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484 lines
19 KiB
C++
484 lines
19 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 Mozilla Communicator client code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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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 of the GNU General Public License Version 2 or later (the "GPL"),
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* or 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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/**
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* nsDoubleHashtable.h is OBSOLETE. Use nsTHashtable or a derivative instead.
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*/
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#ifndef __nsDoubleHashtable_h__
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#define __nsDoubleHashtable_h__
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#include "pldhash.h"
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#include "nscore.h"
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#include "nsString.h"
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#include "nsHashKeys.h"
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/*
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* This file provides several major things to make PLDHashTable easier to use:
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* - hash class macros for you to define a hashtable
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* - default key classes to use as superclasses for your entries
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* - empty maps for string, cstring, int and void
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*/
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/*
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* USAGE
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*
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* To use nsDoubleHashtable macros
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* (1) Define an entry class
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* (2) Create the hash class
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* (3) Use the hash class
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*
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* EXAMPLE
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*
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* As an example, let's create a dictionary, a mapping from a string (the word)
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* to the pronunciation and definition of those words.
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*
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* (1) Define an entry class
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*
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* What we want here is an entry class that contains the word, the
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* pronunciation string, and the definition string. Since we have a string key
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* we can use the standard PLDHashStringEntry class as our base, it will handle
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* the key stuff for us automatically.
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*
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* #include "nsDoubleHashtable.h"
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*
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* // Do NOT ADD VIRTUAL METHODS INTO YOUR ENTRY. Everything will break.
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* // This is because of the 4-byte pointer C++ magically prepends onto your
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* // entry class. It interacts very unhappily with PLDHashTable.
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* class DictionaryEntry : public PLDHashStringEntry {
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* public:
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* DictionaryEntry(const void* aKey) : PLDHashStringEntry(aKey) { }
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* ~DictionaryEntry() { }
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* nsString mPronunciation;
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* nsString mDefinition;
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* }
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*
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* (2) Create the hash class
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*
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* The final hash class you will use in step 3 is defined by 2 macros.
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*
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* DECL_DHASH_WRAPPER(Dictionary, DictionaryEntry, const nsAString&)
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* DHASH_WRAPPER(Dictionary, DictionaryEntry, const nsAString&)
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*
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* (3) Use the hash class
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*
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* Here is a simple main() that might look up a string:
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*
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* int main(void) {
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* Dictionary d;
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* nsresult rv = d.Init(10);
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* if (NS_FAILED(rv)) return 1;
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*
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* // Put an entry
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* DictionaryEntry* a = d.AddEntry(NS_LITERAL_STRING("doomed"));
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* if (!a) return 1;
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* a->mDefinition.AssignLiteral("The state you get in when a Mozilla release is pending");
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* a->mPronunciation.AssignLiteral("doom-d");
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*
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* // Get the entry
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* DictionaryEntry* b = d.GetEntry(NS_LITERAL_STRING("doomed"));
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* printf("doomed: %s\n", NS_ConvertUTF16toUTF8(b->mDefinition).get());
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*
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* // Entries will be automagically cleaned up when the Dictionary object goes away
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* return 0;
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* }
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*
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*
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* BONUS POINTS
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*
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* You may wish to extend this class and add helper functions like
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* nsDependentString* GetDefinition(nsAString& aWord). For example:
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*
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* class MyDictionary : public Dictionary {
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* public:
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* MyDictionary() { }
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* // Make SURE you have a virtual destructor
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* virtual ~myDictionary() { }
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* nsDependentString* GetDefinition(const nsAString& aWord) {
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* DictionaryEntry* e = GetEntry(aWord);
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* if (e) {
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* // We're returning an nsDependentString here, callers need to delete it
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* // and it doesn't last long, but at least it doesn't create a copy
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* return new nsDependentString(e->mDefinition.get());
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* } else {
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* return nsnull;
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* }
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* }
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* nsresult PutDefinition(const nsAString& aWord,
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* const nsAString& aDefinition,
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* const nsAString& aPronunciation) {
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* DictionaryEntry* e = AddEntry(aWord);
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* if (!e) {
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* return NS_ERROR_OUT_OF_MEMORY;
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* }
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* e->mDefinition = aDefinition;
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* e->mPronunciation = aPronunciation;
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* return NS_OK;
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* }
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* }
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*/
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/*
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* ENTRY CLASS DEFINITION
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*
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* The simplifications of PLDHashTable all hinge upon the idea of an entry
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* class, which is a class you define, where you store the key and values that
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* you will place in each hash entry. You must define six methods for an entry
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* (the standard key classes, which you can extend from, define all of these
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* for you except the constructor and destructor):
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*
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* CONSTRUCTOR(const void* aKey)
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* When your entry is constructed it will only be given a pointer to the key.
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*
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* DESTRUCTOR
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* Called when the entry is destroyed (of course).
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*
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* PRBool MatchEntry(const void* aKey) - return true or false depending on
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* whether the key pointed to by aKey matches this entry
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*
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* static PLDHashNumber HashKey(const void* aKey) - get a hashcode based on the
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* key (must be the same every time for the same key, but does not have
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* to be unique)
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*
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* For a small hash that just does key->value, you will often just extend a
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* standard key class and put a value member into it, and have a destructor and
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* constructor--nothing else necessary.
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*
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* See the default key entry classes as example entry classes.
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*
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* NOTES:
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* - Do NOT ADD VIRTUAL METHODS INTO YOUR ENTRY. Everything will break.
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* This is because of the 4-byte pointer C++ magically prepends onto your
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* entry class. It interacts very unhappily with PLDHashTable.
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*/
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/*
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* PRIVATE HASHTABLE MACROS
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*
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* These internal macros can be used to declare the callbacks for an entry
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* class, but the wrapper class macros call these for you so don't call them.
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*/
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//
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// DHASH_CALLBACKS
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//
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// Define the hashtable callback functions. Do this in one place only, as you
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// will have redundant symbols otherwise.
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//
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// ENTRY_CLASS: the classname of the entry
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//
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#define DHASH_CALLBACKS(ENTRY_CLASS) \
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static PLDHashNumber \
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ENTRY_CLASS##HashKey(PLDHashTable* table, const void* key) \
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{ \
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return ENTRY_CLASS::HashKey(key); \
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} \
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static PRBool \
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ENTRY_CLASS##MatchEntry(PLDHashTable *table, const PLDHashEntryHdr *entry, \
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const void *key) \
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{ \
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const ENTRY_CLASS* e = static_cast<const ENTRY_CLASS*>(entry); \
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return e->MatchEntry(key); \
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} \
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static void \
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ENTRY_CLASS##ClearEntry(PLDHashTable *table, PLDHashEntryHdr *entry) \
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{ \
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ENTRY_CLASS* e = static_cast<ENTRY_CLASS *>(entry); \
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e->~ENTRY_CLASS(); \
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} \
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static PRBool \
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ENTRY_CLASS##InitEntry(PLDHashTable *table, PLDHashEntryHdr *entry, \
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const void *key) \
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{ \
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new (entry) ENTRY_CLASS(key); \
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return PR_TRUE; \
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}
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//
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// DHASH_INIT
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//
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// Initialize hashtable to a certain class.
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//
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// HASHTABLE: the name of the PLDHashTable variable
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// ENTRY_CLASS: the classname of the entry
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// NUM_INITIAL_ENTRIES: the number of entry slots the hashtable should start
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// with
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// RV: an nsresult variable to hold the outcome of the initialization.
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// Will be NS_ERROR_OUT_OF_MEMORY if failed, NS_OK otherwise.
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//
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#define DHASH_INIT(HASHTABLE,ENTRY_CLASS,NUM_INITIAL_ENTRIES,RV) \
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PR_BEGIN_MACRO \
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static PLDHashTableOps hash_table_ops = \
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{ \
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PL_DHashAllocTable, \
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PL_DHashFreeTable, \
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ENTRY_CLASS##HashKey, \
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ENTRY_CLASS##MatchEntry, \
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PL_DHashMoveEntryStub, \
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ENTRY_CLASS##ClearEntry, \
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PL_DHashFinalizeStub, \
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ENTRY_CLASS##InitEntry \
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}; \
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PRBool isLive = PL_DHashTableInit(&(HASHTABLE), \
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&hash_table_ops, nsnull, \
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sizeof(ENTRY_CLASS), \
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(NUM_INITIAL_ENTRIES)); \
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if (!isLive) { \
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(HASHTABLE).ops = nsnull; \
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RV = NS_ERROR_OUT_OF_MEMORY; \
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} else { \
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RV = NS_OK; \
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} \
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PR_END_MACRO
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/*
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* WRAPPER CLASS
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*
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* This class handles initialization and destruction of the hashtable
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* (you must call Init() yourself). It defines these functions:
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*
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* Init(aNumInitialEntries)
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* Initialize the hashtable. This must be called once, it is only separate
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* from the constructor so that you can get the return value. You should pass
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* in the number of entries you think the hashtable will typically hold (this
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* will be the amount of space allocated initially so that it will not have to
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* grow).
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*
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* ENTRY_CLASS* GetEntry(aKey):
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* Get the entry referenced by aKey and return a pointer to it. THIS IS A
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* TEMPORARY POINTER and is only guaranteed to exist until the next time you do
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* an operation on the hashtable. But you can safely use it until then.
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*
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* Returns nsnull if the entry is not found.
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*
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* ENTRY_CLASS* AddEntry(aKey):
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* Create a new, empty entry and return a pointer to it for you to fill values
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* into. THIS IS A TEMPORARY POINTER and is only guaranteed to exist until the
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* next time you do an operation on the hashtable. But you can safely fill it
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* in.
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*
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* Returns nsnull if the entry cannot be created (usually a low memory
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* constraint).
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*
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* void Remove(aKey)
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* Remove the entry referenced by aKey. If the entry does not exist, nothing
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* will happen.
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*
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*
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* DECL_DHASH_WRAPPER(CLASSNAME,ENTRY_CLASS,KEY_TYPE)
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*
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* Declare the hash class but do not define the functions.
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*
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* CLASSNAME: the name of the class to declare.
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* ENTRY_CLASS: the class of the entry struct.
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* KEY_TYPE: the name of the key type for GetEntry and AddEntry.
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*
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*
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* DHASH_WRAPPER(CLASSNAME,ENTRY_CLASS,KEY_TYPE)
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*
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* Define the functions for the hash class.
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*
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* CLASSNAME: the name of the class to declare.
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* ENTRY_CLASS: the class of the entry struct.
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* KEY_TYPE: the name of the key type for GetEntry and AddEntry.
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*
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*
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* CAVEATS:
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* - You may have only *one* wrapper class per entry class.
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*/
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#define DECL_DHASH_WRAPPER(CLASSNAME,ENTRY_CLASS,KEY_TYPE) \
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class DHASH_EXPORT CLASSNAME { \
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public: \
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CLASSNAME(); \
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~CLASSNAME(); \
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nsresult Init(PRUint32 aNumInitialEntries); \
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ENTRY_CLASS* GetEntry(const KEY_TYPE aKey); \
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ENTRY_CLASS* AddEntry(const KEY_TYPE aKey); \
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void Remove(const KEY_TYPE aKey); \
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PLDHashTable mHashTable; \
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};
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#define DHASH_WRAPPER(CLASSNAME,ENTRY_CLASS,KEY_TYPE) \
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DHASH_CALLBACKS(ENTRY_CLASS) \
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CLASSNAME::CLASSNAME() { \
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mHashTable.ops = nsnull; \
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} \
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CLASSNAME::~CLASSNAME() { \
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if (mHashTable.ops) { \
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PL_DHashTableFinish(&mHashTable); \
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} \
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} \
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nsresult CLASSNAME::Init(PRUint32 aNumInitialEntries) { \
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if (!mHashTable.ops) { \
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nsresult rv; \
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DHASH_INIT(mHashTable,ENTRY_CLASS,aNumInitialEntries,rv); \
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return rv; \
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} \
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return NS_OK; \
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} \
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ENTRY_CLASS* CLASSNAME::GetEntry(const KEY_TYPE aKey) { \
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ENTRY_CLASS* e = static_cast<ENTRY_CLASS*>( \
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PL_DHashTableOperate(&mHashTable, &aKey, \
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PL_DHASH_LOOKUP)); \
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return PL_DHASH_ENTRY_IS_BUSY(e) ? e : nsnull; \
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} \
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ENTRY_CLASS* CLASSNAME::AddEntry(const KEY_TYPE aKey) { \
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return static_cast<ENTRY_CLASS*>( \
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PL_DHashTableOperate(&mHashTable, &aKey, \
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PL_DHASH_ADD)); \
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} \
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void CLASSNAME::Remove(const KEY_TYPE aKey) { \
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PL_DHashTableOperate(&mHashTable, &aKey, PL_DHASH_REMOVE); \
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}
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/*
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* STANDARD KEY ENTRY CLASSES
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*
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* We have declared some standard key classes for you to make life a little
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* easier. These include string, int and void* keys. You can extend these
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* and add value data members to make a working hash entry class with your
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* values.
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*
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* PLDHashStringEntry: nsAString
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* PLDHashCStringEntry: nsACString
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* PLDHashInt32Entry: PRInt32
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* PLDHashVoidEntry: void*
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*
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* As a short example, if you want to make a class that maps int to string,
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* you could do:
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*
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* class MyIntStringEntry : public PLDHashInt32Entry
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* {
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* public:
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* MyIntStringEntry(const void* aKey) : PLDHashInt32Entry(aKey) { }
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* ~MyIntStringEntry() { };
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* nsString mMyStr;
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* };
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*
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* XXX It could be advisable (unless COW strings ever happens) to have a
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* PLDHashDependentStringEntry
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*/
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//
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// String-key entry
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//
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class NS_COM PLDHashStringEntry : public PLDHashEntryHdr
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{
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public:
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PLDHashStringEntry(const void* aKey) :
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mKey(*static_cast<const nsAString*>(aKey)) { }
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~PLDHashStringEntry() { }
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static PLDHashNumber HashKey(const void* key) {
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return HashString(*static_cast<const nsAString*>(key));
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}
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PRBool MatchEntry(const void* key) const {
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return static_cast<const nsAString*>(key)->Equals(mKey);
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}
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const nsString mKey;
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};
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//
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// CString-key entry
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//
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class NS_COM PLDHashCStringEntry : public PLDHashEntryHdr
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{
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public:
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PLDHashCStringEntry(const void* aKey) :
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mKey(*static_cast<const nsACString*>(aKey)) { }
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~PLDHashCStringEntry() { }
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static PLDHashNumber HashKey(const void* key) {
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return HashString(*static_cast<const nsACString*>(key));
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}
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PRBool MatchEntry(const void* key) const {
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return static_cast<const nsACString*>(key)->Equals(mKey);
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}
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const nsCString mKey;
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};
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//
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// Int-key entry
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//
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class NS_COM PLDHashInt32Entry : public PLDHashEntryHdr
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{
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public:
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PLDHashInt32Entry(const void* aKey) :
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mKey(*(static_cast<const PRInt32*>(aKey))) { }
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~PLDHashInt32Entry() { }
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static PLDHashNumber HashKey(const void* key) {
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return *static_cast<const PRInt32*>(key);
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}
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PRBool MatchEntry(const void* key) const {
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return *(static_cast<const PRInt32*>(key)) == mKey;
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}
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const PRInt32 mKey;
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};
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//
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// Void-key entry
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//
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class NS_COM PLDHashVoidEntry : public PLDHashEntryHdr
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{
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public:
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PLDHashVoidEntry(const void* aKey) :
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mKey(*(const void**)aKey) { }
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~PLDHashVoidEntry() { }
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static PLDHashNumber HashKey(const void* key) {
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return PLDHashNumber(NS_PTR_TO_INT32(*(const void**)key)) >> 2;
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}
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PRBool MatchEntry(const void* key) const {
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return *(const void**)key == mKey;
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}
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const void* mKey;
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};
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#define DHASH_EXPORT
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#endif
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