gecko-dev/xpcom/ds/nsCheapSets.h

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/* -*- 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) 1998
* 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 ***** */
#ifndef __nsCheapSets_h__
#define __nsCheapSets_h__
#include "nsHashSets.h"
/**
* A string set that takes up minimal size when there are 0 or 1 strings in the
* set. Use for cases where sizes of 0 and 1 are even slightly common.
*/
class NS_COM nsCheapStringSet {
public:
nsCheapStringSet() : mValOrHash(nsnull)
{
}
~nsCheapStringSet();
/**
* Put a string into the set
* @param aVal the value to put in
*/
nsresult Put(const nsAString& aVal);
/**
* Remove a string from the set
* @param aVal the string to remove
*/
void Remove(const nsAString& aVal);
/**
* Check if the set contains a particular string
* @param aVal the string to check for
* @return whether the string is in the set
*/
PRBool Contains(const nsAString& aVal)
{
nsStringHashSet* set = GetHash();
// Check the value from the hash if the hash is there
if (set) {
return set->Contains(aVal);
}
// Check whether the value is equal to the string if the string is there
nsAString* str = GetStr();
return str && str->Equals(aVal);
}
private:
typedef PRUword PtrBits;
/** Get the hash pointer (or null if we're not a hash) */
nsStringHashSet* GetHash()
{
return (PtrBits(mValOrHash) & 0x1) ? nsnull : (nsStringHashSet*)mValOrHash;
}
/** Find out whether it is a string */
nsAString* GetStr()
{
return (PtrBits(mValOrHash) & 0x1)
? (nsAString*)(PtrBits(mValOrHash) & ~0x1)
: nsnull;
}
/** Set the single string */
nsresult SetStr(const nsAString& aVal)
{
nsString* str = new nsString(aVal);
if (!str) {
return NS_ERROR_OUT_OF_MEMORY;
}
mValOrHash = (nsAString*)(PtrBits(str) | 0x1);
return NS_OK;
}
/** Initialize the hash */
nsresult InitHash(nsStringHashSet** aSet);
private:
/** A hash or string ptr, depending on the lower bit (0=hash, 1=string) */
void* mValOrHash;
};
/**
* An integer set that takes up only 4 bytes when there are 0 or 1 integers
* in the set. Use for cases where sizes of 0 and 1 are even slightly common.
*/
class NS_COM nsCheapInt32Set {
public:
nsCheapInt32Set() : mValOrHash(nsnull)
{
}
~nsCheapInt32Set();
/**
* Put an int into the set
*/
nsresult Put(PRInt32 aVal);
/**
* Remove a int from the set
* @param aVal the int to remove
*/
void Remove(PRInt32 aVal);
/**
* Check if the set contains a particular int
* @param aVal the int to check for
* @return whether the int is in the set
*/
PRBool Contains(PRInt32 aVal)
{
nsInt32HashSet* set = GetHash();
if (set) {
return set->Contains(aVal);
}
if (IsInt()) {
return GetInt() == aVal;
}
return PR_FALSE;
}
private:
typedef PRUword PtrBits;
/** Get the hash pointer (or null if we're not a hash) */
nsInt32HashSet* GetHash()
{
return PtrBits(mValOrHash) & 0x1 ? nsnull : (nsInt32HashSet*)mValOrHash;
}
/** Find out whether it is an integer */
PRBool IsInt()
{
return !!(PtrBits(mValOrHash) & 0x1);
}
/** Get the single integer */
PRInt32 GetInt()
{
return PtrBits(mValOrHash) >> 1;
}
/** Set the single integer */
void SetInt(PRInt32 aInt)
{
mValOrHash = (void*)((aInt << 1) | 0x1);
}
/** Create the hash and initialize */
nsresult InitHash(nsInt32HashSet** aSet);
private:
/** A hash or int, depending on the lower bit (0=hash, 1=int) */
void* mValOrHash;
};
/**
* XXX We may want an nsCheapVoidSet and nsCheapCStringSet at some point
*/
#endif