gecko/xpcom/ds/nsDoubleHashtable.h
2011-08-18 15:46:39 +02:00

484 lines
19 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Communicator client code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2002
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/**
* nsDoubleHashtable.h is OBSOLETE. Use nsTHashtable or a derivative instead.
*/
#ifndef __nsDoubleHashtable_h__
#define __nsDoubleHashtable_h__
#include "pldhash.h"
#include "nscore.h"
#include "nsString.h"
#include "nsHashKeys.h"
/*
* This file provides several major things to make PLDHashTable easier to use:
* - hash class macros for you to define a hashtable
* - default key classes to use as superclasses for your entries
* - empty maps for string, cstring, int and void
*/
/*
* USAGE
*
* To use nsDoubleHashtable macros
* (1) Define an entry class
* (2) Create the hash class
* (3) Use the hash class
*
* EXAMPLE
*
* As an example, let's create a dictionary, a mapping from a string (the word)
* to the pronunciation and definition of those words.
*
* (1) Define an entry class
*
* What we want here is an entry class that contains the word, the
* pronunciation string, and the definition string. Since we have a string key
* we can use the standard PLDHashStringEntry class as our base, it will handle
* the key stuff for us automatically.
*
* #include "nsDoubleHashtable.h"
*
* // Do NOT ADD VIRTUAL METHODS INTO YOUR ENTRY. Everything will break.
* // This is because of the 4-byte pointer C++ magically prepends onto your
* // entry class. It interacts very unhappily with PLDHashTable.
* class DictionaryEntry : public PLDHashStringEntry {
* public:
* DictionaryEntry(const void* aKey) : PLDHashStringEntry(aKey) { }
* ~DictionaryEntry() { }
* nsString mPronunciation;
* nsString mDefinition;
* }
*
* (2) Create the hash class
*
* The final hash class you will use in step 3 is defined by 2 macros.
*
* DECL_DHASH_WRAPPER(Dictionary, DictionaryEntry, const nsAString&)
* DHASH_WRAPPER(Dictionary, DictionaryEntry, const nsAString&)
*
* (3) Use the hash class
*
* Here is a simple main() that might look up a string:
*
* int main(void) {
* Dictionary d;
* nsresult rv = d.Init(10);
* if (NS_FAILED(rv)) return 1;
*
* // Put an entry
* DictionaryEntry* a = d.AddEntry(NS_LITERAL_STRING("doomed"));
* if (!a) return 1;
* a->mDefinition.AssignLiteral("The state you get in when a Mozilla release is pending");
* a->mPronunciation.AssignLiteral("doom-d");
*
* // Get the entry
* DictionaryEntry* b = d.GetEntry(NS_LITERAL_STRING("doomed"));
* printf("doomed: %s\n", NS_ConvertUTF16toUTF8(b->mDefinition).get());
*
* // Entries will be automagically cleaned up when the Dictionary object goes away
* return 0;
* }
*
*
* BONUS POINTS
*
* You may wish to extend this class and add helper functions like
* nsDependentString* GetDefinition(nsAString& aWord). For example:
*
* class MyDictionary : public Dictionary {
* public:
* MyDictionary() { }
* // Make SURE you have a virtual destructor
* virtual ~myDictionary() { }
* nsDependentString* GetDefinition(const nsAString& aWord) {
* DictionaryEntry* e = GetEntry(aWord);
* if (e) {
* // We're returning an nsDependentString here, callers need to delete it
* // and it doesn't last long, but at least it doesn't create a copy
* return new nsDependentString(e->mDefinition.get());
* } else {
* return nsnull;
* }
* }
* nsresult PutDefinition(const nsAString& aWord,
* const nsAString& aDefinition,
* const nsAString& aPronunciation) {
* DictionaryEntry* e = AddEntry(aWord);
* if (!e) {
* return NS_ERROR_OUT_OF_MEMORY;
* }
* e->mDefinition = aDefinition;
* e->mPronunciation = aPronunciation;
* return NS_OK;
* }
* }
*/
/*
* ENTRY CLASS DEFINITION
*
* The simplifications of PLDHashTable all hinge upon the idea of an entry
* class, which is a class you define, where you store the key and values that
* you will place in each hash entry. You must define six methods for an entry
* (the standard key classes, which you can extend from, define all of these
* for you except the constructor and destructor):
*
* CONSTRUCTOR(const void* aKey)
* When your entry is constructed it will only be given a pointer to the key.
*
* DESTRUCTOR
* Called when the entry is destroyed (of course).
*
* PRBool MatchEntry(const void* aKey) - return true or false depending on
* whether the key pointed to by aKey matches this entry
*
* static PLDHashNumber HashKey(const void* aKey) - get a hashcode based on the
* key (must be the same every time for the same key, but does not have
* to be unique)
*
* For a small hash that just does key->value, you will often just extend a
* standard key class and put a value member into it, and have a destructor and
* constructor--nothing else necessary.
*
* See the default key entry classes as example entry classes.
*
* NOTES:
* - Do NOT ADD VIRTUAL METHODS INTO YOUR ENTRY. Everything will break.
* This is because of the 4-byte pointer C++ magically prepends onto your
* entry class. It interacts very unhappily with PLDHashTable.
*/
/*
* PRIVATE HASHTABLE MACROS
*
* These internal macros can be used to declare the callbacks for an entry
* class, but the wrapper class macros call these for you so don't call them.
*/
//
// DHASH_CALLBACKS
//
// Define the hashtable callback functions. Do this in one place only, as you
// will have redundant symbols otherwise.
//
// ENTRY_CLASS: the classname of the entry
//
#define DHASH_CALLBACKS(ENTRY_CLASS) \
static PLDHashNumber \
ENTRY_CLASS##HashKey(PLDHashTable* table, const void* key) \
{ \
return ENTRY_CLASS::HashKey(key); \
} \
static PRBool \
ENTRY_CLASS##MatchEntry(PLDHashTable *table, const PLDHashEntryHdr *entry, \
const void *key) \
{ \
const ENTRY_CLASS* e = static_cast<const ENTRY_CLASS*>(entry); \
return e->MatchEntry(key); \
} \
static void \
ENTRY_CLASS##ClearEntry(PLDHashTable *table, PLDHashEntryHdr *entry) \
{ \
ENTRY_CLASS* e = static_cast<ENTRY_CLASS *>(entry); \
e->~ENTRY_CLASS(); \
} \
static PRBool \
ENTRY_CLASS##InitEntry(PLDHashTable *table, PLDHashEntryHdr *entry, \
const void *key) \
{ \
new (entry) ENTRY_CLASS(key); \
return PR_TRUE; \
}
//
// DHASH_INIT
//
// Initialize hashtable to a certain class.
//
// HASHTABLE: the name of the PLDHashTable variable
// ENTRY_CLASS: the classname of the entry
// NUM_INITIAL_ENTRIES: the number of entry slots the hashtable should start
// with
// RV: an nsresult variable to hold the outcome of the initialization.
// Will be NS_ERROR_OUT_OF_MEMORY if failed, NS_OK otherwise.
//
#define DHASH_INIT(HASHTABLE,ENTRY_CLASS,NUM_INITIAL_ENTRIES,RV) \
PR_BEGIN_MACRO \
static PLDHashTableOps hash_table_ops = \
{ \
PL_DHashAllocTable, \
PL_DHashFreeTable, \
ENTRY_CLASS##HashKey, \
ENTRY_CLASS##MatchEntry, \
PL_DHashMoveEntryStub, \
ENTRY_CLASS##ClearEntry, \
PL_DHashFinalizeStub, \
ENTRY_CLASS##InitEntry \
}; \
PRBool isLive = PL_DHashTableInit(&(HASHTABLE), \
&hash_table_ops, nsnull, \
sizeof(ENTRY_CLASS), \
(NUM_INITIAL_ENTRIES)); \
if (!isLive) { \
(HASHTABLE).ops = nsnull; \
RV = NS_ERROR_OUT_OF_MEMORY; \
} else { \
RV = NS_OK; \
} \
PR_END_MACRO
/*
* WRAPPER CLASS
*
* This class handles initialization and destruction of the hashtable
* (you must call Init() yourself). It defines these functions:
*
* Init(aNumInitialEntries)
* Initialize the hashtable. This must be called once, it is only separate
* from the constructor so that you can get the return value. You should pass
* in the number of entries you think the hashtable will typically hold (this
* will be the amount of space allocated initially so that it will not have to
* grow).
*
* ENTRY_CLASS* GetEntry(aKey):
* Get the entry referenced by aKey and return a pointer to it. THIS IS A
* TEMPORARY POINTER and is only guaranteed to exist until the next time you do
* an operation on the hashtable. But you can safely use it until then.
*
* Returns nsnull if the entry is not found.
*
* ENTRY_CLASS* AddEntry(aKey):
* Create a new, empty entry and return a pointer to it for you to fill values
* into. THIS IS A TEMPORARY POINTER and is only guaranteed to exist until the
* next time you do an operation on the hashtable. But you can safely fill it
* in.
*
* Returns nsnull if the entry cannot be created (usually a low memory
* constraint).
*
* void Remove(aKey)
* Remove the entry referenced by aKey. If the entry does not exist, nothing
* will happen.
*
*
* DECL_DHASH_WRAPPER(CLASSNAME,ENTRY_CLASS,KEY_TYPE)
*
* Declare the hash class but do not define the functions.
*
* CLASSNAME: the name of the class to declare.
* ENTRY_CLASS: the class of the entry struct.
* KEY_TYPE: the name of the key type for GetEntry and AddEntry.
*
*
* DHASH_WRAPPER(CLASSNAME,ENTRY_CLASS,KEY_TYPE)
*
* Define the functions for the hash class.
*
* CLASSNAME: the name of the class to declare.
* ENTRY_CLASS: the class of the entry struct.
* KEY_TYPE: the name of the key type for GetEntry and AddEntry.
*
*
* CAVEATS:
* - You may have only *one* wrapper class per entry class.
*/
#define DECL_DHASH_WRAPPER(CLASSNAME,ENTRY_CLASS,KEY_TYPE) \
class DHASH_EXPORT CLASSNAME { \
public: \
CLASSNAME(); \
~CLASSNAME(); \
nsresult Init(PRUint32 aNumInitialEntries); \
ENTRY_CLASS* GetEntry(const KEY_TYPE aKey); \
ENTRY_CLASS* AddEntry(const KEY_TYPE aKey); \
void Remove(const KEY_TYPE aKey); \
PLDHashTable mHashTable; \
};
#define DHASH_WRAPPER(CLASSNAME,ENTRY_CLASS,KEY_TYPE) \
DHASH_CALLBACKS(ENTRY_CLASS) \
CLASSNAME::CLASSNAME() { \
mHashTable.ops = nsnull; \
} \
CLASSNAME::~CLASSNAME() { \
if (mHashTable.ops) { \
PL_DHashTableFinish(&mHashTable); \
} \
} \
nsresult CLASSNAME::Init(PRUint32 aNumInitialEntries) { \
if (!mHashTable.ops) { \
nsresult rv; \
DHASH_INIT(mHashTable,ENTRY_CLASS,aNumInitialEntries,rv); \
return rv; \
} \
return NS_OK; \
} \
ENTRY_CLASS* CLASSNAME::GetEntry(const KEY_TYPE aKey) { \
ENTRY_CLASS* e = static_cast<ENTRY_CLASS*>( \
PL_DHashTableOperate(&mHashTable, &aKey, \
PL_DHASH_LOOKUP)); \
return PL_DHASH_ENTRY_IS_BUSY(e) ? e : nsnull; \
} \
ENTRY_CLASS* CLASSNAME::AddEntry(const KEY_TYPE aKey) { \
return static_cast<ENTRY_CLASS*>( \
PL_DHashTableOperate(&mHashTable, &aKey, \
PL_DHASH_ADD)); \
} \
void CLASSNAME::Remove(const KEY_TYPE aKey) { \
PL_DHashTableOperate(&mHashTable, &aKey, PL_DHASH_REMOVE); \
}
/*
* STANDARD KEY ENTRY CLASSES
*
* We have declared some standard key classes for you to make life a little
* easier. These include string, int and void* keys. You can extend these
* and add value data members to make a working hash entry class with your
* values.
*
* PLDHashStringEntry: nsAString
* PLDHashCStringEntry: nsACString
* PLDHashInt32Entry: PRInt32
* PLDHashVoidEntry: void*
*
* As a short example, if you want to make a class that maps int to string,
* you could do:
*
* class MyIntStringEntry : public PLDHashInt32Entry
* {
* public:
* MyIntStringEntry(const void* aKey) : PLDHashInt32Entry(aKey) { }
* ~MyIntStringEntry() { };
* nsString mMyStr;
* };
*
* XXX It could be advisable (unless COW strings ever happens) to have a
* PLDHashDependentStringEntry
*/
//
// String-key entry
//
class PLDHashStringEntry : public PLDHashEntryHdr
{
public:
PLDHashStringEntry(const void* aKey) :
mKey(*static_cast<const nsAString*>(aKey)) { }
~PLDHashStringEntry() { }
static PLDHashNumber HashKey(const void* key) {
return HashString(*static_cast<const nsAString*>(key));
}
PRBool MatchEntry(const void* key) const {
return static_cast<const nsAString*>(key)->Equals(mKey);
}
const nsString mKey;
};
//
// CString-key entry
//
class PLDHashCStringEntry : public PLDHashEntryHdr
{
public:
PLDHashCStringEntry(const void* aKey) :
mKey(*static_cast<const nsACString*>(aKey)) { }
~PLDHashCStringEntry() { }
static PLDHashNumber HashKey(const void* key) {
return HashString(*static_cast<const nsACString*>(key));
}
PRBool MatchEntry(const void* key) const {
return static_cast<const nsACString*>(key)->Equals(mKey);
}
const nsCString mKey;
};
//
// Int-key entry
//
class PLDHashInt32Entry : public PLDHashEntryHdr
{
public:
PLDHashInt32Entry(const void* aKey) :
mKey(*(static_cast<const PRInt32*>(aKey))) { }
~PLDHashInt32Entry() { }
static PLDHashNumber HashKey(const void* key) {
return *static_cast<const PRInt32*>(key);
}
PRBool MatchEntry(const void* key) const {
return *(static_cast<const PRInt32*>(key)) == mKey;
}
const PRInt32 mKey;
};
//
// Void-key entry
//
class PLDHashVoidEntry : public PLDHashEntryHdr
{
public:
PLDHashVoidEntry(const void* aKey) :
mKey(*(const void**)aKey) { }
~PLDHashVoidEntry() { }
static PLDHashNumber HashKey(const void* key) {
return PLDHashNumber(NS_PTR_TO_INT32(*(const void**)key)) >> 2;
}
PRBool MatchEntry(const void* key) const {
return *(const void**)key == mKey;
}
const void* mKey;
};
#define DHASH_EXPORT
#endif