gecko/xpcom/glue/nsTObserverArray.h

213 lines
7.2 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.org code.
*
* The Initial Developer of the Original Code is Mozilla Corporation.
* Portions created by the Initial Developer are Copyright (C) 2006
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Jonas Sicking <jonas@sicking.cc> (Original Author)
*
* Alternatively, the contents of this file may be used under the terms of
* either 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 nsTObserverArray_h___
#define nsTObserverArray_h___
#include "nsVoidArray.h"
class NS_COM_GLUE nsTObserverArray_base {
public:
class Iterator_base;
friend class Iterator_base;
class Iterator_base {
protected:
friend class nsTObserverArray_base;
Iterator_base(PRInt32 aPosition, nsTObserverArray_base& aArray)
: mPosition(aPosition),
mNext(aArray.mIterators),
mArray(aArray) {
aArray.mIterators = this;
}
~Iterator_base() {
NS_ASSERTION(mArray.mIterators == this,
"Iterators must currently be destroyed in opposite order "
"from the construction order. It is suggested that you "
"simply put them on the stack");
mArray.mIterators = mNext;
}
// This function exists solely to avoid having to make the subclasses
// into friends of nsTObserverArray_base
void* GetSafeElementAt(PRInt32 aIndex) {
return mArray.mObservers.SafeElementAt(aIndex);
}
// The current position of the iterator. It's exact meaning differs
// depending on if the array is iterated forwards or backwards. See
// nsTObserverArray<T>::ForwardIterator and
// nsTObserverArray<T>::ReverseIterator
PRInt32 mPosition;
// The next iterator currently iterating the same array
Iterator_base* mNext;
// The array we're iterating
nsTObserverArray_base& mArray;
};
/**
* Removes all observers and collapses all iterators to the beginning of
* the array. The result is that forward iterators will see all elements
* in the array, and backward iterators will not see any more elements.
*/
void Clear();
protected:
nsTObserverArray_base()
: mIterators(nsnull) {
}
/**
* Adjusts iterators after an element has been inserted or removed
* from the array.
* @param modPos Position where elements were added or removed.
* @param adjustment -1 if an element was removed, 1 if an element was
* added.
*/
void AdjustIterators(PRInt32 aModPos, PRInt32 aAdjustment);
Iterator_base* mIterators;
nsVoidArray mObservers;
};
/**
* An array of observers. Like a normal array, but supports iterators that are
* stable even if the array is modified during iteration.
* The template parameter is the type of observer the array will hold pointers
* to.
*/
template<class T>
class nsTObserverArray : public nsTObserverArray_base {
public:
/**
* Adds an observer to the beginning of the array
* @param aObserver Observer to add
*/
PRBool PrependObserver(T* aObserver) {
NS_PRECONDITION(!Contains(aObserver),
"Don't prepend if the observer is already in the list");
PRBool res = mObservers.InsertElementAt(aObserver, 0);
if (res) {
AdjustIterators(0, 1);
}
return res;
}
/**
* Adds an observer to the end of the array unless it already exists in
* the array.
* @param aObserver Observer to add
* @return True on success, false otherwise
*/
PRBool AppendObserver(T* aObserver) {
return Contains(aObserver) || mObservers.AppendElement(aObserver);
}
/**
* Removes an observer from the array
* @param aObserver Observer to remove
* @return True if observer was found and removed, false otherwise
*/
PRBool RemoveObserver(T* aObserver) {
PRInt32 index = mObservers.IndexOf(aObserver);
if (index < 0) {
return PR_FALSE;
}
mObservers.RemoveElementAt(index);
AdjustIterators(index, -1);
return PR_TRUE;
}
PRBool Contains(T* aObserver) const {
return mObservers.IndexOf(aObserver) >= 0;
}
PRBool IsEmpty() const {
return mObservers.Count() == 0;
}
T* SafeObserverAt(PRInt32 aIndex) const {
return static_cast<T*>(mObservers.SafeElementAt(aIndex));
}
/**
* Iterators
*/
// Iterates the array forward from beginning to end.
// mPosition points to the element that will be returned on next call
// to GetNext
class ForwardIterator : public nsTObserverArray_base::Iterator_base {
public:
ForwardIterator(nsTObserverArray<T>& aArray)
: Iterator_base(0, aArray) {
}
/**
* Returns the next element and steps one step.
* Returns null if there are no more observers. Once null is returned
* the iterator becomes invalid and GetNext must not be called any more.
* @return The next observer.
*/
T* GetNext() {
return static_cast<T*>(GetSafeElementAt(mPosition++));
}
};
};
// XXXbz I wish I didn't have to pass in the observer type, but I
// don't see a way to get it out of array_.
#define NS_OBSERVER_ARRAY_NOTIFY_OBSERVERS(array_, obstype_, func_, params_) \
PR_BEGIN_MACRO \
nsTObserverArray<obstype_>::ForwardIterator iter_(array_); \
nsCOMPtr<obstype_> obs_; \
while ((obs_ = iter_.GetNext())) { \
obs_ -> func_ params_ ; \
} \
PR_END_MACRO
#endif // nsTObserverArray_h___