry associated with a key.
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* @param aKey the key to retrieve
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* @return pointer to the entry class, if the key exists; nsnull if the
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* key doesn't exist
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*/
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EntryType* GetEntry(KeyType aKey) const
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{
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NS_ASSERTION(mTable.entrySize, "nsTHashtable was not initialized properly.");
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EntryType* entry =
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reinterpret_cast<EntryType*>
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(PL_DHashTableOperate(
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const_cast<PLDHashTable*>(&mTable),
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EntryType::KeyToPointer(aKey),
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PL_DHASH_LOOKUP));
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return PL_DHASH_ENTRY_IS_BUSY(entry) ? entry : nsnull;
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}
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/**
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* Get the entry associated with a key, or create a new entry,
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* @param aKey the key to retrieve
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* @return pointer to the entry class retreived; nsnull only if memory
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can't be allocated
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*/
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EntryType* PutEntry(KeyType aKey)
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{
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NS_ASSERTION(mTable.entrySize, "nsTHashtable was not initialized properly.");
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return static_cast<EntryType*>
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(PL_DHashTableOperate(
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&mTable,
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EntryType::KeyToPointer(aKey),
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PL_DHASH_ADD));
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}
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/**
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* Remove the entry associated with a key.
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* @param aKey of the entry to remove
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*/
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void RemoveEntry(KeyType aKey)
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{
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NS_ASSERTION(mTable.entrySize, "nsTHashtable was not initialized properly.");
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PL_DHashTableOperate(&mTable,
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EntryType::KeyToPointer(aKey),
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PL_DHASH_REMOVE);
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}
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/**
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* Remove the entry associated with a key, but don't resize the hashtable.
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* This is a low-level method, and is not recommended unless you know what
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* you're doing and you need the extra performance. This method can be used
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* during enumeration, while RemoveEntry() cannot.
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* @param aEntry the entry-pointer to remove (obtained from GetEntry or
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* the enumerator
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*/
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void RawRemoveEntry(EntryType* aEntry)
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{
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PL_DHashTableRawRemove(&mTable, aEntry);
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}
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/**
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* client must provide an <code>Enumerator</code> function for
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* EnumerateEntries
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* @param aEntry the entry being enumerated
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* @param userArg passed unchanged from <code>EnumerateEntries</code>
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* @return combination of flags
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* @link PLDHashOperator::PL_DHASH_NEXT PL_DHASH_NEXT @endlink ,
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* @link PLDHashOperator::PL_DHASH_STOP PL_DHASH_STOP @endlink ,
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* @link PLDHashOperator::PL_DHASH_REMOVE PL_DHASH_REMOVE @endlink
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*/
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typedef PLDHashOperator (* Enumerator)(EntryType* aEntry, void* userArg);
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/**
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* Enumerate all the entries of the function.
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* @param enumFunc the <code>Enumerator</code> function to call
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* @param userArg a pointer to pass to the
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* <code>Enumerator</code> function
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* @return the number of entries actually enumerated
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*/
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PRUint32 EnumerateEntries(Enumerator enumFunc, void* userArg)
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{
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NS_ASSERTION(mTable.entrySize, "nsTHashtable was not initialized properly.");
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s_EnumArgs args = { enumFunc, userArg };
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return PL_DHashTableEnumerate(&mTable, s_EnumStub, &args);
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}
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/**
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* remove all entries, return hashtable to "pristine" state ;)
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*/
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void Clear()
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{
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NS_ASSERTION(mTable.entrySize, "nsTHashtable was not initialized properly.");
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PL_DHashTableEnumerate(&mTable, PL_DHashStubEnumRemove, nsnull);
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}
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protected:
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PLDHashTable mTable;
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static const void* s_GetKey(PLDHashTable *table,
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PLDHashEntryHdr *entry);
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static PLDHashNumber s_HashKey(PLDHashTable *table,
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const void *key);
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static PRBool s_MatchEntry(PLDHashTable *table,
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const PLDHashEntryHdr *entry,
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const void *key);
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static void s_CopyEntry(PLDHashTable *table,
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const PLDHashEntryHdr *from,
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PLDHashEntryHdr *to);
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static void s_ClearEntry(PLDHashTable *table,
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PLDHashEntryHdr *entry);
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static PRBool s_InitEntry(PLDHashTable *table,
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PLDHashEntryHdr *entry,
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const void *key);
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/**
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* passed internally during enumeration. Allocated on the stack.
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*
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* @param userFunc the Enumerator function passed to
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* EnumerateEntries by the client
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* @param userArg the userArg passed unaltered
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*/
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struct s_EnumArgs
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{
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Enumerator userFunc;
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void* userArg;
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};
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static PLDHashOperator s_EnumStub(PLDHashTable *table,
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PLDHashEntryHdr *entry,
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PRUint32 number,
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void *arg);
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private:
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// copy constructor, not implemented
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nsTHashtable(nsTHashtable<EntryType>& toCopy);
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// assignment operator, not implemented
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nsTHashtable<EntryType>& operator= (nsTHashtable<EntryType>& toEqual);
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};
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//
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// template definitions
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//
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template<class EntryType>
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nsTHashtable<EntryType>::nsTHashtable()
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{
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// entrySize is our "I'm initialized" indicator
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mTable.entrySize = 0;
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}
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template<class EntryType>
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nsTHashtable<EntryType>::~nsTHashtable()
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{
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if (mTable.entrySize)
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PL_DHashTableFinish(&mTable);
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}
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template<class EntryType>
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PRBool
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nsTHashtable<EntryType>::Init(PRUint32 initSize)
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{
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if (mTable.entrySize)
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{
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NS_ERROR("nsTHashtable::Init() should not be called twice.");
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return PR_TRUE;
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}
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static PLDHashTableOps sOps =
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{
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::PL_DHashAllocTable,
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::PL_DHashFreeTable,
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s_HashKey,
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s_MatchEntry,
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::PL_DHashMoveEntryStub,
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s_ClearEntry,
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::PL_DHashFinalizeStub,
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s_InitEntry
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};
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if (!EntryType::ALLOW_MEMMOVE)
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{
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sOps.moveEntry = s_CopyEntry;
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}
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if (!PL_DHashTableInit(&mTable, &sOps, nsnull, sizeof(EntryType), initSize))
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{
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// if failed, reset "flag"
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mTable.entrySize = 0;
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return PR_FALSE;
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}
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return PR_TRUE;
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}
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// static definitions
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template<class EntryType>
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PLDHashNumber
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nsTHashtable<EntryType>::s_HashKey(PLDHashTable *table,
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const void *key)
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{
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return EntryType::HashKey(reinterpret_cast<const KeyTypePointer>(key));
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}
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template<class EntryType>
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PRBool
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nsTHashtable<EntryType>::s_MatchEntry(PLDHashTable *table,
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const PLDHashEntryHdr *entry,
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const void *key)
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{
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return ((const EntryType*) entry)->KeyEquals(
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reinterpret_cast<const KeyTypePointer>(key));
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}
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template<class EntryType>
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void
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nsTHashtable<EntryType>::s_CopyEntry(PLDHashTable *table,
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const PLDHashEntryHdr *from,
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PLDHashEntryHdr *to)
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{
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EntryType* fromEntry =
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const_cast<EntryType*>(reinterpret_cast<const EntryType*>(from));
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new(to) EntryType(*fromEntry);
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fromEntry->~EntryType();
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}
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template<class EntryType>
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void
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nsTHashtable<EntryType>::s_ClearEntry(PLDHashTable *table,
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PLDHashEntryHdr *entry)
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{
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reinterpret_cast<EntryType*>(entry)->~EntryType();
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}
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template<class EntryType>
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PRBool
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nsTHashtable<EntryType>::s_InitEntry(PLDHashTable *table,
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PLDHashEntryHdr *entry,
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const void *key)
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{
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new(entry) EntryType(reinterpret_cast<KeyTypePointer>(key));
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return PR_TRUE;
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}
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template<class EntryType>
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PLDHashOperator
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nsTHashtable<EntryType>::s_EnumStub(PLDHashTable *table,
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PLDHashEntryHdr *entry,
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PRUint32 number,
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void *arg)
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{
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// dereferences the function-pointer to the user's enumeration function
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return (* reinterpret_cast<s_EnumArgs*>(arg)->userFunc)(
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reinterpret_cast<EntryType*>(entry),
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reinterpret_cast<s_EnumArgs*>(arg)->userArg);
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}
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#endif // nsTHashtable_h__
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